CMM help -

[BallisticFab]

Hello, we're looking for a CMM (computerized measuring machine) that we can use to plot points on large objects such as bumpers and body lines on cars and trucks. All I can find are table CMMs, but we're looking for the boom style. Does anyone have any info on these? Thanks -Jeff

[Born2Fly490]

Faro International makes such products, as do their competitors. Try a web search, there are many companies, and must be some used stuff out there.

[Jim McCafferty]

Like Born2Fly490 stated do a web search for Portable CMM or CMM arms. The main two are FARO and ROMMER, but there are others. Both of these also offer laser add-on for doing rev. eng. or problem solving. Do your homework and find the one that will do what you need it to do, in a user friendly way.

[stuxstu]

There are essentially four types of CMMs (coordinate measuring machine). Bridge (granite table) Gantry (like and overhead crane), Cantilever (horizontal) and Arm. Arms are manual, which means you are doing the work. If this is in a production aspect or you are going to be plotting hundreds of points, then you should seriously consider a CNC (computer numeric control) or automatic CMM. Take the tightest tolerance and divide by 10. That will tell you the accuracy of the CMM you require.

Software is another thing to consider. Everybody pitches that their software is the best... Truth be told, only if you are at the higher end is there a real difference.

Be careful of "used" CMMs. Most of the time they are junk and will cost you a lot of money down the line.

The main CMM companies are Mitutoyo, Zeiss, Hexagon (Brown&Sharpe, Sheffield, Starrett, CE Johansson, Romer) and Faro.

One note, if you talk to a Hexagon rep, the answer is "no" PC-DMIS is not going to be the standard CMM software, ever.

I won't tell you which of the CMM companies I work for, but I have 18 years experience repairing, calibrating and sell CMMs and metrology products. I like Mitutoyo, Zeiss and Faro, when it comes to the products. All three are reliable machines from good manufacturers. I am not a B&S fan... the have a yearly licensing fee. Don't pay it and you won't get service, until you pay the back fee’s.

Is it obvious I don't work for B&S.

Good luck and make sure you know what your needs are. Accuracy, future usage, and speed are the true factors of a CMM purchase. For you will most likely never need a high-end software package.

Also, don't use 3rd party calibration companies, only Sheffield has them.

http://www.zeiss.com
http://www.hexagon.us
http://www.faro.com
http://www.mitutoyo.com

I found this site because I have Google searches on Metrology related information… CMM is one of them.

[gilchapa]

We have a Faro, they work great for that kind of work.

[John_B]

BallisticFab,

Don't be dissuaded from looking at used CMM's, as it sounds like some folks experiences are from the other side of the coin. When a business man is trying to justify the expense of a CMM, a used unit that has been verified as funtional and sophisticated enough to suit the purpose is often easier to live with than the high lease payment or outright purchase of a new machine. A fixed bed type of machine that is large enough to measure a bumber and bigger parts will easily cost $200 - and that machine is stuck in one spot.

The Mitutoyo, Ziess, and B&S machines are very expensive if you are not intending to use them almost constantly.

As Gilchapa mentions the Faro arm units work great. My shop has a Romer brand arm, with the sliding rail mount (add another 9' to range in one direction!) and this is very well suited to your task. I have used this in pulling surfaces off of fiberglass boats for a few years now,and I have measured boats setting at the dock and in the plant where they are built - which is awful hard to compete with if you have a shop-installed bed type machine. Accuracy can be lower, but I also early on paid for higher precision measurement using more accurate machines and found that when creating point clouds off large parts, atleast for our use, too fine a precision level only complicates things. I've always wound up averaging the surfaces anyway, and too much data makes this a much longer process.

There are also some newer types of systems that use a handheld contact "probe" and communicate position in a variety of ways (laser interferometry I believe). These could really work well for you.

Main thing is to make sure the machine you chose to spend a bundle on will grow with your needs and not completely empty to budget.

Rgds, JB

[John_B]

oops, meant to type $200k...

[BallisticFab]

Thanks for the replys, I had found all of the bed type machines during my searching, but was looking for the arm type. The handheld version sounds perfect for our use. Thanks guys, I have some reading to do now! -Jeff