Power Press Break Questions

I've recently started using the press break at work. This thing is old, worn out and very difficult to get set up to get decent repeatable bends. Aluminum is all ours every sees, and not very thick either. I have some questions for those professionals here who use one.

My boss says that even new CNC press brakes can be troublesome to set up. He says that they often need shims under the dies or on the back stop to get good setups. Someone please tell me that this isn't so. I can't believe that a brand new break press would be like that.

My boss also says that the center of a part will always bend different than the ends, and therefore you need to shim accordingly. True?

Is there an online tutorial for press break setup? I've been going by the seat of my pants and have been very frustrated. Today I literally spent an hour on setup to bend 8 pieces of aluminum into "L" shapes the long way. Even after that I had to manually adjust some of them at the bench afterwards.

Lane

Reply to
Lane
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I know there are two schools of thought on the beds of press brakes. Some manufactures machine the bed under the dies flat. Others machine it with a crown. Several years ago I saw a unit that had a crank handle on the bolster under the bottom die. By cranking the handle the operator could in effect crown the bolster under the vee die. For bottom dies most sheet metal shops use individual bottom dies that have a key protruding that matches the keyway machined in the bolster block. In shops doing plate work four way dies are more common. They are not as versatile when making complicated bends. Your boss is correct in that a vee die set flat will produce a tighter bend at the ends than the middle when bending sheet longer than say four feet. I started on an old verson built in 1947. The crank had about a 1/8 slop on one end. You learned how to bend on that unit. My next machine was a new Acushear 250 ton hydraulic. It was a dream after using that worn out old mechanical. The manual on that new machine called for four inch wide shm stock stips under the main bolster to create the crown. I don't like that method since I have done a lot of right hand/left hand box units and you have to shim your dies just in from the ends with these fancy bends. I used to do door panels: eight separeat die changes and fifteen hits. I found some of the best shim material is the strapping that your sheet often is wrapped with. You will need many lengths ranging from six feet to a foot long. If I was to bend 1/8th material in a one inch vee die and the sheet was say six feet long I would use two three foot strips, one und the front and one under the back of the bottom die. After my fist bend I would check the angle along the length. I might have to add two one foot pieces in the center area. e-mail me if you have other questions. There are several tools you can make to speed things up. Randy

"Lane" wrote in message news: snipped-for-privacy@comcast.com...

Reply to
Randy Zimmerman

Thats the way it is shim here and shim there .New brakes have pistons in the middle . The trick is to bend all your stuff on the same stet up it does not happen like that . Sometime a rubber mallet will fix it Than some time i said shit this thing will be in the scrap some day. There are some dies that will bend better

Reply to
HaroldA102

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