Accuracy of digital scales

[rake60]

When I was a working machinist most of the manual machines I ran were fitted with
state of the art digital scales.

When it came time to hit a critical size the old mechanical dial indicator came out.

Digital scales are great for a quick roughing references.
That is their limit.

Rick

 

[Captain Jerry]

Bogs

My logical thinking is hard at work so I have a few question.

1. Are glass scales rigidly mounted?
2. Can glass scales be accurate if not mounted true and square?
3. If the scales are properly and rigidly mounted, what is the need for position compensation in the head?
4. Are expensive scales easier to mount properly than cheap scales?

I'm not poor but I am frugal (cheap) and after all, this is just for fun.

Jerry

 

[Jasonb]

I can only second what Bogs says. I originally had the cheap scales on my X3, I then added remote readouts. Over the 3 years they were fitted they played up more and more so this summer I replaced the X&Y with glass scales together with a 3 axis universal console and have not had one problem with them and the other functions that teh console offers are a big bonus. As I write there is a long box under the xmas tree with another glass scale (I hope) so I can also do the z-axis.

Jason

 

[Davo J]

Bogs

My logical thinking is hard at work so I have a few question.

1. Are glass scales rigidly mounted?
2. Can glass scales be accurate if not mounted true and square?
3. If the scales are properly and rigidly mounted, what is the need for position compensation in the head?
4. Are expensive scales easier to mount properly than cheap scales?

I'm not poor but I am frugal (cheap) and after all, this is just for fun.

Jerry

1) The scale itself it rigidly mounted and so is the reader head.
2) The scale can still be accurate if not mounted true with the linear error compensation which is a program built into it. You can measure say a 1 2 3 block to determine if it's reading true and adjust it to suit.
3) Their is a small spring loaded mechanism between the scale and reader head to stop any damage (within reason) if the scale is mis aligned. This works if say one side of the scale was lower and as it comes across the reader head the spring will let the reader head follow it's proper position inside the scale. The actual reader inside slides up and down the glass strip on 5 bearings.
4) The glass scales are mounted with one bolt in each end and 2 bolts in the reader head (usually M4-5). The covers have a bolt every 300- 400mm along their length which is usually M3.

Dave

 

[Captain Jerry]

Thanks for the good info Davo. Software trumps harsware every time. Apparently the linear compensation program and calibration software is the key difference. Well written software should be able to handle not only cosine error (alignment) but could also map point to point variations. That certainly justifies the price but for me it doesn't justify the expense. After all, my last attempt to send a rocket to Mars only missed by } { THAT much!

Jerry

 

[mklotz]

Please start a new thread, Bert.