Messages

631

General Mach Discussion / Re: SERIOUS jog problem!

« on: May 25, 2013, 07:32:22 PM »

Hood,
I replaced the keyboard with a usb keyboard. Put it in step jog mode, hold shift to make it constant then press an axis direction. It jogs fast. Release the shift key while the axis is still moving, then release the axis key. The axis continues moving with no keys pressed! Scary, does this on all axis. Just waiting for a big expensive crash.

Gary H Lucas

632

General Mach Discussion / SERIOUS jog problem!

« on: May 25, 2013, 03:06:16 PM »

Working with my mill today, trying to teach my grandson how to jog the machine around and pick up edges. He knows how to do it on a manual mill. He was jogging the x axis in rapid and it wouldn't stop, it ran all the way to the end limit!  I looked into it further and here is what i discovered.

Using the jog pendant brought up by the Tab key. Jog mode set to Step. Use Shift to override step mode. Press an axis key and the axis rapids.  The fun starts when you want to stop.  If you happen to release the shift key before releasing the axis button the axis keeps right on going unless you hit E-stop!  This is completely repeatable and works with all axis.  I'm using mach3 version .066. I am wondering if it my logitech wireless keyboard is the problem. The machine is extremely well shielded with metal enclosures and every motor and control cable properly shielded. Haven't seen any glitches at all.

Can someone try duplicating this problem as described above? I'll try a wired keyboard to see if that is different. This is real machine killer!

Gary H. Lucas

633

General Mach Discussion / Re: Improving mill safety

« on: May 24, 2013, 10:29:41 PM »

Does anybody know how to disable the arrow keys on the keyboard for jogging?  That would be a big help immediately.

Gary H. Lucas

634

General Mach Discussion / Re: need some help with a programming question

« on: May 24, 2013, 10:17:21 PM »

Doing it in rapid could be a real problem. I am not sure what Mach3 does, but on a Fadal a diagonal rapid where the X and Y moves are not equal has the shorter axis finishing its move first, then the other axis continues moving until it finishes its distance.  So instead of a straight line you get a dog leg.  Now apply THAT to every move along your curves!  "Oh yeah that rapid will clear the clamps in a straight line. Oh crap the dog leg goes through the clamp!"

Gary H. Lucas

635

General Mach Discussion / Re: g41 - Tool Compensation Help

« on: May 24, 2013, 10:03:49 PM »

If I remember how I used to do this, its been about 15 years.  For the lead in move I'd just subtract about 0.010 from the X or Y of the G0 move after the G41.  Then after the G0 I'd finish the distance by doing and X or Y G1 0.010 move.  At this move the tool will move over then advance the 0.010, putting the edge of the tool on the cutting line, before plunging in the Z direction.  I like to put all the cutting moves in a subroutine too.  Then I can make a roughing cut, change the tool diameter and make a finish pass along the same path, after pausing to measure the part.

Gary H. Lucas

636

General Mach Discussion / Improving mill safety

« on: May 21, 2013, 09:17:41 PM »

I have finally gotten my machine which I call the Ifactory running.  I have also take a little paying job to run with my grandson who is nine.  The job is to drill 3  thru holes and machine 3 hex pockets in 200 2" diameter polypropylene wheels.  I have a chuck mounted to the machine table, and all the work gets done with 1 tool a 1/8" end mill.  I already did a sample part and got the customer to approve.  Mechanically the machine is very safe. Hard limit switches on all axis that cut off all power and also dumps the DC power supply to the drives.  The whole machine has an enclosure with 3/16" clear plexiglas on two sides with door switches that stop the spindle and all motion. There are two hard E-stop switches too. So the job is mount a wheel in the chuck, close the doors, press start, remove the finished part and deburr a little.  So this is safe for my grandson, but for the machine not so much.  He could easily destroy it!

I find the jogging to be quite dangerous.  There are a couple of reasons.  My keyboard is very compact, and it is real easy to lean on the arrow keys accidentally. If jog is active, away it goes.  In step mode jogging the defaults are 1, 0.1, 0.01. 0.001.  IF you are working in metric that is kind of okay.  In inches however that 1.0 is a machine killer!  It would be really nice if there were two jog step tables, one for inches, one for millimeters.  I'd also like to disable jogging from the keyboard altogether.  Using Tab to bring up the jog pendant is far safer. Then I'd like to do away with the mode switch between steps and continuous.  Needing to press Shift to get into continuous mode is a great safety feature. It takes two hands, your hand can't be between the spindle and the table when it moves except for small steps.  So I'd like to remove the mode change buttons from the pendant altogether. I'd also like the buttons for axis motion to be larger and further apart, so a small hand motion while looking at the part not the screen doesn't move you on to a different button. I want my grandson to be able to jog, otherwise you can't teach the important skills of edge and center finding, and the concepts of origins and work offsets.  Any suggestions on how to accomplish this?

637

General Mach Discussion / Re: Using a PWM signal to run an ESC controller for RC outrunner spindle motor

« on: May 16, 2013, 10:44:17 PM »

I don't think you are doing PWM correctly.  The word here is width.  A fifty hertz rate implies a 20ms time span.  If the pulse is on for 5ms and off for 15ms then the speed should be 25% and conversely if it on for 15ms and off for 5ms then you'd 75% speed.  However I believe that these motors don't have a good turndown (can't go very slow) because they don't have encoder feedback for commutation.  So they rely on the back EMF to determine pole position and that doesn't work well at low speeds.  So while they are very powerful for their size they are probably a poor choice for driving a spindle.  The same motor with a encoder and a controller that could accept an encoder feedback would be a pretty hot setup I would think.

Gary H. Lucas

638

General Mach Discussion / Re: Still confuse about Mach3

« on: May 15, 2013, 10:59:39 PM »

Jaime,
The lines are probably in the order drawn by your CAD program.  When they get chained the lines will all connect, so that doesn't really matter much.

Gary H. Lucas

639

General Mach Discussion / Re: Anyone know where I could get some reasonably priced Large PS Caps??

« on: May 15, 2013, 10:26:38 PM »

I got what I needed off Ebay.  Sounds like you are building a large power supply.  I have a 240 to 48 volt with +- taps 5 KVA transformer I bought that I don't need.  I'll give you a real good deal on it.

Gary H. Lucas

640

General Mach Discussion / Re: Still confuse about Mach3

« on: May 13, 2013, 10:09:02 PM »

Jaime,
Mach 3 isn't a conversational CNC like EZpath.  It is just a straight G-code interpreter. So you have to manually code the program or use a CAM program. LazyCam is a real basic Cam program in that it only reads 2D dxf files and outputs what many would call 2-1/2D.  That is an XY contouring tool path along with stepped Z motion. I think if you look at the mill wizard addons and such you will that they work more like the EZpath CNC.

Gary H. Lucas