The Shop > Electronics & IC Programing
DRO questions
John Stevenson:
I reckon I have a spare built up DRO 350 kicking about somewhere, mumble, mumble, must have a tidy up and see if I can't find it.
Took it off a lathe and replaced it with proper commercial unit.
John S.
picclock:
@ John
That kinda begs the question as to why you replaced it ?
@j45on
http://www.virtualvillage.co.uk/300mm-lcd-display-module-for-caliper-vernier-gauge-new-001481-078.html
may work out OK. The one that's on there at the moment uses a 2032 battery (large coin cell) but I'm happy to change it to the regular style. Looks like an interesting place. Many thanks for the link.
All the Best
picclock
John Stevenson:
The Chinese scale calipers ore useless on a lathe due to the precision and repeatability.
They have a published accuracy of 0.001" which in practice can be as much as 0.002", as a lathe measures and cuts a radius every measurement is multiplied by two.
This also applies to errors.
So that best case of plus or minus one can soon add up to 4 thou on diameter.
If, like me you have to do loads of bearing diameters this is nowhere near good enough.
Another problem I had which others have also had is the numbers danching about making what you are reading pot luck.
They work for some, not everybody.
On a mill for home shop use they may well be all right but like most of the what was cheap options, the price differential between Chinese scales and glass scales are getting closer.
Add to this, and it's not fully understood but 'some' of the latest import scales have a different protocol to the existing ones making them not compatible with the Shumatech and remote displays.
Don't take this as written in stone as it's too early to get a full picture whether it's just some or all and how you recognise the types.
John S.
raynerd:
Just a word of warning - I thought I`d hit the jackpot when I found the virtual village heads at £3 a replacement but the two I purchased wouldn`t link up with the shumatech!!!! The ones I got were the £4 ones that seem to be sold out at the moment.... anyone else experienced this?
Chris
EDIT--
Just read Johns post:
--- Quote ---Add to this, and it's not fully understood but 'some' of the latest import scales have a different protocol to the existing ones making them not compatible with the Shumatech and remote displays.
Don't take this as written in stone as it's too early to get a full picture whether it's just some or all and how you recognise the types.
--- End quote ---
Glad it isn`t just me then! I thought I hadn`t wired it correctly.
kwackers:
Probably worth addressing a couple of the points in Johns post above.
Protocols: The newer 550 (or the DPU upgrade for the 350) can handle most (if not all) the current protocols used.
Jitter: There were whole threads about different ways to fix this, however again the 550 (or DPU) don't suffer from this due to changes in ground layout. Because of this repeatability is higher - although accuracy remains a factor of the scale in question.
The 550 (or 350) doesn't preclude the option to run with glass scales, the beauty of them is you can combine where necessary both types.
Finally, cheap glass scales have a lot of the accuracy issues that the capacitive (Chinese) scales have. If you find cheap scales somewhere probably worth checking to see if they come with a calibration chart which will show how accurate they are for any point on the scale, I believe some of the very cheap ones don't come with any calibration - however they should still have excellent repeatability.
Worth pointing out that capacitive scales tend to be inaccurate due to price rather than some inherent problem with the technology.
However, if like me you tend to make stuff that simply 'fits' something else then absolute accuracy is less important than repeatability. I tend to machine to within a thou or so and then work with either the other part or a micrometer.
I don't think with amateur equipment its worth getting too hung up on accuracy, unless your scale is fitted to the tool point there are a myriad of ways in which accuracy can be compromised.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version