Of course, you could buy some extra motors, controllers, and chains and build this sled.
Ditto on what David and John said; but if you’d like to see some (semi-hypothetical) reasoning as to why the ring might be less accurate you can read this post: Throwing my hat in the sled modification ring (warning, this too, is my opinion!)
Someday we may have a scientific answer…
I don’t think there are currently any rings available but I might be wrong, if you need a solution right now I am still making and shipping linkage kits though!
Yesterday i was playing with the nuts of, the 8 points of rotation watching hoe the braces respond when i just try to rotate the sled… I rotate it just a little and i saw one of the braces move a little, but the ogher not…so, i apply less torque on the nuts, but there are 4…wich is too tight?..after tight and free the nuts to see what happen i end with a state where it look tight in lateral movements, but free enought in the rotation case… its a little triky job…but i hope can help … i will see tomorrow
Are you talking about a kit I made? If so the tightness of the nuts that attach to the sled or the barrel bolts that make the joints should not ever bind the joints, even if they are extremely tight… They are designed so that they can be tightened without affecting the friction of the pivot. The four points that attach to the sled have nylon bushings that are bolted tight to the sled, the linkage pivots on the nylon bushings. For the other pivot points the barrel bolts are about 1-2mm longer than the linkage so they can be tightened tight and linkage pivots on the steel shank of the barrel bolt.
If this is a linkage you made yourself then I don’t think I can be of much help because I don’t know how you made it…
No i dont, i am talkkng about the one i made
Ahhh, got it.
In that case it sounds like loosening bolts until it all works smoothly might be a good idea…
If you find that you have to loosen the nuts so much that they’re in danger of spinning off the screw, replace them with nylock locking nuts. They will stay in whatever location you put them regardless of whether they’re tight to the surface or not.
LI find this topic very interesting. What can I say? I am an engineer and find this topic an interesting read while I await purchase of a CNC kit.
How about using a lazy sussan bearing setup? One that fits around the router (similar to the “ring”). Cut off the three non used ears on each plate and fasten the assembly with some z-clips. See attached picture of what I am talking about.
The chains could be spaced to remain parallel to work surface.
Lazy Susan bearing are not sealed (lots of sawdust will get in them) and they
are designed for axial loads, not radial loads, pulling on them sideways will
pull them apart pretty quickly.
That is the type of bearing that we thought about initially, but quick
experimentation showed that they were not reasonable to use.
Hey!! I was trying to find a copy of the sled template for the triangulation linkage, but the file link seems to be dead. Is there a copy around??
which linkage kit are you refering to?
The link on the page goes to a Google Drive document, but it’s 404-ing!
Since it went from opensource to sale the files are replaced with a link where to buy the kit.
The concept however is simple to replicate. STL file for a plastic one are here.
Can be used as a start.
If you invent a new one, please add bearings instead of material rolling on a screw thread. I will buy 1
I’m starting testing on this one. It’s based on the wood one, and is using skateboard bearings. Will report back.
How tiny are your skateboards?
Skateboard bearings are the 608… Because they’re ubiquitously trashed by riders the world over, they’re dirt cheap and decently sized… I ran into them because one of the early 3d printers I had used them…
I doubt the bearings will make much difference, but they won’t hurt
The biggest difference is that you can then tighten the screw, compared to leave it loose enough for motion.
A minor aspect is that steel does not eat through screw / screw does not eat through plastic.
i love how tiny that sled is!
the reason for the large sled is to bridge over any pockets that you cut in the
workpiece. If you are not going to do that, the sled just needs to be large
enough to hold the componenets.