# Calibrate A Cheap Chinese Dro



## AGCB97 (Jun 19, 2016)

I have a cheap Chinese DRO (Shenzhen Hengxingxing Precision instruments   GCS900-2DB) and the instruction book is unreadable. Anyway. 
I know it needs to be calibrated and have watched several YouTube vids but none just like mine. I have a 3" block to use as a reference, but don't know how to get into the setup to change it.

Also, when trying to do a bolt circle, the only way it seems to work is to specify the degrees of both the 1st and last hole which involves a little calculation beforehand to know how many degrees the last hole is less than 360. This doesn't seem to match the videos.

Also, on the bolt circle, 270 degrees is toward the turret and the circle always goes counter clockwise. Is this normal.

It would be great to find another person with the same DRO that has 1st hand experience and has it figured out.

Thanks
Aaron


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## Wreck™Wreck (Jun 19, 2016)

AGCB97 said:


> Also, on the bolt circle, 270 degrees is toward the turret and the circle always goes counter clockwise. Is this normal.
> 
> It would be great to find another person with the same DRO that has 1st hand experience and has it figured out.
> 
> ...



I have zero experience with your particular equipment however every cad program that I have ever used will draw a bolt circle counter clockwise, use the minus sign before the angle to make it draw in a clockwise fashion.

I suspect that there is a choice of "lathe or mill" this will probably fix your problem, it is an adaptable system by default so just wade in and make it do exactly what you want it to do.

From my experience with fixed machine controls that will not do what one requires,  just lie to them and make it work.


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## MSD0 (Jun 19, 2016)

Not familiar with your particular DRO, but make sure it's in the correct mode (lathe, mill, etc.) and that the resolution is set correctly for the scales (1 micron, 5 micron, etc.). If you can find a link to the instruction manual, we might be able to figure it out.


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## dlane (Jun 20, 2016)

3-4th word said it all


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## AGCB97 (Jun 20, 2016)

MSD0 said:


> If you can find a link to the instruction manual, we might be able to figure it out.



This is the main problem. To me it is unreadable but hopefully you're better at broken Chinese/English.

I only have it as a PDF file. Is there a way to get that posted or sent?

Aaron


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## MSD0 (Jun 20, 2016)

AGCB97 said:


> This is the main problem. To me it is unreadable but hopefully you're better at broken Chinese/English.
> 
> I only have it as a PDF file. Is there a way to get that posted or sent?
> 
> Aaron


Not sure about uploading the file, but you can paste in a link to the file.


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## mksj (Jun 20, 2016)

Easiest way to link/attach a file is to either cut and paste the link to the file if on-line. It is also easy to attach to a posting, just choose the upload tab "Upload a File" a window pops up and hit the "Browse" select the file on your computer and click on that, and the file will be uploaded to your post. I prefer this because links and file hoster's come and go. If you upload an image you have the option to have it load as a full image or a thumbnail.

A DRO usually does not need to be calibrated over a short distance, out of the box it should be accurate. Most scales specify their tolerance over distance, some DROs allow for some correction to the linearity of the scale over the range of the scale. Lower resolution scales, will jump in increments with regard to the scale display, so having a fifth decimal place often seen on Sino  displays is worthless. As others have mentioned, you need to set the scale resolution (micron) and type of machine (lathe vs. mill) into the VFD for it to display correctly.


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## brino (Jun 20, 2016)

Hi Aaron,

There may be a post count you need to reach before you can upload files.
If you send the pdf in a private message (PM) I can add it to this thread.

-brino


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## AGCB97 (Jun 20, 2016)

Here is the PDF. May be worth a few laughs, not much else


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## AGCB97 (Jun 20, 2016)

Thanks for the offer brino but I was able to do it


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## MSD0 (Jun 20, 2016)

Yea, it's poorly translated for sure, but at least they show you what buttons to press. It looks like the resolution and linear compensation are covered on pages 43-44.


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## pav138 (Jan 23, 2017)

AGCB97 said:


> Thanks for the offer brino but I was able to do it


HI 
Could you please tell me how to switch this GCS900-2D from milling to Lathe operation


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## AGCB97 (Jan 23, 2017)

I know this is an old post and would not normally post to it at this point but since it's on top now. I just checked the calibration a few days ago with a 123 block and it's off by .001 in 3"


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## MSD0 (Jan 31, 2017)

You can try using the linear compensation to correct the error.


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## AGCB97 (Jan 31, 2017)

MSD0 said:


> You can try using the linear compensation to correct the error.



Well 1st off I think .001 in 3" is well within my tolerance expectations but I do not understand your statement.

Thanks
Aaron


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## Kernbigo (Jan 31, 2017)

i check mine by using gage block set up 7" and was out  only .001


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## MSD0 (Feb 1, 2017)

AGCB97 said:


> Well 1st off I think .001 in 3" is well within my tolerance expectations but I do not understand your statement.
> 
> Thanks
> Aaron


No problem, I wasn't sure if you were asking a question.


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