Richy,

The resolution that you need will determine the gearing. A 20-tooth gear on an ungeared motor, will give you 0.00157 inches per step when used with a Gecko stepper driver. A 30-tooth gear on an ungeared motor will give you 0.00235 inches per step. A 35-tooth gear on an ungeared motor will give you 0.00274 inches per step. (That's assuming that the 20-tooth gear has a pitch diameter of 1-inch.)

A 3.6:1 geared motor will give you 3.6X greater resolution. So, a 20-tooth gear will give you 0.000436 inches per step. A 30-tooth gear on an ungeared motor will give you 0.000653 inches per step. A 35-tooth gear on an ungeared motor will give you 0.000761 inches per step.

A 7.2:1 geared motor will give you 7.2X greater resolution. So, a 20-tooth gear will give you 0.000218 inches per step. A 30-tooth gear on an ungeared motor will give you 0.0003265 inches per step. A 35-tooth gear on an ungeared motor will give you 0.0003805 inches per step.

Both the PK299-01AA and the PK296A1A-SGxx motors have too much inductance to be used with the G203v stepper driver if the motor is wired bipolar series. The PK299-01AA motor should only be wired half-coil because it has 56 mH of inductance when wired bipolar series. Even the G202 only handles motors up to 40 mH. Either motor can be used with the G203v if they are wired half-coil.

Typical:

1. if I chose PK299-01AA motors I should use it directly (no reduction). If no reduction, What gear should I use? 30 or 35 teeth 20 DP in all 4 motors? 20 teeth 20 DP

2 if I chose PK296A1A-SG7.2 30 teeth (or 3.6 20 teeth)...what gear should I use? 20 teeth 20DP in all 4 motors.

The calculator in post #27 above has been expanded to include speeds and frequencies

Hi Gerald, I phoned Nusaf.co.za, got a lady on the phone. Asked her for DP20 rack..she did not know WHAT I was talking about. Have you got the PART NUMBER or more info that I can give her. Thanks

EDIT.. OK think I got it...I must ask for MODULE-1 rack..

Next question: Ho much. Somewhere I saw X +200mm. What about Y and Z ?

See drawing M2 10 110 W

Just checking I have a 7.2:1 geared motor with 30 teeth. 2000 x7.2 =14400 1.5 x 3.1416 =4.7124 14400 / 4.7124 = 3055.7677 this is my steps pre in the motor tuning. Are the numbers right?

Mark,

On post #27 of this thread, there is a handy spreadsheet for just this. Just plug in the numbers and it does the hard work. :)

Mark, your result is close enough (checking against the spreadsheet).

Have to emphasise this again.

When folk here casually talk of 20 or 30 tooth pinions, they are probably working in inches. The metric people will probably be talking 24 or 36 tooth.

The basic calculator spreadsheet above has been "preloaded" with typical numbers for the inch and metric worlds.

Yup, I made the mistake.. Looked at the old spreadsheet, saw 20 as an option. Remember people talking about 20, and bought 20 tooth pinions. Result....on a 14mm shaft stepper you are not left with enough metal for grubscrews...even with a homemade collar. Be warned..

Thanks Gerald for clearing that one up and updating the spreadsheet.

I am just started using a program that will only put out G-CODE in MM. I set up a profile in Machloader and configed in MM. Do I need to change the motor steps pre to MM or will Mach change In to MM .

If you told Mach that you are using mm, then it will use mm.

milimeters
 

Hello.

Wat is the pinions recomended for a 7.2

This ar the dimensions.
Manufactured in mild steel S45C Induction Finishing with chemical black
Tensile strength (min) 569 N/mm2
Pressure angle of 20 °

I think 30 or 36, the 24 A=8mm

each One 7,49 €

Those are metric module 1 gears. The 36 tooth is the popular choice for metric gears.

But, the E dimension of 10mm looks too narrow. We work with 15mm. Our rack is 15mm wide.

Ok, recommend module 1.5 The 36 tooth?

1 unit 15,10 € !!

For module 1.5 you can go for the 24 tooth. (keep the C dimension at about 36mm)

See http://www.mechmate.com/forums/showt...3&postcount=14

Okay, I'm curious.

Why is it more appropriate for 7.2 geared motor to use 30 teeth, and 3.6 use 20?

Is it because of the torque? Or will it be too slow?

begging for enlightenment....

30 teeth rolls smoother than 20 teeth
30 teeth has less wear than 20 teeth
30 teeth on a 3.6 gearbox has low torque.
20 teeth on a 7.2 gearbox needs very high step pulse frequency.

But, that is only general experience, you can use anything you want. Just remember, in a metric country the numbers 20 and 30 mean nothing.

so i guess the deterrent factor was speed...
is there any noticeable increase cut quality if a machine geared at 7.2 ratio, using 20 teeth pinion?

Sean Reish is using 7.2 ratio and 20 teeth. Doc Tanner & Greg J are using 3.6 ratio and 30 teeth. Lots of people use 7.2 and 30 teeth. Nobody has cut quality problems. Greg J would like a bit more torque at high speed.

Gerald,
I also remember Sean stating he was going to try the 30T to get a little faster rapids and cut speed as the 20T needed too high a step frequency.

Heath,
You are correct. I need a little faster rapids and at 20Khz, my machine could perform better with 30T pinions. Torque is not a problem, so I might even go to 35T if I can get the motors to swing down far enough!

Sean,
I think Doug Ford was running the 35 Tooth pinions at least for a while. His thread indicates he milled a little extra in the slot to allow extra room to disengage the pinions if he had to.

Heath,
Due to my machine being a very early "classic" machine and the fact that I mistakenly made my rails about a 1/4" taller than required, I just had new motor mount plates laser cut last week with longer slots for just this reason.
I noted that Doug did a little "metal removal" :) during his build! Thanks for the reminder.

Sean

The guys in my shop are mounting the new motor plates today and bigger pinions. Longer slide goes on next monday. Wish me luck!

I made this Excel spreadshet for a non Mechmate related project, it may help ppl understand gear values.


Pablo

Sean sounds great, will be interesting to hear about your comparison to the new pinions and the longer Z height. :)

My MechMate does not travel 100mm if I enter G0 X100 but the travel distance is more. the pinion that I used has 24 teeth and DP 20 and pitch diameter of 32.76mm, When I use the formula Gerald posted the steps per value is 26.526 steps per.... if I do calculation : 3.1416x32.76= 102.91881 then 2000/102.91881=19.432793 steps per...... for the Mach motor tuning can someone please tell me where did I go wrong
Regards

If you have direct drive motors, 24 tooth pinions and DP20 (non-metric) pitch, then your setting should be 20.886 steps per mm.

(I don't know where you got the pitch diameter of 32.76? That might be the outside diameter. The pitch diameter is about in the middle of the tooth height. =24/20*25.4=30.48 for 24tooth, dp20(inch), converted to mm.

The key issue is whether you have inch based DP20 pitch, or millimeter based Module1. (obviously the tooth count of 24 is definite)

For DP20 your Mach setting should be 20.886 steps per (mm)
For Mod1 your Mach setting should be 26.526 steps per (mm)

Hi Koning, I calculated my steps more or less then used the facility in Mach3 to fine tune my machine....there is an option on the 3rd page of mach3...I think (green page) where you can do it. I cannot remember it all offhand, but what happens is you tell mach 3 to move a certain distance in the X direction....it will then move there..You then manually measure this distance and enter the ACTUAL distance your axis has moved into Mach3. It then calculates the steps for you. You can do it on X, then Y en also on Z.
But my experience is that you should do it on a LONG distance...not 100mm...rather 1000mm

When I am in front of MACH 3 I can write it up more clearly, or somebody else can explain better...I suck with explaining things to people.:o