Catching on the rails?

Assembly questions and answers for the Shapeoko 3 CNC Mill
apspurgeon
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Joined: Mon Jun 08, 2015 9:18 am

Catching on the rails?

Post by apspurgeon » Tue Jun 23, 2015 8:49 am

Hi all

Shapeoko3 complete...however if I move the X, Y (sometimes Z) by hand, the movement sometimes catches and almost feels like there is a grit in the bearing. I've tried adjusting the offset nuts, checked and checked and checked again the rails and bearing are all clean.

It's strange that all 3 axis do this intermittantly

Anyone else had the same problem?

WillAdams
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Re: Catching on the rails?

Post by WillAdams » Tue Jun 23, 2015 10:50 am

I’ve occasionally had something like that back when I first put mine together, but it seems to’ve gone away
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woodworkerbob
Posts: 244
Joined: Tue Apr 15, 2014 6:31 pm
Location: SVE - Mesa, AZ

Re: Catching on the rails?

Post by woodworkerbob » Tue Jun 23, 2015 2:03 pm

apspurgeon wrote:Hi all

Shapeoko3 complete...however if I move the X, Y (sometimes Z) by hand, the movement sometimes catches and almost feels like there is a grit in the bearing. I've tried adjusting the offset nuts, checked and checked and checked again the rails and bearing are all clean.

It's strange that all 3 axis do this intermittantly

Anyone else had the same problem?
I had the same problem. Hold on to your socks, my conclusion was it's an electrical issue not mechanical.

It was discussed here: http://www.shapeoko.com/forum/viewtopic.php?f=7&t=6324
Summary of url: Don't move the axis if you can avoid it. If you have to move it, do it gently.

Bob
Shapeoko 3 - #13, dust deputy, precision collets, limit switches.
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newtothis
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Re: Catching on the rails?

Post by newtothis » Tue Jun 23, 2015 2:24 pm

Could you test if its mechanical or not by disconnecting the motors temporarily i.e. take belt off motor pulley. and then move xyz - if stoppage or snag still happens its a mechanical bearing or roller type issue. If that all runs smooth with no snag, then the issue is further upstream?
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woodworkerbob
Posts: 244
Joined: Tue Apr 15, 2014 6:31 pm
Location: SVE - Mesa, AZ

Re: Catching on the rails?

Post by woodworkerbob » Tue Jun 23, 2015 2:53 pm

newtothis wrote:Could you test if its mechanical or not by disconnecting the motors temporarily i.e. take belt off motor pulley. and then move xyz - if stoppage or snag still happens its a mechanical bearing or roller type issue. If that all runs smooth with no snag, then the issue is further upstream?
Try moving the gantry along the Y axis slowly first. You should be able to feel any bearing issues. Use a finger to feel the V notches to make sure they are smooth. (Aside: My wood working teacher said you can feel a problem long before you can see it.) Removing the belt would also be a check. Don't know the effect would of disconnecting the steppers from the controller board.

Bob
Shapeoko 3 - #13, dust deputy, precision collets, limit switches.
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WillAdams
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Re: Catching on the rails?

Post by WillAdams » Tue Jun 23, 2015 3:00 pm

I believe there are a couple of possibilities here:

- uneven belt tension --- if the belts aren't evenly tensioned then as the machine moves every so often one of the pulleys will have to jump a tooth to realign
- Carbide Motion stutters occasionally when jogging w/ the button held down --- known issue
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets
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apspurgeon
Posts: 122
Joined: Mon Jun 08, 2015 9:18 am

Re: Catching on the rails?

Post by apspurgeon » Tue Jun 23, 2015 8:10 pm

To clarify, this is all with the power off
Hmmm....removing the belt (which are PERFECTLY aligned) seems to remove the issue.

This means it's either something with the belt (it looks OK)
Tension from the belt is pulling on the bearings causing them to catch
or the Motor is coming into the equation.

Will keep playing. I'm guessing this is from an uneven movement (me pushing unevenly) but even so I wouldn't have expected this.

cvoinescu
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Re: Catching on the rails?

Post by cvoinescu » Tue Jun 23, 2015 8:38 pm

The motors will definitely induce enough current to power the electronics, and you will feel that as you move them.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

apspurgeon
Posts: 122
Joined: Mon Jun 08, 2015 9:18 am

Re: Catching on the rails?

Post by apspurgeon » Tue Jun 23, 2015 10:22 pm

Yes, good point. Will put the belts back on with motors removed from board and see if the problem remains

jayftee
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Re: Catching on the rails?

Post by jayftee » Tue Jun 23, 2015 10:40 pm

cvoinescu wrote:The motors will definitely induce enough current to power the electronics, and you will feel that as you move them.
yeah, do it fast and enough that you could damage board components. I saw it happen on ramps boards on 3D printers...
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Shapeoko 3 #00947, Aluminum Bed, Prototype Z Carriage, Porter Cable 450, Min/Max limit switches, Z-Probe, PreciseBits 1/4 & 1/8 Collets, Super-PID v2, IC Dust Shoe

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