It seems everybody has problem adjusting the distance between the Bearing clamps. To get the correct distance you shall “slide” the clamps back and forth according to Vellemans instruction. I have never been in need of a hammer when “sliding” something before but this time I had to use one. Finally I got to a decent distance and I’m sure it is possible to do it with some luck and a persistent mind set. Still I could feel that the resistance when moving the head there was a heavier resistance at the ends.
However, if you want to get rid of this problem once for all here is what Velleman should have done from the beginning.
Get yourself a pair of sliding bearings (not sure that this is the correct name in English but it is glidlager in Swedish) with an outside diameter of 8 mm. Using that particular size means you can go back to the original set up if you want to. The inside diameter on the ones I got was 6 mm. The bearings can be pushed in the openings in the Bearing clamps with hand force.
You then have to either get yourself a new pair of rods in stainless steel or use the supplied ones and change the end diameter in a lathe to 6 mm. If you try altering the original rods please be ware that they are not stainless but surface hardened so you need a good lathe the modify them. Sparks were flying when I did mine.
A stainless rod will be much easier to modify.
Now you have yourself a Vertex where the distance between bearing clamps is not critical since it is continuously adjusting the actual distance. You can now start serious printing instead of adjusting the printer.
A third option for the rods would be to get a 6mm rod fitting the bearings and then a tube with outside diameter 8 and inside 6 mm which would eliminate also the turning process.
I think I get the concept, but the rod grinding sounds intimidating indeed. The rod-in-tube sounds better, but my question is: can new plastic end caps be designed and printed which would accept the bearing size needed to keep the original 8mm rods?
Yes, new cap ends with for instance 10mm holes can be designed to accomodate 10/8 mm bushings. However it seems a lot easier to keep the original ones and get a 6mm rod with a 6/8 mm tube.
Someone have to design them though.
Maybe you can ad that only one for each axle is necessary and what type of bearing should be installed ? I googled the Swedish glidlager and came up with linear bearing or plain shaft bearing. Maybe someone native English speaking can confirm this.
Nice job on the Thingiverse, BTW. But I’m curious, is there a downside to just slightly sanding, filing or reaming the existing end clamps so that the rods can move more freely in and out of them? Maybe with some lubrication added?
Problem is the clamps are not made to have rods moving in and out of them. They will wear.
Now that Andreas made the very nice clamp and published and I found where to buy the bearings on ebay for no money at all there is no need to hesitate.
I have noticed that outer dimensions of my models get within acceptable limits, but holes often are too narrow. Also this time. I have redesigned the clamp that Andreas has published. Mine has a hole that is designed with a 10.6 mm hole in Sketchup, but comes out just right, ca 10.0 mm. Strange thing, I guess it depends on how finely tuned your printer is. It was trickier than I expected to make the hole bigger. There are lots of things going on inside this clamp, it’s quite crowded inside.
So now I have only to install them… Well, no, perhaps later. “If it works, don’t fix it”. It is a bit scary to rebuild it, it works ok. Well, good enough.
As said earlier in this thread, the clamps are not made to have the rods move in and out and over time they will wear and be too big.
Better print new ones and spare the originals.
Well, I have done exactly that; sanded slightly* and lubricated the inside hole of one of each axis end clamp, and it has been a success. I believe it will never wear out, because
a) the rods are already parallel so any movement during adjusting will not occur during printing;
b) even if the rods are not perfectly parallel, any movement during printing will be very small;
c) wear caused by a mirror smooth rod slowly moving against plastic is virtually zero anyway.
I adjusted by very slightly rotating the 2 end clamps in opposite directions (they do not move much), so that the sliding end clamp was pushed to the proper point by the rods themselves. The friction in my x-y movement is now much less.
*Note that the hole was still a snug fit, but movable with hand pressure. Do not make it a loose fit.
