Re: [CAD_CAM_EDM_DRO] Re: BOSS to servo's and reduction

I think it would be fine even if the wall wound up being as little as 1/8". Use like a 3/16" roll pin. Drill and ream the pulley concentric to the OD. 12.5 lb-in just isnt alot of torque but you have the RPM to reduce to make up for it at the screw. Especially for X and Y, they just dont require a whole lot of torque. Think about how much force is applied when machining manually. All three motor pullies on mine are secured with roll pins and these are 40 lb-in servos and one driving the knee. I wouldn't have opted for this because in tooling practice it's pretty unorthodox except thats how they were originally secured on the steppers and they worked intermittently :-) like that for over twenty years. (The original owners spent a small fortune on that old control, I located the repairman that they used after I bought the machine and he was happy to find out where it went at $85 an hour) I just installed them on the servos the same way. Its easy, just locate the pulley, drill a hole
and drive a pin in it, it isn't going anywhere and the pin eliminates any backlash providing the pulley fits the shaft well.

Ron

Polaraligned <polaraligned@...> wrote:

>
> /// I'm using 12 tooth L series (3/8" pitch) pulleys on a 5/8"

shaft. Could go even less number of teeth and still maintain a 5/8"
bore. The smaller the diameter, the harder they are on the belt. Of
course the problem would be the diameter of the 48 tooth secondary on
the screw to attain 4:1using L series and clearance. I use a 30 tooth
and it fits this application for 2.5:1. I dont know what pitch timing
belts you are using but the best thing to do is bore the pulley to
5/8", you can remove most of the material inside and secure the pulley
with a roll pin. Drill in between the teeth on one side and come out
between two teeth on the other side. Thats how mine are secured. It's
very positive and does not harm the belt if deburred. Not alot of
shearing force at that torque. The 5/8" shaft is just a standard
characteristic of the Nema42 mounting config. If set up this way it
will be easier to upgrade to larger motors later if you decide to. /// Ron



Ron,

I need to use the HTD 5mm pitch belts. It seems to be the only
series that can fit in the BOSS, and get the reduction I need. 3-3/4"
is about the largest I can go on the secondary pulley. I like your
idea about using a roll pin to fasten the pulley. The primary pulley
I need to use has a .63" hub and is just .907" outside diameter. I
wonder how well
it would work if I just bored .625 hole and used a pin. The pulley
would get quite thin (1/4") but maybe there is an adhesive I could use
to bond it to the shaft along with the pin. Make it like part of the
shaft. Any thoughts?

Thanks,
Scott







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