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Turnbuckle manufacture

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Danny M2Z07/01/2021 07:40:51
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963 forum posts
2 photos

G'day all.

I have decided to make some small working turnbuckles for rigging some of my model aircraft biplanes, so plenty needed in a few sizes ranging from 8mm long to 16mm long.

Body material 2024 T4 aluminium alloy (I have plenty) so have devised the following machining sequence.

1.Turn outside to turnbuckle diameter.
2. Drill for tapping size through appropriate length
3. Tap to just under 1/2 length with right hand (conventional) tap
4. Part off
5. Insert threaded rod into tapped end (to prevent collapse) and grip tapped end in soft-jaws drilled appropriately to suit diameter
6..Tap left hand thread
7. Move to mill to drill the x-;hole

My biggest problem is locating some left hand taps and dies for the holes and connector ends. I have decided to use brass for the connectors btw

Typical sizes range from 8BA or about 1mm to 2mm for the larger models.

I can mess around on my C3 minilathe with silver steel (I have both imperial and metric leadscrews, gears and threading dials} to attempt to make a tap and a die or just maybe it would be easier to just buy a left-hand tap and matching die but the respectable suppliers seem to be asking quite a bit and I would rather pay a fair price buy once than some crapola from an unknown vendor on Ebay.

All constructive comments and ideas are welcomed.

* DannY *

John Hinkley07/01/2021 08:08:45
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1310 forum posts
424 photos

Danny,

In your position, my go to source would be Tracy Tools. They list 8BA left hand hss taps at GBP12 each. I can vouch for their quality of both goods and service from experience. I dread to think what the postage would be, though.

John

Bill Pudney07/01/2021 08:46:25
609 forum posts
24 photos

+1 for Tracy Tools. You could also try Drill Service Horley. Once again the postage may surprise you!! If BA taps/dies are hard/difficult/expensive try metric, maybe M1.8 or M2.0.

best of luck!!

cheers

Bill

Martin Connelly07/01/2021 08:56:07
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2125 forum posts
222 photos

There are a couple of ways to create a working turnbuckle without left hand threads.

One is to have two right hand threads with similar diameters but different pitches. This only gives a small adjustment per turnbuckle but works for final tensioning if you have a means of getting close to the required tension some other way.

Another is to have only one threaded end and the other just a swivel. This is harder to implement at small scales but may be something to think about.

Martin C

Baz07/01/2021 09:35:54
714 forum posts
2 photos

As well as Drill Service (Horley) and Tracy Tools there is also The Tap and Die company who do a range of left hand threads.

Danny M2Z07/01/2021 23:01:39
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963 forum posts
2 photos

Thanks for all the repies people. I shall check out the various suppliers and as postage can be a factor it makes sense to buy a single die nut and multiple taps in one go, (Also handy if I break one).

I also plan to experiment with aluminium alloy tubing to speed things up a bit.

Regards * Danny *

William S08/01/2021 11:34:22
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70 forum posts
312 photos

Hello Danny

Been there, I set up about a year ago to manufacture some brass load binders/turn buckles for a neighbour who is interested in Tamiya 1/14 scale RC lorrys.

Tracey tools supplied the left handed taps and dies, I used a 8ba as its an inbetween size:

img_0067.jpg

Blanks ready for threading:

img_0068.jpg

It was an exercise for me in setting up and using the Myfords capstan lathe attachments, This was worth it to me as I did 50 turnbuckles which meant 100 "eyes"

img_3380.jpg

I used a roller box to reduce the the diameters on the body's and the "eyes"

img_3382.jpg

This tool faced the components:

img_3384.jpg

Centre drill and tapping drill:

img_3385.jpg

I made these up for threading the bodys, I used these with the lathe in standard mode, only to keep the motor running the same direction. I kept on using the quick release collet chuck though. the die was held in a tailstock die holder and used in the same way.

img_0069.jpg

This attachment was to drill the cross holes and thickness/flats, for the eyes, the "drill" is an old carbide endmill shank ground to a D bit. The jig enables the component to be rotated 180degrees to produce the the flat on both sides.

img_0070.jpg

The following images show how I made the eyes round and put a round over on the edges, done on a pantograph engraver following the template:img_3467.jpg

img_3464.jpg

img_3463.jpg

I hope that supplies food for thought, The last bit may not be any help as I am not sure on the ends you might require.

William

Danny M2Z09/01/2021 03:12:55
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963 forum posts
2 photos

Thank you very much William.

Excellent work that has given me a few ideas. The little jig for milling and drilling the flats is going to be handy for a star't.

As one of my models is a Free Flight BE2e I want the rigging to be functional and adjustable for trimming purposes, hence the turnbuckles.

Here are a few photos, more in my album BE2e

dscf3818.jpg

dscf3822.jpgdscf3820.jpg

Regards * Danny *

Howard Lewis09/01/2021 14:10:44
6040 forum posts
14 photos

Beautiful work , Danny!

Please keep us posted on progress

Howard

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