[martin_05]

Starting to research options for doing a single belt mod to my RF-30. This won't happen for a while but since I am researching pulleys and belts for my current rebuild of the machine I figured I might as well gain an understanding of where to go once and if I get a chance to take it to the next step.

The idea would be to go to a single belt between the motor and the spindle with possibly an idler for tension control but ideally not.

Option 1 is a long belt going from motor to spindle with pulleys large enough for the belt to clear the round column. Concerned about belt sag in this case and the potential need for greater tension in order to deal with it.

Option 2 would be to bring the motor forward, lose the enclosing sheet metal and mount the motor upside-down on the front of the head with a short belt to the spindle pulley. This would be a much tighter layout but it would shift a lot of weight to the front of the column. Not sure what that would do to such things as being able to crank the head up or down. Could be fixed with an electric jack replacement for the hand crank or slicker motorized version.

Aside from the million choices one could make for such setups, the most fundamental question is about the type of belt to use. There are timing belts and ribbed belts (like they use on superchargers). What would you use and why?


Thanks,

-Martin

[Bubba]

Been researching this myself and based on what I have found, I would tend to go with the ribbed AKA serpentine belt. The biggest factor against the timing belt deals with noise. I have read that at higher speeds, they will scream. Some seem to have minimized this by cutting a groove in the middle of the pulley to let trapped air escape. But then again, if you want to use a motor mounted encoder for positioning purposes, then the timing belt wins!

My .02

[martin_05]

Been researching this myself and based on what I have found, I would tend to go with the ribbed AKA serpentine belt. The biggest factor against the timing belt deals with noise. I have read that at higher speeds, they will scream. Some seem to have minimized this by cutting a groove in the middle of the pulley to let trapped air escape. But then again, if you want to use a motor mounted encoder for positioning purposes, then the timing belt wins!

My .02

You are reading my mind. I am thinking about rigid tapping. Although all indications are that Mach 3 doesn't support it. I'll deal with that when that bridge comes up.

I also found these belts on McMaster called "Tire Track" belts. They are supposed to be self centering. Not sure what other merits they might have.


-Martin

[Bubba]

Just looked on McMaster and could not find the Tire Track belts, got a link??????

[109jb]

LinuxCNC can do rigid tapping.

[martin_05]

Just looked on McMaster and could not find the Tire Track belts, got a link??????

Here you go:

McMaster-Carr

Also, if you search McMaster for "timing belts"


-Martin

[martin_05]

LinuxCNC can do rigid tapping.

I looked at LinuxCNC a while ago. Not sure why I stopped considering it. I'm perfectly comfortable with Linux.

Would you happen to have any links to rigid tapping implementation examples?


Thanks,

-Martin

[Bubba]

Never noticed belts like that, be interesting to see what the design specs are. Have found them for standard V belts, ribbed or serpentine, trapezoidal timing belts, HD type of timing belts, but none like this.

[mactec54]

Never noticed belts like that, be interesting to see what the design specs are. Have found them for standard V belts, ribbed or serpentine, trapezoidal timing belts, HD type of timing belts, but none like this.

Goodyear makes that same belt,you can get the spec's from them, the problem is with the pulleys, not a very good selection are available, & they are difficult to make, if timing belts are needed the GT2's/GT3's belts are by far the best to use, 5mm or even 8mm pitch these run much quartier than most timing belts, the poy-v-belt takes a bit of beating for general spindle use

Goodyear Eagle PD belts

[109jb]

LinuxCNC Documentation Wiki: Rigid Tapping

https://www.youtube.com/watch?featur...&v=g6p1-h5Rlv4

https://www.youtube.com/watch?featur...&v=9HLKXeWqTF0

[martin_05]

LinuxCNC Documentation Wiki: Rigid Tapping

https://www.youtube.com/watch?featur...&v=g6p1-h5Rlv4

https://www.youtube.com/watch?featur...&v=9HLKXeWqTF0

Just looked at the Wiki page you pointed to and did a bunch more research. Frankly, it sounds easy. A quadrature encoder and index pulse on the spindle (or motor) isn't that hard to do. For some reason I was under the impression that rigid tapping required a servo motor for the spindle. From what I gather as long as you have a VFD and reasonable stop-and-reverse time you can rigid tap because the controller is using the encoder pulses to coordinate the Z axis motion.

I've used rigid tapping in the past. It's a wonderful thing. That said, tension-compression tool holders seem to also do a good job.


-Martin

[beltcorp]

Maybe Neoprene Timing Belts, Molded Urethane Timing Belts, or Welded Urethane Timing Belts?