Running another cnc from shopbot control box

[allen head]

just wondering if i can run another smaller 3 axis cnc router from the shopbot control box without to much trouble or even disturbing my shopbot setup. i want to try to make a smaller unit for fun and was hoping to use the control box to run it. i will be using stepper motors. any and all info would be great!!!!

[rgbrown@itexas.net]

Allen,

There should be no problem with using the controller. I think you would need to use the 'old' style software like is used on the original Cable-Bots so you can use the "UC" command. You might need to put a new 'Load' command in the board. And, you would need to check with the kind folks who sponsor this forum to be sure your steppers are compatible with the controller.

I would get a new set of connectors and plug and unplug the motors. Let us know how it works

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

[tlempicke]

That should be a fun project! We had a full sized Shopbot and wanted a smaller machine and also a much more rigid machine so that we could do engraving and very precise work with it. We sold off the table and motors and kept the electronics.
This forum will have just about all of the information in it you will need. The PRT board will drive just about any stepper other than a four wire motor. This is because you can wire just about any of them to work in unipolar configuration.

The major caution is plugging and un-plugging things from your driver board. The whining noise you frequently hear from your machine is the board limiting current to the motor. A simplistic explanation would be that it turns the current on and when it rises to a certain level it turns the current off. Then of course since the current is below the pre-set level it turns the current on again. When you start fooling around with the wiring you take the chance that the driver will turn the current on and leave it on till smoke comes from the chip. About one good whiff of smoke is all that you get, believe me I know!

Have Fun!

[sheldon@dingwallguitars.com]

Tom, could you describe your smaller engraving machine in a little more detail.

[tlempicke]

Sheldon
It is not an engraving machine as such. That is just one of the jobs we have done with it. The table is 30 inches by 30 inches and welded out of 3 inch square steel tubing. The uprights for the gantry are also 3 inch square steel tubing. I made the "Y" axis from a piece that I found in a junkyard and re-built. It is a piece from a textile machine and I don't know what it was originally used for. The "Z" axis was made from a piece that used to be in an IBM check sorting machine.
What I wanted was a very rigid machine. Also a friend and I wanted to see just how close we could keep the tolerances as we were welding it up. As you know welding will cause steel to expand, contract and just generally squirm around.
As it turned out our table is true to within about .010 (Bragging here!) and so after it is surfaced it is no difficult trick to engrave something in the surface of a piece of aluminum or brass.
We are still far from done. I just retro-fitted new motors (More power!) and have a neat idea to use a couple of micro switches to zero the "X" and "Y" axis in a fashion similar to the Z Zero routine.
We set out to learn about these things and have really enjoyed the process. Another guy, who used to have a web site made a machine entirely out of wood.

[valensign]

Heres a Link Page to a bunch of helpful CNC pages it is very helpful for parts and motors
http://www.mendonet.com/cnclinks/

[tlempicke]

E Bay is also a very valuable resource. I have bought stepper motors, ball screws and air cylinders at very good prices.

[RonV]

I built 4 cnc machines from this site
http://www.super-tech.com
But all G-code shotware

Ron V

[violoncello@juno.com]

Here is a fantastic stepper driver board sold by Paul Brewington at www.brewingtontech.com The board includes an on-board rectifier and is cheaper (less than $150) that a Shopbot control box. I have 2 machines running with these things, powered by my original Astro power supply.

It will run 4 axes simultaneously. I use it to run my PRT32 Shopbot. Though I made the mistake of selling my original Shopbot control box. I really like the Shopbot software.

[violoncello@juno.com]

Here is a fantastic stepper driver board sold by Paul Brewington at www.brewingtontech.com The board includes an on-board rectifier and is cheaper (less than $150) that a Shopbot control box. I have 2 machines running with these things, powered by my original Astro power supply.

Paul has a board that will drive 4 axes simultaneously. I use it to run my PRT32 Shopbot. Though I made the mistake of selling my original Shopbot control box. I really like the Shopbot software.

[rgbrown@itexas.net]

John,

There are a bunch of controllers out there. All of CNC has progressed in the last few years.

Your quote, "Though I made the mistake of selling my original Shopbot control box. I really like the Shopbot software." sums it up. To run the ShopBot, one does not need to learn "G" code, the controls are logical. ShopBot does and has supplied the ability to start cutting as soon as the tool is assembled and they DO have a support staff. I have seen many try to start CNC machining only to end up confused, baffled and discouraged.

Ron