# Readhead and scales



## Bamban (May 13, 2020)

I ordered a DRO set for a lathe. The cross slide came in 5u instead of 1u. The seller offered to send me a 1u readhead. Question, would that be enough to make the cross slide 1u system? Does it matter to the scale itself?


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## mksj (May 13, 2020)

Not that I am aware of, the grating is different depending on the scale microns. On magnetic scales you need to specify both the magnetic strip resolution and the read head resolution. On glass scales the head is reading the grating spacing for the particular resolution.


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## darkzero (May 13, 2020)

Sounds like they are glass scales & if the seller offered to send you the 1 micron read head then most likely yes. I went through the same thing for my cross slide. Seller mistakenly sent me a 1 um read head instead of the entire 1 um scale. I swapped it it out & has been working fine for years. It was really easy to do also, pop the end cap off, simply slide out the old one, slide in the new one & that's it. The scales on my lathe are Sino glass scales FWIW.


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## Bamban (May 13, 2020)

mksj said:


> Not that I am aware of, the grating is different depending on the scale microns. On magnetic scales you need to specify both the magnetic strip resolution and the read head resolution. On glass scales the head is reading the grating spacing for the particular resolution.



They are glass scale. So, the grating has to be replaced as well?


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## Bamban (May 13, 2020)

darkzero said:


> Sounds like they are glass scales & if the seller offered to send you the 1 micron read head then most likely yes. I went through the same thing for my cross slide. Seller mistakenly sent me a 1 um read head instead of the entire 1 um scale. I swapped it it out & has been working fine for years. It was really easy to do also, pop the end cap off, simply slide out the old one, slide in the new one & that's it. The scales on my lathe are Sino glass scales FWIW.



The scale is glass, but labeled 5u, original read head is also 5u. Did I read you right that your scale is already 1u?


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## darkzero (May 13, 2020)

Bamban said:


> The scale is glass, but labeled 5u, original read head is also 5u. Did I read you right that your scale is already 1u?



Sorry, I didn't do a good job at wording my post as usual. I ordered a 1um scale but received a 5um scale. Contacted the seller & he then sent me a 1um read head instead of an entire 1um scale. I contacted the seller again & he assured me that I could just swap out the 5um read head for the 1um read head. He said the glass housing is exactly the same. 

I told him I wasn't comfortable doing that in case something went wrong & didn't want to be responsible, I never took one apart before. He said it's very simple & he would gladly send me another complete scale if something went wrong. He was right, was very simple & has been working fine for like 8 yrs or so now. Verified accuracy.


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## Bamban (May 13, 2020)

darkzero said:


> Sorry, I didn't do a good job at wording my post as usual. I ordered a 1um scale but received a 5um scale. Contacted the seller & he then sent me a 1um read head instead of an entire 1um scale. I contacted the seller again & he assured me that I could just swap out the 5um read head for the 1um read head. He said the glass housing is exactly the same.
> 
> I told him I wasn't comfortable doing that in case something went wrong & didn't want to be responsible, I never took one apart before. He said it's very simple & he would gladly send me another complete scale if something went wrong. He was right, was very simple & has been working fine for like 8 yrs or so now. Verified accuracy.




Got it, once I get the read head I should be good to go.

Thanks for the clarification.


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## mksj (May 14, 2020)

It would seem that the glass scales use a 20uM grating and the reader head sets the accuracy.  I always thought the glass scale was specific to the resolution but it appears that the difference is in the reader. Ditto for magnetic scales. Not sure how that is done.




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						DC20-1500
					

DC20-1500 DRO for Lathe & Mill DC series Linear scales are used on all kinds of machines with Ditron D60 digital readout  together, which can help processing in the machines by locating the positions. The scales may also be fitted to co-ordinate measurement or other measurement equipment used...




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## Bamban (May 14, 2020)

Thanks for the research, Doc.


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## Bamban (May 15, 2020)

Well, I was in contact with the supplier, HXX. Sofia, the contact person, tracked down the technician who apparently checked the system. The technician said the label was wrong, but did not replace it. They asked that I connect the scale to the readout, and see if indeed it moves at 0.0001. It does.

I clamped the scale on the swivel vise and put my Mitutoyo 0.0001 indicator on it and carefully and slowly tapped the read head while watching the readout. It tracked.


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## Bamban (May 16, 2020)

One more question on the scales: 

What have you guys done about this plastic piece that is sandwiched between the readhead and scale?


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## darkzero (May 16, 2020)

Remove it, that's protection for shipping.


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## Bamban (May 16, 2020)

Thank you.


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