This will be an interesting build for me, and others to watch. You are certainly not the only one who's wanted a 300x300 version. Others will look forward to seeing your adaptation files. Yes you are using 20x40 extrusions because you have them on-hand, but others considering a 300x300 have thought that something that size should warrant 20x40 extrusions too.

Before you get into remodeling printed parts, please compare the changes between the TrueUp Glide and the TrueUp Kit Version. The Kit version contains subtle changes that make it far superior from both engineering to assembly ease perspective.

 

I've faced that dilemma of having lots of the wrong wheels too. Common problem actually. But, the difference between X and Y is weight/mass, especially for a 300x300. Your Y motor will work a LOT harder moving, and stopping, the Y axis. That's a lot of inertia to over-come. The larger diameter wheels are probably not that much stronger carrying weight, but they are easier for the motor to pull. If you're going to need to order OpenBuild s parts anyhow, I'd certainly spring for those 4 wheels if I was you. One thing to consider - just how much trouble it will be to change those later if needed

 

Download the http://3dwrx.com/TrueUp/kit-assembled.zip file. It is the printer fully assembled. That should be helpful in your reconstruction.

I notice you've turned the two uprights 90 degrees from your first layout. That will require 2 nylon guides for each bushing. It will theoretically be stronger this way however the friction will be doubled, that may be a problem for enough motor power to lift the X axis.

Examine the bushings and body cavities, notice that they are very slightly tapered from top to bottom.

 

The link to the BOM is in the first paragraph. I know, stupid place to put it. I'll list it down with the other files.

It is a 6/6 Nylon 5/16" rod. Amazon.com: Nylon 6/6 Round Rod, Opaque Off-White, Standard Tolerance, FDA compliant: Industrial & Scientific

The reason for the change is that I had a lot of requests for me to supply the printed nylon bushing since a spool of Talman 910 is pretty expensive for just those bushings. And for those hiring a printer to do the parts it was an expensive job.

The two concepts work equally well.

 

Link for the MDS ones? 6/6 nylon is already "self-lubricating". Any nylon, to some extent, is "self-lubricating", it's the surface tension of the molecular structure.

 

Thanks Elmo. I had no idea it existed. I need a new rod, this is what I'll be ordering. It also has enhanced hardness over unfilled 6/6. Changed the BOM to this rod http://3dwrx.com/TrueUp/TrueUp-KIT-BOM .pdf

 

I'll be getting it Wed. Will check it out and respond then. Thanks again.

 

If you are interested, I can take a stab at converting these plastic parts from 2020 to 2040 in openscad? I kind of like these puzzles. I took the liberty of doing the Y-Axis End Plate (maybe it should be called front plate) based on what I saw in your drawing for the12" to see how it went. I made the openscad file so you can cut out some of the center mass to use less plastic, but can also leave it filled by setting the variable CutSize in the openscad file. I chamfered the edges instead of rounding as that is much easier in openscad. Here are the files.

 

Ok, I won't take it any further than this. Here is the back matching plate.

 

Elmo, Curious what are you using for the build plate?

 

When I build

If you use the same spacing (40mm between Y rails) your outer wheel holes will be 100 apart. The openbuilds universal build plate has 7mm & 5mm holes at that position. But then you'll need another plate to get out to the 316mm spacing for your heatbed's corner holes and again, that adds weight and inertia to have to deal with for the Y axis. So instead, do what I did on Steve Jeppesen's 300x300. Use a 12"x12"x1/8" plate. Drill the 7mm & 5mm wheel holes in a centered square pattern 100mm apart. Then print corner extensions to go out from the 12" (304mm) to 316mm for the corner holes. Just bolt the printed corner extensions on to the 12" plate's corners. Steve has over 1000 hrs with that and it worked fine. Something similar to ~

That way David's mods will work too.

 

With the same 40mm spacing between Y extrusions your hole spacing would be 100mm, my hole spacing is 60mm (wheel holes are 10mm out from edge of extrusion). Got the plate off Amazon.

 

The openbuilds one will need 2inch corner extensions or another larger plate bolted to it. Use the 12" Amazon one instead.
FWIW, a 9/32 drill bit is perfect for drilling the 7mm wheel holes if you don't have a 7mm drill bit.