Buying a new CMM system

[geesamand]

Hello all,

We're looking at purchasing a bridge-type CMM to replace an old B&S Validator. We're looking at bridges with a working volume of about 60x50x120" with .0002-.0003" accuracy. We measure machined housings with flat faces and cylindrical bores, looking for positional and form data.

If you can offer your opinions on these questions, it will help us immensely to learn from a source that doesn't also have something for sale.

1) What are the pros/cons of the major CMM brands?

2) Knowing what you know now about your CMM, what would you have done differently if you were to purchase your equipment again?

3) Refurbished vs. new? We're leaning toward refurbished.

4) Some CMMS have add-ons to allow checking of gears on a traditional CMM. We purchase helical gearing in approx AGMA 10 quality and would like to do some basic checks. If you're doing this now I'd like to hear how it works for you.

5) We have some "tall" housings that will be measured horizontally on the table and require 8-12" of horizontal reach. I know this causes a loss of accuracy, but it will be an important capability for us. I'd appreciate any suggestions about fulfilling this requirement.

Thanks in advance.

 

[unclesyd]

If you have time I would attend some of the shows or exhibitions like Westec early next year. i believe that the best way to evaluate a CMM is up close and personal just like buying used equipment as you are the only one that knows the application.
Make sure if you purchase a refurbished one that the machine was returned to OEM specifications including any up grades that may have been missed.

Here is a little more information that might be of help.

http://www.sme.org/srch/search.do?q=cmm&start=1&adv1=&trp=10&advCat=all&st=N&fz=N

 

[HGMorgan]

We have a Mitutoyo CMM 40"(Z) X 48"(Y) X 78"(X).
This is a Inspection Grade CMM certified to .0008 volumetric. Our Metrology Vendor who certifies the CMM says it is one of the most accurate machines in town (Wichita, KS). The software that came with it at first wasn't very user friendly, but a later upgrade works pretty good.

It sounds like you want a Metrology Grade CMM, and several vendors make them (Zeiss used to be the most accurate). They are very pricey.

Most all CMM vendors have software modules that let you buy what you need, I.E.; Gears, Statistics, Best-Fit, etc.
I would look at a machine that runs or is DMIS compatable.

One of the best info sources would be your Metrology Dept or Vendor: what to they use? Which machine they certify is the most accurate, etc.

Refurb vs. New:
A refurb can be just as accurate and fast as a new CMM, but a really good refurb would be almost as much as a new CMM.