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Author Topic: Newbie with inaccurate machine looking for tips  (Read 4775 times)

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Offline stirling

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Re: Newbie with inaccurate machine looking for tips
« Reply #10 on: April 16, 2013, 06:31:08 AM »
OK I was assuming it was direct drive but now I see you have reduction. Anyway it seems from all you've said you may have one or more of:

scewed gantry, backlash, steps/per issues.

I'd tackle these ONE at a TIME in that order. ONLY when you're happy move onto the next one.

Ian
Re: Newbie with inaccurate machine looking for tips
« Reply #11 on: April 16, 2013, 09:10:26 AM »
Ian,

Thank you for your input. Because I can get fairly accurate dimensions (the 4 sides read as they should) on a rectangle and it is just out of square, I am thinking a scewed gantry is a real possibility.  Especially since many other purchasing this brand have had similar experiences with shoddy worksmanship. Unfortunately the customer service for them is non-existent.

While I am fairly handy and can usually figure things like this out, I am not sure how to go about testing for a scewed gantry.  Aside from checking to se that the main beam carrying the spindle is at a right angle to the arms (not sure if that is the correct term) I am not sure what to look for.  If you would be so kind as to explain what to look for/how to test for this,  I would greatly appreciate it. 

Chris

Chris

Offline stirling

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Re: Newbie with inaccurate machine looking for tips
« Reply #12 on: April 16, 2013, 09:42:03 AM »
Can you draw a piccy showing what you mean by the workpiece being out of square. Draw it in relation to the sides and gantry of your machine.

Ian
Re: Newbie with inaccurate machine looking for tips
« Reply #13 on: April 16, 2013, 11:58:03 AM »
Ian,

Will do sometime in the next couple days when I can find the time.  Doing some (very quick, down and dirty) type measurements of the gantry arms in relation to the gantry, it appears that things are slightly out of square, so I believe you may be onto something with an askew gantry.  The measurement from the bearing block that rides on the linear rail is also different from one side to the other.

I very much appreciate you time and responses...........I have a renewed ambition to finally figure this thing out and with help from this forum believe I am on the right track. 

Chris

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Re: Newbie with inaccurate machine looking for tips
« Reply #14 on: April 16, 2013, 12:12:38 PM »
No worries.

Ian
Re: Newbie with inaccurate machine looking for tips
« Reply #15 on: April 16, 2013, 04:20:50 PM »
Chris, you can check squareness approximately with a tape measure. With some kind of scribe, drill or marker in the spindle have the machine layout three holes at x1 y1, x59 y1 and x1 y119. The centers of those three marks should measure 58 x 118 x 131.484. Use A² + B² = C². C should = √ A² + B² Adjust your X and A relationship to get C where it should be.

Lets say C was 131. B should be √ 131² - 58² = 117.460. 118 – 117.460 = .540. You’d have to move A - .540 in relation to Y
« Last Edit: April 16, 2013, 04:38:01 PM by Tony Bullard »