Press Brake CNC Back Gauge

JimDawson

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We are starting on the CNC back gauge for our new (to us) press brake.

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This is Phase 1 of the design. Using only the parts and materials that we have on the shelf (plus some electronics that we had to order). The Y axis will be controlled by a stepper motor. The X axis carriages will be hand positioned for this phase. The finger height will be fixed for the moment. There will be shut height/tonnage control by CNC in Phase 1 that is not shown yet, I'm still trying to figure out the mechanics of that. The machine has a unique micrometer hydro/mechanical shut height adjustment already, I'm trying to figure out how it works and how to control it by computer. Ultimately we will have full 6 axis? control.

Working on the preliminary software now. My son and I switched rolls for this project, I'm doing all of the CAD work, and he is doing the software. He is an accomplished programmer but has never done any machine control programming, and I am struggling to learn Fusion 360. We are taking this phased approach to figure out what we really need, since neither one of us has any experience on production press brake use. And in about a week we will have a few hundred parts that need to be bent.

Here is a little teaser. My first real dive into Fusion 360. Hopefully we'll have this assembly built in the next few days.

1590525738878.png

Stay tuned........
 

JimDawson

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An update:

This is what we had to start with. The rails, carriages, and aluminum bars are from a auction buy of a few years ago. Not sure what the machine was, but it had a lot of high quality parts on it. Those are 23mm rails, about 19'' long and 16mm ball screws. Have a few more bits & pieces, including all of the servo motors and drives and large aluminum tooling plates not shown in the picture.
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This the back of the press brake and the area where the backgauge hardware will be installed. Right now it's a flat surface to store all of the electronics for the backgauge.

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Started on the gussets yesterday and due to a number of interruptions and an emergency office chair overhaul (I've only had this office chair for about 25 years, it shouldn't be breaking down so soon) :mad: I didn't get to making chips until today. I'm a bit behind schedule. :cautious:

So here is the plan

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And a tool path simulation, and a bit of playing around with Screen Movie Studio. Whoever figured out adaptive clearing for the roughing passes was an absolute genius. :encourage:


And the implementation. The actual cutting is somewhat slower than the simulation. :grin: About 1 hr 5 min. Not including the trouble shooting time I spent on the program trying to solve a problem that has been plaguing me for weeks. The computer hangs in the middle of the cutting sometimes. I thought I had it fixed a couple weeks ago, but it reared its ugly head again today. :faint: I think I finally tracked it down to a communication timing problem between the computer and the controller. Maybe I have it fixed now......... Or not, time will tell. :cautious:

3/8, 3 flute aluminum cutting end mill, 0.390 DOC, spindle speed 2500 RPM (245 FPM), 10 IPM feed, 0.040'' stepover, 0.0013'' chip load, mist coolant. Very conservative setup, but I wasn't in a hurry.

Adaptive clearing tool paths are cool, it unloads the tool for part of the cycle and allows for chip clearing, great for deep pocketing and slots. Had I set up correctly, the unloaded period would have been done at much higher speed and saved a bunch of time. But in this case I had it feeding at a constant speed in all the movements. I'll fix that on the next parts, I'm still learning.


And the pieces profiled.
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So tomorrow will be the X axis rail mount. That should be a pretty quick job, just drill & tap 9 holes, and drill & C-bore 4 others, what could go wrong :grin: Oh, I also need to drill & tap the bolt holes in the gussets.

Then get young son to fire up the Haas to machine the mount plate, it won't fit in my mill. Without interruptions, this whole job should have taken about 1 day.
 

JimDawson

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Time for an update. Been a little busy building parts so haven't posted for a few days.

First a major redesign. After reviewing the initial design we made a few changes that make more sense. And scrounged up some bits & pieces to make the Z axis to raise and lower the fingers. Not sure if this is needed, but in some of the videos some press breaks have adjustable height fingers. We had the parts on the shelf so why not use them.

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So we start out with a 25x13x1 chunk of MIC6 aluminum plate, and face it.

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Then slice off one chunk that will be used for other stuff
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Then dig around in what's left to find the parts, while turning a perfectly good chunk of aluminum into chips. About 45 minutes of machining time.
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And the roughed out parts. Those two tiny holes on the motor mount (center left) are 2-56, power tapped on the machine. The surfaces look rough in the picture, but it's really smooth as a baby's bottom.
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Base frame assembled
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The base frame bolted in place.
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The basic X and Y rails set in position. Eventually the X cars will be under computer control, but for the moment will be manually positioned.
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The Z axes are powered by NEMA 17 steppers. The lead screws and nuts still need to be installed.
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Need to use some flat head screws in the Y mount. The cars hit the screws sticking up, and there is not enough material to counterbore them.
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The Y home limit switch mount was machined into the motor mount. The gear will come off of the motor and will be replaced with a coupling. The Y axis is powered by a NEMA 23 stepper, we have a bunch of them on the shelf.

We have a lot of stuff on the shelf. :grin: We'll have about $100 in mechanical materials purchased for this project. About $1000 in controls and computer hardware.
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Stay tuned for more......
 
Last edited:

Boswell

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I love seeing your creations Jim, along with great pictures and good explinations.
 

Lo-Fi

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That's my kinda project. Keep em coming!
 
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