Mostly wooden CNC

[thewoodtinkerer]

Hi,

My name is Marc. I've built a mostly wooden CNC with 1060 x 760 x 100mm travel, a 2.2kW aircooled spindle and Nema23 steppers on each axis. The motion is chain driven and the linear guides are 4 regular bearings on each skid at 90 , running on POM rods, lying in round grooves on the upper and lower edge of the axis' rails. The Z-axis uses a 1605 ballscrew and the same kind of linear rail as the other axis.

This machine will mainly cut and carve wood and foam. Going with MASSO was a last minute decision after evaluating many other options. So far, I'm very pleased with how the machine performs. I run it at 60% of the maximum current for the steppers and also reduced the maximum current of the VFD. Yesterday, I've planed the wasteboard which took 25 minutes and the steppers and spindle were barely warm.

The next project will be a fully enclosed 3-axis CNC router for the makerspace where I'm a part time coach. We'll see if they'll agree to go with MASSO?

 

[cncnutz]

Hi TheWoodTinkerer

Welcome to the forum.|
Nice looking machine. My 2nd machine was wood and pipe and I have only just got rid of the last MDF carriage on my 4th machine.
I like the draws you have in the front of the table.

If I could make a suggestion, please don't run your stepper motors on 60% current unless there is a good reason.
Depriving a stepper of current really kills performance as the faster you turn a stepper motor the weaker it gets. Perversely stepper motors have their most power when not turning.
If you have reduced the current to keep the stepper motor cool please be aware that stepper motors are designed to get hot. So long as you set the drive to the motors specified current you will not burn them out.
If you drive has a half current feature turn it on and when the motor is stopped it will half the current until it starts moving at which point it will use full current and so maximum power otherwise don't worry about it.

Cheers Peter

 

[thewoodtinkerer]

Hi Peter,

Thanks for Your reply. I've set the current to 60% while evaluating how the machine performs. At 30000 mm/s rapids with 3000 mm/s2 acceleration, the whole base, which is on casters and weights about 120kg, begun to move around the shop. The complete gantry weights around 30kg and the acceleration forces where somewhat scary. So, I've backed down the speed to 15000 mm/s and 1500 mm/s2 acceleration. I guess, these values are achieved because the motors run at low speed with high torque because of the chain drive that gives 72 mm/revolution. A downside is of course a resolution of only 0.045mm/step at 1/8 microstepping.

This was known during the design of the machine and it's acceptable for wood and foam cutting. I'll observe the performance of the machine and as soon as I experience lost steps, I can still crank up the current, but for now, there is no obvious reason to do so.

Cheers,
Marc