Mounting motor under table?

[Jonathan]

The stepper & ratio issue is something I've yet to address. I need to work out the benefits of the various ratios first. I'm pencilling in 1:1 until I've had a good think over a hot cuppa.

Smaller pulley on stepper = better resolution, which is generally not that big a benefit.
Larger pulley on stepper = higher speed, up to a point which I've not yet managed to reach.

The main thing is as you increase the speed of a stepper motor the torque to start with is fairly level, then drops. You want to size the pulley such that the motor is operating mainly in the region before the torque drops off.

Also I expect a smaller pulley on the stepper motor will get better acceleration.

Just for example with a 13T pulley on my Y-axis stepper, and 12T pulley (bit too small really) on the 10mm pitch screw I get 36,000mm/min (1417 ipm). Changing the 13T to 30T gets about 55m/min (2165 ipm), and changing to 42T gets 60m/min (ipm = lots). Clearly the 42T pulley isn't worth the extra <10% speed given the significant reduction in resolution. Microstepping the stepper motors to artificially gain resolution is really only cheating yourself after about 1/4, maybe 1/8 of a step. The accuracy of micro-stepping depends on the motor and what it's connected to. In general apparently it is not that accurate, but still use it for general smoothness.

You can do some pretty impressive things with 10mm effective pitch as I'm sure JazzCNC will soon demonstrate...

[JAZZCNC]

You can do some pretty impressive things with 10mm effective pitch as I'm sure JazzCNC will soon demonstrate...

How would you like me to do that Jonathan.? With my little Aztec friend. . Lol

[Jonathan]

How would you like me to do that Jonathan.? With my little Aztec friend. . Lol

Yep, that's just what I was thinking. I'd like to try one of those on my machine.

[JAZZCNC]

Yep, that's just what I was thinking. I'd like to try one of those on my machine.

Ok just for jonathan Here's what 10mm pitch gets you.!!

Johnathan if you want the code your welcome to it, or any body else for that matter. It's a 17mb file thou and over a million lines of code, If I remember correct it took about hour n half.
I did another after that but with the Welsh dragon on the back side but didn't take any pics. . . . Looked good thou.!!

Enjoy and the pics don't show all the detail or do it justice. . . 150mm diameter 10mm Ali plate cut with a 6mm 90deg carbide chamfer/spot drill.

[Jonathan]

Ok just for jonathan Here's what 10mm pitch gets you.!!

Was amazed when I first saw that - I still am.

Jonathan if you want the code your welcome to it, or any body else for that matter. It's a 17mb file thou and over a million lines of code, If I remember correct it took about hour n half.

Yes please! I've got some aluminium that size so why not...I believe you did it with a 6mm spot drill, 90°? As better excuse than most to finally buy some spot drills I guess.

I agree that 10mm pitch is definitely the way to go if you want good feed-rates.

[JAZZCNC]

Was amazed when I first saw that - I still am.

Ye me too I must have looked at it for days and every time I saw a bit more detail I'd missed.
It's also mesmorizing to watch the toolpath do it's stuff the bloody thing bounce's all over the place, so much so when first started cutting I very nearly stopped it because I thought it had FUBARD.

Yes please! I've got some aluminium that size so why not...I believe you did it with a 6mm spot drill, 90°? As better excuse than most to finally buy some spot drills I guess.

No better excuse IMO. . lol . . . . . I'll dig it out and send your way.

[Rogue]

Ok just for jonathan Here's what 10mm pitch gets you.!!

That is several steps beyond awesome, and something to aspire to in the future. Is there a drool icon? If not, why not?