Pulley 20 vs. 16

[critical_limit]

Hi Pro´s,

I have some 16 teeth Pulleys left from another Project. Wouldn´t it increase the resolution and accuracy by installing smaller pulleys?
The torque will be higher and the amps for the motor can be reduced as well.

Why we are using 20 teeth? Is it for the rambo board running at the edge?

Maybe someone knows. But as far as I can see, installing less teeth is better. Or am I wrong and missed something?


cheers
Dirk

[gestalt73]

I designed my second machine to use the 16 tooth pulleys. I haven't finished the build yet, and I can switch back to 20 tooth if there was some good reason to.

In theory it should increase your step resolution by 20% by decreasing the total distance traveled for every full rotation of the pully. I'm not sure I got a firm answer as to why SeeMeCNC switched to the 20 tooth pulleys, but I can guess at a couple of different possibilities:
- maybe 16 tooth pulleys were chewing up the belts?
- maybe the larger pulley decreased the computational workload on the Rambo?
- maybe someone did the math, and slight loss in resolution was drowned out by other inaccuracies in the machine?
- maybe they were easier to get?

[Polygonhell]

Doesn't much matter 15 vs 20 tooth, I have one of the original machines with 15 tooth pulleys and 8x uStepping.
later machines are all 20 tooth pulleys with 16x uStepping.
The 15 tooth pulleys are all aluminum and there were issues with earlier machines eating the belts, I believe the 20 tooth pulleys are plastic on an aluminum cores, so less likely to do this.

[Jimustanguitar]

20% difference in the number of steps required to make a movement.

Is there a motor driver top-speed or ATM processing power limitation that you'd be approaching?

Why did SeeMe switch to 20 toothers initially? Was it cost or something else?

[critical_limit]

I think the only reason is the Rambo.
increasing workload due to 20% more steps will overcharge the rambo.

My 16teeth pulleys looking better than the 20teeth coming with the Rostock. So I don´t be afraid of eating the belts with it.

I will give it a try when I´m ready to install my magnetic ballarms, but first there is a lot to print.
And sparetime is rare at the moment due to high workload. But I will report if it is all done and the Rostock is up with all my mods.

Maybe not a good idea to change arms, hotend, effector, cheapskates, pulleys and heatbed at one time. But I only have a few days a mounth for my Rostock and leave again for 14-20 days going to work.

We will see. Will report when all is done (and of course posting some pics with all my mods...)


cheers
Dirk