The question was - why would you design a Y axis physically out of square with the X & Z axes, not how would you follow such a misbegotten design.

If your printer looks like this, maybe you need a wrench more than you need math


If your print bed looks like this, maybe you need a flat metal heat bed, instead of math

 

That's what I love about using OpenBuilds extrusions and hardware for framing instead of using inner-connected threaded rods - creating anything but perfectly square would be a task in itself.

 

Hi Robert

I've never shipped international except Canada and from that experience I'm guessing that shipping cost even for only printed parts would be equal to or more than the price for the parts. Although I'll pursue that if you want, I strongly suggest finding a UK print shop or enthusiast to do the printing for you. The beauty of 3d printing is that STL's have free shipping and manufacturing can be done locally.

I will be making 2 major update changes over the weekend to this build: (I'll also be changing the SKP, and STL files for this update)

1) 4 parts that now are 250mm long are divided to fit an 8"x8" build bed (including splicing fixtures)
2) recommending PLA for the Z axis bushings instead of Nylon.

Those changes should enable virtually anyone with a 3d printer to print parts for you. Of course, I'll be happy to assist anyone in the UK willing to print the parts should they need it (including suggesting slicing parameters). In fact, if you find someone who'd provide printed parts for TrueUp in UK, I'd be more than pleased to promote them as such a supplier in the UK, EU zone. I do not see that zone as a market for me and would welcome anyone in that zone who wants to fill up their plate.

I assume you'll be relying on RepRap 3D Printer Parts Supplier - V-Slot CNC - Ooznest for OpenBuilds parts, etc. Since they sell 3d printers and filament, ooznest might be able to recommend someone who'd love to do the printing for you.

Let me know how you want to proceed.

 

I'm starting a fresh set tomorrow for a TrueUp (want to verify that these new parts are 'good' before publishing them). That 93 pounds does seem high.

Tell you what, let me get this set finished so I can see what packaging and weight will be, then I'll look at creating an Ebay item for it. Ebay has an option for UK shipping where they handle the import/export nonsense and arrange for UK delivery (all I do is ship to the US facility). Don't know, but it's worth looking at, we may find it's a good deal even with Ebay's charge added.

As for slicing parameters, I wrote a Perl utility which can unpack a gcode file and create a zip of the Slic3r settings used for it that can be imported into Slic3r. Think I'll just publish those also.....

 

BTW, the under Y pieces for PSU and control box are black. The other pieces are orange. OK?

 

Correct! I've fixed that, download again.

 

That's a price delivered I probably can't beat.

I'm reorganizing the SKP and STL files into 2 folders - Black and Color. You get to chose the color. I've quit making all black as the Black/Orange sells better

 

I used to use green, but I changed to orange when I saw Prusa's MK2 in orange. It's not my favorite, but I figured Joe Prusa has better market research than I have, so....

PLA bushings are really slick. No lub needed. Keep in mind the X axis is weight balanced and the bearing surface is small. The bushing's 45 degree angle center against the extrusion slot is the surface - and only the outer perimeter line of the bushing is touching since each layer is staggered 45 degrees.. There was a design on reprap.org a year before Deezmaker's Bukobot use of UHMW Z bushings that used very small surface bushings in 80/20 extrusions. I built that as my first proto and it got more than 1000 hrs on those bushings with no wear before I junked it when OpenBuilds came out with V-Slot.

The most critical print fit is the bushing must fit flush in it's housing at these two surfaces to prevent any play there. The printer guy will likely end up reprinting bushings with slight scaling changes until he finds the perfect tight fit, depending on his machine's tolerances.

 

Yes. I print all TrueUp parts with 20% infill, 0.2 layers (0.4 first), and 4 perimeters with 4 solids top and bottom. No printed parts contribute to the frame strength or alignment on this design. The extruder parts I do use 30% infill just because the lever arm gets a lot of pressure for it's size.

 

Yes, everything is in millimeters. I don't even remember how to do inches.....

 

I neglected to respond to this part. Yes. If there are few, list them here and I'll check them. If there's quite a few, how about doing this in a conversation instead (click the envelope next to your login name on the black header bar above and select Start A New Conversation)

 

Fixed. Thanks Chris.

 

Actually, what I do is take two aluminum heat beds and use one for the build plate. That converted heat bed, and the OB universal build plate, do NOT have the holes noted in the Step 28, TrueUp Glide Print Bed Assembly. You need to drill them.

 

I use 8"x8" because it's most common. AND, a 250mm bottom and top frame piece work at that width (no scrap to buy and toss). A 12" x 12" would certainly be doable.

The goal with the Z axis was to require full-steps-only since steps are physical locations in a stepper motor, and variation effects layer height. With a 1 pitch screw, 0.005 is easy to achieve with full steps. In all candor, while Z 0.005 is possible, it would never be practical, 0.01 would allow 0.24, 0.25 or 0.26 for example.

With X & Y, you do not want to require full step movement. Microstepping, while inherently less accurate than full steps (because microsteps are result of current fluctuations rather than positions), also use less power, create less sound at high speed, run cooler, and produce much smoother movement (all important considerations for X & Y movement, but not for Z). To get to 0.005 with a belt you'd need a 400 step motor, running 1/32 microsteps with a 32 tooth pulley - and probably not be able to see an improvement without magnification.

 

The math for movement would not change. But you still need to recompile the firmware to set X_MAX_POS Y_MAX_POS Z_MAX_POS which define the size of cube the printer works in. The main considerations you have for expansion are finding a hot bed the size you want and being aware that you'll need to somehow fashion an aluminum build plate that size. Also, with greater mass to heat, the heat bed needs to be 24 volt, so the PSU must also be 24 volt (the MKS Gen board is 12/24V). All doable, somewhere between Logo simple and Erector Set skills.