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Author Topic: 28800 to move one inch  (Read 4249 times)

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28800 to move one inch
« on: December 06, 2006, 07:18:15 PM »
Hi everyone!..I built the David Steele large table using the Xylotek board and the 269 steppers,using the Mach three software..The control board came set at 1/8th step...the router table uses 18 thread to the inch all thread...if the math is right,and I am sure it is because it moves exactly one inch when you jog it, that takes 28800 impulses to move one inch...8microsteps X 200 steps to revolve one revolution and then X 18 to move one inch...8X200X18=28800...Doesn't that seem awfully high??..moving the pin to the 1/4 or 1/2 step would really cut down on that number..Do i loose anything like torque or speed by changing this?

Also when it comes to tuning the acceleration..I am not after super speed on this table..Making the axes acceleration slope a gradual one instead of straight up,doesn't that help with the accuracy of the table,not missing steps or possible going off course of the cuts??

Offline Chaoticone

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Re: 28800 to move one inch
« Reply #1 on: December 06, 2006, 07:46:58 PM »
The only thing you will loose going to 1/2 or 1/4 is resolution. At 10,000 pulses per you will have a resolution of 0.0001. With the screw you are using you could go straight for 1 pulse and still have a res. of 0.00028.
Yes, having a gradual accel ramp will help keep from skipping steps. I would however want it as high as I could go with no worries. I think this will make your CV mode a little easier to tune.

Brett
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Offline chad

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Re: 28800 to move one inch
« Reply #2 on: December 06, 2006, 08:08:28 PM »
I agree with everything below.  Basically it is what it is. The gearing and pitch and motors/encoders dictate what that number is. On my BP clone my x axis 100,000 , y is 100,000 and my z is 50,000 steps per inch.

Now these big numbers really start to count when you factor in speed. I have a grex so i have pretty much no speed limit, but mach is good to 45k for a licensed version and that wouldn't allow me to get full speed out of my servos..

Chad
Re: 28800 to move one inch
« Reply #3 on: December 06, 2006, 08:15:09 PM »
I have seen posts of peoples machine where they have like 2000 or 3000 to move a unit...that might be millimeter though...At 25 mhz setting ,does that mean that Mach at its best spits out an impulse 25000 times per second?? ..It just seems that it is running at its max..I guess there is no problem with that ??

Hood

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Re: 28800 to move one inch
« Reply #4 on: December 06, 2006, 08:27:55 PM »
its 25, 35 and 45 KHz, wish it was MHz ;) BTW thats for each axis (up to 6)
 Yes thats what it means, yours at steps set at  28,000 would allow a max velocity of  53 IPM  on 25KHz if my calcs are right. Dropping the stepping down to 1/2 would give you 208IPM, thats if your motors can run that fast.
Hood

Offline Chaoticone

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Re: 28800 to move one inch
« Reply #5 on: December 06, 2006, 08:32:08 PM »
You can go to 45KHz when you buy the licenses. ;D
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: 28800 to move one inch
« Reply #6 on: December 06, 2006, 08:38:50 PM »
All right then..at 53 inches per minute,when this table is designed around 30 inches,I am sure that the all thread would fling it self off the table and impale the ceiling!!!.. :D  It  looks like that Mach is more than capable of this setting..I am headed for the "purchase section " right now...

Offline Chaoticone

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Re: 28800 to move one inch
« Reply #7 on: December 06, 2006, 08:43:01 PM »
Get yourself some good oil for the all thread, the cheap stuff stinks when it smokes.  ;D
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!