Bending 1/4" Stainless allthread

Walter A · Mar 11, 2017

Got a quick question about best grade of 1/4"-20 stainless all-thread for making a few hundred "J" hooks.

These are only 8" long but the customer wants a fairly small radius bend on the "J" so I want to avoid a chance of a fracture in the corner. He wants them to hook well to bar grating

It's not a critical part as they will only be used to hold treadplate down to bar grating on a cargo ship.

Anyone know what grade has the best chance of not cracking when bent?

Walter

guest · Mar 11, 2017

Walter A said:
Anyone know what grade has the best chance of not cracking when bent?

Walter

Can you even find different grades in all-thread? Seems like it's all 18-8, which can be 302 or 304 or something else but it's all just called 18-8 by the fastener mfg's.

Think all you can do is buy a piece and see how it handles the bend.

dave powelson · Mar 11, 2017

Walter A said:
Got a quick question about best grade of 1/4"-20 stainless all-thread for making a few hundred "J" hooks.

These are only 8" long but the customer wants a fairly small radius bend on the "J" so I want to avoid a chance of a fracture in the corner. He wants them to hook well to bar grating

It's not a critical part as they will only be used to hold treadplate down to bar grating on a cargo ship.

Anyone know what grade has the best chance of not cracking when bent?

Walter

It's not a critical part as they will only be used to hold treadplate down to bar grating on a cargo ship.

? and tightly bent 1/4-20 SS thread stock is not prone to tight, stress cracking during the bending, plus cracking thru the thread roots under stress and salt water corrosion?

? and customer isn't aware of or doesn't like the cost of readily available clip systems used by tread mfg's. to secure the tread/grating?

? and failure of grating hold downs, used to support people on overhead areas on cargo ships is not critical or any safety issue?

? and your description of this attachment is in conformance with BuShips, etc.--relevant ship construction codes?

Walter A · Mar 11, 2017

guest said:
Can you even find different grades in all-thread? Seems like it's all 18-8, which can be 302 or 304 or something else but it's all just called 18-8 by the fastener mfg's.

Think all you can do is buy a piece and see how it handles the bend.

Yes stainless threaded rod is available in at least 18-8 and 316. Buy a piece and do a bend test is a novel idea. If nobody else has hand on knowledge I might have to do that.

Walter

Walter A · Mar 11, 2017

dave powelson said:
It's not a critical part as they will only be used to hold treadplate down to bar grating on a cargo ship.

? and tightly bent 1/4-20 SS thread stock is not prone to tight, stress cracking during the bending, plus cracking thru the thread roots under stress and salt water corrosion?

? and customer isn't aware of or doesn't like the cost of readily available clip systems used by tread mfg's. to secure the tread/grating?

? and failure of grating hold downs, used to support people on overhead areas on cargo ships is not critical or any safety issue?

? and your description of this attachment is in conformance with BuShips, etc.--relevant ship construction codes?

1 - I really do not know how much fracturing to expect which is why I asked if anyone had experience.
2 - Needed length is not standard so standard J-Bolts in stainless is not an option. Why would I want to send customer elsewhere anyway.
3 - As I stated the J-Bolts hold treadplate on top of grating as a cover while other deck repairs are going on. Gratings are welded in place and I guess they do not want crap falling thru the grating while the deck is being worked on?
4 - Suitable for temporary measures and already cleared by the port engineer.

I take it that you too do not have any experience with bending stainless threaded rod?

Walter

Walter A · Mar 11, 2017

I have to apologize. I really tried to put up a post with a simple enough question and enough details to convey the purpose.

Apparently I did not include enough detail to get an answer.

So...
This is one of many jobs I have done over the last 15 years for a local Marine repair business. This particular request is to make some J-bolts to hold down some temporary treadplate covers that will be attached on top of some deck openings currently covered by welded in bar grating sections.

The ship is a tramp freighter in a local yard undergoing repairs. The J-bolts are temporary while the ship is in the yard.

Stainless threaded rod in 1/4"-20 is available in common grades of 18-8 and 316 from my local fastener house. Yes, I can buy a length of each and do some test bends but since it's Saturday evening and the fastener house does not open counter sales until Monday morning I figured to save some time and ask the forum if anyone knows from experience.

One more thing. If this was for a permanent part I would not be using all thread and the material I use would be certified and the finished product pull tested.

Anyway... That's the rest of the story. Hope it's enough to attract someone who actually can answer.

Walter

Bondo · Mar 12, 2017

I install Stainless platforms and I don't use 304/316 stainless all thread. All 400x series, I can't remember what grade exactly. It's magnetic but it doesn't matter. It's stronger and threads are more resilient to damage.

With that said, I highly doubt any stainless 1/4" all thread will handle being bent at a tight angle without breaking. 1/4" has a 0.160 base thickness which is nothing when you bend it. Your best bet is to either bend them up and run a mig bead all the way around to reinforce it or to bend 1/4" solid and use a piece of all thread welded to it using a all thread coupler welded to both sides.

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gbent · Mar 12, 2017

Could you bend 1/4 rod as required and then thread in a lathe using a die head?

Walter A · Mar 12, 2017

Bondo said:
I install Stainless platforms and I don't use 304/316 stainless all thread. All 400x series, I can't remember what grade exactly. It's magnetic but it doesn't matter. It's stronger and threads are more resilient to damage.

With that said, I highly doubt any stainless 1/4" all thread will handle being bent at a tight angle without breaking. 1/4" has a 0.160 base thickness which is nothing when you bend it. Your best bet is to either bend them up and run a mig bead all the way around to reinforce it or to bend 1/4" solid and use a piece of all thread welded to it using a all thread coupler welded to both sides.

Sent from my 2PS64 using Tapatalk

Thanks for the information on the 400 series stainless. I have not worked with it much and never where I had to bend rods.

Walter

Walter A · Mar 12, 2017

gbent said:
Could you bend 1/4 rod as required and then thread in a lathe using a die head?

That's my alternate plan. Only the longer straight needs threads so I would have to set up my little Logan turret with a geometric head and cut-off. Bending would be 2nd operation. The only reason I am looking to bend allthread is the customer's need of less cost for a temp install.

Walter

adama · Mar 12, 2017

If its just tempory why not just use the commonly avalible steel J hooks? they will hold up fine for a good few months???

Larry Dickman · Mar 12, 2017

I gave up on trying to bend allthread back when I was 16. Why? Because it doesn''t work. If it's not cracked today, it will be tomorrow. Bend it first, then thread it.

Chip Chester · Mar 12, 2017

These guys get pretty close.
http://www.bosunsupplies.com/J-Bolts/
If they won't do a "special", you might be able to get there with a coupling nut.

Chip

Walter A · Mar 12, 2017

adama said:
If its just tempory why not just use the commonly avalible steel J hooks? they will hold up fine for a good few months???

I would use plain steel but customer rejected the idea. They would accept galvanized. I can understand. They did a similar one last year and made some plain hooks in their shop. Even with a coat of zinc rich paint enough nuts had rusted to where they twisted a few off in removal. I guess that triggered a below deck search for the remaining part.

I have looked for a "off the shelf" J-Hook with same dimensions (1/4"-20 x 4" Thread on 7" long leg x 1" short leg) and could not find. Either it's not a standard or most likely I really stink at doing a good search.

All in all I will be doing this simple job by either bending threaded rod or threading and bending. Since it's the weekend I just thought I would throw it out to the forum to try for a few ideas.

I do appreciate those who took the time to answer.

Walter

Chip Chester · Mar 12, 2017

J-Bolts w/ nuts, Stainless steel 18-8, 5/16"-18 x 7" - Bolt Depot

3.19 each, qty 100

Only problem is it's 5/16-18 instead of 1/4-20.

(I'll send you a bill for the 4 minutes of search time.)
Chip

Walter A · Mar 12, 2017

Chip Chester said:
J-Bolts w/ nuts, Stainless steel 18-8, 5/16"-18 x 7" - Bolt Depot

3.19 each, qty 100

Only problem is it's 5/16-18 instead of 1/4-20.

(I'll send you a bill for the 4 minutes of search time.)
Chip

Too bad they are not 1/4"-20. I already bent up a 5/16"-18 from mild steel and give to them Friday to test fit. Unfortunately they need 1/4". Good site though! I bookmarked it.

Walter

Ries · Mar 12, 2017

if you bend em hot they shouldnt crack.
Set up a line of a hundred of em on a steel workbench, get one guy to heat em, one at a time, with an oxyfuel torch, the second guy picks up each one, bends it, drops it in a quench bucket. Bending will go faster hot, and quenching will normalize the SS and mean minimal rust.
Remind em they will want to paint anti-seize on the threads before using- mild steel nuts may rust on, but stainless nuts on stainless all thread will gall, and a percentage of em will lock up.

Walter A · Mar 12, 2017

Ries said:
Remind em they will want to paint anti-seize on the threads before using- mild steel nuts may rust on, but stainless nuts on stainless all thread will gall, and a percentage of em will lock up.

And gall in a blink of an eye they will. I will remind them. Also plan on air bending in my small Chicago press brake but there in no reason that can't be done hot.

Thanks Ries!

Walter

Chip Chester · Mar 12, 2017

If you can find an OEM supplier of battery hold-down bolts, they are bendably-close to J-bolts, usually have rolled 1/4-20 threads, and often available in stainless.

Chip

Sea Farmer · Mar 13, 2017

Reis' suggestion of antisieze on the nuts is excellent. I confront this on boat and trailer and various other gear constantly. Here are a few other suggestions for threaded fasteners exposed to salt water or salty air.

1) use square nuts. McMasters has them in galvanized,. More meat on them, and even if they start to rust a wrench takes a stronger grip. If McMaster's product doesn't suit their needs, easy as pie to make from square stock, and you can make them as thick as you like. I bought 5C square collets just for this purpose. Paint with ZRC afterwards, and use anti-sieze.

2) antisieze protects the threads inside the nut, but another troublesome area is the bit of threaded fastener that remains uncovered after the nut is threaded on. Antisieze may not stay on it, and makes an awful mess if rubbed against. Cover that threaded projection with something so the nut doesn't jam on the rusted threads when removing the nut. Various things I have used include: cheap grease protected by plastic bolt caps from either McMaster or my local hardware store, rattlecan rubberized undercoating from NAPA, or in a pinch, any kind of rattlecan paint, both of which are sprayed on the protruding thread after the nut is tightened. No need to remove the paint when you want to twist the nut off, it'll cut right through.

An alternative to antisieze is the weakest grade of Loctite, though it may be too strong for 1/4-20 nuts to twist off easily.

My go to brand of zinc paint is ZRC ZRC Worldwide - ZRC Worldwide which I get at my local welding supplier. Local company too

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