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Chains constantly hanging up in gears

I’ve been trying for 2 weeks to do the setup and the chains keep wrapping around the gears or jumping one. I haven’t even been able to cut the final sled. HELP

are the chains parallel to the workpiece or are they angled? where do you have
the slack (across the top beam or down the side)?

David Lang

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Did you buy one of our kits? If so, PM me your order number and address and I’ll send replacements.

-Chris

I used the bolt together frame plans and the chains run along the top board. Any ideas?

Thanks I’ll get the number to you shortly.

The order number is 06066. I was quite sick for over a year so I’m just now putting it all together. Thanks again for the help.

what about the chain angles? (note the chain angles are when viewing the machine
from the side)

IIRC, the original bolt-together instructions ended up wiht the motors a bit too
far out for the chains to be parallel.

David Lang

To illustrate what David is saying:

2019-06-06%20Chain%20Alignment

The image on the left shows the chain aligned with the sprocket. The image on the right shows the chain misaligned. In the latter case, the chain is more likely to catch on the sprocket teeth and start to wrap around.

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I have been running in to this as well. While I do think I have some angle issues, I can usually prevent the wrapping by placing my finger next to the sprocket. (As I’m saying that, I’m thinking that may not be an OSHA friendly procedure) A small fin positioned at 7-8 o’clock (for a right motor), maybe out of HDPE or similar might keep this from happening?

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Is this during calibration or just during normal operation? If it’s wrapping during normal operation than there’s a good chance there’s not enough tension on the slack side of the chain. If it’s happening during calibration (i.e., when you are extending the chain off the sprocket) that’s not uncommon to occur and you have to sometimes be holding onto the chain and applying tension to it to make sure it doesn’t wrap (I’ve wrapped my chain tens of time because I wasn’t paying attention).

There are also several chain wrap mitigation devices that people have developed. A quick forum search should bring them up.

I will take a look at the angles. I’ll check the forums as well

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Jumps:
Following this steps, chain guides are not essential (still can be good to have):

  • first balance the sled by adjusting the ring on the sled
    That gives you a distance of the chains over the worksheet on the sled side
  • adjust the motors so that the sprockets are at the same distance as the chains on the sled
    This eliminates chain jumps on the chain going to the sled
  • for the slack side the chain also need to be aligned with the sprocket bringing them out the same distance

For a nice gallery from ply to 3d printed chain guides paste

forums.maslowcnc.com chain guide

in your favorite search engine and change to images

When does this happen? If that is on the slack chain side, it could be not enough ‘pull’
Check out replacing bungee cord with a weight system.

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you end up with problems on both the slack and sled sides, chain guides help
mask the symptoms a bit, but you still can run into problems and it causes more
wear on everything.

the right fix is to get the angle right.

David Lang

Chain skip is most likely a chain alignment (angle) issue. Chain is not meant to be twisted.

If the chain wrapping occurs with the slack portion of the chain, then its likely because there’s not enough tension on it. If the wrapping occurs on the sled side of the chain during normal operation, i.e. the chain is attached to the sled, then it’s probably a really bad chain alignment issue.

I agree with David on this.

That said, some folks with balanced and aligned chains did still experienced skipping, wrapping, or both. I implemented a simple and cheap chain wrapping solution early and never had to think about it again (of course, I also never experienced either problem, but it is hard to say whether that is because I took the time to balance the sled and get the ring height correct or if the chain wrapping solution took care of it.) So YMMV and you may wish to implement something along with getting your chain angles correct.

Click here

Please note that the chain should be parallel with the sprocket on both the sled side and the slack side for best operation.

Yes, check out pics of this in the community garden.

is this done by moving the motor back some? And do you do this while sitting on the wasteboard or on your normal project thickness?

Yes, it is a combination of moving the motors and where (how high in the z) your chains are mounted on the sled. Your sled should be balanced on the chains, and then the motors should be moved so that the chains remain parallel to the sprockets and work surface.

As for whether to do this on the waste board or project thickness, if you always use the same thickness of material, definitely do it on that thickness. If you will have varying thicknesses, try to get one that is somewhere in the middle to do it. There have been some set ups posted that allow for adjustment of the motors, but I have not found that necessary, and I have cut stock from 1/4" thick to 2" thick without issue. I did my motor set up with 3/4 inch stock thinking that it would be the most likely material that I would use.

is this done by moving the motor back some?

depending on your frame, it’s move the motor back some of change the frame
(depending on how far you have to move

And do you do this while sitting on the wasteboard or on your normal
project thickness?

ideally on your project thickness

David Lang