Author Topic: Designing and building my own .049 (Read 3934 times)

Dane Martin · « **on:** May 25, 2020, 08:12:05 PM »

So I believe I have the majority of the particulars figured out on building my own 1/2a engine. Yes, I already know it's entirely more work than it's worth. But this is the part of the hobby I enjoy.
So I have some questions for some of the more experienced machinists and tool and die makers. On a crank such as the Cox TeeDee, or reed valve cranks for this, the prop drive is a simple as pressing a special broach. But how do you get that type of spline on the tiny crank? Is it pressed through a die? For 1/2a, would I be better suited to simply make it tapered and taper the prop drive?

Dane Martin · « **Reply #1 on:** May 25, 2020, 09:00:32 PM »

Real basic rough draft but almost to scale. Here's most of the case. I think I want the backplate to bolt in like a wasp. It's kinda based on my favorite aspects of the wasp, VA, and CS engines. I love the CS case and liner, but it's kinda bulky. The VA is an unbelievable size case, but split. So it'll be in between that somehow. It will be a single exhaust port in an effort to keep the plane clean...

Dane Martin · « **Reply #2 on:** May 25, 2020, 09:55:45 PM »

Quote from: Motorman on May 25, 2020, 09:45:02 PM

Straight shaft with tapered collet is what I did. Do you make aluminum castings or will this be a billet case?

Billet case, at least on the first one. Let's see how it goes first. Might end up being a lot of hand work. But there's a few CNC companies here like Dolphin Machine who do aircraft stuff, if I get real hard up. They're really cool. When I made a small production run of yo-yo's, they did the halves.

pat king · « **Reply #3 on:** May 25, 2020, 10:12:04 PM »

Dane,
The "spline" on the little cranks (Cox) are nothing more than a fine straight knurl. The hole in the prop driver is very slightly larger than the pitch diameter of the knurl. The metal needs enough room to flow without trying to compress the metal of the prop driver when it is pressed on the crank. The crank should be machined from something pre-heat treated so it is tough but there is no heat treat distortion. I don't know if I have any Stressproof or ETD 150 the right size. If nothing else it can be turned from a 1/2" socket head cap screw. The socket heads are about 38 Rc, not hard to machine with carbide tools.

Pat

Trostle · « **Reply #4 on:** May 26, 2020, 12:58:52 AM »

Quote from: Dane Martin on May 25, 2020, 08:12:05 PM

So I believe I have the majority of the particulars figured out on building my own 1/2a engine. Yes, I already know it's entirely more work than it's worth. But this is the part of the hobby I enjoy.
So I have some questions for some of the more experienced machinists and tool and die makers. On a crank such as the Cox TeeDee, or reed valve cranks for this, the prop drive is a simple as pressing a special broach. But how do you get that type of spline on the tiny crank? Is it pressed through a die? For 1/2a, would I be better suited to simply make it tapered and taper the prop drive?

dane,

You probably do not need more inspiration since you seem really serious to do your own 1/2 engine. You might already be familiar with the work that Wayne Trivin did several years ago. Unfortunately, this master machinist/craftsman and really a good person left us several years ago far too soon. His work can still be seen at

http://www.nclra.org/TechTopics/WayneTrivin/MyHalfAEngines.html

There is more on how Wayne built his 1/2A engines at

http://www.nclra.org/TechTopics/WayneTrivin/HalfAEngine.html

I have one of his engines, the one like the one in the picture that has the venturi on the bottom of the crankshaft which does not show very well in the photo. Needless to say, it is in a prominent location in my display case.

The NCLRA racing people are maintaining Wayne's site at http://www.nclra.org/TechTopics/WayneTrivin/Actualindex.html . Maybe Bob Whitney can add more to this.

Good luck with your endeavor. Hope you keep us updated on your progress.

Keith

Oldenginerod · « **Reply #5 on:** May 26, 2020, 03:08:51 AM »

If you're not familiar with it, this site is well worth spending a few hours browsing through.
http://www.modelenginenews.org/index.html
Sadly, due to Ron Chernish's passing, the website is now only an archive, but all the info is still there. Adrian Duncan would be well worth talking to regarding your plans.

Rod.

Dane Martin · « **Reply #6 on:** May 26, 2020, 07:08:42 AM »

Quote from: Motorman on May 26, 2020, 06:50:36 AM

Will this have an iron piston or did you plan on chrome plating, do you have a source for high silicon aluminum?

How do you plan to hold the wrist pin in?

I'm thinking of a leaded steal for the cylinder liner. From reading up on Cox, that's what they used with the addition of the black oxide finish. I won't need that step.
I don't know if I'd be able to chrome and then hone for quite some time. That's a lot more stuff I don't have.

Looking at some of these 1/2a cranks I got laying around, there seems to be a lot of CNC ground ends. I'm thinking like we talked about, just have enough weight material to press the pin and hope for the best. But I'm reading through the material listed above. I may end up finding a better way

Dane Martin · « **Reply #7 on:** May 26, 2020, 07:12:37 AM »

Quote from: Trostle on May 26, 2020, 12:58:52 AM

dane,

You probably do not need more inspiration since you seem really serious to do your own 1/2 engine. You might already be familiar with the work that Wayne Trivin did several years ago.
Keith

There are so many helpful ideas in the link you've supplied. I remember seeing those a while back, but now it means a lot more! His engine is FAR more advanced than what I have in mind to start with, but a lot of his processes are very helpful.
Thank you very much Keith. Hopefully I'll see you again at a contest soon, and I'll bring whatever I come up with, with me!

Dane Martin · « **Reply #8 on:** May 26, 2020, 07:15:34 AM »

Quote from: Oldenginerod on May 26, 2020, 03:08:51 AM

If you're not familiar with it, this site is well worth spending a few hours browsing through.
http://www.modelenginenews.org/index.html
Sadly, due to Ron Chernish's passing, the website is now only an archive, but all the info is still there. Adrian Duncan would be well worth talking to regarding your plans.

Rod.

Rod,
Thank you for the resources. I'll read through and see if I can grab a few ideas! I'll also try and reach out to Adrian

Fredvon4 · « **Reply #9 on:** May 26, 2020, 08:11:50 AM »

Brother Dane

On CEF we have a 3D printer wizard...here is one of his way cool projects

https://www.coxengineforum.com/t14093-ball-bearings-you-say-3d-printed-bb-crankcase

Dane Martin · « **Reply #10 on:** May 26, 2020, 06:29:07 PM »

After work, I figured I'd try to make the crank for this CS .061 as practice. I wasn't successful but I learned a few things. I was cutting a grade 12.9 bolt, hrc 39-44. With the carbide tools I have, it was peeling material off like butter!
The reason it didn't work, was my bolt head selection. It left no material where the crank pin needed to be. I'll get some more bolts and try again. I think I figured enough out today to get it done!

Tim Wescott · « **Reply #11 on:** May 26, 2020, 06:54:21 PM »

I actually built all of the moving pieces for a Cox TD 09, plus the cylinder and head. It was crap. It wore out about 5000 revolutions after it was nicely broken in. But it did that wearing out under it's own power!

I learned a lot -- starting with the fact that just scrubbing the parts with Dawn and a toothbrush won't get all the lapping compound out of steel. I think I also learned not to use Mystery Metal in critical wear areas like pistons and cylinders.

It even got written up (without the bit about wearing out half a second after breaking in -- I sent in the pictures after the first run in-hand): http://modelenginenews.org/ed.2012.04.html

Based on all that -- I'd suggest finding some plans for an engine (there's a few "beginners engines" on modelenginenews.org) and just building to plan. Or grab a clapped-out engine and make some new bits (unless you've done that). Once you get that working, even if it's not strong enough to get the skin off of hot milk, then go and build an engine.

A bit of advice that I see over and over in Model Engine News is to start with an engine from about .15 to .35 displacement -- it's felt that's a good compromise between fiddly bits that are too small for the beginner to machine effectively, and materials cost.

These may be nice, too. You need to search out the download link: https://rclibrary.co.uk/title_details.asp?ID=2122, https://rclibrary.co.uk/title_details.asp?ID=2139

Tim Wescott · « **Reply #12 on:** May 26, 2020, 06:55:46 PM »

This forum will be helpful, although they'll start by telling you that the last engine a beginner wants to build is a two-stroke: https://www.homemodelenginemachinist.com/. They may be right -- but I don't want to build anything else!

Dane Martin · « **Reply #13 on:** May 26, 2020, 07:00:05 PM »

Quote from: Tim Wescott on May 26, 2020, 06:55:46 PM

This forum will be helpful, although they'll start by telling you that the last engine a beginner wants to build is a two-stroke: https://www.homemodelenginemachinist.com/. They may be right -- but I don't want to build anything else!

Very cool, I'll check it out.

The reason I've decided to build my own is that I've built almost any engine part at some point or another with varying degrees of success. I've just never built everything for one engine at once! I'm just more of a 1/2a guy than anything else. So that's pretty much the reason for the size.

bob whitney · « **Reply #14 on:** May 26, 2020, 11:53:35 PM »

Quote from: Oldenginerod on May 26, 2020, 03:08:51 AM

If you're not familiar with it, this site is well worth spending a few hours browsing through.
http://www.modelenginenews.org/index.html
Sadly, due to Ron Chernish's passing, the website is now only an archive, but all the info is still there. Adrian Duncan would be well worth talking to regarding your plans.

Rod.

I still have all of Wayne's engines except for the one Keith has Rad

Dave Hull · « **Reply #15 on:** May 27, 2020, 01:55:19 AM »

Danish,

I used 4140 for cranks. Machines just fine. Haven't gotten one to the running stage so I can't say anything about reliability.

A few different engines so far: A modified 1/2A Dragon from Clough plans while in High School; a custom 1/2A motorcycle engine based on a Cox piston and cut down cylinder (made into a liner); and a 2x-sized Morton radial.

My Dragon used a 2024 piston with a tiny compression ring. I bought 4130 tubing to make the liner, but the lathe available did not have sufficient stiffness to bore the ID.

I made a fixture to offset-machine the crank pins in place, instead of using a 4-jaw chuck. Used multiple setscrews to dog the part to the fixture. It worked fine.

I agree with Pat that straight knurling could produce the splines on Cox cranks. However, if you are not familiar with knurling, be aware that it puts much higher tool loads on a part than most other machining. I don't know for sure if Cox knurled or broached these pieces. You may need a specific sequence for success as well. For example, N-condition rough machine, knurl, heat treat, then grind.

Carbide inserts may be a bit bulky for smaller parts. Also, they often do not have positive rake, so the tool pressure is higher. Might make it tougher to prevent chatter and hold tolerance on small parts.

Sounds like you are having fun!

The Divot

Dane Martin · « **Reply #16 on:** May 27, 2020, 08:34:35 AM »

Thanks guys. Let's face it, if it doesn't work... it's still really fun. From my current plans, I'll only be using carbide on the crank itself. Everything else is "softer" metals.

McDivot, I think for this project I'm going to can the knurled crank. The taper seems to be the easiest way with what I currently have.
I'll upload pictures of my progress so far.

Tim, I'm also taking a cue from you about a wrist pin. I'd much rather do that than try to make a ball / socket!!

Tim Wescott · « **Reply #17 on:** May 27, 2020, 09:20:09 AM »

Quote from: Dane Martin on May 26, 2020, 07:00:05 PM

Very cool, I'll check it out.

The reason I've decided to build my own is that I've built almost any engine part at some point or another with varying degrees of success. I've just never built everything for one engine at once! I'm just more of a 1/2a guy than anything else. So that's pretty much the reason for the size.

Oh, well then -- carry on! And let us see the results!

Quote from: Dave Hull on May 27, 2020, 01:55:19 AM

... I agree with Pat that straight knurling could produce the splines on Cox cranks. However, if you are not familiar with knurling, be aware that it puts much higher tool loads on a part than most other machining. ...

You can get knurling tools that clamp the knurls onto the part, instead of pushing against them. So instead of the force coming from the cross-slide and being opposed by the part, the force of the top wheel is opposed by the bottom wheel.

It's said to be gentler on the parts and the lathe -- and certainly looks like it. I can't compare: I have a cheap lathe, so when I got knurling tooling I just got the clamp style.

Dane Martin · « **Reply #18 on:** May 27, 2020, 09:29:47 AM »

Quote from: Lauri Malila on May 27, 2020, 09:02:31 AM

I agree. Knurling is a cheap mass production method, not a precision connection. Especially if you need to dismantle it later. Conical & cylindrical holes are easy to make, just keep the cutter exactly on centerline.
I found some old pieces of Mahle #138 piston material (18% Si). If you want you can have them. It's just in a bit weird shape so you'd have to start with band saw:
L

I would definitely take that! From that scale there, it looks like I could make several pistons.

FLOYD CARTER · « **Reply #19 on:** May 27, 2020, 07:12:16 PM »

Dane. That sounds like a great project! Not a fun project, but a great one anyway.

I think the splined shaft on Cox engines is a poor idea. Great as long as you don't bugger up even the smallest part of it. Once a spline is even slightly damaged, it will then require massive number of Newtons to get it back on. Once wrecked, the drive washer is next to impossible to get back off. Others have suggested a taper shaft. Great. That can't get stuck.

pat king · « **Reply #20 on:** May 27, 2020, 09:10:21 PM »

If the knurl (spline) is damaged the engine is probably very badly damaged unless someone has gone "hammer mechanic" on the engine. The crank to prop driver is not desired to be a slip fit as would be with a spline. Cox made millions of engines with a zero clearance crank to prop driver fit. So, I don't think we can say that is a bad way to build a 1/2A engine.
You say a taper shaft can't get stuck, that is not true. Axles on Ford banjo housing rear ends were tapered. When we would shear an axle key on our coupe the hubs were almost impossible to remove. We were never able to get them off at the track. A puller would only break the hub, The only way to get the axle-hub apart was to remove them from the rear end and use a hydraulic press to remove the axle. They were not friction welded. The axles were hardened steel the hubs were cast iron.
Pat

Dane Martin · « **Reply #21 on:** May 27, 2020, 09:14:45 PM »

Quote from: FLOYD CARTER on May 27, 2020, 07:12:16 PM

Dane. That sounds like a great project! Not a fun project, but a great one anyway.

Thanks Floyd. I figured I've done enough case, muffler and engine reconditioning for friends and family I should just combine it all into making one.

So if everything goes according to plan, I cut a crank blank from this grade 8 bolt. I'm completely winging it here. Looks goofy, but I'm trying to make the excess of the crank part of its own offset fixture. I only have a 3 jaw on the chuck now. I found a 4 jaw on Ebay... I'm watching it.

Dane Martin · « **Reply #22 on:** May 27, 2020, 09:16:44 PM »

Just as a practice run, I'm making a crank for my cs .061. It suffered a 50 percent crank departure.

Dave Hull · « **Reply #23 on:** May 27, 2020, 11:33:35 PM »

Danish,

Looks like lots of fun.

That machine ought to have plenty of horsepower to turn 1/2A cranks! Based on the picture, I'd try a tool with a smaller tip, if you can. Try to have clearance behind the cutting edge so you are not dragging an edge. Hone the edge that is doing the work. You can stiffen the setup by running the live center into the bolt head. (You may be giving up some stiffness chucking on the threads, as well.) If you get rid of any chatter and get good tool geometry it is a lot easier to get the tolerance and finish you want.

A soft wheel or diamond hone would help dress the edges when using brazed carbide inserts.

I'll have to go look for these "self-supporting" knurling tools that guys are talking about. I haven't used one of those before.

McDivot

PS--The FAA got on me years ago with my excessive crank departures. They apparently rated my Mouse racing by whether all of my departures were on-time or not. I finally got to the point--after a lot of work--that all of my departures were on-time. One every heat. Usually right where they wanted it after the pit stop. So oddly, my government rating went up, but my scores (DNF) did not.

Dane Martin · « **Reply #24 on:** May 27, 2020, 11:43:17 PM »

McDivot! So while going through my stuff, I found that my live center doesn't fit in my tail stock. It's too large. You're right about the tool being too large. I went back and forth several times at a slower rpm, and SLOWLY fed in the tool. I got a reasonable cut for the poor processing I'm using, but I'll continue to inventory my tooling and set up properly.
Thanks buddy

pmackenzie · « **Reply #25 on:** May 28, 2020, 04:35:56 AM »

Quote from: Lauri Malila on May 28, 2020, 03:08:49 AM

If I had to choose one cutter for general work, I would take a boring bar, as stiff as possible, with insert shaped like in picture below. They are easy to grind sharper when needed, and the geometry gives a small relief angle to both x and y directions. It improves the surface quality.

CCGT, high positive?
Normally high positive is for non-ferrous.

Dane Martin · « **Reply #26 on:** May 28, 2020, 06:41:48 AM »

I didn't use that giant tool to cut, I just tried to clean up the 90 degree corners, without having to change tools , but i see what you mean. I have a nice tool grinder. It was just a lot of work to get it out yesterday. My garage is a mess. I probably should clean it and get it organized before I started this project!

Dane Martin · « **Reply #27 on:** May 28, 2020, 07:11:25 AM »

I have the lathe in the video. Also I watched the video again and saw a few things I probably shouldn't be doing, and some things I should add. Time for a reeducation!

Tim Wescott · « **Reply #28 on:** May 28, 2020, 08:20:20 AM »

Quote from: pat king on May 27, 2020, 09:10:21 PM

...You say a taper shaft can't get stuck, that is not true. Axles on Ford banjo housing rear ends were tapered. When we would shear an axle key on our coupe the hubs were almost impossible to remove....

The degree of taper makes a big difference. Those Ford axles have a taper of something like 5 degrees or 10 degrees, and there would have been bits of key in there to jam things up. The tapers I see on model airplane engines are more like 20 or 30 degrees. I'm not saying they won't get stuck -- but they should be less likely to.

Tim Wescott · « **Reply #29 on:** May 28, 2020, 11:54:05 AM »

Quote from: Motorman on May 28, 2020, 09:34:09 AM

... or you could go with a threaded hole and stud arrangement which would cut down on material removal. ...

An advantage to this arrangement is that when you bork the plane, there's a good chance that the stud will bend but not the crankshaft.

I deleted the part where you mention 12-32. If Dane is building an 049 then he probably doesn't want bigger than a #6 thread. Cox uses a 5-40 on theirs, and the Norvel 049 and 061 engines use M3.5 (Edit: or M3). If it were me I'd probably use a 5-40 just because of the sheer weight of all the Cox stuff I have around.

Dane Martin · « **Reply #30 on:** May 28, 2020, 12:12:32 PM »

I'll be drilling and tapping for 5-40. Like everyone else, I got plenty of Cox parts laying around.

MM,
I'm drawing up how you've described the offset fixture. Would it be unwise to make a clamp collet to hold the shaft off center that aligns the crank pin? The collet would be held in the jaw rather than a bolt on? Something like this crude drawing?

Tim Wescott · « **Reply #31 on:** May 28, 2020, 12:20:41 PM »

Dane, these may help.

Drill an offset hole in some round stock, then make a slit from hole to the stock edge, across the widest part of the remaining stock. If you make the hole a slip fit or light press fit on the crank, then when you tighten up the holder in your 3- or 4-jaw, it'll tighten the holder on the crank.

In my case I didn't care about getting the stroke exactly right, so I just kind of threw things together. With a 3-jaw you set the crank throw with the hole location in the stock. With a 4-jaw (or a 3-jaw and shim stock) you can use a dial indicator with enough range (or if you use an indicator plus the readout on your cross slide) to get the stroke more accurate.

This was for a TD 09 rebuild; I was aiming for exactly 1/2 inch stroke, plus or minus a mile.

Tim Wescott · « **Reply #32 on:** May 28, 2020, 12:22:31 PM »

I suppose you could get fancy, and drill and tap the holder for clamping screws.

Dane Martin · « **Reply #33 on:** May 28, 2020, 12:36:59 PM »

Ah, see that's what my half @$$ed picture was alluding to. I believe that would be the simplest thing for me to do without restoring to buying a bunch of stuff. I am not tooled up for this... I'm working on it. And I will be. But a little at a time.
Thanks for the pics

Dane Martin · « **Reply #34 on:** May 28, 2020, 01:31:00 PM »

Quote from: Motorman on May 28, 2020, 01:25:21 PM

If you think your jaws will hold the collet straight, then your offset pot chuck will work. Not sure how you would make one without a 4 jaw.

Motorman

I did find a nice condition 4 jaw on the 'bay. I think I'm going to bid on it anyway. It would be a nice addition

Tim Wescott · « **Reply #35 on:** May 28, 2020, 01:44:45 PM »

Quote from: Motorman on May 28, 2020, 01:25:21 PM

If you think your jaws will hold the collet straight, then your offset pot chuck will work. Not sure how you would make one without a 4 jaw.

Motorman

In my top picture that's a 1" diameter hunk of aluminum with a piece of stock roughly 1/4" think behind one jaw, to offset the aluminum round.

Tim Wescott · « **Reply #36 on:** May 28, 2020, 03:29:36 PM »

Dane, I just took another look at your sketch, and it looks an awful lot like an Owen's Mate, with plans in the Motor Boys International plans book. You could do worse than take inspiration off of that engine, I think.

Dane Martin · « **Reply #37 on:** May 28, 2020, 03:48:55 PM »

Quote from: Tim Wescott on May 28, 2020, 03:29:36 PM

Dane, I just took another look at your sketch, and it looks an awful lot like an Owen's Mate, with plans in the Motor Boys International plans book. You could do worse than take inspiration off of that engine, I think.

Awesome. Thanks for the tip. I'll look it up!

Dane Martin · « **Reply #38 on:** May 29, 2020, 03:46:38 PM »

Ok first of all. I want you, my friends, to take notice that I listen. I shimmed up my tool to be even with the tail stock center. I believe I have my tool geometry set correct. I definitely got a better finish while making my offset collet.

Tim Wescott · « **Reply #39 on:** May 29, 2020, 03:57:40 PM »

For an even better finish, round off the end of your tool. I can't remember the right name (the real machinists will), but there's a round-nosed tool profile that's specifically made for nice finish cuts. The idea is that a sharp-point tool is going to make a 'V' groove; a round-nosed tool is going to make a lot of really shallow overlapping 'U' grooves.

Dane Martin · « **Reply #40 on:** May 29, 2020, 04:23:54 PM »

Will do Tim.

I got the crank pretty well cut out. Not pretty. But, I'm gonna pretend for my first one it's ok. The fit is good, everything is straight. So, I guess it's going oooook. I definitely need more practice. But that's what this is! Thanks everyone for the help and advice. Here's a very quick video update.

Dane Martin · « **Reply #41 on:** May 29, 2020, 07:21:54 PM »

Well through my desire to learn the proper ways to do things... I happened upon this. I just so happen to have a compound tool reset so now I can accurately cut my crank taper!

Now the question... can I make the prop drive and cut the taper with a sharp reamer, and then just copy that angle on the shaft? Or is there a pre existing known angle I should be using?

Tim Wescott · « **Reply #42 on:** May 29, 2020, 09:09:50 PM »

I don't think there's a magic number -- I'd go look in my MBI International Plans Book and shamelessly copy something. Less of an angle will be more likely to bind; more of an angle will be more likely to spin when you're running the engine (this is considered an advantage on "sport" diesel engines, because it can save the crank when the engine's in hydraulic lock and some idiot goes at it too hard).

When I did mine, I just cut the taper on the shaft, then cut the taper on the prop drive without changing the setting on the compound. That's not the repeatable way to do it, but it certainly makes a matched pair of parts.

Dane Martin · « **Reply #43 on:** May 29, 2020, 10:14:17 PM »

Tim, I'm really liking this Owens Mate. It's a good inspiration for ideas.

Dane Martin · « **Reply #44 on:** May 30, 2020, 12:28:32 PM »

I should have drilled out the pilot for the front first, yes. But with the aluminium collet I made to hold the crank, it wasn't "that" bad. I ended up with a taper of 40 degrees on the crank tip, and tapped it for a 5-40
It's not a professional job by any means. But it's ready to put back together and run.

Dane Martin · « **Reply #45 on:** May 30, 2020, 07:25:02 PM »

Well not a monumental failure, but not flyable. My intake window is not big enough. I purposely made the window and the crank center slightly undersized. That sounded reasonable, because I think it broke originally due to how thin the crank was. But, doesn't really draw fuel as well. Once I got fuel to it to lubricate the crank, it feels normal. Nice and loose. But it runs. So there's hope for the next one.

Dane Martin · « **Reply #46 on:** May 31, 2020, 07:56:28 AM »

It's not. There's just no needle. If I get out in a sweet spot it'll run the tank out no problem. It doesn't seem to be getting hot anywhere

Edit; see below where I eat my words

Tim Wescott · « **Reply #47 on:** May 31, 2020, 08:27:06 AM »

Quote from: Dane Martin on May 30, 2020, 07:25:02 PM

Well not a monumental failure, but not flyable. My intake window is not big enough. I purposely made the window and the crank center slightly undersized. That sounded reasonable, because I think it broke originally due to how thin the crank was. But, doesn't really draw fuel as well. Once I got fuel to it to lubricate the crank, it feels normal. Nice and loose. But it runs. So there's hope for the next one.

It sounded like you could pull a small, relaxed, sport free-flight with that, if you could get it to hold a needle setting. Something designed for a 1950's 049, or a TD 020.

Flying engine first, fire-breather second...

You could put in a smaller venturi to match your smaller crank -- they'd still be undersized for the transfer ports (assuming everything was nicely balanced), but you'd have better needle response, and maybe something that would run. You could just do a quick & dirty insert with a piece of wood, for a test.

Did you check the intake timing? A smaller window would reduce the intake time, which up to some point (that I don't know, but I'll bet it depends on the porting) should make for easier starting and lower-speed tractability -- but if you put it too far over one way or another it'd mess things up. It would be good to check your work on that. An A/B comparison of the old and new intake timing may help you figure things out (or you could post it, we seem to have experienced engine modifiers here).

You could modify the crank easily enough. You could open up the window with a Dreaded Dremel Tool, or you could figure out a work holder for it in your mill. Opening up the hole would only take chucking the crank in a 3-jaw.

Dane Martin · « **Reply #48 on:** May 31, 2020, 08:31:22 AM »

Well you see, that's the problem. I don't have an old crank to work with. Just a broken nub that I was trying to get measurements from. I figured I had the important part, the crank pin side.
That was the whole start to doing this. To see if I could get it to run again. With the exception of the no needle ability, it's pretty much still a terrible engine. It just used to needle a lot better!

Tim Wescott · « **Reply #49 on:** May 31, 2020, 08:39:37 AM »

Are you saying it was a terrible engine before? So you haven't lost much?

You may have also have introduced a crankcase leak -- I would think (someone correct me if I'm wrong here) that you'd want the crank to be just a bit tighter than a good running fit initially, to give it a chance to wear in. So if you start with the right clearance for "after it's broken in" then it may be leaking now (or will be).

My approach (and I'm trying not to push -- really!) would be to experiment with getting the most you can out of that part, for the learning experience, and then move on to the next one.

Dane Martin · « **Reply #50 on:** May 31, 2020, 09:07:57 AM »

Power or RPM may be a little down. But it is an 061 that barely flew a light baby ringmaster. It's not as good as it was. But .... I pulled it apart to see if I see any shiny siezy parts. And I found this. So my stroke ended up slightly taller than the original! Let me fix this and clean up a little and we'll see what's up.

Great suggestion on the finished size though. That makes sense.

Oldenginerod · « **Reply #51 on:** May 31, 2020, 04:41:18 PM »

Quote from: Dane Martin on May 31, 2020, 09:07:57 AM

Power or RPM may be a little down. But it is an 061 that barely flew a light baby ringmaster. It's not as good as it was. But .... I pulled it apart to see if I see any shiny siezy parts. And I found this. So my stroke ended up slightly taller than the original! Let me fix this and clean up a little and we'll see what's up.

Great suggestion on the finished size though. That makes sense.

Well that's not good.

If BDC is lower then TDC must be higher. At least that may give a little more compression

. Is that the original backplate? Or did you make it?

bob whitney · « **Reply #52 on:** May 31, 2020, 07:12:17 PM »

I have about 20 bank brass sleeves left over from waynes work u are welcome to them .will include a completed chromed sleeve to see how he did his if u are interested RAD

Dane Martin · « **Reply #53 on:** May 31, 2020, 08:06:34 PM »

RAD, I would definitely be interested!

Rod, yeah i put a stroker kit in it!! Haha. That it's an original CS backplate. My crank pin ended up a few thou farther out on the flange than the oem.

I cleaned up the piston bite on the backplate. There was a gouge on the liner top where it contacts the head. It was all the way across the face, so I figured I'll fix that while I got the engine pulled apart. I also lengthened the intake window in the crank so it fills the venturi area. Not wider, it just wasn't centered fore and aft correctly. Best run yet. Got 2 minutes.

Dane Martin · « **Reply #54 on:** May 31, 2020, 08:08:17 PM »

Here's the 2 minute run. Checked temp with the super scientific finger on the case method. Not any warmer than a normal engine. Still terrible on the needle. There's about a 1/4 turn total sweet spot. Balsa in the venturi didn't help

Dane Martin · « **Reply #55 on:** May 31, 2020, 10:10:24 PM »

It's hard to say, but it didn't look like it's twisting.
Also however, the piston kissed the back plate again. No where near as bad, but I can't imagine any at all is ok.
And... the con rod fit is noticeably looser than what it was. It's getting to the point I'd say, I need to stop and analyze. It looks oblong. Maybe from hitting the plate and pulling up. Maybe my crank pin sucked. Maybe both.

And in addition to all that... the compression is, and has always been terribly low. So should I start over on the crank, but this time also make a rod and piston?

Yes, I already know this is entirely too much work for an obsolete .061. But I'm getting a great experience and a lot of practice.

Tim Wescott · « **Reply #56 on:** May 31, 2020, 10:16:48 PM »

I suspect that letting the backplate try to pull the piston off of the rod was what did that in.

What's the liner made of? I'm not sure you can do anything other than steel & cast iron DIY, unless you have a DIY chrome or anodizing setup.

Dane Martin · « **Reply #57 on:** May 31, 2020, 10:35:31 PM »

Quote from: Tim Wescott on May 31, 2020, 10:16:48 PM

I suspect that letting the backplate try to pull the piston off of the rod was what did that in.

What's the liner made of? I'm not sure you can do anything other than steel & cast iron DIY, unless you have a DIY chrome or anodizing setup.

I'm thinking possibly this to make a matched cylinder and liner set?

https://www.ebay.com/i/283843231040?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=283843231040&targetid=884131384999&device=m&mktype=pla&googleloc=9030753&poi=&campaignid=9426356364&mkgroupid=96480183780&rlsatarget=aud-412677883135:pla-884131384999&abcId=1140476&merchantid=6296724&gclid=CjwKCAjwq832BRA5EiwACvCWsR8NztE6ckeTTfj22ZWDfUgSWGlEiO_r3sgfQhLuMOMsjgC6slQw9hoCaDEQAvD_BwE

Dave Hull · « **Reply #58 on:** May 31, 2020, 11:18:37 PM »

Danish,

Looks like you having more fun per oz. of chips than is legal--even in the Silver State!

You might want to look at the P/L material combinations used on older production engines as a way to gauge longevity.

1. Liner or integral fin sleeves made from Ledloy or something similar to your 12L14 alloy. Often used with fine grain cast iron (Mehanite) pistons and using a lapped fit. Taper is recommended.

2. A steel liner as in (1) above, but with an aluminum alloy piston and a compression ring. This makes the running fit achievable since there is initial clearance that is sealed by the ring.

3. A steel on steel setup as you mentioned. Perhaps more like a Cox setup? But I'd bet they were using different alloys. I'd have to go figure that out.

4. More modern stuff that we all prefer nowadays that generally requires plating for longevity.

I'm sure guys can fill in details on these, and other variations. There actually was a great deal of experimenting using different materials and platings to try to find a magical pair. I think I read a few articles by Don Jehlik and John Kilsdonk about some of them. I would worry about galling with a lapped fit of identical materials.

The Divot
"Leaving distinguished holes in the ground wherever my airplanes may fly"

PS--I'm late to the discussion on the collet design, but take a look at tool tapers, such as on your lathe tailstock. Most of these are around 3 degrees and are self-seizing. Somewhere around 7 degrees of taper on a precision ground steel shaft is considered self-seizing limit if in good condition and clean. Increasing the amount of taper more would be better for a crankshaft hub application. The old Mickey Red Heads probably exploited(?) the far end of that feature. They were really blunt--but worked.

Dane Martin · « **Reply #59 on:** June 01, 2020, 08:08:44 AM »

Quote from: Dave Hull on May 31, 2020, 11:18:37 PM

Danish,

Looks like you having more fun per oz. of chips than is legal--even in the Silver State!

You might want to look at the P/L material combinations used on older production engines as a way to gauge longevity.

Good day sir! I am in fact, having loads of fun. To hear that thing pop off and continue to run left me wanting to try more!

So, in my "research" I found some fellows saying EN1A was a good material to use, but replies and more reading on "practical machinist", and other sites, lead me to believe 12L14 was possibly the way to go. I didn't research Cox too much, but what I did; they just kept saying leaded steel.

I am not at all opposed to the idea of plating. I am simply not set up for that, so it's all things I'm weighing the options on.

bob whitney · « **Reply #60 on:** June 01, 2020, 09:35:14 AM »

if I am not mistaken the cox pistons are hard plated

I need your address I will send u some odds and ends to look at,plus the sleeves

Oldenginerod · « **Reply #61 on:** June 02, 2020, 05:24:32 AM »

Quote from: bob whitney on June 01, 2020, 09:35:14 AM

if I am not mistaken the cox pistons are hard plated

Hardened rather than plated I believe. The inside and crown of the piston was copper plated so that the chemical hardening didn't prevent the rod being swaged into its socket. So, only the outside surface (sides) of the piston was hardened and ground. In time the rod socket work hardens.

Dane Martin · « **Reply #62 on:** June 02, 2020, 07:33:01 AM »

Quote from: Tim Wescott on May 26, 2020, 06:54:21 PM

Based on all that -- I'd suggest finding some plans for an engine (there's a few "beginners engines" on modelenginenews.org) and just building to plan. Or grab a clapped-out engine and make some new bits (unless you've done that). Once you get that working, even if it's not strong enough to get the skin off of hot milk, then go and build an engine.

Tim,
I may have dismissed the idea of a beginner level engine earlier... but it was purely an aesthetics concern. I will also eat my words here again (twice in the same thread) and look more into that. But also... I'm thinking of making a "bench test case" , where it will be the internal dimensions of this CS... but just a dumpy little blocky thing. Something super easy to make accurate with what I have.
As it turns out, making parts and then hearing them run is pretty fun anyway!

Tim Wescott · « **Reply #63 on:** June 02, 2020, 08:05:08 AM »

Quote from: Oldenginerod on June 02, 2020, 05:24:32 AM

Hardened rather than plated I believe. The inside and crown of the piston was copper plated so that the chemical hardening didn't prevent the rod being swaged into its socket. So, only the outside surface (sides) of the piston was hardened and ground. In time the rod socket work hardens.

What would it have been hardened with? Nitride? Or plain old case-hardened with carbon?

Dane Martin · « **Reply #64 on:** June 02, 2020, 08:24:26 AM »

Quote from: Tim Wescott on June 02, 2020, 08:05:08 AM

What would it have been hardened with? Nitride? Or plain old case-hardened with carbon?

From my research (but I don't actually know) nitride was the most consistent answer

Tim Wescott · « **Reply #65 on:** June 02, 2020, 09:17:14 AM »

Quote from: Dane Martin on June 02, 2020, 08:24:26 AM

From my research (but I don't actually know) nitride was the most consistent answer

Now that's interesting -- because my understanding is that nitriding is something that can be done in a small shop.

But then, the gist of the passage that I read was that it would harden your steel, but it would warp it enough that you'd need to do a final grinding pass, and if you're building motors for fun it's easier to just go with 12L14 cylinder and cast pistons. I think the author's opinion was that long before you wear out an engine, you'll have another one freshly built that wants to fly something.

Dane Martin · « **Reply #66 on:** June 02, 2020, 12:53:00 PM »

So according to other successful small engine hobbyists, I've come to a conclusion for now. 4140 for the liner and 6061 for the piston. There's a machine shop in AZ that sells excess material on Ebay for a very good price with combined shipping, so I ordered a few pieces of each. Now, if this leads to low run time, so be it. Like you say Tim, I'll have some extras!
Maybe if I can see some continuous success in small batches, I can work towards a goal of plating and what not. Get a little more modern as I develop my skills

Tim Wescott · « **Reply #67 on:** June 02, 2020, 01:35:24 PM »

Quote from: Dane Martin on June 02, 2020, 12:53:00 PM

So according to other successful small engine hobbyists, I've come to a conclusion for now. 4140 for the liner and 6061 for the piston. There's a machine shop in AZ that sells excess material on Ebay for a very good price with combined shipping, so I ordered a few pieces of each. Now, if this leads to low run time, so be it. Like you say Tim, I'll have some extras!
Maybe if I can see some continuous success in small batches, I can work towards a goal of plating and what not. Get a little more modern as I develop my skills

If you use 6160 for the piston you'll need cast-iron rings, with all the hassle that brings. I don't think that 6061 running on steel will last for any time at all.

Dane Martin · « **Reply #68 on:** June 02, 2020, 01:50:44 PM »

Quote from: Lauri Malila on June 02, 2020, 01:48:58 PM

I suggest that you read Robbies article about their TR engine. Just google "FMV story". The metallurgy is explained well there.
I allready offered you some Mahle #138, it's good enough for your purpose. L

I will gladly accept your offer! Thank you. I'll look up that research material also.

Dane Martin · « **Reply #69 on:** June 02, 2020, 02:40:57 PM »

Quote from: Lauri Malila on June 02, 2020, 01:48:58 PM

I suggest that you read Robbies article about their TR engine. Just google "FMV story". The metallurgy is explained well there.
I allready offered you some Mahle #138, it's good enough for your purpose. L

Also, can you help explain some of the statements made?

It shows also that an 18% Si-Aluminium alloy should be good for brass or a 12% Si-Aluminium alloy cylinder.
The mentioned alloys can for instance be obtained in bars through dealers of Mahle-Germany. (Mahle 138 and
124 alloys respectively).

When they mention a brass cylinder, is that a chrome plated brass cylinder?
And is the second part of the statement using an 18% si piston in a 12% si alloy liner, and would that be plated or without?

Thanks for your time everyone

Dane Martin · « **Reply #70 on:** June 02, 2020, 04:34:06 PM »

Quote from: Motorman on June 02, 2020, 04:27:13 PM

btw speaking as someone who has done chroming in my home shop, I would avoid attempting any kind of plating operation unless you are highly versed in industrial hygiene.

Motorman

I am versed in industrial hygiene because of my career, and our strict safety practices. And because of that, I know enough to know that I don't want to get involved in that with my young kids and my active household!
When I get to the ABC or AAC side of the experimentation, i would farm that out, knowing it would be expensive...

Thanks for all the notes guys. I'll keep reading up on the FMV steel / iron experimentation.

Tim Wescott · « **Reply #71 on:** June 02, 2020, 06:48:47 PM »

Quote from: Dane Martin on June 02, 2020, 04:34:06 PM

I am versed in industrial hygiene because of my career, and our strict safety practices. And because of that, I know enough to know that I don't want to get involved in that with my young kids and my active household!
When I get to the ABC or AAC side of the experimentation, i would farm that out, knowing it would be expensive...

Thanks for all the notes guys. I'll keep reading up on the FMV steel / iron experimentation.

What, you have a problem with hexavalent chromium in your basement? Wimp.

If I ever build a home-grown "modern" engine, the furthest I intend to go is a hard anodized cylinder for an AAO combination, because sulfuric acid scares me less than chromium in solution. But I suspect I'll pass away before I get to that check mark on my bucket list.

Dane Martin · « **Reply #72 on:** June 02, 2020, 06:56:18 PM »

Quote from: Tim Wescott on June 02, 2020, 06:48:47 PM

What, you have a problem with hexavalent chromium in your basement? Wimp.

I fear my kids may get into chroming parts for harleys and get in with the local biker clubs. Then dad ain't so cool anymore....

Tim Wescott · « **Reply #73 on:** June 02, 2020, 07:07:16 PM »

Quote from: Dane Martin on June 02, 2020, 06:56:18 PM

I fear my kids may get into chroming parts for harleys and get in with the local biker clubs. Then dad ain't so cool anymore....

Yup, that's worse than any chemical damage...

Chrome plated bongs. Hmm.

Dane Martin · « **Reply #74 on:** June 04, 2020, 08:52:16 PM »

I Successfully made a spray bar for the wasp 049 today. Pretty faithful replica, I think. Drilled and tapped for 1-72. I ordered some 1-72 screws to make the needle easier. Lol I know, I cheated. But I'm happy I got the hole centered in the spray bar. That came out classy. Main section was 0.111 and the step down / minor diameter of the barb is 0.100. Barbs are 0.125

Great practice for making my own

Tim Wescott · « **Reply #75 on:** June 05, 2020, 09:47:47 AM »

Quote from: Motorman on June 05, 2020, 09:28:46 AM

Good luck making the point on the needle.

Tool post grinder on the compound.

Dane Martin · « **Reply #76 on:** June 05, 2020, 09:56:17 AM »

I'm feeling lucky these days. Ha!

Check this little sweet heart out

https://images.app.goo.gl/TNv7JUWcr3AG7V8Z6

Tim Wescott · « **Reply #77 on:** June 05, 2020, 10:02:07 AM »

Quote from: Dane Martin on June 05, 2020, 09:56:17 AM

I'm feeling lucky these days. Ha!

Check this little sweet heart out

https://images.app.goo.gl/TNv7JUWcr3AG7V8Z6

If you want to grind tapers it'll need to go on the compound. I'm not sure which Smithy you have, but that grinder looks like it'll go on the cross-slide directly, but not the compound.

I've heard stories and maybe seen a picture at some point, of folks mounting a Dremel tool on a lathe as a tool post grinder. A real true Dremel won't be as accurate, and won't do heavy stuff -- but for that task it may work.

Dane Martin · « **Reply #78 on:** June 05, 2020, 10:07:56 AM »

Quote from: Tim Wescott on June 05, 2020, 10:02:07 AM

If you want to grind tapers it'll need to go on the compound. I'm not sure which Smithy you have, but that grinder looks like it'll go on the cross-slide directly, but not the compound.

I've heard stories and maybe seen a picture at some point, of folks mounting a Dremel tool on a lathe as a tool post grinder. A real true Dremel won't be as accurate, and won't do heavy stuff -- but for that task it may work.

Oh, didn't notice that. Ok well no prob. I'm sure I can whip something up. May take some trial and error, but that's half the fun

Tim Wescott · « **Reply #79 on:** June 05, 2020, 10:53:50 AM »

It may be easiest to get that grinder and modify it. You would have to check spacings, but you might be able to cut that foot off and braise one on that is right on the housing.

pmackenzie · « **Reply #80 on:** June 05, 2020, 04:01:42 PM »

This sort of looks like a needle valve, no grinding required.

Dane Martin · « **Reply #81 on:** June 05, 2020, 04:03:49 PM »

Quote from: pmackenzie on June 05, 2020, 04:01:42 PM

This sort of looks like a needle valve, no grinding

Awesome! I've been watching a lot of Joe Pie's videos. Trying to get educated

Tim Wescott · « **Reply #82 on:** June 05, 2020, 04:27:40 PM »

Quote from: pmackenzie on June 05, 2020, 04:01:42 PM

This sort of looks like a needle valve, no grinding required.

Nah, that looks like a push-pin.

pmackenzie · « **Reply #83 on:** June 05, 2020, 04:43:12 PM »

Add a thread and knurl and it is pretty much a needle valve.

The point was to show how you can cut a small diameter taper without having to grind it.
He has lots of good tips in his videos.

Tim Wescott · « **Reply #84 on:** June 05, 2020, 04:47:53 PM »

Dane, if he's using the technique of machining the cylinder (or point) a bit at a time, then with your 1-72 screw, you'll need to make a block that's threaded through with a jam nut at the end -- and hope that it holds your screw accurately enough.

Tim Wescott · « **Reply #85 on:** June 06, 2020, 02:35:33 PM »

Quote from: Motorman on June 05, 2020, 09:21:36 PM

That's funny. I got some drill rod the same diameter as the needle stem and tried to put a point on that LOL. I ended up just using a bench grinder by hand to make the taper. It works ok....

That's exactly what I've done for needles. "OK" is about the best I've attained -- for me the point is never quite on center, so as you're adjusting it there's a quadrant of the turn where the needle doesn't make much difference, or even works backwards, and then it's back to working normally.

Dane Martin · « **Reply #86 on:** June 09, 2020, 11:54:11 AM »

I ordered a set of 7, 8, 10 and 12mm Boring bar with replaceable tip inserts. I also got a 3 piece set, right left and center turning tools. I built a table for my grinder so I can start using it properly. Not it's final resting place, but it's made of 1.25" steel tubing and a stainless tool box top.
I'll be building a nice work bench for the lathe tonight.
Then on to organizing the garage to be able to make stuff successfully

Tim Wescott · « **Reply #87 on:** June 09, 2020, 12:33:56 PM »

Quote from: Motorman on June 09, 2020, 12:10:53 PM

Nice grinder, I put little sheet metal trays under mine to catch most of the dust.

I have a workbench that does that

Christopher Root · « **Reply #88 on:** June 11, 2020, 11:12:09 AM »

How are cast iron pistons made? Cast? Machined?

Dane Martin · « **Reply #89 on:** June 11, 2020, 11:24:47 AM »

Quote from: Christopher Root on June 11, 2020, 11:12:09 AM

How are cast iron pistons made? Cast? Machined?

I bought some class 40 grey cast in rods. The material spec sheet says its easy to machine but has poor welding compatibility... lol

Tim Wescott · « **Reply #90 on:** June 11, 2020, 12:44:48 PM »

Quote from: Christopher Root on June 11, 2020, 11:12:09 AM

How are cast iron pistons made? Cast? Machined?

For home-built engines, you buy high-quality cast iron stock and machine the piston. The point isn't so much to cast a piston -- it's to have dissimilar metals at the piston to cylinder interface.

Christopher Root · « **Reply #91 on:** June 11, 2020, 01:35:43 PM »

So is the engine case the only cast part? Everything else is machined?

Dane Martin · « **Reply #92 on:** June 11, 2020, 01:50:23 PM »

Quote from: Christopher Root on June 11, 2020, 01:35:43 PM

So is the engine case the only cast part? Everything else is machined?

Not always. The case can be machined also. Mine will be. I'm just making something that can fly a little 1/2a plane that is 100% from my garage

Steve Helmick · « **Reply #93 on:** June 15, 2020, 04:10:55 PM »

Dane's crankshaft is probably every bit as good as the original CS crank, if not better!

What sort of lathe is that? Mine is a 3" x 14" Grizzly....they don't sell it anymore. It's a lot like the HF equivalent, but longer between centers. The Chinese factory apparently offers options and quality choices like a Chinese restaurant. Choose one from column A and two from column B sort of thing. I put a 1/2 dowel pin in my 3-jaw and was pleasantly surprised by how little runout it had. It's fine for fiddling with heads, adapting spinners, and making venturi/restrictors. I also modified a pendant light fixture part awhile back, for our bathroom remodel.

Steve

Dane Martin · « **Reply #94 on:** June 15, 2020, 04:17:37 PM »

Hey Steve.
Thanks for the vote of confidence. Here's what I did... Bill Hughes sent me all new parts for this CS engine. Comparing the crank, I have found no difference in the run quality between mine and the factory. So that's kinda cool.

My lathe is this one

https://smithy.com/Smithy-Combo-Lathe-Mill-Midas

Dane Martin · « **Reply #95 on:** June 17, 2020, 05:37:34 PM »

Getting my work station together. The bench is new, to me anyway. Painted and sanded and cleaned up real good. Then my friend came over today with the cherry picker so we could put the lathe on the new bench.

Dane Martin · « **Reply #96 on:** June 17, 2020, 05:41:10 PM »

Also got a few new turning tools. Bore bars down to 7mm and a variety of turning tools

Dane Martin · « **Reply #97 on:** June 26, 2020, 07:44:30 PM »

This might sound pretty basic, but it was good practice. I made some sleeves for some venturis (venturii?) today. These were 0.281, so I sleeved them down to 0.256.
I had a tube that was 0.256 ID and 0.390 OD. I turned them down to an interference fit. So the practice was getting back into reading a mike properly.

Dane Martin · « **Reply #98 on:** June 27, 2020, 06:29:54 AM »

Easy in the mill with new center drills