That’s correct, but the weight distribution is pretty much fixed when the sled is built and since it has to deal with the weight of the router moving in and out, will be varying a fair bit in any case.
As such, I think (don’t know because my kit is still in it’s box) that this doesn’t need a lot of adjustability, just a little when it’s first built.
That’s my reasoning for the top mount links to just use a hunk of 2x3 or 2x4, trimmed down a little if needed (it seems as if the ideal height is in the 2.5-3" range, so a 2x3 may be within the zone with no modifications)
@bar , what is your feeling now, as before you improved by going smaller. Was that from flex in the ring? With this design a larger ring should make no difference, or would it?
Looks great @bar! Could you expand on how you set up the chain connection to the bearing mounts? Also, what is the inner diameter of your ring? (this last goes along with @Gero’s question regarding whether a smaller diameter ring performs better than a a larger diameter).
Nice find @meddesign. How are those v-groove bearing working on the edge of the ring @bar? I can’t tell from the image you posted, but it doesn’t look like the inside circumference is beveled to match the v-groove. I am thinking this wouldn’t matter much, and that the v-groove (or perhaps the u-groove) bearings would ride on a flat edge just fine and still act to keep the bearings centered. Is this what you’ve found?
@meddesign For some reason I was searching with the wrong keywords and coming up with not much, thanks for letting me know what to look for!
@gero Right now I am using a 105mm radius on the interior surface. I’ve found that having a smaller ring makes a really big difference in how smoothly the carriages move. When the ring is smaller the weight of the bricks pulling down has more mechanical advantage to turn the sled against the friction of moving the chain attachment carriages.
If you want to see the whole cad file it’s live here (so it will always be up to date):
@Keith Right now the chain attaches by passing through a square hole in the end of the carriage and is then held in place with a cotter pin. On the other side the two 30mm v-groove bearings are held in place with shoulder screws so that they can’t be over tightened which would add friction.
Would like to be included in this beta project of possible. I have bit different setup with motors not being as powerfull so I understand if I can’t get in on this beta. I can just wait till it shows up in store if needed. Thanks again for all you do Bar!
Edit, when stock motors show up I hope to get two of those as well. That puts my setup closer to stock for comparison.
I’m on the wait list for when the full kits come up for sale, so I’ll opt out of asking to be on the beta list for this, but it seems to be a pretty mechanically simple solution. I’m interested in seeing what sort of accuracy changes come from this modification.
I will certainly like to be part of the Beta group. Have my maslow and started construction.
I also have ordered the Linkage kit so it would be good to compare both options.
I got the newest version of the ring back from the laser cutter today. The design is very similar to the last one, except that the bottom two mounting points are splayed out to the sides which makes them more rigid and prevents interfere with the z-axis attachment bracket.
I’ll need to do a little bit of testing but I’m hoping this is the one!
I was thinking last night about a simplified version in order to achieve the same thing (triangular kinematics) as per the linkage and ring options but am not sure if it would work so thought I would put it out there [Again I don’t have the same level of expertise as the people in this thread]
If you go back to the two mounting point model if the connectors could rotate around a single cylindrical post (vertical mounted) with rotation around the horizontal plane a the top of the post would this not achieve a similar outcome at less cost. Not sure if it would address the rotation due to torque from the cutter.
