Messages

201

General Mach Discussion / Re: Ebay 4 Axis USB CNC Controller?

« on: January 07, 2013, 12:06:03 PM »

I used to use the SmoothStepper.  I've lost count of how many times a change was made in Mach3 that required new firmware and/or a new plug-in for the SmoothStepper to keep things working properly, but those updates always came fairly promptly, and bug reports were always dealt with in a timely manner.  What are the chances a low-cost, no-name Chinese motion controller will get updated often enough to keep it working reilably?  How are they going to respond to bug reports, if at all?  Personally, I would not waste the money.  Spend a little more and get something with a proven track record, like the SmoothStepper.

Regards,
Ray L.

202

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 06, 2013, 12:30:37 AM »

Scott,

I don't think you quite understood what I was suggesting.  For control, the PWM is implemented purely in software, the only hardware being an external pass transistor to drive the solenoid.  Then there's just the solenoid valve itself.  An automotive idle air control valve would probably do the trick for next to nothing.  Feedback is provided by a simple potentiometer, read by a built-in A/D in the MCU.  Can't get any cheaper than that.  I'd bet the whole thing wouldn't cost $10.

Regards,
Ray L.

203

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 04, 2013, 09:57:25 PM »

You could push Light hydraulic fluid(ATF) instead of air .

Just a thought, (;-) TP

But that would require a hydraulic cylinder, pump, reservoir, etc....

Regards,
Ray L.

204

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 04, 2013, 09:43:28 PM »

Scott,

If he were to do what I suggested, using a PWM-driven solenoid valve, if he put some kind of encoder, or even just a potentiometer, on the arm, I bet he could actually control the speed of the air cylinder quite easily, with a very simple, very low bandwidth PID controller.

Regards,
Ray L.

205

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 04, 2013, 09:33:57 AM »

Steve,

Thinking about it some more, I think a solenoid-controlled needle valve driven by a simple (even software) PWM would be the way to go.  Simple to implement, and should give very good control.

Regards,
Ray L.

206

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 04, 2013, 09:18:04 AM »

The servo drive is easy enough to change speed, of course, but the air cylinders would be a bit more complicated to speed control. Anyone have some ideas on how to accomplish that?

Steve,

You have to do it be either throttling the air flow, or damping the motion.  I would think you could make an adjustable air flow valve by making a needle valve actuated by a small stepper or servo - perhaps an RC servo?  You might be able to adapt something from an automotive idle air control valve, or perhaps even a fuel injector and a simple PWM control. 

Regards,
Ray L.

207

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 02, 2013, 05:17:39 PM »

Steve,

Smooooooooth as a new baby's you-know-what.  Nice!  Can't wait to see it running full-speed!

Regards,
Ray L.

208

General Mach Discussion / Re: New years resolution

« on: January 02, 2013, 01:36:34 PM »

Sometimes, it seems to boil down to just plain laziness.  I'm constantly amazed that people will go to all the trouble to make a post, and ask others to provide information that could be had by a 2-second Google search.  About once a week I see someone make a post like "Where is the website for XYZ?", when simply Googling "XYZ" will bring it up as the very first hit.

Then there are the guys that make a post asking a question, when they've already made up their minds what they're going to do, and seem to be just looking for like-minded souls.  If you point out the flaws in their thinking, or recommend a clearly more "correct", or even simpler/cheaper way of doing it, they throw up a smoke-screen justifying why they're stocking to their clearly flawed approach.

I remember when I first came across this, when I was in high school.  I worked after school at a hardware store, and we'd get people coming in all the time saying basically "I don't know anything about XYZ.  Can you tell me how to do this?".  I'd explain to them the right way to do it, and they'd listen, then say "No, you're wrong.", and walk away!  Of course, as often as not, they'd be back the next week, to ask for help in undoing the mess they'd made by doing it their own way.  Or, they'd blame it on defective parts, despite the obvious evidence the part had been majorly abused in installation....

Regards,
Ray L.

209

General Mach Discussion / Re: New years resolution

« on: January 02, 2013, 03:11:09 AM »

Geez, Terry!  What are you going to suggest next?  People should RTFM??  :-)

Regards,
Ray L.

210

General Mach Discussion / Re: Tool Sensor / Probe G31 assistance

« on: January 01, 2013, 04:59:11 PM »

OK.....  That makes no sense at all now.  You can't mix G-code and VB.  It is either G-code, OR it is VB, not both.  The first code you posted should work with the changes I suggested.  The second code you posted will not work at all.

Please post the EXACT code you are trying to run, NO CHANGES OR EDITS.

Regards,
Ray L.