rack & pinion control question

[cambridgecnc]

I am building the controls to a 48 x 72 router which has dual steppers on the Y. The cheaper software I am looking at only allows once control signal for both steppers. The more expensive software allows individual homing/control of both steppers. Is it very important for both steppers to have individual homing? Thanks

[ger21]

Is it very important for both steppers to have individual homing?

Only if it get out of square. If the machine is built square, and stays square, then you shouldn't need separate homing.

[cambridgecnc]

Thanks...one more question. Can someone recommend a board/controller to use with Gecko 203 that can take one control signal and run two y axis?

The software I am using is winpc-nc. The cheaper version of the software has tangential cutting with 4 axis but its a thousand dollar leap for their hardware module that allows separate synchronized outputs for the two Y steppers.

I know mach 3 allows slaved motors but winpc-nc has a much better tangential cutting ability

[ger21]

You may be able to just connect the two Gecko's to one set of pins.

[cambridgecnc]

Thanks...so the same pin on the breakout board? Can you recommend something to use with the Gecko 203?

[Pandinus]

At the moment I just have a couple of blocks of wood clamped on one end of my table... I "gently" move the gantry to the blocks then move away, it'll do till I fix up some home and limit switches. As long as your gearing is not sufficient to break things befor the motors stall... No problem squaring things up under power, otherwise power down and butt up to the stops then jog away afterward.

If you are talking EMC2 VS Mach3...Both will output to multiple pins/motors. You just tell EMC2 that two different pins are on the same axis... I don't think it will jog both motors in the setup utility, but will when running, and as far as I understand it, EMC2 "can" be made to home a two motor axis, but it takes some special setup and a little research which I haven't done yet, but will look into one day. And then there is Mach3... click a check box and your done

[cambridgecnc]

I am using a german software called Winpcnc which supports tangential cutting. The cheaper version of the software has only one signal out for the Y axis which I would have to use to drive both Gecko 203's for the rack and pinion. If I spend an additional 1000$ they have a version which has separate synchronized Y signals. It would be nice not to do this

[ger21]

Check out the PMDX breakout board.

[cambridgecnc]

Thanks I spoke with them today and they said it work if I paralleled the outputs. The only downside is that if one Y stepper lost a step than it would not correct itself when it homes due to the one limit switch. Although I could just shut the power off and manually home the gantry on the two sides.

[Pandinus]

Hmmmm how about this...

three switches and a 555 timer...
I have to think about the minimum circuit requirements, but basically you home the machine via the software, and then you press a button to square the gantry, which sends low speed pulses to both stepper drivers, the motors advance each side of the axis to a switch that interrupts the pulse for its side. when both motors stop it is square.

On the other hand, can your software export G-code... and use EMC2 (free) or MACH3 as your controller software. (Although it means you have two software packages and/or machines to run, it also means you can design on one WHILE cutting on another...)

[cambridgecnc]

so two more limit switches? I will talk to whoever is building my breakout board to see if they can do this...or just use the cheaper software and upgrade later and square it manually if it gets out of wack. This will be a plotter/glass cutter with tangential cutting so it will "hit " anything which would get it out of wac k hopefully, MAch 3 and EMC2 do not support full tangential cutting out of the box so I cant use them.. the 1200$ winpcnc comes with a hardware box between the breakout board and computer and allows full multitasking... in the short run though it would be nice to save 900-1000$.

[Pandinus]

no breakout board.. I was thinking more of a small dedicated circuit on the machine to square the gantry.

Oh, now I think you meant have it built by the other dude... or included on the breakout board, that's an idea and a half!!

(Use one of those safety switches you have to lift the cover off to activate or something to prevent "mishaps" lol