Belt for CNC Lathe Machines

[agrimm0105]

I work at a coupling threading facility where we have several CNC lathe machines. Originally a timing belt is used to turn the chuck. This is the best option in theory because the metal shavings are supposed to be prevented from going into the motor area by walls and wipers. But after years of operation the walls no longer block all the shavings and some become lodged into the belt.

To solve this, all the timing belts were replaced by v-belts; but this would decrease the precision of the machines. I was wondering if there was a type of timing belt that could be as resilient to shavings as a v-belt.

Both timing and v-belts have the steel wires inside the rubber for tension purposes so I am skeptical about the v-belts being a better option.

 

[MikeHalloran]

I'm unsure how subbing a v-belt reduces the machine precision, unless the timing belts were being used as gears, e.g. for indexing the spindle for some reason.

Both belt types have their pitch diameter outside of the pulley diameter, roughly where the wires or cords are found. I don't have a strong preference for either, assuming both installations are properly engineered, except of course where positive drive is required.

As for resistance to shavings, there may be options within the world of timing belts. I think the earliest timing belts, with trapezoidal teeth, rode on the pulley OD, and that some of the newer profiles like parabolic and semicircular teeth, may not. Look at the fine print and dimensions in their engineering manuals.

As for specialized belts, I worked with a CNC mill that used 'scrum' belts, having a fluffy fiber array like Scotch=Brite projecting from the back opposite the teeth. I never understood what the scrum was for. I also never understood why the original scrum belts were relatively quiet, but all the replacements, scrum back or not, howled like a banshee at high spindle speeds.



Mike Halloran
Pembroke Pines, FL, USA