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Counter weight on chain slack sprocket

Hey folks, I have an ongoing chain skipping problem. Mainly near the top of the sheet. Its very consistent, if I loop back to the same few lines of gcode it will happen in the same spot everytime. Im sure alot of my problems will be solved by modifying my frame (extending top beam outwards & making a better chain guide) and upgrading to v 1.00 of software and firmware. I would like to finish my current cut project before doing more mods/updates.

I added a counterweight to the chain slack sprocket which I think causes more tension on the motor sprocket, and that has resolved 80% of my chain skipping, I can loop back to the same gcode spots and it will no longer skip. Has anyone experimented with this before? I haven’t been able to find anything in the forum.

Happy holidays!

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Sorry for the trouble! I did play around with a counter weights system early on and it worked well. It got removed from the design because it added cost and complexity, but it always worked well. I found that to keep the chain aligned with the sprocket (because the sprocket is tilted and the weight wants to hang straight up and down) I had to give the weight a guide so that it would move parallel to the sheet instead of vertically. Overall I think it is a great solution!

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Hey Bar, thanks for the info. I will set something up like that when I do my next round of mods! I may cut a pvc pipe length-wize to crate a travel channel/gutter.

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It might not be suitable based on your frame design, but I’ve been successful in preventing any chain jump using the kit-included materials by mounting the motors and chain guide in the manner seen in this link:

The ‘chain guide’ is just loose enough to allow the plastic (which i trimmed to length) to spin freely. The angle maintained by the chain to the sprocket is tight enough to force the chain onto the sprocket at no higher than 225 degrees (ie: SXSW, or ~7 o’clock). it acts like a chain tensioner andalignment guide immediately prior to the sprocket.

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Your approach to attaching the motor bracket that way is a good idea - easier access to the adjustment slots and this approach to a chain guide!

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is it skipping as the sled is moving towards the motor or away from the motor?

if it’s skipping as it moves towards the motor, you don’t have the chain
parallel to the workpiece, move the motors in or out to make them parallel.

If it’s skipping as it moves away from the motor, look at the plywood chain
guide that was posted recently, that keeps the chain wrapped around the sprocket
and keeps gravity from pulling it too far back

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Thanks, primarily skipping while moving away from the motor on the top opposite side of the skippy motor. Ill give that a shot.

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I like the look of that. It cant skip if it cant lift. But how do you calibrate chain length without being abe to attach the chain?

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huh? When I calibrate it, I loosen the roller/screw and put the chain on, hand tighten the screw and go. it’s no hassle.

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i was planning to put a counterweight on mine too instead of the stretchy string, just makes sense to keep the tension equal at all times, i thought to just let a piece of rope take the path of the stretchy string now, and add a pulley at the top so the weight can freefall, that way you don’t need to guide the weights, and the chain stays alligned with the motor.

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this sounds like a great idea. I am hoping to have some more time to work on my build this weekend, so may give it a try

Here is my solution, dirty and quick, fender washers…

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That is fantastic! I love it.

Is anyone else having an issue with the chain continually wrapping around the sprocket on the actual motor? I’m finding that for some reason my chain isn’t loosening up from the sprocket, which causes two issues:

  1. sometimes its stuck on the sprocket for just a little while, which causes it to pull up the router passed it’s desired cut, and then the weight of the router will pull the chain from the sprocket, causing it to sink back into where its supposed to be
  2. sometimes it gets stuck to the point where the chain will continually wrap around the motor sprocket, which can lead to damaging the machine.

I’m think I need some type of guide for the chain after the motor sprocket to keep this from happening, but wanted to see if anyone else had to deal with this?

The classic reason for that to happen is if the chain is not feeding directly in line with the sprocket, does it look like the plane of the sprockets is in line with where the chain is feeding onto the sprocket?

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I think it looks pretty in line, but I’ll move it around a bit and see if that solves it. I think this plane keeps based on how I’m leaning the Maslow with the temp frame, since the legs are just the 2x4’s with the pulley, so I’m thinking that the contact of this bottom piece with the ground might have shift. I’ll double check to see if moving it fixed the problem

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@bar I tried leveling the plane of the sprockets and I’m pretty sure it’s pretty in line. However, still seeing the issue =/ i took a video to show an example of what I’m seeing

video of sprocket issue

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Just an FYI for everyone on this thread. In the “new stock frame” thread, it looks like we are going to end up with the chain moving horizontally across the top bar. That will go a long way towards eliminating this problem

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can you do a video from the edge so we can see the chain alignment?

it would probably also be good to have your chain output not hitting the input. But I doubt that’s the cause of the skipping.

will do - i’ll have to take it tomorrow after work though, thanks for all the quick responses

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