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A drawing just showed up in my email inbox that calls for a 10mm bend radius on Ø13mm rebar. That's just about exactly 25% of the CRSI standard. For those of you who don't work in metric, that's a 3/4" bend diameter (because rebar bends are generally called out as diameter instead of radius) on a #4 bar (Ø1/2"). The standard is 6 x Ø, so 3".

You could bend it that tight, maybe, but not without seriously weakening it. Rebar is relatively brittle compared to common structural steel, and even that isn't generally bent to a tighter radius than the material thickness.

Glenn Schroeder wrote: ↑Wed Dec 14, 2022 9:33 am A drawing just showed up in my email inbox that calls for a 10mm bend radius on Ø13mm rebar. That's just about exactly 25% of the CRSI standard. For those of you who don't work in metric, that's a 3/4" bend diameter (because rebar bends are generally called out as diameter instead of radius) on a #4 bar (Ø1/2"). The standard is 6 x Ø, so 3".

You could bend it that tight, maybe, but not without seriously weakening it. Rebar is relatively brittle compared to common structural steel, and even that isn't generally bent to a tighter radius than the material thickness.

That's someone who doesn't understand process. Has to be longer, bent and then cut to the desired length. Maybe he's trying to avoid having to pay for the excess required plus the additional operations lol

They are just boat anchor.
You're thinking too much.

We struggled with this at our factory. They didn't like us putting the bend radius on drawings for sheet metal parts because they didn't want to change the bend dies in the press brakes. The material was fracturing when they bent 7 or 10 ga steel with dies for 16ga.

jcapriotti wrote: ↑Wed Dec 14, 2022 10:00 am We struggled with this at our factory. They didn't like us putting the bend radius on drawings for sheet metal parts because they didn't want to change the bend dies in the press brakes. The material was fracturing when they bent 7 or 10 ga steel with dies for 16ga.

Having them repair every fracturing that occured helped getting the point across about the need for specific radiuses. For some reason, dies breaking seemed "routine procedure" until we got the designed radiuses put in place.

Frederick_Law wrote: ↑Wed Dec 14, 2022 9:42 am They are just boat anchor.
You're thinking too much.

There's something I don't often get accused of.

Not repair. Get QC to reject those parts.
Typical brake press are "air bend". Top die never bottom out on lower die. Top die have a typical 0.03" rad.
If you're "corning" the bend then you could fracture.
For 7 and 10ga steel, something wrong with the process.

Frederick_Law wrote: ↑Wed Dec 14, 2022 10:28 am Not repair. Get QC to reject those parts.
Typical brake press are "air bend". Top die never bottom out on lower die. Top die have a typical 0.03" rad.
If you're "corning" the bend then you could fracture.
For 7 and 10ga steel, something wrong with the process.

Quality Control rejected them and the options were:
1. scrap them and produce new ones. (And delay delivery)
2. Fix the non-complient part and have the workers comply to the procedures. (Did not delay delivery)

Option 1 delayed delivery and cost more.
Option 2 didn't delay delivery, cost less and also thought a lesson to the shop workers about proper tooling.

The repair involve welding which could affect material properties and strength.

Frederick_Law wrote: ↑Wed Dec 14, 2022 10:47 am The repair involve welding which could affect material properties and strength.

What's your point?

Repaired part will be weaker. Not all parts are allowed to be "repair". The weld need to stress relieve and heat treat back to spec.
Not saying your parts need to go through that.

Frederick_Law wrote: ↑Wed Dec 14, 2022 11:19 am Repaired part will be weaker. Not all parts are allowed to be "repair". The weld need to stress relieve and heat treat back to spec.
Not saying your parts need to go through that.

Of course it can be weaker. The original design can also be 'stronger' depending on what the reparation consists of.

The point was that having people fix their own errors lead us to figure out the real cause of the issue and then enforce proper procedure. Re-reading Mr. Capriotti's reply made me notice the distinction between the two that you were trying to make. He's working with gauge sheet metal, we're working with thicker sheet metal (From 1/8" to 3"). Repairing fractured gauge sheet metal must be hell compared to repairing a 3/8" part that had fractures in it's bends.

That and I don't think welding a cracked rebar is legal, LOL

We (previous job) had to repair 12" thick plate because getting a new one will be costly and long time.
Still cut, machine weld-prep, weld all 12". Ultrasound inspection. Stress relieve. It's a week work.
We make parts for CAT and other heavy equipment. All "repair" require approval.

Well we could put scarped part on the employee's car and let them take it home LOL
Or show them the cost and take it out of their raise and bonus if they keep making same "mistake".

Frederick_Law wrote: ↑Wed Dec 14, 2022 11:56 am That and I don't think welding a cracked rebar is legal, LOL

While I don't know about illegal, it's definitely frowned on, but did anyone say anything about welding rebar? If they did then I missed it.

Glenn Schroeder wrote: ↑Wed Dec 14, 2022 12:07 pm While I don't know about illegal, it's definitely frowned on, but did anyone say anything about welding rebar? If they did then I missed it.

We moved onto repairing cracked, fractured parts. So welding is the only way to repair.
Assuming a tight bend rebar could crack and the customer might just weld it.

Yes, I'm thinking too much

One time, the mill crashed and bend the ball screw.
A few days later someone is straightening it on the press.

Frederick_Law wrote: ↑Wed Dec 14, 2022 11:56 am That and I don't think welding a cracked rebar is legal, LOL

We (previous job) had to repair 12" thick plate because getting a new one will be costly and long time.
Still cut, machine weld-prep, weld all 12". Ultrasound inspection. Stress relieve. It's a week work.
We make parts for CAT and other heavy equipment. All "repair" require approval.

Well we could put scarped part on the employee's car and let them take it home LOL
Or show them the cost and take it out of their raise and bonus if they keep making same "mistake".

12 inches thick, now that's some real thickness, gotta be crazy to manipulate that stuff.

Moving anything there need atleast 30 minutes.
1000lb is light. 10000 is normal.

Steel toe boot is required but I don't it'll help LOL