Z axis Belt - Tension (am I doing this right?)

Assembly questions and answers for the Shapeoko 3 CNC Mill
punkassbob
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Re: Z axis Belt - Tension (am I doing this right?)

Post by punkassbob » Tue May 26, 2015 12:50 am

I had same issue with belt tension and missing M5x16.
I made larger diameter stand offs to take up just enough of slack, so I can use motor position to tighten belt.
Stand off I made is about 16mm diameter. Any larger it'll interfere with GT2 pulley or 6mm flanged bearing.
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zamp
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Re: Z axis Belt - Tension (am I doing this right?)

Post by zamp » Tue May 26, 2015 1:36 am

I had the same problem with the Z-axis belt tension being much too low. I also didn't care for the Z-axis plate's geared pulley's teeth not being in the same plane as the geared pulleys on the Z-axis stepper motor and at the bottom end of the X-axis carriage plate.

I used a round file and did about 15 minutes of aggressive hand filing to turn the Z-axis plate mounting hole for the geared pulley into a slot that's about 3/4" long. I chose to make make the slot extend downwards from the original mounting hole position.

I filed down one face of the the Z-axis plate geared pulley to make it shorter. The face I filed is the one closest to the geared pulley's set screws. I machined a countersink (an angled recess) to accept the angled head of the mounting screw. The countersink was made in the face of the geared pulley farthest from the set screws.

I then mounted the geared pulled (flipped from it's original orientation) at the lower end of the slot I'd made in the Z-axis plate.

These small changes put the geared portion of all three geared pulleys on the Z-axis stepper motor, X-axis carriage plate, and Z-axis plate in the same plane. It also took the slack out of the Z-axis belt. And if I ever need to get a shorter/normal length replacement Z-axis belt, I can move the Z-axis plate geared pulley back to it's designed mounting position.

I'm now happy with my Z-axis.

derbytimer
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Re: Z axis Belt - Tension (am I doing this right?)

Post by derbytimer » Tue May 26, 2015 3:03 am

Belt on Z seems a bit loose on my #102 as well. However, once my 611 is mounted, the weight of the spindle seems to keep one side "guitar string tight."

Please let us know if Carbide swaps out the belt for a slightly smaller one. My impression is it's slightly loose, but would probably work just fine for real world use.

WillAdams
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Re: Z axis Belt - Tension (am I doing this right?)

Post by WillAdams » Tue May 26, 2015 3:38 am

I suspect that both sides need to be "guitar string tight" --- if a belt is not really tight, you'll skip teeth and lose position, which can be really bad on the Z-axis, even if just doing a simple profile cut.

Test the Z-axis on scrap first. If it doesn't work well and hold/maintain/return position well, contact support@carbide3d.com
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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Wooster
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Re: Z axis Belt - Tension (am I doing this right?)

Post by Wooster » Tue May 26, 2015 11:28 pm

I'm also having trouble tensioning the z-axis. Belt seems too big. I can "tension" it all the way moving the aluminum spacer all the way down, but that still isnt enough.
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rtlflatt
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Re: Z axis Belt - Tension (am I doing this right?)

Post by rtlflatt » Wed May 27, 2015 2:59 am

i have same issue with belt as well. my tensioner cant move to very bottom of oval hole. it traps belt against other spacer before it reach end... and it seem like if it could that might be all it needed i cant tell. it just short of being "tight". also anybody else having issue getting small extrusions perfectly parallel? i can get all four wheels to touch but then z axis wont drop (without springs attached) without me pushing down lightly, and any adjustment to loosen wheels would keep leaving me with only 3 making contact so it could wobble. no spindle mount or spindle attached tho so maybe i had it right the first time.
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WillAdams
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Re: Z axis Belt - Tension (am I doing this right?)

Post by WillAdams » Wed May 27, 2015 3:22 am

Contact support@carbide3d.com if you can’t get adequate Z-Axis belt tension.

For the Z-axis, if you don’t have a good quality square, my suggestion would be to use the spindle carriage:

- adjust both eccentrics so the wheels are about one fourth of the way from their narrowest adjustment
- loosely position the Z-axis extrusions
- put the spindle carriage on
- begin tightening the Z-axis extrusions at one end
- remove the spindle carriage and put it on rotated 180 degrees. If need be, adjust the eccentric to make the wheel distance the same
- run the spindle carriage down to the other end and begin tightening it.
- tighten and adjust the Z-axis extrusions until they are as square and parallel as you can get them
- once assembled, adjust the eccentric wheels for tightness

Getting a good square is highly recommended though. Precision has to start somewhere.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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rtlflatt
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Re: Z axis Belt - Tension (am I doing this right?)

Post by rtlflatt » Wed May 27, 2015 3:31 am

ya i just ordered a machinist square set couple days ago.hoping those get here soon. i was using my dads plastic triangle square (<--- :shock: hmm... is that the right name?) and it is far from being "square"

and as for contacting carbide im still waiting on reply to email i sent this past weekend about missing parts and some of extrusion taps that dont look usuable. didnt know about belt issue yet when i sent email although i think i have idea on how i can make it work with what i already have
Shapeoko 3 #??? (Missing serial plate?)
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WillAdams
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Re: Z axis Belt - Tension (am I doing this right?)

Post by WillAdams » Wed May 27, 2015 3:39 am

Plastic drafting squares are usually spot on, albeit hard to use in this instance.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

edh
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Re: Z axis Belt - Tension (am I doing this right?)

Post by edh » Wed May 27, 2015 10:55 pm

zymurgy wrote:I just wanted to chime in that I'm having the same issue with the Z axis belt tension. I looked to see what sizes these belts come in and came across York Industries: http://www.york-ind.com/product.asp?type=belts&pitch=1. The belt I have is labeled 524-2GT-06. I see York has a 516-2GT-06, that's 8mm smaller. I wonder if that is the size the Carbide 3D sent Ed. I've sent a email to support@carbide3d.com and hope to hear from them soon. The other option would be to find a flanged bearings with a larger diameter. For now I've got the belt pinched between the two standoffs and the Z-axis motor as far from the idler pulley as possible. I then put the belt on the GT2 pulley and slid it on the pulley on the Z-axis motor shaft. There is still a lot of slop but it's the best I can achieve with the current belt.

I also have read a few posts that people were missing 2-5M x 16 bolts. I guess it wasn't just me. I was wondering if I lost them somewhere or didn't follow the assembly instructions.
I do't think the new belt I received was 8mm smaller. Maybe 2mm smaller, max. With a little use it has stretched enough my stepper is now bottomed out and the belt is a little slack.

Also, for those buying their own 5Mx16s - be careful of the head size - the ones I got were too large, and I had to mod my router a bit to get it seated correctly.

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