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machine percision
« on: January 31, 2015, 01:24:56 PM »
How can i make my machine more precise.  y axis is running longer than my x axis.  Ive done motor tuning and step calibration. I used a very pointy bit and drew a line on a piece of wood and used a micometer to measure and its still off.  I need to be more precise then this.  I do have a chinese router with the blue controler.  Im using windows 8 and a uc100 motion controler. 

Offline BR549

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Re: machine percision
« Reply #1 on: January 31, 2015, 01:56:42 PM »
The machine normally will be as accurate as YOU set it up to be in Motor tuning. IF you are loosing steps OR you have set the steps per incorrectly then you machine will be OFF.

There are volumes here on setting up  Motors step per. Same with lost steps.

(;- )TP
Re: machine percision
« Reply #2 on: January 31, 2015, 02:56:20 PM »
ive done searches on lost steps and precision and the read is too technical for me to understand.. haha   ive tried to set the machine up as exact as i can but im still off almost an 1/8 in on an 11in circle and a 4 bolt hole circle wont match up when 2 diffrent cuts are matched up. 

Offline RICH

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Re: machine percision
« Reply #3 on: January 31, 2015, 08:11:18 PM »
You could use a yard stick to measure and get better accuracy than 1/8".  ???

Use the axis calibration feature which can be found on the Settings screen (ALt 6) lower left corner fo the screen.
The axis move you make shoud be as long as possible with backlash removed. Refine to hearts desire........

RICH
Re: machine percision
« Reply #4 on: February 03, 2015, 04:08:23 PM »
Ok tried a better way of measuring my steps per unit and tried setting backlash.  Still trying to figure out how to measure backlash more accurately had it set to .005 on y and .004 on x and still was off alittle reset my kernal speed to 25000 was at 35000 and retuned motors and now the the stepper motors stall and jerk while running x and y at same time while jogging.  Does not matter motor speed or accel.  Rest set to 35000 kernal speed and still haveing the same problem am i doing something wrong.
Re: machine percision
« Reply #5 on: February 03, 2015, 04:12:08 PM »
If you guys dont already know Im new to cnc and machining and not very good with computers haha.  I was a mechanic for 16 years so Im pretty good at figuring stuff out but this is too much to learn all at once trying my best though
Re: machine percision
« Reply #6 on: February 03, 2015, 04:19:59 PM »
Turned off backlash and reset system is working fine now turned back lash back on and the motors stall and jerk again is my backlash set to high  its only at .004 inches ill try and recalculate
Re: machine percision
« Reply #7 on: February 03, 2015, 04:50:27 PM »
Take a look at this video & see if it helps. https://www.youtube.com/watch?v=A27nOkTFYDY

I had trouble until I reset the settings like Hoss shows.
Milton from Tennessee ya'll.
Re: machine percision
« Reply #8 on: February 03, 2015, 05:39:16 PM »
thanks that did help.  Now when im measuring backlash i type in a g0y1  g0y0 code and measurehow much its off correct does it matter what direction im doing it, Should i be checking a larger or smaller distance

Offline RICH

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Re: machine percision
« Reply #9 on: February 04, 2015, 07:06:00 AM »
Quote
does it matter what direction im doing it, Should i be checking a larger or smaller distance

In general:
A short distance is fine and you only move in one direction and then measure the non movement (backlash) of the axis when going in the  opposite direction.

Some things and refinements to be aware of:
1. Steps per unit need to be correct for best accuracy of backlash measurement.
2. Backlash can vary some due to mechanical items.
3. There is no such thing as ZERO backlash, may be small but it is there, just a matter of amount
4. Bearing preload can affect backlash location along the axis since you need to apply opposite force to load up
    the bearing. You need adjust / remove any play in the bearing and yet minimize amount of torque used post adjustment.
5. Backlash can vary due to the quality of the screw / nut. You will have what you got. Some screws are not linear, IE
    +- accuracy over say 3 feet, but that +- can be happening in say a 12" section of the screw! Or the screw pitch can be slightly
     different in the opposite direction.
6. Belt tension, quality of belt/pulley/gears / rack etc come into play etc

So rather easy to get the backlash down to some small amount,but, to really minimize it you got to get very meticulous
about everything. Thus in the end you got what you have and overall mechanical system  affects backlash.

RICH