# JCS900 2AE calibration problem fix



## A10 guy (Oct 23, 2019)

Just installed a JC900-2AE DRO on my Grizzly 4003G lathe and had trouble calibrating it. Found the good manual mentioned in this thread, which was a great help along with all the utube videos, but nothing helped my problem. The display was off by 30% or so, nothing in the set-up process helped. Finally figured out that I had left too much clearance between the read heads and scales. I had used an .008" shim between them just because it didn't seem right to have them touching. After closing that gap to barely touching the system worked perfectly. Just wanted to share in case someone else has that issue.
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## MrFettler (Oct 31, 2019)

Can I ask what encoders (read head) your using please.
Because of the gap I take it it's magnetic.

Nick


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## A10 guy (Nov 1, 2019)

MrFettler said:


> Can I ask what encoders (read head) your using please.
> Because of the gap I take it it's magnetic.
> 
> Nick


They are the glass (optical) scales.


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## Rata222 (Nov 2, 2019)

A10 guy said:


> Finally figured out that I had left too much clearance between the read heads and scales. I had used an .008" shim between them just because it didn't seem right to have them touching. After closing that gap to barely touching the system worked perfectly. Just wanted to share in case someone else has that issue.



Hi A10 Guy - Glad you got the scales working. I don't know if incorrect gap can damage the scales.
When installing my unit all the info I found - for what I felt were similar units -suggested much larger gap (around .040".)  But one scale did act erratically and was replaced - so perhaps gap was a factor.  Just wanted to pass along info that I found FWIW.



			https://www.primadilna.cz/fotky49990/fotov/_ps_3044Warco-DRO-Install-Manual.pdf
		



			http://www.team358.org/files/mechanical/MillDigitalReadoutInstallationManual.pdf
		


Jim


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## 6literZ (Nov 19, 2019)

Can you cite the thread with the calibration info? I’m having trouble with understanding the manual for setting up linear deviation. Thanks


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## 6literZ (Nov 19, 2019)

Chinese JCS900-3AE DRO - Good Manual found !!!
					

I purchased a model JC900-3AE DRO for my mill.  The manual is awful.  The screens and buttons shown do not correspond with the unit.  I could not get into some of the functions and the vendor could not help.  New to DRO’s I was frustrated – I searched all the manuals for different DRO’s that I...




					www.hobby-machinist.com
				




I’ve located the manual, I believe. Here it is for those interested. At some point I’d like to stack some gage blocks together and get it really dialed in.


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