Author Topic: Physical buttons for plasma  (Read 82775 times)

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Offline Davek0974

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Re: Physical buttons for plasma
« Reply #300 on: March 27, 2016, 03:55:42 AM »
I think tube is better than shaft, IIRC there is no difference in torsion effects. I started off with a little table 600mm square and thought it was cool only having one motor and a 12mm cross-shaft. That was until I tried getting speed and acceleration out of it when you see it wiggling. That table was 100% aluminium too so pretty light gantry etc. OTOH it did allow me to cut the parts for my new machine ;)

I would still go with two personally, but watch out for the runaway effect especially with servos - you need monitoring to ensure both motors move as if one stalls or fails the the other will rack the gantry to death, not important on steppers as they just stall eventually.

The machine in that picture is a bitch ;) Hate seeing stuff in that state.
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Offline Hood

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Re: Physical buttons for plasma
« Reply #301 on: March 27, 2016, 04:30:59 AM »
Robert,
 don't worry, as far as I am concerned, no matter what type of machine, Accel is King :)
Hood

Offline Hood

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Re: Physical buttons for plasma
« Reply #302 on: March 27, 2016, 04:46:01 AM »
Dave, yes tube should be but it will depend on material of tube and material of shaft I think, certainly for same material the tube should be better.
Funny thing is boats always have solid shafts, usually Duplex nowadays.

Wont really have to worry about RunAway, AC Servos are pretty good at monitoring things and always have error signals tied into my E-Stop chain.

If I do go with dual motors I will likely just use one side as a follower to the other.

Yes it is a shame but the machine was bought as scrap to rob the control off, the trucks on the profile rails were in a bad way, only managed to get 5 rebuilt out of 12 that were on it but managed to pick up 3 new on eBay for a decent price. The rails are not the best either, one is excellent, one not too bad but the others have a good bit of pitting. Still accurate enough for a plasma but will be a lot noisier than they should be.

The rack and pinions are all good from what I have seen so far (covered in greases) so that was a bonus.

pic below of rack and pinion.


Hood

Offline Davek0974

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Re: Physical buttons for plasma
« Reply #303 on: March 27, 2016, 04:58:36 AM »
Nice :)

With those bits, your table should be built like a battleship!

Somehow I doubt acceleration is going to be an issue;)
Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Physical buttons for plasma
« Reply #304 on: March 27, 2016, 08:14:13 AM »
Certainly trying to make it sturdy.
Just took a vid of me pushing/pulling one side of the gantry to see what it is like, camera shaking a bit but everything else seems solid.
https://youtu.be/0fy3EpkbxlY

Hood

Offline Davek0974

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Re: Physical buttons for plasma
« Reply #305 on: March 27, 2016, 04:22:26 PM »
Interesting experiment would be to mount a laser pointer on each end, facing the far wall, dots close together then swing the gantry and watch the dots wobble in different directions ;)

It may look rigid but plasma will show a deficiency, it's good at that ;)
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Offline Hood

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Re: Physical buttons for plasma
« Reply #306 on: March 28, 2016, 03:13:20 AM »
I would imagine it would show it moving about a bit.
Hopefully I will get a chance next weekend to get a bit more done, ran out of cap screws yesterday so could only get the top profile rail on the gantry fitted. 35 of them in each rail, wish my Chiron had the room around it to slide the gantry through for drilling and tapping :D

Hood

Offline Davek0974

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Re: Physical buttons for plasma
« Reply #307 on: March 28, 2016, 03:21:42 AM »
Yep, been there. The X axis on my table was double-width HiWin rail so two rows of parallel screws, drilled and tapped each blasted one of them ;)
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Offline Hood

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Re: Physical buttons for plasma
« Reply #308 on: March 31, 2016, 05:24:14 AM »
Got the highly accurate ::) lasers yesterday and got a chance to clamp them to the gantry legs this morning.
Not too bad although as said the laser quality leaves a bit to be desired.

https://youtu.be/DaoQKbDxmus

Hood

Offline Davek0974

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Re: Physical buttons for plasma
« Reply #309 on: March 31, 2016, 05:57:38 AM »
Nice :)

That is a pretty rigid gantry there, while you have the lasers, sling some weight on or under the gantry to represent the Z axis & motor, torch, cables, etc then try the same test with the load parked at different points of X from left to right :)
Mach3 V062, CSMIO-IP/A controller, AC Servo Drives