warped steel plates

Assembly questions and answers for the Shapeoko 3 CNC Mill
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fredmud
Posts: 6
Joined: Tue Dec 22, 2015 7:02 pm

warped steel plates

Post by fredmud » Sat Jan 02, 2016 8:18 pm

I picked up a Sparkfun Shapeoko 3 right before x-mas (Sparkfun's kit uses the mechanicals provided by Carbide, but adds their own electronics). I'm new to the CNC world, but decided that I would go for as much precision during setup as I could. I noticed almost immediately that the two y-axis carriage plates, the z-xis plate, and the x-axis carriage plate were not flat-- they were subtly but visibly warped, and would rock when set on a flat surface. I contacted Sparkfun, and went to their location to exchange the plates. The y-axis plates they brought out had the very same issue; I didn't think to check the other two plates at that point because I was discouraged and it appeared to be a manufacturing defect.

Using a straightedge and feeler gauges to measure deviation, here's what the plates look like:

https://imgur.com/a/BOAVJ

So the y-axis plates have a vertical trough, and the x- and z-axis plates a horizontal one. I'm guessing it's a result of the stamping process?

I went ahead and assembled the machine to see what would happen. I assembled the x- and z-plates with their warps spooned together, figuring they'd fight each other less. But I'm concerned about the y-axis plates doing the following, leaving the v-wheels not parallel with each other or the y-axis extrusions, leading to wear and tear:

http://imgur.com/unPmnZT

The Shapeoko seems to run smoothly, and has no problem doing a Hello World with a sharpie. Amazon is being uncharacteristically slow in getting my router to me, so I haven't been able to test the machine under load.

My questions:

1. Is this warpage common, or did a bad batch come out that I should seek to have replaced? Anyone else have this issue?

2. Is the warpage within tolerance-- am I making a big deal out of nothing?

3. If the warpage is going to cause problems, is there a way to flatten out the plates? I suppose I could look locally for someone to stick them in a press (how strong for this thickness steel?); I don't think a mallet would do the job.

Thanks in advance for your input-- one of the reasons I decided on the Shapeoko was its awesome community support, and the fact that others have done the heavy lifting to get the project to its current state.

WillAdams
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Re: warped steel plates

Post by WillAdams » Sun Jan 03, 2016 12:15 am

I’d thought the plates were laser cut. That said, there are heat stresses, so I could see some warping happening.

With the larger end plates on the SO1, warping was a problem, and it was simple enough to lay them on a towel across a threshold and stand on them.

Probably you could use fine shim stock to make up for the difference?

Contact support@carbide3d.com to see what they say.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

Fablicator
Posts: 113
Joined: Thu Jul 02, 2015 7:59 pm

Re: warped steel plates

Post by Fablicator » Sun Jan 03, 2016 1:24 am

WillAdams wrote:I’d thought the plates were laser cut. That said, there are heat stresses, so I could see some warping happening.

With the larger end plates on the SO1, warping was a problem, and it was simple enough to lay them on a towel across a threshold and stand on them.

Probably you could use fine shim stock to make up for the difference?

Contact support@carbide3d.com to see what they say.
I believe its par for the course when working with thin cold rolled material. You might need minor shimming when assembled, but shouldn't pose a huge problem.

fredmud
Posts: 6
Joined: Tue Dec 22, 2015 7:02 pm

Re: warped steel plates

Post by fredmud » Thu Jan 14, 2016 8:46 pm

So I ended up bending the plates straight, and thought I'd share my method in case someone else runs into the same issue.

(The plates are indeed laser cut, but are made from cold-rolled steel. The warpage may have come from one or the other. The issue was bad enough that the v-wheels weren't tracking parallel on the makerslide, and not something that shimming could have solved.)

Lacking access to an arbor press, I used my truck jack and some scrap wood screwed to the floor of my shed. Since the warp was along one axis only, I was able to flatten out all four plates with very little effort.
IMG_1997 (2).jpg
IMG_1997 (2).jpg (23.76 KiB) Viewed 1049 times
Thanks for the suggestions; it turned out to be a case of me overthinking the issue instead of just fixing it.

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