Alternative Use of CNC Router Parts Nema 34 Rack and Pinion System

I have a few jobs coming up that require me to make thousands of feet of custom alley scraper track using an Edwards Ironworker, and there is no way I`m going to measure/mark every piece, so I started looking into options to fully automate this process. There are commerical options available, but what`s the fun in that right. I came across CNCRP Nema 34 Rack and Pinion system and it looks like it will do job.

I plan to use the R&P running parallel with a roller table. I already have the control box which I put together for a 36in brake backgauge located on the other side of the machine. Now that I`m adding twice the control I wish I wouldn`t have used my e-scrap enclosure and just spent the 300 bucks on a 24x24x8 because as you can see from the photo, its a little full. Touch screen will be mounted on an extended swivel to go to both stations. I plan on putting a few pneumatic rams to control and lift work out of custom dies that don`t punch holes. Since this will be a PLC based control I was also going to add high volume air nozzles to clean off the R&P based on cycle times or just manually via screen. (cooler than brushes)

Finally started to get parts in, and I will try to document the build and update this thread.

Features I hope to have when completed:

Full control via touchscreen (PLC Based Control System)
Jog FWD/REV with relative move
Absolute move
Semi Auto User Job Recepie (with workpiece offset)
Full Auto User Job Recepie (with workpiece offset)

Pneumatics
Lift work out of custom dies
Dual high pressure air nozzles
1 each side on pinion to clean rack based on cycle time

Progress Update

The backgauge is coming along, although it feels like it`s moving at a snails pace. I got alot of the mechanical work done and now I`m working on the electrical Aux I/O box which will interface to my main control box as well as the Ironworker and contains all the pneumatic controls. One issue I came across when assembling the motor mount was that my stepper motor shaft hit the rack clamps. I ended up having to make a motor spacer plate that raised the motor about an 1/8". Looking at the shaft length of the motors that Ahren sells compared to the Gecko 960oz/in motor that I bought, there is a difference. 1.18" motor face to shaft end on Ahren`s motor and 1.46" on the Gecko. Not knocking Ahren`s parts, there great, just a minor issue that was easily resolved. Check out the photos below. Details in photos.

Pinion Force

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To maximize the life of the parts, I wanted to set the pinion force as light as possible to meet my needs. Using a formula I found the math comes out to be:

Nema 34 965oz/in at 2:1 = 1930oz.in
1930 oz.in / .5in (Pinion pitch radius) = 3860 oz
3860oz to lbs = 241.25lbs
241.25 x .364(Seperating force for 20 deg components) = 87.815lbs max pinion seperation force needed to produce 241.25lbs.

So Pinion Force= 0.364 x Desired Work Piece Force (Up to Max 241.25Lbs)

Max Force Lbs / Pinion Seperation Force on Rack Lbs

25 / 9.1
50 / 18.2
75 / 27.3
100 / 36.4
125 / 45.5
150 / 54.6
175 / 63.7
200 / 72.8
225 / 81.9
241 / 87.815

I plan to start out at 75lbs of force which is 27lbs pinion force. The only way I could think to measure that is wrapping a cable around the pinion and using a scale, pull until the pinion comes off the rack. I wanted to be semi-scientific about it but, like a lot of things, it might come down to trial and error.

I am I full of S@#% or will this work? What do you guys do?

Brake Backgauge

Before I started building the punch push feed table, I made a 36inch acme screw gauge for the brake section on the ironworker. I built it out of 80/20. Its cheap and that part of the ironworker does not see much use so it should hold up awhile. To save money I got the cheapest aluminum blocks on Ebay that I could find and milled/bored all of the parts. Bearing blocks have recessed radial bearing on one side and thrust washer/bearing on the other. The motor was little heavy for the 80/20 at 30in so I had to make a slotted support bar to level and help support the unit.

Both gauges use the same control box, all I need to do is plug in the sensors and motor. Eventually when I get a touchscreen I will be able to auto switch between workstations, simply by selecting which station your at changing the motion profile.

I'm not a machinist by any means, I quite despise it really, but I am building it because these gauges will save alot of time and I really like the control work that's invloved. Please by kind to my design.

Progress Update

Well I got the pinion force set and found that I was overthinking the math.
Pinion Force= 0.364 x Desired Work Force(up to max).

Max Force Lbs / Pinion Seperation Force on Rack Lbs

25 / 9.1
50 / 18.2
75 / 27.3
100 / 36.4
125 / 45.5
150 / 54.6
175 / 63.7
200 / 72.8
225 / 81.9
241.25 / 87.815


Anyway, I got most of the electrical done. I found an electrical box plug that fit perfectly in the stepper motor to help keep the crap out. My E-Scrap Aux I/O box, with scrap terminal blocks, is done and tied to my main control box, R&P Gauge, and the Ironworker. I added a few relays to the ironworker tied to the up/down stroke sensors with one contact connected to where the sensors use to be and one contact as an input to the PLC (position feedback so I don't smash the punch) I'm also tied into the autocut circuit and can now control the punch with a click of the mouse. As you can see, the ironworker box is, for lack of a better word, a cluster@#$%. I added some relays but the ironworker essentially came that way; no prints, wire numbers, generally a mess. Thanks Edwards.

Well I finally got a hold of some conveyors locally saving a ton of money. I got two 10ft conveyors with 3in roller centers, 5 stands(although they don't go high enough), and 16ft of stand channel for $315.00. Would cost over $1000 delivered. The stands only go up to 24" so I have to fabricate to make longer ones. I also have to make a base with casters that extend past the center point of the backgauge which gets bolted to the side of the conveyor with 1545 80/20, so it doesn't tip. You know, it seems like everytime I save money, my workload doubles, (Control boxes, conveyor stands). Luckily labor is free right?

Well I got the other conveyor stand built and bolted to the conveyor. I'll probably have to square up the legs and either weld a piece of tubing the length of the table between the 4in square tubes or make a sliding tube bracket that I can adjust; something to keep the legs from collapsing. The rest of the 80/20 will be here this week and I hope to get everything put together and then torn apart to prime, paint, and clear coat.

As an alternative to the mechanical means of loading the pinion into the rack.....a small air cylinder works quite well and is very easily adjustable.

Nice job.....btw.

Mike

michaelthomas said:

As an alternative to the mechanical means of loading the pinion into the rack.....a small air cylinder works quite well and is very easily adjustable.

Nice job.....btw.

Mike

Click to expand...

I've seen other builds using an air ram and I have no doubt that it would work just fine.

Moved to different thread

For further updates see thread "Home Made Edwards 55 Ton Ironworker Punch Push Feed System Build Thread" in Fabrication. Going to let this one die.

http://www.practicalmachinist.com/v...r-punch-push-feed-system-build-thread-253395/