Thread: XinXing Measuring Tools Factory Granite Surface Plate Vs HP Laser Interferometer

Originally Posted by Dave J

Your DRO might have the linear compensation but it might not be in the manual. My book describes it being measured in PPM (parts per million) so 100 PPM is 1 micron, which can be added or subtracted.

Yeah but I couldnt figure out how to enter it. I'll have another read of your and my manuals tonight and see how I go tomorrow.

Stuart

Send me a pm or start a new thread and I will help you out if you need it. I did the cross slide of my lathe a while back, I might be a bit rusty but don't mind getting into it all again if you need the help to correct it.

Dave

I just re-setup to to the linear compensation, I ended up putting in 86ppm for the X axis linear compensation.

I'll post video is you like?

Originally Posted by Brobdingnagian

I just re-setup to to the linear compensation, I ended up putting in 86ppm for the X axis linear compensation.

I'll post video is you like?

0.86 of a micron is not much out, unless the Easson DRO have different PPM to the Meisters?

Dave

flipping through my manual....... page 13.. Linear Compesation............. I swear it wasnt there the last 10 times I looked

Sorry for the side track

Good news for Josh, I also have Non-Linear error Compensation so while he is here checking my plate he can tweak my scales in 50mm steps

Stuart

The number I got from the calculation in the manual gave me the wrong correction factor, so I just kept bumping it up until I got to 90 and then it was too much so I brought it back down to 86. close enough that I can't tell if its a rounding error or not.

-Josh

PS I just shot a video of the post calibrated dro at the end there is a print out of the compensation factors used. This is what they mean
Total Compensation Factor -0123.07060
Air Compensation -1000.07402
Humidity -2000.00023
Air Pressure -3000.07515
Air Temperature -4000.00295
Materiel Temperature -5000.00285
Meteriel coefficient of expansion 10.5 ppm (grey Iron) -9000.00105

This video is more for my documentation, but here it is anyway it will take ~45 minutes.

I will leave it setup overnight and test it again in the morning like Stuart asked


Seriously you have a non linear correction as well as a linear correction??? Sweet.

I will have to check my manuals tomorrow, but I remember reading about non linear and linear as well.

Dave

Great stuff Josh

Originally Posted by Brobdingnagian

Seriously you have a non linear correction as well as a linear correction??? Sweet.

Welll its a little early to claim that.......... the manual says I do........I'll see tomorrow.

Stuart

Well up extra early for me today to test how the temperature variations effect the DRO

According to the Automatic Compensator it is

Total Compensation Factor -0123.07134
Air Compensation -1000.07356
Humidity -2000.00031
Air Pressure -3000.07527
Air Temperature -4000.00247
Materiel Temperature -5000.00255
Meteriel coefficient of expansion 10.5 ppm (grey Iron) -9000.00105

So that equates to about a 3°C temperature drop

First Run
DRO = 531.15
Laser = 531.13847

Second Run
DRO = -532.04
Laser = -532.02061

Third Run (slow speed ~1mm/sec)
DRO = 528.59
Laser = 528.57555

These give me a thermal expansion coefficient of, 7.2, 12.1 and 9.1 *10−6m/°C for their respective runs, lots of error in that though. and I can't be bothered to work out exactly what the error is this early, well not with out another coffee or 6. But I think it is the expansion rate for the glass scale not the aluminium housing or the iron table

-Josh

This is fantastic Josh.
Great work in getting this info on something that I have always wondered about but had no hope of actually knowing.

Phil

Hi Josh,
So there must be some flex in the mounted between the glass and the Alum? That would make sense I guess.


Well I've got no idea what manual I was reading when I first got the DRO but I swear it wasn't this one. Turns out I can do all sort of useful things like change the imp display from 0.0001" to 0.00001"........ so that should come in be handy

I dont have non linear correction and linear correction. Its "or" but that makes sense. Whats a little strange is you seem to be able to enter the distance between points with no mention of a limit to the number of points. Anyway enough waffle.

Did the maths on my numbers from yesterday. came up with a correction of 1.205, entered that and checked. 550.05mm, so the DRO is now "as good as" correct to the hieght gauge, certainly with the gear I am currently using. Though the height gauge maybe about 0.2mm out over that distance.


Stuart

Hi Stuart,

Nice work, having a known reference to calibrate against is a handy thing.

We will have to get the HP gizmo down to Melb for you to have a play with.


Regards
Ray

PS Don't forget that it was your inspection at the Auction, that opened up this particular rabbit hole...

Hi Ray,
Thanks. Feel a little stupid that I've been wandering around for about 2 years thinking it couldn't be fixed when its right there in the manual. As I said I even got Dave to send me a copy of his manual(which fortuitously I seem to have lost as that's what made me dig my manual out)............So its lucky you guys got me thinking about it again.

Now the height gauge is a little strange, I wouldn't have thought Mitutoyo would bother putting 0.02mm grads on it if it wasn't better than 0.1mm over 300mm? But then I am assuming the master height gauge to be correct(at this level). Still no matter what I'm a lot closer than I was.
I haven't checked either of them for square and the height was freighted from Canada.
A little more careful checking in order I think

I think the operator might have a bit to do with it as well.

Stuart

Originally Posted by Stustoys

Hi Ray,
Thanks. Feel a little stupid that I've been wandering around for about 2 years thinking it couldn't be fixed when its right there in the manual. As I said I even got Dave to send me a copy of his manual(which fortuitously I seem to have lost as that's what made me dig my manual out)............So its lucky you guys got me thinking about it again.

Now the height gauge is a little strange, I wouldn't have thought Mitutoyo would bother putting 0.02mm grads on it if it wasn't better than 0.1mm over 300mm? But then I am assuming the master height gauge to be correct(at this level). Still no matter what I'm a lot closer than I was.
I haven't checked either of them for square and the height was freighted from Canada.
A little more careful checking in order I think

I think the operator might have a bit to do with it as well.

Stuart

when you got the master height gauge did it have the setting block with it?