Geometric constructional "stability"

I have/want to renew/replace defect parts of my MPCNC which was the latest version BEFORE “burly”. Question: Are the three-dimensional distances between the tubes (here OD 25mm) from my version are the same as of “burly” so that an exchange is easily possible? (e.g. (1 ) one complete roler, vertical distance frame tube to cross tube?, (2) complete middle assembly, vertical distance of crossing tubes?)

Why not provide an archive for older versions? Just for spare parts…

Greetings Ernst-Dieter

I can’t say if the design dimensions are the same or not but some things are invariant. In the roller, the vertical distance between the side rail and the gantry rail doesn’t really matter as long as all four rollers are the same. Larger distance just makes the entire center assembly higher. The vertical disatance between the gantry X and gantry Y is the same as the vertical distance between the side rails where they meet in the corners. In other words the little corner spacers determine the distance between the gantry rails.

I suspect they are the same between burly and pre-burly but it might not matter. E.g. if you want to replace just the center assembly you can replace the corner spacers and know that the rest will fit.

Here only Ryan can enlighten us … He did the CAD

If you have any of the original stl files, you can load them into tinkercad.com and overlay with the new part to check if the spacing is the same.

Maybe @vicious1 just didn’t see this. He knows this stuff right away.

Sorry I am two days behind on posts.

You want to replace the entire center and one roller? Jaime has it right. Everything has to be replaced in sets. All the rollers, or all the corners, or the entire center assembly.

Can I just replace the center set with the burley set and not the rollers?

You should be okay to replace the entire center assembly and not the rollers or corners. I’ll assume the corner spacer is the same between the two.

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Actually I take that back. I just measured the STL files for the J version and the corner spacers have a 2.1mm gap in the Burly version and a 1.7mm gap in the older “525” version. This would be reflected in the Z distance between the gantry rails too, so you will have a small error unless you also replace the corner spacers with the Burly corner spacers. But everything else will be okay.

It might not be noticeable but if you are tearing down everything anyway you might as well replace the corner spacers. Just the spacers is very fast to print since they are tiny. You can reuse 99% of the older corners.

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Yes. That’s what I did.

If there is a difference in the corner spacing as Jamie says, I’m not seeing any issues from it.

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