Help with stepper motor choice, T5/T10 belts , 1.5Kw makita router

Hi everyone

I am building up a CNC router using a Makita 1.5Kw M3600B router as spindle.

I am going for a 2.5m * 1m bed and need a belt drive to make use of longer rails (2.5m). I also need to increase the machining speed in wood well beyond what the lead screws will take.

I have a choice of using either T5 or T10 belt 16mm wide. Both of these should be adequate considering the steel core and published specs.

I will be using T10/15 tooth (150mm/rev, approx 50mm or 2 inch diameter 8mm shaft)
or T5/16 tooth (80 mm/rev approx 27mm or 1.1 inch diameter 6.35mm shaft)

I have a choice of Nema23 motors

  • 50mm (9Kg.cm 6.35mm shaft) ,
  • 75mm(20Kg.cm 6.35mm shaft)
  • and 115mm (30Kg.cm 8mm shaft) motors

I also have some 75mm Nema23 motors geared 7.5:1. Unfortunately there is a lot of hysteresis/backlasy in the spur gears. Perhaps someone has a way to remedy this?

I have used dual 115mm motors T10 belt on a gantry with success in the past, but would like to use a smaller, lighter motor and perhaps save some cost.

I have also used the smaller motors with 3mm pitch lead screw sucessfully.

Does anyone have experience of using Tseries belt drive on a router CNC?

I’m looking for spectacular fails and success and practical hints and advice

  • “Support a 6.35mm shaft at both ends in this application”
  • "Only try this with a Nema34,T20 25mm wide " etc
  • " I do this every day with GT2/6mm at 4000mm/minute"
  • “I snapped the belt, the router went AWOL down the road and bit my mother in law”

thanks in advance

I haven’t used T-series belt, so there’s not a lot I can say, but FWIW I chose fiberglass-core HTD5M for the Z stage in my large-format laser build. That’s a 5mm pitch, and I used 15mm wide belt. No danger of skipping as far as I can tell.

If you want to go fast, don’t use the geared stepper. Steppers have a relatively low max speed even unloaded, and their torque decreases as speed increases. That torque rating you quoted is probably their full step stall torque.

The longer the belt, the more the stretch. Two things to consider there:

  • Steel core belt will stretch more than fiberglass core belt.
  • Consider the stacked Everman belt layout, with the bottom belt glued down. This tensions over a much smaller range of belt, and the range doesn’t change depending on how long the axis is…

Steel belt doesn’t like tight pulleys. I don’t remember the rule of thumb because I avoid steel core entirely, but I’d be worried about the 27mm pulley with steel core.

Good luck.

Hi Michael,
Thanks for the reply,

I will not be using geared steppers - not only from a speed perspective, but also due to the inevitable backlash. I have some geared NEma 23s and am looking to see where I can use them. Someone suggested to use two in opposition and see if I can take the backlash out that wy. More likely I will use them o a rotary table that only ever turns in one direction and does not attempt to back-drive.

I hadn’t thought of fibreglass belts having less stretch, and will definitely test out an HTD5M belt.
I have considered the stacked arrangement and will probably go there once the basic machine is operational. I have left clearance for the second belt and added a spacer to take it up at initially.

The rule of thumb is in the fine manuals and it comes to about 16 teeth, regardless of the T number.

I managed to find a very nice VEXTA PK596BW-A10, complete with 14mm shaft and 5mm pitch 20 tooth pulley. At 0.72 degrees (500 steps) per rev it gives me 0.2 mm steps - good enough for woodwork. Second hand cost me about US$30. Now just for some drivers… I’ll make my own.

Chris

1 Like