Need some help? Check out our new Help Centre

Upgraded Rails

When I first setup my emblaser I had a bit of a problem with the right gantry carriage. There was quite a bit of wobble from left to right. This was partly due to having the belt a little too tight, and little bit due to print of the carriage itself. I reprinted the carriages and properly set the belt tension. After a while I noticed that it was beginning to lean a little. It wasn't much, but enough to make the belt not want to sit properly. Since there is only a single rail on the y axis there isn't a lot to hold the carriage perpendicular.

I decided to give a redesign a try. I contacted support and Domenic was able to help me out. I can't give him and the rest of the folks at Darkly Labs enough thanks. They were extremely helpful in letting me experiment.

Here is a rendering of the idea that I had.

image

The extra rail is 20mm away from the original rail. I chose to keep the new rail a little closer to the original than the rails on the "x" axis. I didn't want the rail brackets to have to be too tall. The rest of basic dimensions are identical to the original design. I wanted to make sure the belt tension process would not change. I added a spine down the back of the bracket to give it a little more support since it was taller.

I also changed the type of retention system for the bearings. I had a difficult time getting the clips to stay put and decided to use screws to attach the clips to the carriage.

Here are some actual pictures of the end result.

image

image

image

image

I was going to post a video as well, but I don't know if that is really necessary. There is no noticeable difference in how the unit operates after the change. Except, of course, more stability in the "y" rails. I re-ran the calibration image and it looks great.

I didn't attach the bearing retainers for a couple of reasons. First, they are in there *very* securely. I had a very hard time snapping them in. Secondly, I didn't have screws that worked well. I don't really like using screws in plastic, but I don't think it will be a problem.

Just about the only thing I don't like about how it turned out most likely is due to my 3D printer. The gantry carriages printed great. I couldn't have been more please. The rail brackets are what gave me fits. I sized the holes at 8.2mm which is an appropriate size for receiving an 8mm rail. That same size was perfect for the gantry carriages. For some reason the rail brackets measured around 7.6mm. I must have re-printed them 3 times before I gave up and just made the holes bigger. PLA is usually pretty good about retaining size. I want to re-process the STL files to have two different rail brackets. One the "right" size and one the size that I had to use. Look for those files in a future update.

Sorry for the long read, thanks for looking. Now I need to go find something to cut. :)

Comments

  • Very well done. Looks to be a great, well thought out, update for Emblaser users. I hope a kit of update parts can be made available (hint, hint, hint).
  • I've found that holes I build into a 3d printed part are never the size I wish. It's been easy enough to get them close, then hand-force a sharp drill bit through to get the right size.

    Would you consider to provide the STL files for other Emblaser owners to use? Also if you have sourced the rails and bearings, that would be great information to share. What modeling program did you use to create the aprts? I'm an OpenSCAD user at the beginner level, but find it's easy enough to use for stuff I need. Your engineering (art-work) looks great, but it's well beyond my abilities at present.
  • Hi Matthew,

    I too face a similar problem with the gantry carriages i.e. they wobble from left to right. Also the bearings tend to slip out probably because the belt is a little too tight. Even after upgrading to the new carriages (with the retaining ring) it did not help as the bearings still tend to slip out.

    Your upgrade seems to be the solution to that problem. Would really appreciate is you could share the STL files.

    Joel.
  • edited March 2016
    We drilled & tapping holes for screw clamps (washers) to retain each bearing in the carriages, but after running several long and fast streamed image gcode files, the plastic ended up cracking where the tapped holes were.

    We ended up using http://www.gorillatough.com/gorilla-glue to retain the linear shaft bearings in new carriage supports (earlier non retaining clip type). We have not had any problems with them loosening up since.

    The L&R carriages do lean slightly, but the belts have not popped off. We may end up making spacers to fill the gaps in the linear rod holes, so the carriage supports can not pull inwards from the belt tension.
  • I have fixed more than a couple of things with Gorilla Glue, great stuff! My only concern would be that since it expands, it could affect one bearing in a slightly different way than the other. This could cause undue tension on the rail. The design of the gantry carriage specifically allows for the bearing to be able to align themselves to each other. (I think I am explaining that in the right way)

    Another option I thought of for the retaining clips would be to put the hole all the way through the carriage and use bolts, nuts, and washers. Again, I would have to figure out how to source the appropriately sized hardware.
  • They were new carriage supports and the bearings snapped in tight with a small amount of Gorilla Glue applied on them. There is a relief in the center of the bearing pockets that allowed for the glue expansion. I also inserted the rod through the bearings when the glue was curing to ensure alignment.

    It requires very precise movement for raster photo engraving and it worked perfect.

    We don't have the luxury to 3D print new parts and I have considered machining new parts out of Delrin or UHMW polyethylene, but the Gorilla Glue fix was much quicker & easier. :wink:
  • This topic has been re-posted to the new community site. The STL files are over there. It is in the Tips and Tricks section.

    https://darklylabs.zendesk.com/hc/en-us/community/topics
Sign In or Register to comment.