1/4 UNF Stainless Steel Turnbuckle?

[Skylark]

I’ve managed to bend my guard wire turnbuckle, per the pictures. One option is to try to bend it back straight but I’d prefer to replace it, if possible. (Ideas to straighten it welcome, too).

My first assumption is that it would be M6 as these are cheap and readily available. Boat is 2013, French made.

To my surprise, it appears to be 1/4 UNF and I’m not having much success via Google.

At a minimum, I need a 1/4 UNF left hand thread, fork. Length from end of thread to pin hole centre is about 3 inches. Pin is 1/4 inch, fork gap is 7.5mm.

Any ideas?

 

[[70521]]

Got any riggers nearby?

I use Allspars in Plymouth, quite far from you, and their service is outstanding. Might be worth a call.

 

[earlybird]

I'd think that a direct spare will be like proverbial rocking horse droppings, but best of luck, you might be able to cannibalise from a new, complete unit
It will straighten IMO with a well mounted vice , a piece of tube a neat fit over the threaded section and a bit of care. A drilled split holder to go close to the fork would be useful to support the threads there. Heat will be a great help, red heat, but that means some final cleaning up with very fine abrasive paper and repolishing if you're fussy.

 

[Tranona]

While the turnbuckles are dimensioned in mm pretty sure the threads are imperial. See here s3i.co.uk/turnbuckleClosedForkFork.php

 

[Skylark]

While the turnbuckles are dimensioned in mm pretty sure the threads are imperial. See here s3i.co.uk/turnbuckleClosedForkFork.php

Thank you. I did find that website in my search but dismissed it. I struggled to reconcile why they charge £35 for 1/4 inch compared to £5 for widely available M6 version ?

I may have to think again.

 

[Skylark]

I'd think that a direct spare will be like proverbial rocking horse droppings, but best of luck, you might be able to cannibalise from a new, complete unit
It will straighten IMO with a well mounted vice , a piece of tube a neat fit over the threaded section and a bit of care. A drilled split holder to go close to the fork would be useful to support the threads there. Heat will be a great help, red heat, but that means some final cleaning up with very fine abrasive paper and repolishing if you're fussy.

Thank you, I’ll probably follow this route. I’ve asked an ex-work colleague, a metallurgist, for his advice regarding heat and subsequent strength etc.

 

[Skylark]

Got any riggers nearby?

I use Allspars in Plymouth, quite far from you, and their service is outstanding. Might be worth a call.

That’s a good thought, I’ve sent the picture and a quick note to my rigger (based Edinburg but supports my Clyde marina).

He replaced my headsail furling drum and forestay last year. I remember him saying that my boat had odd fitting / sizes. Maybe it was built with the contents of the bin ends on a Friday afternoon ?

 

[MikeCC]

Threaded forks are available separately. Eg Blue Wave distributed by Proboat. RRP is around a tenner, so should be worst case expense. Theirs is 68mm from split pin hole to clevis pin centre.

 

[ean_p]

I’ve managed to bend my guard wire turnbuckle, per the pictures. One option is to try to bend it back straight but I’d prefer to replace it, if possible. (Ideas to straighten it welcome, too).

My first assumption is that it would be M6 as these are cheap and readily available. Boat is 2013, French made.

To my surprise, it appears to be 1/4 UNF and I’m not having much success via Google.

At a minimum, I need a 1/4 UNF left hand thread, fork. Length from end of thread to pin hole centre is about 3 inches. Pin is 1/4 inch, fork gap is 7.5mm.

Any ideas?

View attachment 136806View attachment 136807

Are you sure that's UNF.........the tread pitch doesn't look sufficiently fine.......or maybe I'm losing my eye for such things...?

 

[penberth3]

Thank you, I’ll probably follow this route. I’ve asked an ex-work colleague, a metallurgist, for his advice regarding heat and subsequent strength etc.

Don't do it. Seriously, I wouldn't attempt to straighten it. There's a good chance it will fracture at the threads. Even if there's no obvious crack it could fail later, and you don't want to risk that, do you?

 

[Zing]

Allspars. I’ll second that previous suggestion. Likely to be proper stuff. Not all stainless steel is equal.

 

[savageseadog]

When I made enquiries with Stalok they told me that their rigging screws were left and right hand threaded BSF. I'm not saying that's the case with the OP's example.

 

[Skylark]

Are you sure that's UNF.........the tread pitch doesn't look sufficiently fine.......or maybe I'm losing my eye for such things...?

Try Specsavers Yes, it definitely is 1/4 UNF. My cheap and cheerful metric thread gauges suggests that its 0.9mm pitch (M6 is 1.0mm). 0.9mm is very close to 28 tpi, UNF. My final test was to try a 1/4 UNF bolt, from my Triumph Spitfire spares box.