cant bend stainless?

I

IanP

Member
Joined
4 May 2011
Messages
30
Location
Ireland
Visit site
I need a chainplate like this. As you can see they are angled inboard and forward. hole centers 50mm.
I actually have two suitable for port side, and i need a starboard one.
I think I read somewhere on this forum that "you can only bend stainless steel once" Perhaps in a posters signature.
Is it true? I was thinking that if I could bend the spare port chainplate, then it would be suitable for the starboard side.
Would that weaken the chainplate too much? even if I heated it?
I have searched the internet for something similar. The nearest I could find was angled inward , but there was no forward angle to it. And the hole centers only 40mm.
http://marinestore.co.uk/PBBW-408518.html only £15
I have had a quote for making one up. 80 pounds, plus vat plus postage. Probably would cost me 120 total.
So, Is it really not possible to bend my spare one? Anyone know where I might buy such a chainplate? Any other Ideas?
 
You call it a chainplate, but it just looks like a bent U-bolt to me? What sort of boat is this on? In what aspect is it asymmetric?

(don't seem to be able to blow up the thumbnail, so probably missing something)

Vic
 
Last edited:
Vic. Boat is elizabethan 23. yes its just a big ubolt, or a-bolt. Bolted through the deck, to reinforcing pads under the deck. It is angled inboard towards the mast. And it is angled forward also. This is maybe a better picture to give you an idea of the angles.
 
Last edited:
IanP said:
So, Is it really not possible to bend my spare one? ?
Click to expand...


If that's the spare, it looks like it was bent from a straight bar to make it. A slight bend done over a radius, not a vice jaw, I would have thought should be okay. But it does depend on the material, and what has been done to it,
so we over no warrenty.

Brian
 
Bending Stainless steel

I will be brave here and say yes bend it. That is what I would do if you can heat it up to dull red that will make it easier to bend and perhaps reduce chance of stress cracks. The bend forward is very slight as I see it and perhaps could be ignored. ie a bend back wards is not going to change things much.
Now I am aware that this component is critical to integrity of the mast and rigging but I suspect a welder will do similar to produce a copy for you. So his may not be any better than if you bend it. i susp[ect the metal of the U bolt is a lot heavier than the metal of the rigging wires and screws o naturally much stronger.
All of course open for comment and no guarantees. olewill
 
Your original will have been bent cold. Assuming it to be made from either 304 or 316, these are both very ductile but they work harden rapidly. Hence the statement that you can only bend it once, the bending hardens it locally making it difficult to re-bend in the same place. You could heat to above 723 C, i.e. to a good red heat, which would recrystallise it and remove the work hardening effects. However I suspect that the amount of bending applied is so little that work hardening is minor. I would try bending it back, as suggested using a radiused former, not just clamped in vice jaws.
 
Bending Stainless

Looking at the item I would not want to use an item such as this on any where critical if it was bent AFTER manufacture.
The bar would be bent to shape before welding! so that re-bending it would be in the area of the weld.
Chainplates( U bolts) like this have abad reputation of failing at the best of times, I would have one made by somone who knows what they are doing and make sure that the weld is pickled afterwards to prevent corrosion.

the price appears high

shop around and try fabricators that do work for the food industry rather than marine...shoud be cheaper!

best of luck
Andy
 
vyv_cox said:
Your original will have been bent cold. Assuming it to be made from either 304 or 316, these are both very ductile but they work harden rapidly. Hence the statement that you can only bend it once, the bending hardens it locally making it difficult to re-bend in the same place. You could heat to above 723 C, i.e. to a good red heat, which would recrystallise it and remove the work hardening effects. However I suspect that the amount of bending applied is so little that work hardening is minor. I would try bending it back, as suggested using a radiused former, not just clamped in vice jaws.
Click to expand...

I agree-such a small bend as to be relitivly insignificant.
 
Wouldn't it be OK to use it as it is? Obviously you would mount it facing in and it would then slope slightly back rather than forwards. I think this would be of no consequence.

I would rather do that than risk compromise it by rebending. I crossed the pond on an ancient Westerly - the only storm damage we suffered was one of these holding a lower shroud snapped - fatigue, I think. Why encourage it?
 
Thanks for the info guys. On balance I think I wont bend it. I would never be sure how much I had weakened it. The quote I got was not 60, it was 80+vat+postage to me in Ireland.Probably about 120 total.
I really dont want to pay that much for it. Every little thing I buy for renovating this boat seems to cost over a hundred. I will try davidej's idea today. I will put the spare port one on the starboard side, and try to visualise how much of an unfair pull will be on it.
If that seems to be no good, I might get the item from marinestore, even though it doesn't have the forward angle. Then epoxy the existing holes and drill new holes with 40mm centers.
Thank you all for your input and ideas.
Ian
 
You must log in or register to reply here.

Share this page

Top