Accuracy

Agree with reservations...

Hi Careful -

You have an ironic name for this thread...

I agree with all that Bill says about the millimeter/micron thing. Which makes me wonder how you have 8 years on an arm but would make such a faux pas in front of this audience.

Regarding Romer accuracy, (you haven't ever checked this out during eight years? sorry) I agree also with Bill but not to his magnitude of pessimism. I think - with a skilled manual CMM guy at the helm, good (not perfect) environmental conditions, a rigid, direct-connect fixturing method between arm and component - that very good accuracy and repeatability is possible with a Romer, at least one of recent vintage. I can't speak for the older 3000 series or even earlier, but I know the encoders are a lot better now than they used to be. I own an 2008 Infinite 2.0 3meter machine and I have been very happy in general, but I also better understand what Bill has also learned... sometimes admittedly, to my own consternation.

You gotta be Careful. very careful. Sheet metal, no bigger than 2/3 of the arm's range, +/-.015 all day. Machined parts +/-.005 is realistic with conditions described above. With the smaller parts, you might approach position within .005, but you have to have the trifecta, presuming also that your arm hasn't been banged around for eight years. I also run a client's arm that has been through the wringer, same year as mine, and I have significantly less confidence in that tool. Lucky for me, I am the only one to have ever held my Romer and all my equipment is pristine. Another part of the formula for Romer accuracy. If you have your arm C-clamped to a plate or some other missing link type of fixturing problem, forget it.

Scott

Agree with reservations...

Hi Careful -

You have an ironic name for this thread...

I agree with all that Bill says about the millimeter/micron thing. Which makes me wonder how you have 8 years on an arm but would make such a faux pas in front of this audience.

Regarding Romer accuracy, (you haven't ever checked this out during eight years? sorry) I agree also with Bill but not to his magnitude of pessimism. I think - with a skilled manual CMM guy at the helm, good (not perfect) environmental conditions, a rigid, direct-connect fixturing method between arm and component - that very good accuracy and repeatability is possible with a Romer, at least one of recent vintage. I can't speak for the older 3000 series or even earlier, but I know the encoders are a lot better now than they used to be. I own an 2008 Infinite 2.0 3meter machine and I have been very happy in general, but I also better understand what Bill has also learned... sometimes admittedly, to my own consternation.

You gotta be Careful. very careful. Sheet metal, no bigger than 2/3 of the arm's range, +/-.015 all day. Machined parts +/-.005 is realistic with conditions described above. With the smaller parts, you might approach position within .005, but you have to have the trifecta, presuming also that your arm hasn't been banged around for eight years. I also run a client's arm that has been through the wringer, same year as mine, and I have significantly less confidence in that tool. Lucky for me, I am the only one to have ever held my Romer and all my equipment is pristine. Another part of the formula for Romer accuracy. If you have your arm C-clamped to a plate or some other missing link type of fixturing problem, forget it.

Scott