Nothing too crazy here, I haven’t actually cut anything yet (Arduino connection issues) but this seems to keep decent tension on the chain. I have 4 18oz bottles of water (~4.7lbs) on each chain.
Hopefully I’ll get it running tonight and see if my setup works well.
2 Likes
you don’t want too much here, if the weight on the slack side is more than the
tension on the sled side, you will have backlash issues. There is a 2:1
mechanical advantage for the sled, so with a stock system getting ~3 pound of
tension on the sled side, 5 pounds of weight on the slack side should be good.
David Lang
2 Likes
Thanks for the post. While reviewing your post I noticed some very small detailed design from your Maslow. I haven’t see many small things on here. How small have some of your designs been and what kind of bit do you use for that? I’m brand new at this so I’m sorry if I’m out of the loop. Thanks!!
I have this same setup. But my chain will wrap around itself on the sprocket. Maybe I need a shorter bungee cord. Is yours tight enough that there’s no slack at anytime in the chain?
Any tips on how to calculate the best values for counterweights? Like if one has 13KG sled, complete with router, whats the best counterweight value in regard to not overstress the motors but get enough tension?
put your machine dimensions in the spreadsheet and you don’t want the tension
from the counterweight to be higher than the tension from the sled
you want the gears in the motor gearboxes to alwasy be loaded the same
direction.
so normally this ia about a 3-4 pound weight (remember the mechanical advantage
of the pulley)
David Lang
3 Likes
Thanks. Them i am pretty close. I do have around 1.3KG on each chain and had been thinking of putting more weight on it. Probably double of this. So i better stay with the 1.3KG, i guess.
if you have no chain on the gear, attach a vice grip or something to it and you
can wiggle it back and forth just a tiny bit (the clearance of all the the gears
means that there will be just a little bit of movement between them being loaded
on one side and loaded on the other side.
when the sled in is the far bottom corner, you have the least tension on the
chain, at that point you want the tension on the slack side of the chain to be
less than the tension provided by the sled.
in any case, you want enough tension on the slack side of the chain to keep it
out of your way, more than that is not going to help. you cannot add enough
tension on the slack side to reduce the load on the motor significantly in the
high tension areas (where the tension gets to around 40 pounds) without causing
grief in low tension areas (where the tension gets below 4 pounds)
David Lang
1 Like
On each side? Then whats a 2.5" rise?
Where do i find this spreadsheet?
2.5’ = 30" = 76.2cm
distance from motor axel to top of cutting surface
Adding my build to the list. This reuses the bearing pulleys used by the bungee plus some 3D printed parts. The kitty ears on top aren’t strictly necessary but it does greatly the chain rubbing on the rope.
2 Likes
I added a guide for the other rope to my tension sled. This prevents the rope from tangling with the chain and sprocket. Everything stays in order even when moving across the entire X axis. The links above have been updated with the new files.
5 Likes
So looking to update my rig with a pulley/counterweight system similar to what @Snapperhead posted he did to his. Looking at Lowes, they have these (in both steel and nylon) https://www.lowes.com/pd/Prime-Line-2-Pack-1-in-Steel-Sliding-Screen-Door-Roller/3043872. I’m just wondering on anyone’s thoughts on if they would work for the top pulleys (I plan on keeping the rollers I have with the bungee system as they are currently mounted in the position that @Snapperhead has on his. Thanks in advance for the assistance!
this works better, it fits the chain very nicely
as for the other end, you can get fancy with multiple pullies, but a simple
electrical sweep of plastic works well
see the pictures in this thread
https://forums.maslowcnc.com/t/weights-for-chain-tension
David Laang
1 Like
@dlang That’s an idea as well. I was looking to go with the weights to the back in the center, and that sweep can work like that as well. I’ll have to ponder some more as to what I’m going to do. I have been contemplating mounting my frame to the wall, so this is an idea that I can keep in mind for that.
Thanks!
with a 10’ top beam it gets a bit crowded in the middle, with 12’ top beam you
would have pleanty of room.
David Lang
I copied the dlang solution and it works great!!! (use it on a 12’ beam).