Low budget plasma setup, what do I need?

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29 Apr 2019 12:24 #132274 by tecno
Is rack module with tighter pitch better? I was a bit worried that it will be easier to clog dirt so I opted for Module 2.

Also 12 teeth M2 gives me 25mm with 3:1

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29 Apr 2019 12:43 #132275 by tecno
And a smoother ride with 24 teeth and 6:1 reduction.

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29 Apr 2019 13:03 #132277 by rodw
I don't really have any experience to help here. What I used worked. I think I'd use the 24 tooth pinions. I went with 5:1 reduction and NEMA34's on my gantry but that was only for convenience as I purchased 5:1 timing belt drive reduction gears with pinion drive at a price that I could barely purchase the parts I used for the X axis reduction.. I bought the smallest NEMA34's I could to stay within power limits. Nema 23's would have been fine I think.

It might depend a bit on what timing pulleys you can get. I know the small pulleys (and gears no doubt) are hard to mount as if you have to bore them out to suit a shaft, there is no meat there. I bought some so I could get 5:1 or so out of my existing timing pulleys but they would not work for my motor shafts.

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29 Apr 2019 13:14 #132280 by andypugh
If you have a primary reduction then yes, I would go for something like 20 teeth and 5:1 reduction. Not that 6:1 is excessive on a belt reduction (though you would rarely want to run > 10:1 )

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29 Apr 2019 13:18 - 29 Apr 2019 13:18 #132281 by tecno
Low budget 6:1
www.thingiverse.com/thing:1934991/files

Printed in PETG or ABS

Crazy or ??
Last edit: 29 Apr 2019 13:18 by tecno.

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29 Apr 2019 13:28 #132282 by andypugh

rodw wrote: I know the small pulleys (and gears no doubt) are hard to mount as if you have to bore them out to suit a shaft, there is no meat there.


You can glue them on. Loctite 648 works well. It should have 18N/mm shear strength. Bonded area on 6mm shaft (Nema 23 smallest size) and 12mm long is 220mm^2 = 4kN. 4kN @ 3mm = 12Nm.

If you have motors > 12Nm then you will have pulleys more than 12mm wide,and shafts > 6mm dia.

Basically no stepper motor will have a shaft small enough that it can break free a pulley bonded on with 648.

Alternatively, you can bore out the pulley to a taper and draw in a tapered sleeve: photos.app.goo.gl/WfJHqqecYbyZcBvd9
But that's a deal more work, and may not have any advantage.
The following user(s) said Thank You: rodw

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29 Apr 2019 13:32 #132283 by andypugh

tecno wrote: Low budget 6:1
www.thingiverse.com/thing:1934991/files

Printed in PETG or ABS

Crazy or ??


I wouldn't. But then I can make metal gears easily (though I might be tempted to print the internal gear....)

I would prefer to use a timing belt drive, as they do not introduce backlash.

On my lathe I used motorcycle camchain. Inverted-tooth chain is backlash free and more plasma-spark resistant than polymer belts.

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29 Apr 2019 13:37 #132284 by tecno
If.... I would print all but outgoing shaft/plate but as you say the backlash might be a bit too much.

Tempted to try though ;)

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29 Apr 2019 13:45 #132288 by pl7i92
Backlash on a Plasma can be up to 0,4mm no problem on that
many are going with timingbelt long distance there you see speed but also backlash

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29 Apr 2019 14:06 #132289 by tecno
I have no personal experience with long timingbelt so then the 6:1 gear reduction might work but outgoing parts must be better than printed parts = outgoing shaft needs to be with bearing support.

I am tempted to print the rack and pinion just for kicks ;)

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