Need to build Mach3 Controller - HELP

[Brady Watson]

This is a very 'touchy' subject - this Mach controller business. Fact be known, I own 3 Mach licenses, LazyCAM and a few other 'pay to play' plug-ins. I was messing with Mach before it was Mach (Master5) and it is a good piece of software. At the end of the day, it is YOUR machine, and you are 110% free to do with it as you please.

Personally, I will never run Mach on my ShopBot. SB3 is reliable, robust and has a clean, straightforward interface perfect for both new & seasoned users alike. I can run it on my laptop, just as reliably as a desktop. I have successfully run parts over 170 hours without stopping. I cannot say the same about Mach & I do my homework and build my own PCs to spec...but that's my experience with it. I still run it on a mill & 2 lathes. I tolerate it. The mill is getting converted to run SB3 with an Alpha control.

There was a brief time in history where Mach made sense because it wasn't easy to interface Geckos to a v3.x control board. With the advent of the 4G board, any advantage Mach had over SB3 for speed & resolution as the result of going from 1/4 stepping drivers to microstepping drivers, has past. Granted, there are probably a few features Mach has that would allow easy integration of some hardware (such as a PID controller for a router), but there are not many, and of those few, they probably are not 'professional duty' hardware choices. Again - a matter of preference and you afford what you can.

Let me make clear again, I really don't care what YOU run for a controller in your shop. My perspective is to 'pay it forward' and 'hook yourself up' and not shortchange yourself on the support end of things. If something goes down, I don't want to be the last guy on the support chain (and really didn't want YOU to be that guy either!) - which was my point in mentioning it in the 1st place. Also, IF you had to ever sell your ShopBot, it would be much easier and more valuable if it had OEM components all the way around. It's a little like selling a Camaro with a Ford 302 in it. Just sayin...So - just to be clear, my comments were from a place of empathy & understanding, rather than a proverbial stone breaking.

I hope you get it running soon, the way you like it, with whatever hardware you can afford.

-B

[bruce_taylor]

I think Brady's point of view is always well thought out and candid, I really appreciate the effort he puts out to help other botter's through the maze that is cnc. I find the support that shopbot offers is PRICELESS-PRICELESS. When your in the middle of cutting a job and your machine has a problem and you can call and get someone as knowledgeable as Frank,Ryan or now Gary Campbell, that support has saved me more than once . When it stops working right and you don't know why, a simple phone call helped solve simple issues, I was able to continue my path to make whatever it was. You may put a post out looking for the parts you need, you never know botters are continually upgrading and letting old parts go at a reasonable price so you could get lucky. I certainly wish you well with your project.

[gc3]

I think Brady's point of view is always well thought out and candid, I really appreciate the effort he puts out to help other botter's through the maze that is cnc. I find the support that shopbot offers is PRICELESS-PRICELESS. When your in the middle of cutting a job and your machine has a problem and you can call and get someone as knowledgeable as Frank,Ryan or now Gary Campbell, that support has saved me more than once . When it stops working right and you don't know why, a simple phone call helped solve simple issues, I was able to continue my path to make whatever it was. You may put a post out looking for the parts you need, you never know botters are continually upgrading and letting old parts go at a reasonable price so you could get lucky. I certainly wish you well with your project.

yup well said!

[richards]

Listen to Brady. Buy a used Shopbot controller that works. Don't worry about the 4G for now (unless you find one at a really good price - because you'll need to modify the 4G if you want "alpha" torque and speeds).

After you've learned to run your machine and after you know its limitations, THEN think about changing a few things to let it make heavier cuts at higher speeds.

If you decide to upgrade to the 4G model:

- Change the motors. The motors you have only have four wires exiting the case. That means that you have to wire them in the bipolar series connection. Bipolar series has great low-speed torque, but that configuration was not designed to produce speed. Buy some Oriental Motor PK296-F4.5A motors, wire them bipolar parallel and build a 3:1, 3.6:1 or 4:1 belt-drive gear box. Look through the archives and you'll see enough photos to see how a belt-drive gear box is put together. The PK296-F4.5A wired bipolar parallel with a 3.6:1 belt-drive will give you 99 in*lbs of torque, which is 20% MORE than the 7.2:1 alpha gear box is rated to handle. Resolution per step will be exactly the same because the Gecko G203v produces 2,000 per revolution and the Alpha drive produces 1,000 steps per revolution.

- Add a good 35VDC power supply to drive the motors. (A toroidal transformer runs much cooler than a standard transformer.)

- Add heat sinks to the G203v stepper drivers to keep them from overheating. The PK296-F4.5A motors pull a lot more current than the motors that you have. Heat sinking the stepper drivers keeps the heat within tolerance.

- Add opto-isolation to any digital I/O. Most digital lines toggle at 2.2VDC. In a CNC shop, with long runs of wire going to the router/spindle and to the motors, with dust extractors and vacuum hold-downs, you're going to produce a lot of electrical noise. That electrical noise has an amplitude much higher than 2.2VDC. Do yourself a favor and learn about the 4N2x series of optical isolators. They cost less than $1 each and they work wonders when it comes to reducing/eliminating electrical noise.

- Learn how to use ALL the Shopbot commands. You'll be surprised at what you will be able to do when you know what the Shopbot CAN do. Just like Brady, I had a licensed copy of Mach 3 on the test bench but I never used it on my PRT-Alpha Shopbot.

[myxpykalix]

There are far WISER guys on here technically then ME and there are some who use Mach3 to control their bot. For me the interface is confusing and I just don't like the way it is set up, but thats just me.

The problem that i see you running into, is when you have technical or software issues you have eliminated a vast pool of knowledge here and can only pull from the mach3 botters for most of your issues, and you have to ask yourself, what am I saving, or what is the major point in running mach3 as opposed to the regular shopbot software?

I think you also eliminate technical support from shopbot as i doubt they support mach3.

[richards]

Sometimes we get into the wrong state of mind when we think about a tool. The Shopbot is just a tool. Like any tool, it has characteristics that make it different from other tools. Most of those characteristics (at least to me), make it easier to use for someone who is new to the CNC world. But, like any tool, it has its limitations.

When you fight against a limitation, then it's time to decide whether another tool or modification will allow you to do the things that you need to do.

Some of us are very comfortable tearing into the electronics on a CNC machine. Some of us have the proper instruments to check signals and to verify proper operation. To us, it's "no big deal" to try different components or to custom build part or all of the controller; but as others have said, once the machine has been modified, YOU are automatically the technical expert.

One of the traps that most of us fall into is to make a wish list of things that we would like to have without knowing IF those things are necessary or what real advantage those new "bells and whistles" really provide.

A basic Shopbot, no matter which model, is an extraordinary machine. It can replace most of the machines in a typical shop and it allows a knowledgable operator to do things that he couldn't do with other tools customarily found in a typical shop.

During the years that I owned a PRT-Alpha, I resisted the urge to make major modifications, mechanical or electrical. I added 3:1 belt-drive gearboxs and then replaced them with the 7.2:1 Alpha that was offered as an update. I custom built a proximity switch interface and replaced the original proximity switches. After a while, I added a 3hp spindle and several variations of vacuum hold down systems. I replaced the original MPU on the controller board when it failed with a newer model. Other than that, the machine remained "factory fresh". It served me well during the years that I owned it, and, the last I heard, it is still serving its new owner well.

I knew my machine's limitations and more importantly, I knew MY limitations. I didn't try to make the machine do things it couldn't do and I didn't expect it to do things that I couldn't do. Other than being frustrated with excessive chatter that the geared motors almost eliminated, the machine worked better than expected. The learning curve was steep, even though I had been building and using computers since 1976. Once I learned to do my part, the Shopbot performed very well.