# Knotted String as Replacement for Toothed Belt

I'm at a location where I don't have easy access to toothed belts for my printer (a RepRap Wallace). While trying to look for some solution, I saw some talk of using fishing line as a belt, along with a log of admonitions of Don't.

However, as I have easy access to fishing line, but almost no access to a toothed belt, I was thinking of using multiple strands of fishing line with regularly spaced knots to simulate a toothed belt. However, Google didn't help much with either usage or possible Gotchas.

Is there any possible issues that I may face with this solution?

• There is some successful documented use of printed belts for low loaded belts. See e.g. this design. – 0scar Oct 22 '18 at 8:45
• Can't you buy reinforced GT2 belt on AliExpress or eBay and get it delivered via the post? Thailand is very expensive for parts and I just ordered everything from China, often at 20% of the price on the street. – Greenonline Oct 23 '18 at 18:57

I’m going to recommend not using a fishing line with knots. Probably the biggest problem you’ll have using the fishing line with knots is if the knots are not perfectly spaced, movement along the X or Y axis is not going to be consistent. This could result in weird deformations in your print.

Depending on how you tie the knots they may not grip the teeth of the gears quite well enough to prevent slippage.

Both of these issues will mean that you will not get very good quality prints assuming the print doesn’t outright fail.

You would be better off waiting to get the correct belt then attempting to use fishing line.

• Fishing line will also have a lot of flex, with stretch and rebound. This, too, would cause a lot of issues in print quality. – Pᴀᴜʟsᴛᴇʀ2 Oct 22 '18 at 12:46

If you are using fishing line, it would perhaps work to wrap the line around the pully and fastening it to the pully (both ends), so that the line wraps around the pully. One side would play out from the pully while the other was wrapping around it.

By attaching the ends of the line to the pully, there will be no slippage between the line and the pully. The knots aren't needed, and their irregularity won't affect the print quality. The problem will be if and when the fishing line wraps tightly over itself and jams. This can be mitigated a bit by having the two ends on opposite sides of the pully, and perhaps adding guide wires to direct the line to the proper side.

Usually, mechanisms like this involve good control of the wrapping and unwrapping, but this might work well enough to print a new pully.

Thin aircraft cable might be a good alternative to fishing line.