Messages

561

General Mach Discussion / Re: How to know how much khz to set in mach3

« on: March 16, 2014, 09:52:30 AM »

Some things are indeed better when bigger - but this doesn't necessarily include stepper motors. Unfortunately your 23s aren't ideal either - they're quite high inductance and would require approx. 100Vdc to get their *max* torque/speed potential.

All this said - don't make the mistake of chasing speed for the sake of it. As long as you can achieve the cutting speeds you need, rapids can be somewhat less important. The thing often not considered is what acceleration can you get - now that IS important.

562

General Mach Discussion / Re: How to know how much khz to set in mach3

« on: March 16, 2014, 08:41:33 AM »

There's no 1600 oz/in motor on that page. Anyway - IMHO you're making a rod for your back trying to use those motors on a small router - personally I'd switch to your 23s. You can't just say they behave the same - they're completely different motors and will need driving differently. Do you have a part number or spec sheet for them?

FWIW I use 3Nm 23s on my router which is just a little bigger than yours and I can get 15m/min rapids and 0.5G accel.

563

General Mach Discussion / Re: How to know how much khz to set in mach3

« on: March 16, 2014, 07:54:29 AM »

when I set the  velocity to 3000 or 4000 the motor turns ok (I tried to stop it but they are to strong) but when 2 or more axis are engaged at same time i get missing steps.

This is curious. When you say "engaged" do you mean enabled or moving?

And not to mention they are not connected to anything yet.

Do you mean they're not bolted to anything i.e. sitting on a bench? If so then this can be misleading. Resonance is more likely to occur on an unmounted motor. Which also takes me back to your lack of microstepping. This is also likely to cause resonance problems.

Out of interest - do you have a link to the data sheets for your motors and drivers?

564

General Mach Discussion / Re: HELP. newbie to mach but not CNC'ing

« on: March 16, 2014, 05:37:31 AM »

You are using a pirated license. If you believe this to be in error please contact licensing support. You'll get no further help here until you resolve this.

565

General Mach Discussion / Re: How to know how much khz to set in mach3

« on: March 16, 2014, 04:56:13 AM »

kernel speed required = (steps per unit * velocity in units per minute) / 60. Choose the lowest kernel above this figure. Choosing anything higher is a) pointless and b) likely to cause problems.

Depending on what type of machine you have, you may well be another victim of the bigger is better mistake. Large stepper motors are NOT good for speed. They're better at shifting large loads slowly. Smaller motors may well be the way to go if you want speed.

Microstepping "typically" should be set to 10.

566

General Mach Discussion / Re: Stepper Trouble

« on: March 15, 2014, 01:03:04 PM »

Hey Fastest1 - you might want to give your keyboard a quick clean - I think your zero key is sticking a tad.

567

General Mach Discussion / Re: FEED RATE QUERY

« on: March 15, 2014, 05:04:09 AM »

If the circle is made up of straight lines then Mach has no idea it's a circle and plans each individual move just as if it was a "random" sequence of moves. If it's a G1/G2 then by definition Mach knows it has to produce a circle (or part of i.e. arc). In that case the relationship between the X and Y axes is a simple formula that holds for the whole arc/circle. Each axis simply describes  simple harmonic motion where one is a sine and the other a cosine.

568

General Mach Discussion / Re: FEED RATE QUERY

« on: March 15, 2014, 04:11:02 AM »

So a circle must have hundreds/thousands of calcultions?.

To get the feedrate of each axis at any given time? Well it depends on how you command your circle. If it's "hundreds/thousands" of G1 moves then yes but if it's G2/G3 then no.

569

General Mach Discussion / Re: FEED RATE QUERY

« on: March 14, 2014, 10:41:57 AM »

So it will do 6" at .01/rev and 3" at .005/rev to arrive at the same spot.
So in my case of the axis both moving in the same direction it will be a combined feed of .015/rev???

No - it will do 6.7" at 0.01/rev. So will do the 6" at ~0.0089 and the 3" at ~0.0045

So an additive feedrate of ~0.0134

570

General Mach Discussion / Re: What has gone wrong????

« on: March 08, 2014, 05:37:32 AM »

I think the big fix was disconnecting the PC case, another idea bought about by internet dredging, definitely not a good idea it seems though.

I'd certainly not use your cabinet. Grounding is never as straightforward as perhaps we'd like but I'd be thinking your passing all that noise straight into your cabinet and onto the electronics ground plane.