Hi all. I have had my workbee for some time and have a couple of cracked wheels and am replacing them. While doing so, I wanted to make sure everything was in the best alignment I can make it. I had issues using the acentric to get the right load on all wheels when I built it. I think I know what the issue is and am wondering if anyone else has had it and knows how to correct it. All the sets of v wheels have a fixed side/row of wheels and an acentric set of wheels to pull the top and bottom wheels together. If I am not mistaken, The fixed sets of wheels would need to be in perfect alignment to start with. If they are not, when you tighten the acentric on the bottom wheels to get the correct preload, it would have to warp the cbeam to get the top fixed wheels to have any load on them and it would increase the load on the top wheels that are lower than the bottom ones. Am I correct? If I put a plate with no load on the cbeam (hanging on the fixed wheels, they are not at the same height and some can spin freely and others are able to grab the rail. I have tried to align them without much success. I could torque the acentric on the bottom, but that would either crush the wheels to much on the lower riding wheels or try to bend the cbeam. I would think that these wheels not being parallel would cause the load on only the wheels that hit first. Any suggestions or any clarification I
I re-designed the plates on my Workbee style printer to have only a 3 pair wheel set at the top for the very reason you are experiencing problems (I have 2 fixed outer wheels and an adjustable inner wheel). I never liked the original set-up because I knew getting them balanced would be a nightmare. In your case, I would probably remove all the inner wheels and just keep the outer ones - (I think the Openbuilds Lead machine is something like that). If I had designed the Workbee from scratch, with a 4 wheel row, I would probably have put each pair of wheels on a rocker so they would automatically sit perfectly on the C beam.
Thanks for your reply. I wonder if putting acentric's on the top and bottoms would be a good idea. You could then adjust the top to be parallel and then adjust the bottoms.....
You could do that. Just remember that the outer rollers are what I call the "registration" rollers - they ensure that the plates are square to the extrusions So, if you use 2 inner eccentrics on top, adjust those rollers to "just" revolve on the C beam channel - the "reg" rollers must be in firm contact with the channel to prevent rocking. Remember though, that the inner holes would need to be enlarged to 7.2mm for the eccentrics which would need to be accurately done. Personally, I would try having just the outer rollers on top and removing the inner ones and see how that goes. As i said, my machine has 2 rollers on top and one eccentric roller in the middle but it works just the same even if the middle one is not touching. I don't know where you got your machine from but if its from Oozenest or Openbuilds, you can expect the wheels to be dimensionally accurate. For a chinese import however they can vary quite a bit, not just in diameter but in the amount of bevel. Of course, this all assumes that the upper holes in the plates are perfectly parallel or rather on the same plane. Cheers
OK, I did buy the 1010 kit from openbuilds a few of months ago. I disassembled the plates and measured the holes for accuracy and they were very close. Upon further inspection, I measured the wheel heights and there were slight variations. To try to resolve the issues, I tried to pair the wheels with the closest measurements to each other on the top (non movable). I reassembled and its not perfect, but, the wheels are very close now and I think I can live with it. If the wheels were not so expensive, I would order all new wheels. I picked up a few spares that were not from open builds, however, they are about .2 mm smaller. I have some cracked wheels to replace and my plan is to put them on the adjustable side and match the top wheels the best I can.
Yeah, I don't think its worth agonising over too much, just get it the best you can and it should be fine.
Slight deviation in wheel height acually plays to your advantage if there are slight deviations in extrusion width so agreed, don't obsess over them too much, us long as most are touching. More importantly: - don't overtighten eccentrics. It can cause flat-spots on the wheels - A well adjusted wheel transfers the load, it doesnt run with resistance - How to calculate V-Slot® deflection is making a bigger difference to the performance of your machine than wheel adjustment ever will
