Ajax CNC Mach3 3-axis mill conversion thread

[skyg]

Scott -

I've noticed that the error seems to be more in one direction than the other for z, precisely because the axis is unbalanced. I'll play around with Kg and see what I can get.

-Sky

[skyg]

Okay, so here's one of those hilariously basic questions, in fact I'm embarrassed to ask it but I will anyway. We currently have a router for our spindle, and we'd like to have it turn on and off at the beginning and end of each job. I have the E-Stop contactor from Ajax, but I'm not really sure how to connect it all up to accomplish that. Little help please.....

[cncsnw]

In short:

Use your E-stop contactor to guarantee that all moving things cannot move when E-stop is pressed.

Use relay outputs on your PLC unit to turn the router on and off, through an intermediate relay or contactor.

I.e. the relay output on the PLC switches whatever appropriate voltage to the relay coil (12VDC, 120VAC, etc. at a few milliamps) to make the relay close. The relay switches whatever appropriate voltage (120VAC, 240VAC, etc. at several AMPs) to run the router motor.

Since the E-stop contactor is supposed to guarantee that the router stops when E-stop is pressed, you should run either the intermediate relay's coil circuit through one pole of the E-stop contactor, or run the router's power supply through one or more poles of the E-stop contactor as well as through the intermediate relay.

The E-stop contactor would not be used for routine switching on and off. It is an extra layer to ensure things are powered off even if your PLC software or hardware isn't working right.

[skyg]

After reviewing your post and looking at the schematics, it all made perfect sense. We got the contactor all wired up this weekend, and once we finally figured out that the contactor only worked in the "flat" orientation, it worked perfectly. After having to worry about when a cut is going to end, it's really nice to know that the spindle will start and stop automatically.

On another note, we sent out the z axis leadscrew to be reground, and once it came back we no longer had the problem of the axis sagging down under estop.

We had a slight problem with a Ajax and Mach setting fighting each other. The max speed in the Mach motor tuning pages was set at 500 ipm, but the rapid travel setting in the Ajax screen was set to 300. So when the mill was moving into position for cutting, it was erroring out and causing the sequence to stop. Once I figured out that the max speed in Mach and Ajax need to be set the same, it stopped erroring out.

I'm going to try to work out the homing issue this week - once that's done, as far as we're concerned the conversion is complete. We've got a few more things we'd like to do, but those are all considered optional upgrades, not must haves.

-Sky

[skyg]

Okay so I'm still having some homing issues. X and z home just fine - I've disabled the homing switches and now I'm only using the limit switches. They travel towards the home position, hit the limit, and then back off it a bit. The y axis is still problematic - it hits the limit and then just jerks to a stop. Any suggestions?

Anyone else out there have homing working with Mach3?

-Sky

[skyg]

Here's video of the mill cutting, and a photo of a finished mold. We're now cutting at 180 ipm, before the upgrade it was at 60-80 ipm. I'm going to bump it up to 200 and see how it looks - at 300 it was rounding the corners of the edges too much, since we're running in CV mode. The system has been rock solid - it's VERY nice to have the spindle now under control of Mach - get to put a cut in at the end of the day and not worry about the spindle just running all night.

http://www.youtube.com/watch?v=HyXdQmXj2kQ

-Sky

PS - Scott any idea about the y axis homing issue?

[skyg]

I've been using the Ajax setup on the mill for quite some time now and I've been really happy with it - so far just rock solid!

Scott - I have a question for you, but I'm not sure if I should be asking you, or if it's a Mach3 question. I'm looking at a way of making g-code which will output arcs instead of line segments - I understand that for really smooth shapes like the stuff I do, this can be much better. However, not all of these arcs will be aligned in the primary plane of movement - in fact ideally they would NOT be. A friend of mine said that most systems cannot handle arcs that are not in the primary plane. I know I can define the primary plane in Mach3, but I'm not sure if that has any effect on an Ajax setup, since Mach3 is basically just offloading the g-code to the external board. So, with the setup that I have (Ajax board, Mach3) - can I use g-code which contains arcs that are not in the primary plane?

-Sky

[cncsnw]

I don't know for certain, but I am pretty sure that Mach3 is doing all the G code interpretation. It should only be sending motion requests (speeds and distances for all the axes) to the controller. So your question should be firmly Mach3's responsibility.

For what it's worth, CNC11 can process arcs in any plane. Not only does it accept G17, G18 and G19 for the three standard cartesian planes, but it also has extended G117, G118 and G119 codes that take rotation angles. You can therefore program circular arcs in any plane. For example, "G117 P10 R20" lays arcs in the plane that results from taking the XY plane (G17) and rotating it 10 degrees about X+, then rotating it 20 degrees about Y+.

[skyg]

What does CNC11 cost? I can't seem to find the price listed anywhere on the website. Also, is the file size limited to 4mb unless you get the upgrade?

[cncsnw]

CNC11 costs $500.

Standard file size is 4MB.

The "Unlimited part program size" software option is $550. With it you can run any file that fits on the hard drive or other storage device.