What have I screwed up here?

I cut the 611 plate with my 525 MPCNC, then I somehow murdered my MPCNC while doing a test run for one of the side plates (basically I nuked the Z axis allthread…yes that’s how old that MPCNC is). I ended up cutting the side plates with a jig saw and a drill press. I got a LR2 kit from @vicious1 and everything assembled just fine.

Got my DOM tubing yesterday, and here’s my issue: The tubing was extremely difficult to insert through the rollers on the 611 plate, and there is quite a lot of tension. The top bolts on the rollers are not even snug, and the tubes do not move freely. There’s so much tension I am actually worried about skipping steps.

The side plates are fine and the tubing moves like I would expect.

So I’m wondering if my MPCNC drilled the holes for the rollers just ever-so-slightly too close together? And when I assembled the 611 plate the rollers were “pulled in” because of it? Maybe?

Should I just drill some larger holes and hope that fixes it? Literally my plan with the LR2 is to use it to make new plates for itself as one of the first projects, so it would be a short-term fix.

Take the printed bearing holders off the plate and check their snugness on the tube without the plate. This will determine if the tube is the right size for the printed bearing holders or if the holes on your 611 plate are in the wrong place.


Took one of the rollers off and the tension was fine. As a test, I put one screw back in and then looked at the other side while inserting the tubing. It flexed out about 1mm or so. I did verify that I have the “J” version printed.

I’m going to try to put the whole thing together without the rollers for the plate actually attached to the plate. Then I’ll see if I can attach them to the plate without introducing a ton of tension and keep it aligned properly.

Yep…good progress…it sounds like your holes in the 611 plate are not aligned properly…that being the case then judicious use of a dremel to ‘relieve’ the blocks would be in order (and I can think of a good first job to test out the machine!!)

Or, just use the next size up drill bit. If you do it one hole at a time, hopefully you won’t end up with slop, and you can cut a new plate when you get running (or in 6 months when you feel like it).

Yeah I think that’s probably what I’ll end up doing (larger hole). Covid has got me working 125% of my hours for 90% of my pay, plus two elementary-aged boys that have had all their summer camps cancelled. Needless to say I don’t get a LOT of time to do hobby work.

The boys want to help daddy build the big robot but I can’t trust them with power saws yet.

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Sorry to but in. I have a question related to this. Since the dxf files have no dimensions, how do you know they are the correct size when printed out to make a paper template. I don’t have a CNC machine to make them so I need to hand cut.
About your holes. It would seem if the printed parts fit the pipe, you have picked the correct pattern as all the parts are grouped into a 25 or 25.4mm file.
It would sure be nice to have an IRC group to ask these questions. Or a subgroup in the forum for initial build questions, like what are recommended print settings.
Please excuse the intrusion. Just had to ask.
Good luck. I’m beginning the printed part stage.
Take care,

No apologies needed. The first rule here is probably, “it’s better to be nice than right”. Making a build post or an advice post is usually applicable for questions like this. You can also stack on when your issue is the same, although can can be hard to tell.

IRC, or another chat doesn’t work well here, because these conversations help people who are searching for similar issues (hello, future problem solvers!). I have never seen anyone be chastised for asking a genuine question. I haven’t seen people suggest you search first, or read the manual. I am going to assume that every question is from someone who would rather solve it themselves. So if we’re reading it, then they deserve help.

The dxf is unitless, but not dimensionless. If you imported it into cad or cam, you would select a unit, which I believe is mm for these files. I don’t know the best way to print them 1:1. But if you have a printed part, you might want to verify it fits with the paper before spending too much time cutting and sanding.

We keep waiting for someone to show up and take away our Internet card, but I think they’re waiting to wrangle all the Oxford commas and misplaced apostrophes first…

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Hi Jeffeb3, This is where I started. There isn’t a settings section for either the printed parts or the cut parts. I have seen things on thingiverse with recommended speed, %infill, layer height etc. While they are recommendations, they are a big help in ensuring the parts come out properly. This is especially true for something link the lowrider, where strength is important. I had a heck of a time getting my first layer to stick, adjusting, adjusting and re-adjusting the bed for level. In the end, I increased first layer height to 0.28mm. Likely a problem with my printer but… Just sayin.
As for the cut parts, at least having outline dimensions, or even a dimension line one can measure to verify the printout is correctly scaled would be of great help.
It’s unclear to me how units vs dwg file works. Are units embedded in the dwg file or can you change the printed object size simply by changing the units. If you can, than it would really help to specify what units the drawing is in.
I did a lot of scanning to find the answers before I hooked onto this thread and I have to think I’m not the only guy with these questions. It would seem devoting a little space to this would be of great benefit.
I know I’m complaining a lot considering the work already done by the designer. Sorry.
The starting curve is a little steep and these initial details would make starting so much easier.
Take care everyone and stay safe.

That’s precisely how dwg works- it has a line that is ‘100’ units long, and when you open it in your CAD program you tell it if that is 100 millimeters, 100 miles, or 100 smoots.

I just had a look and couldn’t information about importing the plate cutouts in mm. I guess I just inferred that from the Thingiverse names being in mm.

I ended up marking up my files with dimensions that I thought would make verification easy. Most CAD software should be able to do this.

Do you have some calipers to test your tubing? I’m suspicious that testing with the rollers dismounted wouldn’t show up a size discrepancy.