[R.M.S.]

Can any one tell me the proper way to determen the correct timing pulley to table ratio when one decided what they would need.
Im convering my 6x26 g3102 grizzly. Im doing the Z as the knee instead on the quill.
Motors are XY 640 OZ 8 wire 6.3 amp Z 1805oz 8 wire 8.3 amps
2505 ball screws 8070D divers at 80V
Ive always hooked my machines up direct to the stepper . I realize this wont fly on this machine.
Thanks

[arizonavideo]

That driver delivers 7A peak or 5A RMS. Your Z stepper will be driven at almost half power.

It looks like the stepper inductance is 5A which is not too bad for one of the big ones. It will make almost full power up to around 200 RPM or 40 IPM.

It will lift about 3200 pounds peak with a 5 TPI ball screw at 8.3A if you had a driver that would do that.

With a better driver like a Gecko you could go 1 to 1 and not even run a spring.

I would run a spring and you can get 80 IPM fairly easy with a 1 to 1 ratio.

[R.M.S.]

You right I dont know what I was thinking. SO tired today . I will have to run the 1200oz 6 amp stepper for the Z.
Of coarse I will be running a gas spring. Its going to a chore lifting that knee up and down when rapid drilling .
80 IPM is a little on the slow side.
I already own every thing , but a Z stepper at the moment. So Im not really looking to buy anything new. But a Z stepper motor.
Arizona do you happen to know the proper way to decide what gear ratio to use when picking pulley sizes for steppers?
Or does every one just pick what suits them best?
When a persons building a 4th axis what makes them decide to use a 3:1 ratio rather than 2:1 or 5:1.

[arizonavideo]

Well you can look at top speed or max power.

Look at the power curves for any of the stepper motors. None make good power at high RPM. The higher the current and the lower the inductance the better they will perform with gear reduction but generally you only gear down for a rack system.

I generally build for a 100 IPM top speed and to have about 40% extra power at that speed. You will rarely cut at over 30 IPM. 100 IPM rapids is fine for a hobby mill, you will get better than that if you use better drivers.

Believe it or not the larger stepper you were planing on using is not that bad of a choice. It will not make full power at low RPM because the driver can't deliver the current but you don't need that much power anyhow. It will make more power at higher RPM because it has 5mh of inductance and the the 1200 oz stepper has 6.5mh. I never really liked the middle range steppers in the Nema 34 line because of the 6.5mh - 6A power rating. A 7A to 8A would have been much better allowing direct drive and high speed for a lot of uses.

I am running the 906oz on the Z of a Weiss 30 and it works great. It is quieter than I thought and will even lift the head at 4A. It has OK inductance at 3.3mh so I'm going to use it and Gecko drives for the table of the IH mill. With shocks the 906 might be OK with a gecko drive and a 1 to 1 or at most 1.3 to 1 belt drive. For the 1805oz stepper I would go 1 to 1 and I don't really like the 1200oz steppers much but 1 to 1 should be OK but it will be slower than the others.

I'm doing up plans for a IH mill now and I'm going with a mix of steppers and a servo. The 904oz for the X and Y and a servo for the Z. The cost is about the same and I have 5 extra servos sitting around. The head of the IH is about the same as your Z perhaps 50 to 80 pounds less. I found some low cost air shocks at McMasters so I'm going to get two smaller 16" ones. They have larger ones too.

McMaster-Carr

[R.M.S.]

arizonavideo,
Thanks for the link I defiantly will check out Mcmaster after I write this.
I have the 906oz stepper with a 8070D drive @ 1/8 stepping @ 50V 20a power supply , on my G0704 also Ill post a pic . As you can see with the 4 stage air cylinder PDB and 3.5hp motor it still lifts the head at 100 ipm. ( the picture doent even do the cylinder justice you only see two of 4 stacks of the cylinders in the picture) but I can run my disk sping washers at triple the pressure hoss recommends.
Believe it or not the 6x26 weighs more than the IH mill by 100 lbs but has smaller travels . The 6x26 is solid . The knee is pretty heavy . I use solidcam and when im using imachining tool paths I usually running at 50 ipm and up. I like to cut on the lighter side but faster. I was hoping to build a tool changer on this build . Im not looking for blazing fast speeds but around 200 ipm on all axis . With no faults. same 1/8 stepping. I think Ill take the 906 off the 0704 and give it a try .
Im getting the feeling I should look at servos though. I kind of jumped the gun with buying everything . Maybe Ill look on ebay for other places with steppers rather than kelling.
Im trying to understand the whole by multiplying the tq on a stepper . It makes the stepper run slower but since it give it more tq you can turn up the setting in mach on motor controls. So in turn you can run them faster? Is that correct?
I would consider myself a profession shop by any means but I do make quite a few parts to sell so speed is up there .
My first CNC I ever built ran at 20 ipm max my god that was horrible.
I seen your work on youtube and your IH cnc . I love that mill . If I didnt already own the 6x26 I would buy one. Still may. Charter oak happens to be 5 mins from me . Ive been there a few times. Very impressive machine.

[arizonavideo]

I almost bought a 6x26 from Grizzly. They had a supper deal on a "wood workers" model that had a high speed spindle and a 2" hole cut in the center of the table. It had A/C bearings stock and was listed for $$1600 or about!

I look at steppers as a anti motor. Max power is always made at a fairly low speed. 100 -200 RPM is max power draw for most steppers.

I like almost all of kelinginc products. The 6A 1200oz steppers should really be run around 100V or so for the widest power range.

This is a torque of one of the 8A steppers.

http://www.kelinginc.net/KL34H2160-62-8AT.pdf

That is with a 100V drive but it looks like they wired in series at 4.4A so have twice the inductance. Double the speed for parallel hookup.

With the larger steppers you don't get full power with a 5A driver. You need to look at the ratings and see most of the China drives are using peak current ratings. Take .707 times the peak value for the RMS average value. A Gecko drive will produce a lot more power than your current driver.

The only thing here is a Gecko servo drive is almost the same price as the stepper driver so why not do that? The only reason not to go with a servo is so you can direct drive but your going to run a belt anyhow. With the price of the larger stepper it will cost less for you to do a servo setup. There is no problem mixing servos and steppers as long as the PS can be a single voltage.

[R.M.S.]

I got the 6x26 for a steal older guy( Than me bought 65 ) who purchased 8 months prior to me buying it new from grizzly decided he wanted a larger Bridgeport.
Now I would if I didnt see the grizzly sales recite my self I would have said it was sales tactics and all BS but the guy hands me a grizzly recite when he went to grizzlys PA ware house along with a certificate that shows various test they performed to make sure it was true and straight and the owners manual in the plastic still. With the sale I received an older 5 inch vise , set of R8 collets , R8 Drill ,the stock tool box with all the wrenches allen keys ect and one of the red Chinese 49 piece clamping fixtures. Had it up for 1200 paid 1000$ . I jumped on that deal.
I was the first person who replied to his add and bought it right away.
I wont lie though Im very jealous of the IH mill. Its videos like your that make me jealous. I cant wait to see some one make one into a 5 axis cnc. Ever see centriods 5 axis cnc that setup would go on there great .
Im hoping that going from my G0704 to my 6x26 will well sooth that feeling . There have been quite a few times Ive almost sold the 6x26 or my 4 axis G0704 to buy the IH mill . But I cant be with out a cnc I use it for something daily.
So if it were you were would you start off with . What pulley to tooth ratio would you try? Im thinking XL 2:1 and see how that pans out .
As far as the drives maybe ill upgrade in the future but now I have what I have and its not complete garbage I can work with it. I just purchased a 80 or 100a if forget 3kv Bicron toroidal psu to power my 6x26 and 9x20 lathe. Im not even sure Im going to keep the 6x26.