D-bot X/Y motion system linear guide blocks and pads made from Igus tribofilament

thingiverse

****** Note: I just posted a version 2.0 of these Igus-filament slider blocks and pads here: https://www.thingiverse.com/thing:2444422 Version 2.0 offers a more refined shape for the carrier blocks that blends better with the original D-bot parts. The version 2.0 sliding pads use less Igus material and reduce the surface contact area between the pads and the v-slot rail. I don't consider version 2.0 as a necessary upgrade for anyone who has already made and installed the version 1.0, though it may well perform better over time due to the improved slider pads. The carrier block changes are entirely cosmetic. ****** Hi. I removed all of the V-slot mini wheels from my D-bot's X/Y motion system and replaced them with sliding blocks that are lined with pads printed from Igus tribofilament. This system consists of a block which uses the same hole spacing as the D-bot gantry end caps and also the print carriage plates. The block is the same width as the two spacers and the mini v-slot wheels used in the D-bot design. To this block is applied a bearing pad printed from Igus tribofilament, which rides on both the 20mm wide flat surface of the 2040 V-slot rail, but also fits down into the V-shaped slot to keep things nicely aligned. The purpose for using these blocks is: 1) Tighter fit between the print carriage and the 2040 v-slot print gantry, and between the ends of the gantry and the 2040 v-slot printer frame side rails. With these mounted fairly tightly there is no detectable play or slop in the system at all. Zero. 2) Low friction for a fully contacting sliding pad system. There was more friction in the moving parts as compared to the ball-bearing mini v-slot wheels, but I presume that this will smooth out in time as the parts "wear in" to each other. Also that friction is not necessarily a bad thing, as it could likely act as a sort of dampener that could reduce ringing. The steppers in a D-bot are plenty powerful enough to move these things around, so a slight dampening effect I see as a positive. 3) Long service life. I fully expect these pads to last longer than the rest of the D-bot itself. Igus advertises that their tribofilament wears up to 50 times less than other printable plastics. Their charts seem to bear that out, but then they would, wouldn't they? 4) The pads don't stick out beyond the ends of the plates the way the v-slot mini wheels do, so the pad blocks can move on the Y axis all the way up to the rear idler corner blocks of the frame. This means that the Y axis end stop screw has no problem getting to the Y axis end stop switch. With the mini V-slot wheels I had to bend the switch lever of the Y axis end stop switch out a little in order to get contact with the end stop screw. This seems like a trivial benefit, but was actually quite a nice little bonus to those of us whose end stop screws just didn't quite reach the switch. I've been wanting to try the Igus filament for some time, and seeing quite a few people create D-bot mods that involve bolting Hiwin linear guide rods to their D-bot's top rails and print gantry inspired me to create this. I want the same benefits of the Hiwin linear guide system, without adding all of the weight of the Hiwin rails and sliding blocks, and while being much cheaper. One of the aspects of the D-bot design that really appeals to me is how the D-bot frame itself, because it's made using the OpenBuilds v-slot rails, can act as the guide rail for the Z and X/Y motion systems. The Hiwin solutions are adding tons of crap to the D-bot, and especially when you add the Hiwin rails and blocks to the 2040 print gantry of the stock D-bot design, you're adding quite a lot of weight to it that I just think is unnecessary and likely detrimental. I've had these sliding blocks installed for going on a month of printing as of this posting, and my printer is busy for most of nearly every single day. So far these blocks have worked out great. Because the pads are designed to the exact dimension of the outer flat surface, and the V-slot itself, of the OpenBuilds V-Slot rails that the D-bot's framing is made of, they are a decently tight fit, and yet because they are printed from Igus's tribofilament, they will probably last forever, and show very low friction. It's not no friction, but the friction is surprisingly low for such full contact My original idea for these used two shorter pads at either end of the sliding block, rather than a full-length pad, in order to minimize the surface contact area of the Igus material on the aluminum v-slot rail to drop friction even more, but it was more difficult than I'd assumed it would be to get all four pads (two each for top and bottom block per side) exactly aligned with each other. The full length pads fit down onto the tangs printed into the top surface of the blocks allowed extremely good alignment of the pads. As printed, since I use a Bowden feed on my D-bot, I had slight blobbing at the corners that required a couple of minutes' worth of cleanup with an Xacto knife. Depending on how you print these, how the first layer goes down, etc. you may have to do some minor trimming to get the pads to snap down onto the tangs on the block. I left the tolerances extremely tight, tighter than you'd reasonably expect to achieve with a 3D print, specifically so that the pads would be exactly aligned on the bearing pads, and would be a good, tight fit in the v-slot slots. Once printed and test fit to each other, I put a few drops of CA (super glue) onto the Igus filament pad bottoms, snapped them onto the blocks, and then clamped them down pretty hard onto a section of spare 2040 Vslot rail that I have left over from my D-bot. I left them clamped hard like this for a couple hours until I was sure the CA was dry. I printed the blocks from PETG at 97% infill. I printed the pads from Igus tribofilament i170 at 70% infill with 3 perimeters in order to save material. I used 7 top layers at .1mm layer height, for fine resolution on the pads' bearing surfaces. I've also tried the i180 filament. The 180 filament prints easier, and the prints look better, but it seems somehow softer than the 170, and the 170 also seems to have less friction. Igus claims in their marketing materials that 170 has the best wear behavior, but is more demanding of production technique. I can vouch for at least the second part of that. I printed the Igus pads at 260 C with the bed at 90 C. I used a brim to lock it down after several attempts pealed up from my PEI sheet a little in one or two corners. I removed the brim with an Xacto knife afterward. I also used a brim on the main PETG blocks for the same reason. This is version 1.0 of this item. My intent was to clean up the design of the blocks so they blend in better with the existing D-bot print carriage plates and the gantry bar end plates. I haven't done that refinement yet, but someone asked me for these files, so I'm putting it up now as is so they can be used. When I've refined the block design I'll post that updated block as 2.0. The change will only be cosmetic. While these blocks look fine as is, they can look better if I tweak the dimensions slightly and add a radius to the bottom ends of the block so they match the radius on the corners of the stock D-bot plates. Here's a short Youtube video that I made showing this system in use on my D-bot: https://www.youtube.com/watch?v=ChPcBsqxBR4&feature=youtu.be I'm attaching my SolidWorks 2016 source files for both blocks and pads. All of this is released with the Creative Commons - Attribution - Non-Commercial license.