Is my leadscrew ok?

[max90272]

HI guys,
I am building a CNC mill from scratch with parts from other equipment. I have gotten my hands on a great X Y AXIS rig... It came from a wafer handler.. It has rails, bearing trucks, leadscrew, plastic nut etc... It's pretty much ready to accept the nema23 motor mounts. My question though (i'm new at this so forgive me): Is my leadscrew ok for CNC milling? Why do I ask? Because 1 rotation gives 1 inch of travel... It seems a lot to me... I would think that a finer thread would yield more precise results but then again, maybe what I have would be good for "fast machining".. or would it?

Please let me know if I need to change the leadscrew and if so... what am i looking for in terms of travel per rotation. My motor is Vexta 2 phase 3v with quite a lot of torque.

I will be using Kcam to operate it.
Thanks
MAX

[mikebackrib]

hi max yeah it should be fine /your motors have 200 steps per rev /and setting your steps per inch on your software/ should work well

[max90272]

Thanks guys,
So is it safe to say that 200 steps per inch is precise enough for CNC machining aluminum?? In other words I should just go into Kcam set up and enter 200 instead of the default 4000/inch??? Now how should i adjust the feed rate? In the set up menue, the default values for feed rates are 50 ipm for travelling, 10 for cutting and 50 for jogging. My MAX feed rates is at 20 ipm... Any tips on that? thank you

[jalessi]

Max,

At 200 steps per inch the travel per step of your axis will be .050, that is not very good.

You might want to check and see if your stepper drivers can be set to micro stepping mode 1/8 step with give you .0016

If your stepper drive can be set for smaller fractions of steps the accuracy will increase.


As far as the cutting feed rates are concerned that would be determined by the material. the diameter of the cutter, the number of flutes and the r.p.m. of your spindle motor.

The jogging speed will be limited by the performance (reliable, repeatable movement) of the stepper motor and your power supply voltage.

Jeff Alessi

[jalessi]

Max,

With the one t.p.i lead screw your machine is going to fly.
Most likely much faster than 50 i.p.m if the stepper turned only 300 r.p.m you would have 300 i.p.m

If you don't have a micro stepping drive you might conceder some sort of pulley reduction scheme.

5 to 1 reduction would net you .001 travel per
step.That would slow your machine down a lot in the process.

Jeff...