Sometimes you don't know whether to laugh or cry
- Glenn Schroeder
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Sometimes you don't know whether to laugh or cry
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.
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.
"On the days when I keep my gratitude higher than my expectations, well, I have really good days."
Ray Wylie Hubbard in his song "Mother Blues"
Ray Wylie Hubbard in his song "Mother Blues"
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
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 lolGlenn 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.
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
They are just boat anchor.
You're thinking too much.
You're thinking too much.
- jcapriotti
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Re: Sometimes you don't know whether to laugh or cry
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.
Jason
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
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.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.
- Glenn Schroeder
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Re: Sometimes you don't know whether to laugh or cry
There's something I don't often get accused of.
"On the days when I keep my gratitude higher than my expectations, well, I have really good days."
Ray Wylie Hubbard in his song "Mother Blues"
Ray Wylie Hubbard in his song "Mother Blues"
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
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.
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.
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
Quality Control rejected them and the options were: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.
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.
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
The repair involve welding which could affect material properties and strength.
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
What's your point?Frederick_Law wrote: ↑Wed Dec 14, 2022 10:47 am The repair involve welding which could affect material properties and strength.
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
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.
Not saying your parts need to go through that.
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
Of course it can be weaker. The original design can also be 'stronger' depending on what the reparation consists of.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.
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.
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
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".
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".
- Glenn Schroeder
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Re: Sometimes you don't know whether to laugh or cry
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.Frederick_Law wrote: ↑Wed Dec 14, 2022 11:56 am That and I don't think welding a cracked rebar is legal, LOL
"On the days when I keep my gratitude higher than my expectations, well, I have really good days."
Ray Wylie Hubbard in his song "Mother Blues"
Ray Wylie Hubbard in his song "Mother Blues"
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
We moved onto repairing cracked, fractured parts. So welding is the only way to repair.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.
Assuming a tight bend rebar could crack and the customer might just weld it.
Yes, I'm thinking too much
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
One time, the mill crashed and bend the ball screw.
A few days later someone is straightening it on the press.
A few days later someone is straightening it on the press.
- AlexLachance
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Re: Sometimes you don't know whether to laugh or cry
12 inches thick, now that's some real thickness, gotta be crazy to manipulate that stuff.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".
- Frederick_Law
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Re: Sometimes you don't know whether to laugh or cry
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
1000lb is light. 10000 is normal.
Steel toe boot is required but I don't it'll help LOL