Custom Pulley Help - ATC over hall

[Boyan Silyavski]

So are thinking to do away with the Geneva wheel.? If so then I'd re-think it because with such large diameter disc and lot of weight then stepper may struggle to hold position good enough, esp with higher rotating speed with more weight. You'll certainly need fair ratio on it.!

What i wanted to say was that a stepper with a gear could do the job.

[andy_con]

So then you are stuck with min size pulley HTD 5m 20 teeth having in mind 20mm bore:




Then we go to the belt calculator, play a little with it and find that voilaa, if i am not wrong you have a hit.



we search the web for the 180mm HTD 5m belt and find that indeed there is one existing in this size:




So more or less problem solved. Pulleys from belting online, contact them if they have the belt if not search and buy. its a good idea to pay them to bore the pulley as they do it well and wall thickness will be alright at 3mm as per drawing above.


So problem solved? Right? if you want to mill them or to do them i could pass you a dxf drawing of any tooth count you need for HTD5 pulleys

that is perfect, thank you very much.not sure I understand it all but I will contact them with this detail and buy a bits.many many thanks

[andy_con]

So are thinking to do away with the Geneva wheel.? If so then I'd re-think it because with such large diameter disc and lot of weight then stepper may struggle to hold position good enough, esp with higher rotating speed with more weight. You'll certainly need fair ratio on it.!

yes I want rid of the Geneva wheel.the current disc is mounted via bearings and once in bits the ally disk that holds the tools is very free flowing in the green cast iron arm.I don't want it to run at high speed, but a bit fast then the current setup which is painfully slow. ill give it a go and see how it works, if it becomes a problem ill have to redesign

[JAZZCNC]

What i wanted to say was that a stepper with a gear could do the job.

Yes I know that but it's needs a High Ratio and decent sized stepper to handle the inertia of large diamter wheel fully loaded with tools and they do struggle if run fast resulting in overshooting. Which actually slows tool changing or If toolholder isn't perfectly lined up they rub and wear spindle/Pullstud resulting in dropped tools.!!

Geneva while still needs gearbox or ratio it does index perfctly and is more reliable. That's why they are used in ATC.!!