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  #1  
Old 01-19-2021, 03:44 PM
berntd berntd is offline
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Default Bending brake not bending crisp edges - why?

Hello
I have a 4ft bending brake (a pan brake) that I use to bend panels for my restoration projects. i tis identical to the one pictured but I have mine on a stand.

It is essentially a chinese machine that I purchased some years ago.

It has never really produced sharp crisp bends. they always appear a lot rounder that I need.

I have the clamping blade edge set to about 1 metal thickness behind the bending line.

What can I do to fix that?

s-l1600.jpg
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Last edited by galooph; 01-20-2021 at 03:43 AM.
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Old 01-19-2021, 04:48 PM
Gareth Davies Gareth Davies is offline
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If youíve got the blade set back, is the folding arm set level with the lower clamping surface or is that set down one thickness as well? I always have the blade level with the front of the lower surface and gap the folding arm. What material and what thickness are you struggling with? Are the blades sharp cornered or have they got a radius on? They might just need skimming to get those crisp folds. Another thing to check is how much clamping force youíre using. Lots of potential reasons why itís not performing as youíd want it to.
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Old 01-19-2021, 05:31 PM
berntd berntd is offline
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Quote:
Originally Posted by Gareth Davies View Post
If youíve got the blade set back, is the folding arm set level with the lower clamping surface or is that set down one thickness as well? I always have the blade level with the front of the lower surface and gap the folding arm. What material and what thickness are you struggling with? Are the blades sharp cornered or have they got a radius on? They might just need skimming to get those crisp folds. Another thing to check is how much clamping force youíre using. Lots of potential reasons why itís not performing as youíd want it to.
Thanks. I don't use it very often but every time I do, I get annoyed that I have to hammer the edge tighter.

I bend 18gauge (1.15mm) cold rolled steel mostly. sometimes the odd 16 Gauge (1.6mm). Often short pieces up to 10" (250mm) long

The bending surface (movable arm) is level with the clamp surface/bed.

I usually have a scrap piece of same gauge on the right side on the clamp when I bend short pieces on the left.

I will have to check on your other suggestions.

Regards
Bernt
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  #4  
Old 01-20-2021, 03:48 AM
skintkarter skintkarter is offline
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Bernt, sorry mate, it's the machine - you would be lucky to do 4' of 22 gauge with it (0.80 mm). A decent machine for up to 16 gauge steel probably weighs 6-800kgs. Your machine will be flexing everywhere unfortunately. Raffle it off and buy a decent second hand machine. Machinery house do have some decent 4' gear, but their Kleene type folders are $4k+. A wise old bugger years ago said to me that you buy a lathe by the tonne - same goes for sheetmetal gear unfortunately. If you try folding lighter gauges they will no doubt be crisp. You could try setting the top back to 2x or 3x material thickness, but I'm not sure it's going to help on over 20g.
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Old 01-20-2021, 05:09 AM
Jaroslav Jaroslav is offline
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Bernt. Take a photo of the detail of the bending edge.
This machine should bend 1.5mm sheet metal. Of course he needs to adjust.
Yes, the cast iron professional machine is not in dispute about that.
I had some bad home-made machines in my shop that we bought for consideration when someone bought a machine from us. After our modifications, some other customers still use them today. That's enough for what they do and for the little money. No stress.
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Old 01-20-2021, 10:59 AM
John Buchtenkirch John Buchtenkirch is offline
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Adjust your upper beam forward so thereís room for only 1 metal thickness between the beam edge and the bend line (the split between the lower beam & the front apron). Remove the bumper bar from the front apron. Try bending a sheet. If it bend tight at the ends and soft in the middle your brake is springing and canít handle the gauge you are attempting. Just looking at the height of your upper and lower beams Iíd say your brake is very light and rated only for very light gauges. ~ John Buchtenkirch
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