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T-2.5 Vs T-5 Belts

Posted by jimcking 
T-2.5 Vs T-5 Belts
June 09, 2012 01:55PM
Just thought I would post this picture of the difference I got after switching from T-5 Belts to T-2.5 Belts. The belts and pullies were an exact replacement so did not have to change anything in firmware.

Got them here:


Jim K.
Re: T-2.5 Vs T-5 Belts
June 09, 2012 03:05PM
Which machine and do you have a link to the model?

Re: T-2.5 Vs T-5 Belts
June 09, 2012 03:28PM
I have an SAE Prusa that I built. Not a kit. Used machined pulleys for the T-5 also.

Jim K.

Edited 1 time(s). Last edit at 06/09/2012 03:32PM by jimcking.
Re: T-2.5 Vs T-5 Belts
June 09, 2012 05:28PM
Did you have the cogs of the belt running over the idlers, or the smooth side?

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Re: T-2.5 Vs T-5 Belts
June 09, 2012 05:48PM
Thank you for the before and after
Comparisons like this with photos and ander info would be a nice addition on the wiki page Choosing_Belts_and_Pulleys.
Perhaps close ups of critical parts/major improvement areas.
Re: T-2.5 Vs T-5 Belts
June 09, 2012 06:40PM

Initially I had both belts running over the idlers on the cogs with the T-5 belts per the original Prusa build instructions. After noticing the herringbone pattern on both the X and Y dimensions of a box I was building and reading nopheads information on turning the belt 180 degrees so that the smooth side of the belt ran on the idlers, I turned the X axis belt 180 degrees. Although that worked great for the X axis, the twist was too sharp for the Y axis. The right side of the picture was taken with the X axis running on the smooth side of the belt and the Y axis running on the cogs. That is why the herringbone pattern in only in the Y dimention in the photo. It actually looks much worse with both axis running on the cogs.

Then tried the T-2.5 belts on both axis. The left side of the picture is the result of that. The cogs are running over the smooth bearing idlers on both axis. I am sure that using toothed idlers with the T-5 belts would work just as well. The easiest fix was just to change the T-5 belt to the T-2.5 belt. That appears to have worked just great. Since the new drive pulley is the same diameter as the original 8 tooth drive pulley for the T-5 belt , it worked great with no modifications to the firmware.

Jim K.
Re: T-2.5 Vs T-5 Belts
June 10, 2012 05:07AM
Odd I have never seen this effect but many others have reported it. I have some machines with T5 belt and some with T2.5, some with the flat side of the belt over the idler and some with the toothed side. That is why I asked for a link to the stl as I would like to try it myself.

Edited 1 time(s). Last edit at 06/10/2012 07:24AM by nophead.

Re: T-2.5 Vs T-5 Belts
June 10, 2012 06:44AM

Sorry, I did not notice that part of your request.

The model is at:


Thing 22268

That plane flies great with a 5/8” 6/32 bolt in the nose, about 30 degrees of up elevator, and 15 degrees dihedral. When launched with a #64 rubber band it will fly to a height of about 50 ft., loop and then glide gracefully to the ground

Thanks for all of the help you have given me. I follow all of your articles and really appreciate the print you made to help me figure things out.

Jim K.

Edited 2 time(s). Last edit at 06/10/2012 07:22AM by jimcking.
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