Squaring Issues, missing screws and Z axis belt tension

Assembly questions and answers for the Shapeoko 3 CNC Mill
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Chembro
Posts: 21
Joined: Sat May 09, 2015 3:09 pm

Squaring Issues, missing screws and Z axis belt tension

Post by Chembro » Sun May 10, 2015 2:23 am

Received machine #49

I'm having an issue with the machine squaring up tried loosening everything and measuring in multiple places but the gantry is constantly 1mm taller on one side versus the other causing the gantry to have an 1/4in offset when the gantry is resting against the steel plates. I could really use some tips from veterans as this is my first machine.

Also just letting others know I'm also having tension issues with the Z axis.

NOTE:
My local ace hardware had the missing m5-16mm screws for anyone else missing the required button heads.

WillAdams
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Re: Squaring Issues, missing screws and Z axis belt tension

Post by WillAdams » Sun May 10, 2015 2:35 am

Tim Foreman had a similar issue and chose to drill out the holes on the end plates so as to make adjustment possible: http://www.shapeoko.com/wiki/index.php/ ... uild_Notes
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

LTEPM
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Location: no where near the end of the rainbow

Re: Squaring Issues, missing screws and Z axis belt tension

Post by LTEPM » Sun May 10, 2015 3:14 am

Have you squared the base? I measured corner to corner. I had to use a clamp to bring it into square corner to corner. I was out 1/16" consistently on the base until I completed this. Make sure you are on a level flat surface. I placed the assembly on some 1"x2"x30" MDF runners on my bench so the PEM nuts weren't touching anything and could move with minimal force.

Use a machinist square to ensure your rails are square to the base. I shined a flashlight behind my square so I could see if I had any gap. I was able to get my Y rails square to the waste board while tightening without removing paint or enlarging any holes. Overall my Y axis rails were within .0015" to the waste board overall. Close enough for my tolerances.

Check all of your steel plates for flatness. One of my Y carriages was not perfectly flat, I did not notice when I was assembling. Trying to figure out how to square the X axis without tearing it down again, I was able to put a block on top of the Y rail between the end plate and Y axis plate on the Side which hit the end plate and use a quick grip clamp on the side with a gap to pull the X Gantry square. It took a couple of tries, you need to make sure you don't over-do it. It doesn't take much force. Not the most orthodox way to do it but I didn't feel like tearing it down to flatten the plate. I did check my rails and nothing bowed while I did this. I had to use 1-2-3 blocks clamped to the X rail to check square to the Y rails. Using this method got me to be right on for square.

Chembro
Posts: 21
Joined: Sat May 09, 2015 3:09 pm

Re: Squaring Issues, missing screws and Z axis belt tension

Post by Chembro » Sun May 10, 2015 5:45 pm

Took it all apart, and measured everything. I do not have a good squaring tool which squaring tools/companies would be recommend good to start with I wouldn't mind buying good quality tools since I could use them in the garage as well.

I included a picture of the problem.

I'm sure I can compensate for the tolerance issues in the software but would really like to get he machine as square as possible.
Attachments
image.jpg
X axis gap
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mwdsonny
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Location: Charleston SC area

Re: Squaring Issues, missing screws and Z axis belt tension

Post by mwdsonny » Sun May 10, 2015 6:28 pm

I had that issue in the back. My front was good. I inspected it and noticed that the belt was doubled up and the bearing was hitting the doubled up belt and (springing back). Since my front was fine i didn't take belt off and trim 1/4 inch. if it were front I might have.

Chembro
Posts: 21
Joined: Sat May 09, 2015 3:09 pm

Re: Squaring Issues, missing screws and Z axis belt tension

Post by Chembro » Sun May 10, 2015 6:41 pm

I don't have any belts on except for the z axis.

The base seems to be tweeked in oposing corners,no matter how I move the machine base the Y rails pull it out of square once tightened.

WillAdams
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Location: Pennsylvania --- south of the Turnpike, East of US-15
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Re: Squaring Issues, missing screws and Z axis belt tension

Post by WillAdams » Sun May 10, 2015 6:57 pm

Buy a good square --- a drafting triangle from a kid's geometry set is surprisingly good if you can't find anything else in stock --- remember, precision has to start somewhere.

Make a set of pinch sticks --- you just need a pair of straight lengths of scap aluminum or something and some clamps (tape will do in a pinch, but is a nuisance).

At this point, my inclination would be to carefully measure how out of square it is (ideally you could justify buying at least a cheap digital caliper for this) and use geometry to puzzle out how out of square the extrusion pieces were cut (which is my suspicion if the motor mount plates aren't warped) and then get some different thicknesses of aluminum foil to make up shims for the end plate mounting to it.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

LTEPM
Posts: 271
Joined: Tue Jan 06, 2015 4:34 am
Location: no where near the end of the rainbow

Re: Squaring Issues, missing screws and Z axis belt tension

Post by LTEPM » Sun May 10, 2015 7:46 pm

Looking at your photo, it is not anywhere as far off as mine was. If you have the same issue on the other end, but opposite side, then you will need to square your base. This can be done easily with a tape measure and clamp, or strap.

veng1
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Re: Squaring Issues, missing screws and Z axis belt tension

Post by veng1 » Sun May 10, 2015 9:37 pm

There is a draftsman's trick for verifying if an L-square is not square.

Draw a line with the square one way on a sheet of something, paper, cardboard, plywood, anything with a straight rigid edge, and then turn it the opposite way on the same edge. Draw another line as close as possible to the first one. If the lines still match (as in exactly parallel), the square is accurate. If they diverge, then is is not square.

Chembro
Posts: 21
Joined: Sat May 09, 2015 3:09 pm

Re: Squaring Issues, missing screws and Z axis belt tension

Post by Chembro » Mon May 11, 2015 3:28 am

I used a ratchet strap as a come-along and then tightened the wasteboard down. I have a "visibly perfect" machine which is good enough for what I'll be using it for. I'll be tinkering to increase tolerances later.
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image.jpg (269.24 KiB) Viewed 2625 times
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