Understanding & Selecting gear pinions - setting the steps per mm[inch]

[fabrica]

Gerald, What do they mean by the diametrical pitch and how does it relate to the distance travelled per revolution. My pinion has a diametrical pitch of 20 as per Boston gear specs.


********************************************

For those trying to follow this thread, please do not mix:

- inches, diametral pitch, DP, steps per inch

and

- millimeters, module, steps per mm

they are not compatible with each other

Gerald

[Gerald_D]

It means that 20 teeth make a precise diameter of 1 inch. I suppose your pinions do have 20 teeth and so you are on the "standard" number of teeth for the 1 inch diameter. The distance travelled will be Pi times diameter, equals 3.1416 X 1, equals 3.1416 inches (X 25.4 = 79.79645mm)

What is your gearbox ratio?

[Gerald_D]

If you had a 20 tooth DP20 pinion direct to motor with no gearbox, Mach3 will want a "Steps per mm" setting of 2000/79.79645 = 25.06377.

If you have a 3.6 : 1 ratio gearbox with that pinion then Steps per mm becomes 90.22957

Etc.

[fabrica]

Thanks for your explanation. My pinion does have 20teeth as you guessed and the gearing ratio is also 3.6 : 1 and the motor rotates .5 Deg per step.

[Gerald_D]

Okay, if you are setting up Mach to work in millimeter, the magic number you need for calibration is 90.22957 steps per mm.

Just to explain a little further....
Most stepper motors have 200 full steps for one revolution (1.8o per step). Your motor has a 3.6 reduction gearbox on it therefore the output shaft is 0.5o per step. In other words, the motor must receive 720 full steps before the shaft will make one turn.

The Gecko driver employs 1/10th micro-stepping....meaning that the Gecko must receive 7200 full steps from the computer before it will produce 720 full steps to the motor, before the shaft (pinion) will make one turn and move the machine 79.79645mm. Divide 7200 by 79.7964 and you get your calibration value.

[Hugo Carradini]

Hello Fabrica.
¿What is the difference in performance between using motor direct to the pinion and working with a motor with gearbox?
Thanks for your answer
Hugo Carradini

[fabrica]

I think by using a gearbox you get a better torque and also a better finish on the cuts that you make.

[Hugo Carradini]

Hello fabrica. I understand that but you also reduce speed . ¿Do you have and estimate off the IPM you can archived with your actual configuration and the IPM going direct to the motors? I am getting ready to start buying my stuf and want to have everything clear in my head . Thanks for your time.

[Gerald_D]

Hugo, maybe you want to look at this thread: Selecting motors for the MechMate (http://www.mechmate.com/forums/showthread.php?t=1114)

[fabrica]

Hugo, With modern software like Mach3 you could increase the RPM of the motors by taking advantage of their in built higher pulsing speeds. These RPM increases of the motor through higher puilsing sppeeds adequetly compnsate for the lost speeds due to gearing. You have a win win situ here. Higher torques at the same cutting or jogging speeds which you had earlier. With higher torques you have better cutting or engraving quality. No lost steps on steppers.

If you need furher info on this issue you could follow the links provided by Gerald.

[Hugo Carradini]

Thanks fabrica and Gerald.
I am just getting use to the order of the deferents links.

[reza forushani]

As you know, I got movement. Now I am studying the Mach3 and Vcarve. Can somebody help me with numbers to plug in for English system (inch)
Thanks

[Gerald_D]

Reza, I've forgotten the gear ratio of the motors you ordered? are you using 20 teeth pinions?

[reza forushani]

3.6 and yes.

[Gerald_D]

20 teeth make a precise diameter of 1 inch. One turn of the pinion makes 3.1416 inches of linear movement.

With the 3.6:1 gearbox, 3.6 turns of the motor make 3.1416 inches of linear movement.

The Geckos need 2000 pulses to make one turn of the motor, so you need 7200 pulses to make one turn of the pinion, to make 3.1416 inches of linear movement. That gives a value of 2291.8 pulses per inch to be set in Mach.

[reza forushani]

Thanks Gerald. On the Calibration screen, it's asking for other stuff. Where do I plug this number in (2291.9) Thanks again

[Gerald_D]

In Mach, you first do the Config > Select native units, and I am sure you picked inches there.

Then you do Config > Motor Tuning, and at bottom left there is a block "Steps per", it actually means "Steps per selected native input", which in your case is "steps per inch" or "pulses per inch"...

For the rest, you can play with any value on that screen, because you pick the final speed and acceleration values once the whole machine is moving.

[reza forushani]

Got it boss. Thanks a million $$$

[Hugo Carradini]

Hello Gerald and friends.
I have been reading different opinions and get a little confused. I got my motors with a 7.2 : 1 ratio gearbox . ¿What is the optimum numbers of teeth for my pinions and the magic number for setting Mach3 in steps for mm? I just don't want to make a mistake with the calculations, and don't want to end with an incorrect pinion. I all ready got my racks 1/2 /side like Gerald suggest and need to get my pinions.

[Gerald D]

The popular choice of DP20(1/2"Wide) pinion for the motors with 7.2:1 gearbox now seems to be the 30tooth. Doc Tanner, and all the latest ShopBots, are going with that choice. (for the 3.6:1 gearbox, or direct-drive, the American DP20 choice is 20tooth, and the metric M1 choice is 24teeth)

Hugo, I am a bit lazy to fetch my calculator now, but this is more or less how you can calculate it....

A 30tooth DP20 gear will have an effective diameter of 1.5". One full turn of the output shaft will make that gear roll a distance of 1.5 X Pi (about 5" ?) along the rack (You must calculate this exactly with a calculator)

The number of steps needed to make that gearbox turn one full turn is 2000 x 7.2

So, take 2000 x 7.2 and divide it by 1.5 x Pi (My memory has Pi = 3.1416, or you can also use 355/113.....the old schoolboy 22/7 is not good enough :))

[Hugo Carradini]

Thanks Gerald.
Very precise.

[Hugo Carradini]

Gerald I will have my pinions made here. Before I go to the turner I want to know if the "effective diameter" is measure from the bottom of the tooth or the top of the tooth.
Thanks

[Gerald D]

It is near the middle of the tooth.

I used the words effective diameter, but the guys who work with gears all day call it the Pitch Diameter, or the diameter of the Pitch Circle.

[bbreaker]

ok now can anyone tell me, i whant to go to metric and i have a 7.2:1 gearbox, how many teeth can can my pinion have, if gerald know.

thank's

i'm on the forum, from a moment but i start my Mechmate now
Michel from France

[Gerald D]

Hi Mickey, I presume you are going to use metric Module 1 gears. If this is the case, then I suggest a 35 tooth pinion to go with the 7.2:1 gearbox.

*** The following added at top of thread as well *******

For those trying to follow this thread, please do not mix:

- inches, diametral pitch, DP, steps per inch

and

- millimeters, module, steps per mm

they are not compatible with each other

[bbreaker]

thanks gerald. ok i search now the good number for Mach.

[Gerald D]

Now that everyone understands how to calculate these things . . . .

1139

. . . . and the zipped spreadsheet where you can play with your own values in the green area: 1140

[bbreaker]

Thank's a lot gerald, not a problem for everyone now.

[Greg J]

Gerald,
Thanks for the spread sheet. I'm assembling the "kitchen project" and learning the Mach program at this time.

Greg

[Gato Richy]

Congratulations for this excellent forum.:)

I have tried to read every thread concerning to gears. Unfortunately, I got lost in the woods.

I trying for more than a year to finish this plasma cutting machine, and I'm stuck right now, just when I've got little more time for it.:mad:

My "FAQs" are:

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?

2 if I chose PK296A1A-SG7.2 (or 3.6)...what gear should I use? 20 teeth 20DP in all 4 motors. What about the G203V problem?

As my cnc will be use for cutting, is it necesary to reduce on all axis?

Thanks

Richy

Chile

[Richards]

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.

[Gerald D]

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.

[Gerald D]

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

[Kobus_Joubert]

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 ?

[Gerald D]

See drawing M2 10 110 W

[shaperx]

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?

[Greg J]

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. :)

[Gerald D]

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

[Gerald D]

The popular choice of DP20(1/2"Wide) pinion for the motors with 7.2:1 gearbox now seems to be the 30tooth. Doc Tanner, and all the latest ShopBots, are going with that choice. (for the 3.6:1 gearbox, or direct-drive, the American DP20 choice is 20tooth, and the metric M1 choice is 24teeth)


*** The following added at top of thread as well *******

For those trying to follow this thread, please do not mix:

- inches, diametral pitch, DP, steps per inch

and

- millimeters, module, steps per mm

they are not compatible with each other

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 (http://www.mechmate.com/forums/showthread.php?p=4089&postcount=27) has been "preloaded" with typical numbers for the inch and metric worlds.

[Kobus_Joubert]

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.

[shaperx]

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 .

[Gerald D]

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

[isladelobos]

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 €

[Gerald D]

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.

[isladelobos]

Ok, recommend module 1.5 The 36 tooth?

1 unit 15,10 € !!

[Gerald D]

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

[Gerald D]

See http://www.mechmate.com/forums/showthread.php?p=14773&postcount=14

[Nikonauts]

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....

[Gerald D]

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.

[Nikonauts]

20 teeth on a 7.2 gearbox needs very high step pulse frequency.

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?

[Gerald D]

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.

[domino11]

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.

[smreish]

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!

[domino11]

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.

[smreish]

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!

[PEU]

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


Pablo

[domino11]

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

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

[kaartman]

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

[Gerald D]

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)

[Kobus_Joubert]

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

[kaartman]

Thank you Gerald
I have played with the settings this afternoon, used the 20.886 and it worked perfectly, Kobus i will have a look for that page and measure over long distance, learn-learn that is the only way, thank you for the input, much appreciated

[felix]

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.

Hi all,

one might consider the power supply as well in all this drive selection process. Torque problems can come from inadequate PS as well as gearing.

Yves

[sailfl]

I am looking at every thing since I realized I had a problem with my cutting on my machine. I am looking at threads that I might have read before or skimmed over in the past.

If I understand the "Gear Speed Step Freq Calculator" correctly, for gear box of 7.2 and with 20 pitch, 30 tooth pinion gears, my motors steps should be set at 3055.775 which they are but my kernal should be set to 37 kHz which it is not. I am currently running at 25 kHz.

What I don't understand is what effect does this have on the way the machine runs? Further clarification, please.

Thanks

[bradm]

Nils, you may have put your finger on a problem here.

25 Khz, or 37 Khz is the number of update cycles your system can make per second.

If you are familiar with the concept of a 'carrier wave' in radio transmission, it's similar.

If you attempt a movement that requires more updates than your kernel can sustain per cycle, it will "jump" to catch up. This can cause stairstep like patterns.

Unfortunately the max kernel Khz is a function of the computer you are running on, and isn't always directly related to the clock speed; it's related to the I/O and interrupt handling capacity of the machine, which is much harder to predict.

If you push it too high you'll know, because the machine will hang, or you'll get errors reported.

[sailfl]

Brad,

Thanks for that explination and I will at least set kernal at the speed recommended by the Geard, Speed....Calculator. That is a good place to start.

[domino11]

Brad, Nils,
Correct me if I am wrong here, but isn't the nubmer for kernal speed in the calculator for MIN kernal speed for the gearing/pinions/max move speed? All I mean is that number is the kernal speed you would need to do the max speed move (rapids). When cutting at slower speeds , as long as the kernal is capable of covering the speed your at you should be fine. There is also a risk of running your computer at too high a kernal speed for the hardware you have also.

[bradm]

Heath, you are correct. However, I don't know what the max speed of Nils' machine is, and the fact that his setting is low in combination with the other symptoms makes me suspicious. It may turn out the the problem is that it's too high for the computer to sustain, and that's what causes the issue.

What I'm looking for at this point is some evidence that changing his computer configuration affects the periodicity of the cut problem.

[domino11]

Brad,
Thats a good point, it might shed some more light on the computer in use. I did not mean to discredit your test.:o

[sailfl]

Don't we have to look at what is being processed and what is being sent out.

Lets look at an extreme example. When a computer is running simulator software, it is taking in lots of data, sending out data or commands and processing lots of data so the kernal has to be set at a level that will handle all this processing or traffic.

If I understand how Mach works, G Code is processed one line at a time. A line of G Code is sent one after the other. I don't know if there is a message sent back from the PMDX that says I got the line send the next or if mach is just sending lines and assumes the PMDX is processing but I suspect there has to be some communication because if you push hold it takes a little time to process that command and send a message back that says "ok, we will hold".

This is simple communications and so the kernal is not going to be handling a lot of traffic. So the Kernel needs to be set at a very low level but it still needs to be high enough so it can handle the traffic. To low and we have a problem and to high, it might use processing that could be used some place else but we don't have any thing else going on so high doesn't matter as long as it is not too high.

Is that the way it works or is my thinking off?

I don't think that having the kernal too high will be a factor but too low could be.

[bradm]

We're definitely drifting off topic here in gear pinions (my fault).

The PMDX never sees the GCode. All it sees are the step and direction signals that are calculated in software. Generally software that handles GCode will pause after it completes a line. So if you start a long slow cut from one end of the table to the other, and press pause, the pause takes effect after that cut completes, not in the middle.

The kernel is handling a pretty substantial amount of traffic, in that to move an inch, it has to output thousands of step pulses, and each one has to come at precisely the right moment. You are correct that having it's setting too high is not a problem unless it exceeds the capacity of the computer in question.

[felix]

Nils,

I'm not sure about how Mach3 does it but here is what I understand about g-code. First, this is a command language which means it as to be interpreted and transformed into signals then you have what is called a trajectory planner which basically looks ahead for the next move(s) in order to keep the path as smooth as possible (set by config) and all this while taking into account accel. and decel. and a few other things as well.

All this planning and calculations take quite a bit of time compared to just maintaining the signal (pulse) stream at a desired level. There are also real time events such as an E-stop that needs to taken into account, the response time for this also affects the overall system performance.

Basically, you need to have a signal (pulse) cycle active time long enough so that the CPU as time to do its other (required) tasks with time to spare just in case it needs to stop on a dime and this active time needs to be short enough that the cutting speed is acceptable.

One other thing to consider is the rather steep decline in torque of the stepper motors as its RPM increases. This physical limitation also limits the maximum signal frequency required for the controller. In other words, even if you could generate pulse in the hundreds of Khz there will come a frequency beyond which the motor will stall and begin to miss steps.

Hope this helps,
Yves

[sailfl]

Brad and Yves,

Thanks for the clarification.

[Claudiu]

Hello Guys,

I did some calculations on my Gears etc. As I use Module 1, OM7.2, gears 35 teeth I get a magic Number of 130.962. Everything looks ok up to here..but when I calculate with the max rot of the OM of 250rpm I get out a speed of only 3800 mm/min. One whole minute for the spindle to go one full x direction? Can this be really correct? How long will it take to surface the table?
Please tell me I did a mistake and the working speed will be higher...:)

[Gerald D]

I don't know where you see: "the max rot of the OM of 250rpm"?

Maybe the output shaft max speed is 250rpm while the actual motor turns 7.2 times faster?

If the output shaft can turn at 250rpm, the pinion has about 100mm circumference, the x-speed is about 25000 mm per minute which is fast enough! :)

[Richards]

Gerald,
Oriental Motor lists the permissible speed on page C-231 of one of their older catalogs. I haven't downloaded the current catalog, so that information might be missing.

Claus,
That is the output speed of the gearbox, which, with a 7.2:1 gearbox, means that the motor would have to be spinning at 1,800 RPM. At that speed, the motor only produces only 30 oz*in of torque, so it is not practical to run that fast.

Because I'm on the inch system, I haven't paid any attention to the metric spur gears, but a spur gear with 1.25" pitch diameter (25 tooth) moves about 3.925 inches per revolution, so 250 X 3.925 = 981 inches per minute, or 16 inches per second. Getting 50% of that speed would meet most needs.

[David Bryant]

Hi
I have a Mod 1 rack, 31 tooth pinions 5:1 gearbox microstepping to give 1600 pulses per rev of the stepper.
I set Mach 3 to 82.144 steps per mm.

I am getting about a 6% error in the movement distance.
Where have I gone wrong in my Calc?
Thanks
David

[Gerald D]

What drives are you using for the motors, and what are they set to for micro-stepping? (The geckodrive is fixed at 10 micro-steps).

The 5:1 gearbox 1600 pulses has me scratching my head....

[Gerald D]

Also count the number of rack teeth over 100mm to verify that it is Mod1. (a quick mental calc says 32 teeth?)

[David Bryant]

Hi Gerald
The drives are motion King pulse per rev set for 1600 pulses per rev (8 micro steps 1.8 degree per step) followed by a gearbox mechanical gear reduction by G5
32 teeth on the rack very close to 100mm.
Cheers
David

[Gerald D]

Then 82.144 is correct. Are you sure that you didn't type in 87.144? :)

[David Bryant]

Thanks for checking I will keep looking...? Not a typo.
Cheers
David

[Kobus_Joubert]

Use Mach3 calibration to get it spot on.

[David Bryant]

Hi All
I did further testing today. I isolated the Z axis from the machine and got a counter onto the pulses out of Mach3.
I found mach3 pulses out to be correct (No surprise.)
I then set pulses per unit to 1600 to match the stepper drivers setting. I then counted revolutions of the MotionKing stepper motor. Always about 6% revs indication more than actual moved.

On Testing I found that 1700 pulses per set into mach 3 give the correct number of turns (allowing for the 5:1 ratio on the gear box).
So my testing has shown that the Motion king driver needs 1700 X 5 pulses to drive the stepper motor with gearbox one revolution. According to the instructions with the driver and stepper motor this should need only 1600 X 5 pulses per rev.

Is anyone else using MotionKing drivers and motors?
Cheers
David

[David Bryant]

Hi
I have four 34HS9801-G5 MotionKing stepper motors
I have been trying to work out why my mech mate does not move the correct distance(accordind to theory). So I put a signal generator onto the step input and measured the time for a number of revolutions using the MotionKing driver. (tried DC supply and AC supply to MotionKing Driver, no difference)
I always needed 17/16 more pulses than theory said I needed.
I changed to a gecko drive and repeated the test with a bench power supply and wiring direct to the motor. Still needed 17/16 times more pulses than the expected 200 steps at the motor X 5 for the gear ratio.

My conclusion is that the gearbox is not exactly a 5:1 ratio.
I have not seen any other problems with the motor or drive.

[David Bryant]

Hi
Just redid calcs and set the new numbers into Mach3 put it all back together, still out by 1-2mm in 1000. ???

Did many of you guys get the exact number or does everyone set up by adjusting afterwards?

Cheers
David

[danilom]

Mine calculation was

200 steps * 10 microstep = 2000
2000 * 3 times belt reduction = 6000 steps per rev
travel per rev = 3.14159265 (tooth distance = Pi) * 30 tooth = 94.2477796

steps per mm = 6000 / 94.2477796 = 63.6619662

but using dial indicator and mach calibration from SETUP page for one axis it was lower than 62 steps per mm, and other greater than 64. It must be because of in precision in motor movement as I think belt gears are pretty much the same.

[KenC]

10 micro steps per pulse is not a practical setting, almost all the article I read says 1/8 is the highest practical setting. maybe this is the problem.

[David Bryant]

Hi Ken
10 micro steps is standard for the Geckodrives

Cheers
David

[David Bryant]

Thanks Danilo

That is very close to the variation I have found. It will be good to hear some more if they got it exact.
thanks again
David

[KenC]

Ooops, I don't use Gecko :p

[Gerald D]

Hi
Just redid calcs and set the new numbers into Mach3 put it all back together, still out by 1-2mm in 1000. ???

Did many of you guys get the exact number or does everyone set up by adjusting afterwards?

Cheers
David

Have got 5 tables running with 3 different motor/gearbox combinations and 2 different rack suppliers/pitches. ALL of them were set to the calc and needed no tweaking afterwards.

[David Bryant]

Thanks Gerald That is what I expected. I will keep looking.
Cheers
David

[sensei]

Please somebody give me an advice. If my Motors 86HS9802 is
200 steps * 10 microstep = 2000
2000 * 3 times belt reduction = 6000 steps per rev
travel per rev = 3.14159265 (tooth distance = Pi) * 30 tooth = 94.2477796

steps per mm = 6000 / 94.2477796 = 63.6619662
what "Move speed mm per minute" and what "Min freq. kHz" is ok to use thank you

[danilom]

These are same as mine, I use Velocity = 18000 , acceleration = 600, this works with 25khz kernel speed.

[sensei]

thanks Danilo ... did you cut at that speed and what materials

[danilom]

Those are rapid move G0 feedrates. For cutting I rarely use over 4000mm/min

[IamDave]

Was this whole conversation, a discussion on what Mach 3 does automatically for you when you tune the motors?