# Help with M3 turnbuckle info.



## GiantScale (Sep 12, 2002)

This is a bit off topic because Im not using this on a rc car. But I hope someone might help me find a steel turnbuckle with M3 .5 pitch threads and the shoulder must be at least 1/8" dia. I need at least 20mm of thread length. And about 15mm of shoulder length.

Does this exist? Or will I have to try to thread a 1/8 steel rod?


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## MIKE VALENTINE (Mar 12, 2002)

I don't think your going to find 20mm of threads, from any RC turnbuckle with a 55mm total length. can you live with the ends being threaded the same, or do they have to be left and right handed threads? Can you use an M6X1 thread instead of the M3X.5?


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## GiantScale (Sep 12, 2002)

Thanks Mike.

Here's the project. Its a micro rigger boat powered by a norvel AME .061 R/C engine. The engine prop screw is M3 .05 with a 1/8" shoulder but its not long enough to mount a custon flywheel and then a octura flex hex used to tighten a .098 flex cable which drives the prop. I was told car turn buckles might work so I asked here.

I do need at least 20 mm of thread. And 15 mm of .125 shoulder to fit the flex hex.

I tried to thread a 1/8" steel rod. But the Hanson die wore out after about 1" of work and broke the rod. 

Now Im looking for a titanium nitride coated die.


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## MIKE VALENTINE (Mar 12, 2002)

Can you post a picture of the parts your having issues with, maybe I can help with a solution. You may need to find a local machine shop to make one for you.

Try www.mcmaster.com and type in Part Number 91290A137. This may work, but it doesn't specify what the no threaded dia is.


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## JH Racing (Apr 22, 2005)

GiantScale said:


> Thanks Mike.
> 
> Here's the project. Its a micro rigger boat powered by a norvel AME .061 R/C engine. The engine prop screw is M3 .05 with a 1/8" shoulder but its not long enough to mount a custon flywheel and then a octura flex hex used to tighten a .098 flex cable which drives the prop. I was told car turn buckles might work so I asked here.
> 
> ...


Did you try AeroMarine in Seaford,DE


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## GiantScale (Sep 12, 2002)

Thanks guys. I did look at Aeromarine but they deal with larger boats.

Here's a pic of the prop screw. I need the same thing but the threaded area needs to be twice as long. The shoulder on it is .125

All of the M3 shouldered screws Iv found have a .118 (3MM) shoulder Mike. Im not sure how .005 of slop would effect vibration. I wish this engine had a stud instead of the screw because I will need some luck to keep the flywheel and flex hex all centered.

Here is a pic of the flex hex. http://www.rcgroups.com/forums/showthread.php?t=527964


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## MIKE VALENTINE (Mar 12, 2002)

I think your headed to the machine shop.


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## Bill Johnson (Jul 12, 2004)

After looking for a few minutes, 91287A028 (McMaster-Carr) is the longest one I found which is 40mm, and they scale down in 5mm increments. They are Stainless Steel, which would be good for Marine applications, but with this selection, the head of the bolt is to shallow, you could have a nut Tig or Heli Arc Welded to the top of the bolt, and then the sides/weld Ground flush to achieve the Head height your looking for on the flex drive.......


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