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new hardware same problem
« on: March 06, 2015, 03:52:27 PM »
Hi im new to cnc router stuff.  Bought a chinese router and it worked fine but I couldnt get accurate messurements so i bought a new controler with a g540 and motors and a new power supply . Im still haveing the same problem.  I cant get my machine to be accurate enough.  I set steps per unit with a 6 inch caliper and recheck it with a one inch dial indicator and ill be off a thousandth or 2  some times im dead on. Tuned my motors way down really slow and still my circles are almost .090 out of round.  iKnow my machine is chinese but i should be able to get better accuracy then that. am i missing a setting or something.  any help will be appreciated

Offline RICH

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Re: new hardware same problem
« Reply #1 on: March 06, 2015, 04:23:02 PM »
Do you have the steps per unit set correctly?
Are you skipping?
Is backlash set correctly?
Is the velocity and acceleration settings appropriate for YOUR machine?
Is the tool perpendicular to the table?

RICH

FWIW,
0.09" is lot to be out, heck, one can use an acme threaded rod with nuts to drive the axis and get closer. In fact that is what a friend had for his lathe
which had 1/8" backlash and he could cut darn good threads with it!

Re: new hardware same problem
« Reply #2 on: March 06, 2015, 04:49:45 PM »
I was just setting steps again messureing 4 inches with a dial caliper and double checked with a dial indicator at one inch and was .002 short both x and y axis.  i keep checking for backlash but there doesnt seem to be any. i adjusted the machine up pretty good and it doesnt bind  i can move it by hand with the motors removed.  just got new motors and had to get new couplers for the motors so i know there tight and not skipping.
The acc is set to 7.6 and vel is 103  step pulse and dir pulse is set to 0 and the tool is perpendicular to the table.
 My material is teflon and its only .150 thick. you can almost cut that stuff with a butter knife so I dont think the table or tool is flexing
Re: new hardware same problem
« Reply #3 on: March 06, 2015, 06:46:56 PM »
Ok i redid my step per again measured to 5 inchs and rechecked is working fine i think. Also found out my harbor fright dial indicator is not acurite haha  cut 2 pieces 12 in round its at 12 in x and y but at 45 degrees y+x- im .055 under and y+x+ im .045 under sounds like backlash to me but when i check for backlash there really isnt any.  ill check againg  has anyone ever seen this before

Offline Bodini

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new hardware same problem
« Reply #4 on: March 06, 2015, 06:50:00 PM »
Are you sure you don't have metric ball screws?  I pulled my hair out for days on my Italian made machine before I figured out the screws were 25mm per turn and not 25.4.  Just something to check. ;)
Re: new hardware same problem
« Reply #5 on: March 06, 2015, 07:41:23 PM »
If it's a chinese machine there is a 100% chance the ball screws are metric.  The most common is 5mm pitch.

Offline RICH

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Re: new hardware same problem
« Reply #6 on: March 06, 2015, 08:49:37 PM »
Chinese routers, the famous 3040, 6040 drives..........

Once I made a dumb comment to a psychitrist that I was introduced to. Told him that I heard that they are the first to jump off the bridge.
He corrected me and said that was not true and said it was dentist's that jumped first. ???

Everytime this dude see's a post with Chinese or 3040, 6040............I feel like a dentist!  ;) :) :D ;D

RICH
Re: new hardware same problem
« Reply #7 on: March 06, 2015, 08:56:11 PM »
Haha I heard that too.  The ball screws are probably metric but what does that mean. is there a setting in mach3 for metric screws..  Does this mean I have to convert to the metric system because that would suck haha 

Offline RICH

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Re: new hardware same problem
« Reply #8 on: March 06, 2015, 09:06:53 PM »
Use the axis calibration feature of Mach which can be found via the ALt6 page. No need to to convert to metric system.

RICH
Re: new hardware same problem
« Reply #9 on: March 06, 2015, 10:03:02 PM »
the axis calibration works great i do it all the time.haha  still cant get the accuracy.  i keep checking for backlash and not finding any and theres always backllash.  Im using mill wizard to write my gcode could there be some inaccuracy in the wizard