Dual X-Axis > Flex with heavy spindle. Solutions?

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Dual X-Axis > Flex with heavy spindle. Solutions?

Post by typomaniac » Thu Jan 22, 2015 10:26 am

Hey : )

i have been using my shapeoko for a while but i have been problems with accuracy all the time which may be a result of my heavy spindle. I use a 1.5 kw china spindle which puts a lot of weight on the x-axis. Therefore i use the dual x-option. If i lift the spindle manually (by pulling the spindle) i can see that there is a lot of flex. The v-wheels can be lifted for about 1 or 2 mm which seems really a lot since the whole spindle can be moved up and down a lot. I uploaded a video to youtube where you can see this.
What do you think. What would be the best way to reduce this flex? I read a lot about bolting the x-rails together but this does not seem to be the
solution for my problem because i cannot really see very much flex there.

The link to the video:

Thank you so much!
Proud owner of eShapeOko #17 :-) (Dual-X, Grbl 0.8a)

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Re: Dual X-Axis > Flex with heavy spindle. Solutions?

Post by Gadgetman! » Thu Jan 22, 2015 11:01 am

Bolt them together!

Verify that the cennter distance between V-wheels is perfect.
(Even 0.2mm off is enough to cause problems)

Check that they're adjusted to correct tightness.
Weird guy...
Shapeoko 2014F: 1000mm X/Y, 300W Quiet Cut spindle, Arduino Uno/G-shield and GRBL 0.9i
15x30 drag chains, custom spindle mount, 9mm belts, 8mm endplates, 6mm motor plates.

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Re: Dual X-Axis > Flex with heavy spindle. Solutions?

Post by AlBorland » Thu Jan 22, 2015 2:10 pm

Gadgetman's suggestion is a good one to lessen sag and twisting of the X axis, and for the SO1 there are more tuning methods like replacing the plastic spacers and adding additional spacers.

In the video the front wheel is lifted completely from the Makerslide, meaning that the eccentric spacers are not correctly adjusted. Do this first, then look for additional mods if the accuracy is still bad.
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

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Re: Dual X-Axis > Flex with heavy spindle. Solutions?

Post by Hans » Thu Jan 22, 2015 3:53 pm

Do the adjustments without the spindle installed. The weight can make things feel snug when they're not, as well as making everything more difficult. Also, the wheel spacing that matters is from the front wheels to the back wheels. Getting everything snug should be a big improvement, but you might want to take fine measurements and shim everything into even better alignment to get maximum accuracy out of the machine.
Shapeoko #1,123

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Re: Dual X-Axis > Flex with heavy spindle. Solutions?

Post by cvoinescu » Thu Jan 22, 2015 4:07 pm

Yeah, that's very bad, with any spindle. Check that you have the correct distance between the V-wheels. Nylon spacers will squeeze quite a lot, which is why I've abandoned them for this purpose. Read this: http://www.shapeoko.com/forum/viewtopic ... 227#p38452 . Once you've got the right distance between the V-wheels, adjust the eccentric spacers to get all V-wheels nice and tight. It should then be much better than what you have now.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

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