Drill and thread this! Muffler bolt!

[Avaiojet]

Anyone ever drill and tap this?

I'm thinking of doing this to hold the muffler I made in place.

What thread choice and do you think it will hold without vibrating out? Lock-tight?

Thanks in advance.

Charles

[pat king]

Charles,
I would recommend a 4-40 screw. It is not so big as to compromise the integrity of the web, but plenty strong enough to hold the muffler. If that hole ever gets damaged you can always go out to 6-32.

Pat

[bob whitney]

u can even go to a 5-40 before going to the 6-32

[Avaiojet]

Charles,
I would recommend a 4-40 screw. It is not so big as to compromise the integrity of the web, but plenty strong enough to hold the muffler. If that hole ever gets damaged you can always go out to 6-32.

Pat

Pat,

Thanks for the reply. Do they call you "Sky" King? I like having handles for people.

I have a 4-40 tap, but not a bottom tap. Is the bottom tap necessary?

u can even go to a 5-40 before going to the 6-32

Bob,

Thanks for the reply.

Now if you hung out at our field we would call you, "JC." As in JC Whitney.

That 5-40 is good to know.

Thanks for that.

Charles

[Tim Wescott]

I have a 4-40 tap, but not a bottom tap. Is the bottom tap necessary?

First, given how nice that engine is I think I'd use a strap.  I usually only modify vintage stuff like that if it's already a bit bunged up -- but that's me.

I would want to start that job by completely disassembling the engine to keep the metal bits away from the innards of the motor.  Strip it down, put the innards in a margarine tub, drill, tap with a through tap, clean the case thoroughly, then reassemble with after-run oil.  At the very least you should do the job on a drill press after finding a way to hold the motor securely -- I'd make a fixture to hold perfectly, and do it on a mill, or I'd sweet-talk a real machinist into doing it for me.

When I went to put it all back together, I'd use a spacer inside the muffler that is almost as long as the unloaded distance between the web and the end of the muffler.  That way you can tighten the screw tight without wadding up the muffler, yet you can still hold some pressure on the muffler to keep it in place.

Keep in mind that the muffler is going to blow back at the engine -- it'll probably get slightly hotter than if it made a good seal, and the engine will get castor goo burnt on good and proper.

[Motorman]

There should be a space behind the lug. Close the port and stuff with paper towels. Use a drill block to get it square. The big problem is drilling into the piston when you break through. You can use a wheel collar as a drill stop. 4-40 is ok but moving up to 6-32 from 4-40 will give you 30% threads and good luck finding a 5-40 that's long enough. Loctite doesn't work on header bolts, the heat just melts it. Best bet is a split washer. Looks like you'd be tightening down against the sheet metal edge. I think vibration might deteriorate the edge and loosen the assembly.

MM

[Avaiojet]

I really don't want to tear the engine down unless I really have to, that woiuld mean I would have to replace each and every gasket.

Two? Three?

Where do you get them.

ebay, they want 23.00 for a single gasket.

I have thin straps someplace from years gone by. I would have to spend some time looking for them.

Possibly one single bolt for the strap.

BTW. The muffler has a stop that would sit against the exhaust port.

Thanks for the info and the replies.

Charles

[Dick Pacini]

If I ran the zoo...


Once the hole was drilled and tapped, I would use a threaded stud (long enough to extend out the end of the muffler) and run a locknut up against the lug.  Use double nuts inside the muffler just at the inside face of the muffler end.  Lock them together.  Then, install the muffler snuggly against the double nuts and use an elastic stop nut on the end to hold the muffler on.  The advantage is you aren't pulling the lug when the muffler is installed.

Second comment; if those two holes in the end are all there is, that Mac isn't going to breathe very well.

[Jim Thomerson]

I had a Fox 59 which had a hole drilled and tapped as you are thinking of.   Second or third flight the case broke through the drilled and tapped hole.  Does the exhaust flange stick out far enough that you could put a bolt through it longways to hold the muffler on?  And, yes, you need more holes. 

[Mark Scarborough]

Talk to
Scott Reise,, he knows how,, why and more so why not,,

you stand to ruin this motor if you do it wrong,,

[John Stiles]

If I ran the zoo...


Once the hole was drilled and tapped, I would use a threaded stud (long enough to extend out the end of the muffler) and run a locknut up against the lug.  Use double nuts inside the muffler just at the inside face of the muffler end.  Lock them together.  Then, install the muffler snuggly against the double nuts and use an elastic stop nut on the end to hold the muffler on.  The advantage is you aren't pulling the lug when the muffler is installed.

Second comment; if those two holes in the end are all there is, that Mac isn't going to breathe very well.

This^^^is a great plan....

[Avaiojet]

Gentlemen,

Thanks for the replies.

Dick'd idea about the stud is a good one. No pressure on the muffler end. Threaded stud can have a nut and lock washer at the interface inside the exhaust port. Should hold it.

That dimple was meant to be threaded and drilled for a butterfly on the R/C engine. I think.

Holes. Yes, I just haven't gotten around to it. They have to be aligned and look nice.

Mark,

I have purchased stuff from Scott. Does good work.

Thanks again,

Charles

[Paul Smith]

Is that web there to hold one of the long bolts that secure the top end of the engine?

You are correct in avoiding messing with the gaskets on a black fin engine.

[Avaiojet]

Is that web there to hold one of the long bolts that secure the top end of the engine?

You are correct in avoiding messing with the gaskets on a black fin engine.

Paul,

WOW! Nice observation. 

How did some of us miss that?

Unfortunately that throws what's on the table related to that web right out the window, stud, nuts and all.

Bummer!

And to think I would have drilled and tapped that puppy.
 
OK, so that's it, I'm going with a strap. KISS. How come I don't learn this simple KISS thing?

I have some thin brass strapping stock someplace just gotta find it.

One "U" piece, not two, and I'll run the bolt right through the muffler. The SS bolt, of small diameter, will be fine. Fuel will go right by it. While I'm drilling the holes for that I can drill a dozen or so for fuel exit.

That'll work! Right? 

Paul, that's a really good heads up, thanks for that.

Charles

[Randy Ryan]

See the last photo, the nose of the Ringmaster Sportster. I make music wire bales, no drilling or mods required, no case distortion like strap-ons.

http://stunthanger.com/smf/index.php/topic,7960.msg67901.html#msg67901


HAHAHAHAHA< I struggled to find out how to copy that shortcut just to find Charles was the salt post on that thread!!

[Paul Smith]

Big Art recommended just using old fuel or paint can stock for muffler brackets.  Two pieces with a 4/40 bolt on the bypass side to adjust the tension.  That's what I use of strap-ons.

[Avaiojet]

Randy,

That is a clean setup.

Music wire? The spring steel stuff you buy at the LHS?

I guess the dimples can be holes, I only have .064 there in two layers.

I'll try to make one.

What guage do you use?

[john e. holliday]

Unless your flying sight says it needs to be muffled, why worry about it.   I have several planes that are not equipped with mufflers I fly.

[Randy Ryan]

Randy,

That is a clean setup.

Music wire? The spring steel stuff you buy at the LHS?

I guess the dimples can be holes, I only have .064 there in two layers.

I'll try to make one.

What guage do you use?

Hi Charles, I use .046 wire, anything lighter doesn't withstand the combustion pressure and vibrates, anything heavier gets really hard to hook onto the muffler. Holes will work for sure.

[Avaiojet]

John,

Our field is sometimes used as a baseball field or soccer field. Many in one area. Always people around doing these activities.

Be pointless to run an engine without a muffler here. Would only bring attention to ourselves and could be an annoyance to others.

Always have to keep this in mind. Wouldn't want to loose the field because of a single complaint.



Randy,

Thanks for that. I will try to make one.

[Randy Ryan]

John,

Our field is sometimes used as a baseball field or soccer field. Many in one area. Always people around doing these activities.

Be pointless to run an engine without a muffler here. Would only bring attention to ourselves and could be an annoyance to others.

Always have to keep this in mind. Wouldn't want to loose the field because of a single complaint.



Randy,

Thanks for that. I will try to make one.

It'll probably take a few tries but once you get the idea they're very simple.