Hi,

I have added a youtube link to my GT2 belts in action (the Y and X axis are both in the same video). There seems to be a small twisting motion whenever the movement changes direction. Is this expected? Does it mean I have to make them tighter or do I have an alignement problem?

Here is the link: [youtu.be]

Thanks

My guess is that the axis of the pulley is not perpendicular to the plane that the belt lies in. You may need to raise or lower the pulley to get them perpendicular. I can't be sure this is the problem because you haven't provided a side view.

Edited 1 time(s). Last edit at 04/03/2016 05:14PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I think that the stepper is not square. Leaning back or forward.

Your clothes pin spring tensioner could also be twist loading the belt.

I have solved the first axis problem (the first part in the video). The plastic part holding the pulley was being slightly bent under the pressure of the belt. I reprinted that part and this twisting is minimized now. The twist in the other axis seems to be due to the motor being slightly bent, again due to the belt pulling it. This is harder to solve, as the motor is being held by the plastic part, which isn't very thick. In addition I have a vibration dampener in place (Astrosyn), which also adds to the bending. I might try to remove it but don't know if that will be enough. I've read in the forums that the exact amount of tension required by the GT2 belts was very high and could even destroy the frame.

There is a fine line between tight and to tight. Over tightening can cause the motor armatuer to rub on the housing not to mention the adverse effects on the bearings. I can deflect my belts about a 1/4".

It is hard to decide how much is enough. Some people suggest that it should be as tight as a guitar string. I find this hard to achieve. Also, the level of tightness seems to be asymmetrical on both sides of the belt.

As tight as a gitarstring is to tight, some parts will be damaged or break at last.
If you can move the belt 1cm up and down with the least amount of power it's tight enough.

I think the problem is to little space for the belt in the wheels, so it will move on the sideways.

Aad.