Carbon fiber tubing

[Steve Dwyer]

Can anyone tell me a retail source to purchase the carbon fiber rod Tom Morris use to sell? This is the rod that accepted with a little reaming the threaded adaptor he offered to attach a Dubro ball fitting.

Steve

[John Rist]

https://okieair.com/shop/ols/categories/pushrods

Okieair  has bought  Tom's business.

[Paul Walker]

Try Central Hobbies in Billings Montana.
The have a good mail order service. I use them for my pushrod applications.

[Avaiojet]

I don't know if this is true or not, but someone told me these rods are available at kite shops.

[Motorman]

https://www.centralhobbies.com/cat4.php?cat=27&subcat=124&sub2cat=44

[Mark wood]

Amazon has them. Amazon drives me crazy but they deliver quickly.

https://www.amazon.com/gp/product/B0878DF82R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Dennis Nunes]

I order 48" lengths from ACP Composites. I use this one for all my pushrods: https://store.acpcomposites.com/carbon-fiber-pultruded-tubing?quantity=1&dimensions=38


Dennis

[Ken Culbertson]

I never measured Tom's diameter.  What diameter is best for a 18-20" pushrod.  I have arrow shafts but making the ends is a bummer.  I am guessing the somewhere around 5/32 but that is just a guess.

Ken

[Dennis Nunes]

I never measured Tom's diameter.  What diameter is best for a 18-20" pushrod.  I have arrow shafts but making the ends is a bummer.  I am guessing the somewhere around 5/32 but that is just a guess.

Ken

Ken, this is how I make mine using 3/16" or .188 diameter carbon fiber tubing and a 4-40 bolt for ball links. On some of my pushrods ends I've use 3/32" piano wire end using the similar method. I've used this on all my planes from .25 to .61 engine and on my electrics.


Dennis

[Ken Culbertson]

Ken, this is how I make mine using 3/16" or .188 diameter carbon fiber tubing and a 4-40 bolt for ball links. On some of my pushrods ends I've use 3/32" piano wire end using the similar method. I've used this on all my planes from .25 to .61 engine and on my electrics.


Dennis

Thanks - the .188 is what I am finding available.  Just wanted to make sure.

Now off to find a supplier for LH thread 4-40 all-thread!

ken

[Ken Culbertson]

Amazon has them. Amazon drives me crazy but they deliver quickly.

https://www.amazon.com/gp/product/B0878DF82R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Thanks for the tip.   I was wondering why 420mm when most of our modern tails need about 18 even with the ball link, then I realized with the logarithmic sitting behind the TE it was enough.  I spent/wasted an hour trying to find 500mm.   By the time you get past all of the sponsored links that don't come close to fitting your search you give up.  Amazon is fantastic/sucks.

Ken

[Paul Walker]

Thanks - the .188 is what I am finding available.  Just wanted to make sure.

Now off to find a supplier for LH thread 4-40 all-thread!

ken

If you are using all thread for control system parts, I would use the Central Hobbies titanium ends. Made to fit, and avoids much of the threads experiencing vibration, and early failure.

[Ken Culbertson]

If you are using all thread for control system parts, I would use the Central Hobbies titanium ends. Made to fit, and avoids much of the threads experiencing vibration, and early failure.

Thanks.  I checked them out and it looks good.  I emailed them to find out if they had left as well as right.  All of their pictures show 2 rights.  Plan "B" is to use turnbuckles.

Ken

[Motorman]

I got carbons tubes from various places over the years.  If they don't list the inside diameter I suggest you call and ask. Drilling/honing ect it's very easy to split the tube and it weakens it too much for my comfort. Below are some good combinations from what I have in the shop:

.125 x .068  for small planes glue over 1/16" wire push rods
.180 x .106
.195 x .117  * RSM ends
.197 x .110  * 4-40 bolt
.210 x .127  * CH Titanium

Threaded end sizes

RSM stainless steel  .117"
Central Hobby Ti      .120"
4-40 shcs shank       .110"

Motorman

[Steve Dwyer]

Thanks guys,

Central Hobbies looks to have exactly what Tom Morris was selling, they have the same CF tube and the 4-40 connector.

I'm now thinking a better alternative (more economical) is what Dennis suggested going to APC composites to buy the tube with the .188 ID that will accept the threaded 4-40 rod instead of the expensive machined Central Hobbies connectors. The 4-40 all treaded rod is available from Brodak.

I use 30 min epoxy and not CA as Central Hobbies is suggesting for joining the connectors to the tube. Using the 4-40 rod instead of the machined connector you probably will not need to wrap the outer CF tube diameter with thread coated with epoxy.

Thanks for the help.

Steve

[Jim Hoffman]

I have had great success with the titanium fittings from central hobbies as Paul Walker suggested. I use JB Weld and epoxy a small length of aluminum tubing over the CF tube at the end to prevent any splitting if the fibers lengthwise

[Dave Harmon]

I use 30 min epoxy and not CA as Central Hobbies is suggesting for joining the connectors to the tube. Using the 4-40 rod instead of the machined connector you probably will not need to wrap the outer CF tube diameter with thread coated with epoxy.

Thanks for the help.

Steve

I had used the CH pushrod system on Pattern planes for years.
At first I used CA glue....then after a while I tried to make a pushrod adjustment and found the ends were rotating in the tubes!
I could not pull them out because the glue in the slots kept them in....but....I never used CA glue again on these things!
I had always been a little concerned about the 'titanium' breaking where the threads end considering the airplane had high vibration for every 8 minute flight using YS 170 and larger engines....but they never did!

I don't use thread to wrap the tubes either....I don't know why other than it's a lot harder to find Kevlar thread than aluminum tubing.
I cut the tubing longer than the 4-40 all thread that is inserted into the tube...then epoxy it over the tube and I don't think that pushrod is gonna cause a problem....ever!

I just checked the price at CH on the titanium ends....$9.95 for 2.....then $8 for the tube!
Then the cheapest shipping is $9.98.
Sounds like $28 for one pushrod.....not on my airplanes!
That's not even considering some carbon tubes that have off center ID.
Not the case with OAKIE though.....carbon tubes are good from them.

For electric Pattern planes...some years ago I started using .110 carbon rod epoxied into Du-Bro ball links that were drilled and tapped for a nice push fit.
Then drill a small hole toward the ball end to allow an air escape hole as the rod was pushed in.
The epoxy gets in the threads and of course sticks like crazy to the rod.
Not adjustable of course but you can tow a garbage truck with that pushrod.
The neutral (in trail) of the surface can be adjusted at the transmitter to get it exact.

For C/L airplanes with enclosed flap coupler I do the same thing with the bellcrank to flap pushrod.
I use slow epoxy on these rods.
Works great...easy to do....cheap and available.

[Motorman]

4-40 all thread is soft. If you want to go that way I would suggest Micro Fastener has 3" long 4-40 bolts threaded up to the head that are grade 8. What I do is use a 2-1/2" 4-40 with a long shank. Cut the head off and cut grooves in the shank then rough it up with 60 grit paper.

You need something wrapped on the outside of the CF tube to prevent splitting. It can be .5oz glass cloth or just about anything. I use 7/32" aluminum tubing cut slowly with a small pipe cutter so the end forms a cap.

Glue everything with JB weld or Devcon steel filled epoxy.

Motorman

[Dave Harmon]

4-40 all thread is soft. If you want to go that way I would suggest Micro Fastener has 3" long 4-40 bolts threaded up to the head that are grade 8. What I do is use a 2-1/2" 4-40 with a long shank. Cut the head off and cut grooves in the shank then rough it up with 60 grit paper.

You need something wrapped on the outside of the CF tube to prevent splitting. It can be .5oz glass cloth or just about anything. I use 7/32" aluminum tubing cut slowly with a small pipe cutter so the end forms a cap.

Glue everything with JB weld or Devcon steel filled epoxy. 

Motorman

Motor....I didn't mention every detail.
But just to be perfectly clear....all thread is soft(er) than grade 8 bolts but after doing this for quite a while I have never heard of an all thread breaking or experienced it after several pile drivers.
I cut grooves in the all thread.....then degrease the oil and finger mung off it with lacquer thinner.
Then I use plenty of 5 min epoxy with milled fiberglass.

As I said in my first post.....I put aluminum tubing on each end longer than the all thread is inserted into the tube....also with 5 min epoxy.

Nothing wrong with using bolts at all....and they ARE stronger but I don't think either is a concern.
After flying a difficult event which almost all material had to be shipped to me....for several years now I try to use what I can get locally that I can adapt to perform as needed.

Electric airplane pushrods are probably less of a concern but in the end....I think I would do the pushrods the same way.

Another problem is blind nuts....
Du-Bro continues to mfg 4-40 blind nuts with the tapped hole off center.
This make it hard or impossible to insert a bolt if the hole in the wood is right-sized.
So....I stopped using them. I called Du-Bro and asked about this and a guy named Ray Charles said he would take a look at them and send me some good nuts.... 

Great Planes blind nuts were good but I don't have any more so now I git em' from Micro Fasteners.

[Jim Svitko]

When you say the tapped hole is off center in the Du Bro blind nuts, I assume you mean it is not in the center of the barbed flange.  Is this what you mean?  Or, maybe you discovered what I found on these blind nuts--the tapped hole is not square with the flange.

If you install such a blind nut so that the flange is against the motor mount beam, with contact all around, then the tapped hole is not 90 degrees to the flange and you will have a hard time getting the 4-40 screw in. 

[Dave Harmon]

When you say the tapped hole is off center in the Du Bro blind nuts, I assume you mean it is not in the center of the barbed flange.  Is this what you mean?  Or, maybe you discovered what I found on these blind nuts--the tapped hole is not square with the flange.

If you install such a blind nut so that the flange is against the motor mount beam, with contact all around, then the tapped hole is not 90 degrees to the flange and you will have a hard time getting the 4-40 screw in.

Hi Jim....that's right.
The tapped hole is off center from the 'barrel' of the nut which makes it off center in the wood hole.
Something I didn't mention is these nuts need to be 'deburred' and a tap run through each one.
I ain't got time to mess around with each blind nut anymore.....well...actually I have the time but ain't doing it.

[Jim Svitko]

Dave, it took me a while to find this problem.  I was wondering why things were "off" even though I went to the trouble to make sure of everything being straight.  What I do now with these blind nuts is put a 4-40 screw in and then I can see if the screw is centered in the hole in the beam at the time of installation.  I have to adjust the flange position on the back side to achieve this.

I also found that many need to have a tap run thru them to clean up the threads.  Maybe I need to find a better blind nut.

[Dave Harmon]

Dave, it took me a while to find this problem.  I was wondering why things were "off" even though I went to the trouble to make sure of everything being straight.  What I do now with these blind nuts is put a 4-40 screw in and then I can see if the screw is centered in the hole in the beam at the time of installation.  I have to adjust the flange position on the back side to achieve this.

I also found that many need to have a tap run thru them to clean up the threads.  Maybe I need to find a better blind nut.

I hate to point out any inconsistencies with Du-Bro mfgd products especially since they have been a reliable supplier for so many years but this blind nut issue has been ongoing for quite awhile now.
It isn't like they don't know about it.....they DO!
I'm afraid you are correct in needing to find a useable blind nut.

[Motorman]

Well, we all have our pushrod methods, there's more than one way to do things of course. I've been using Dubro 4-40 blind nuts for decades and I've never seen the problems you guys are talking about. Going to go check a big bag I've got for defective threads. For profile fuselage engine mounting I've been making my own brass blind nuts with 1/2" diameter to prevent wood crushing.

Motorman

[Steve Dwyer]

All good points, one additional item I'd like to add is I have carefully radial scored the inside diameter of the carbon tube using a very fine sharp drill bit twisting it by hand to assure some teeth for the adhesive to better hold to.  However, after attempting to remove some excess Smith Industries 30 min epoxy once cured from the outer tube I concluded the Central Hobbies titanium fitting or a threaded rod end or hardened bolt will never come out even with or without ID scoring. The epoxy holds like concrete. Coating the OD of the tube with a light film of epoxy to prevent splitting is all I do without thread wrap or a tube collar.

To prove out the strength of the connection on an off dimension tube I was going to cut off and discard I instead attempted to break out and save the fitting. The epoxied connector did not break free where inserted into the tube but next to the fitting where to tube was unfilled and hollow. And yes the titanium connectors have gotten way to pricey for my liking.

It's been a good discussion....thanks all.

Steve

[Steve Helmick]

"a guy named Ray Charles said he would take a look at them". I guess you knew then that nothing would happen? 

FWIW, the only blind nut failures I've had were Hobbico or Great Planes. Pulled the center out.     Steve