Need help purchasing a Digital Borematic gage (Mitutoyo was suggested)

[Sue]

I'm not sure this is the correct place to post this question, but here goes...........

We have a customer that would like us to check their parts with a digital Borematic gage (Mitutoyo was suggested). From what I've been able to glean on Google, this gage is a bit expensive for us to purchase when we would only be using it for this part.

Can anyone advise an alternative gage or method for measuring a bore other than the Comtor gage?

Thanks,
Sue

[Al Rosen]

In Reply to Parent Post by Sue

I'm not sure this is the correct place to post this question, but here goes...........

We have a customer that would like us to check their parts with a digital Borematic gage (Mitutoyo was suggested). From what I've been able to glean on Google, this gage is a bit expensive for us to purchase when we would only be using it for this part.

Can anyone advise an alternative gage or method for measuring a bore other than the Comtor gage?

Thanks,
Sue

you didn't mention the range or depth, but some suggestions:

1. Try finding a used one on e-bay and use the internet to search for an auction or company closing.
2. Try fowler, they may have a less expensive alternative or again use google to search on the internet using "digital bore gage".

[Wes Bucey]

Another important factor is "how many pieces - per hour, day, week, etc.?"
Other factors which come into play:

• nominal bore size and depth,
• tolerances
• access on the workpiece

If the number of pieces is small, you might consider farming the measurement out to a company with the proper instrument.

Are they asking you to use that particular gage so you can download the data readings directly to SPC software via wire? Interesting and clever if they are. If so, part of the scenario (possibly money saving) is uploading the hard data and SPC data directly to the customer [even in real time], eliminating paper copies tucked into the packing box - just use serialized barcoded label. If you can use the bore gage for other bores, too, it might justify the cost of a new one. (When life hands you lemons . . .)

[Ron Rompen]

Is this a new requirement for an existing part? Or is it something that is coming out in APQP for a new part?

In either case, you may want to pass on the cost of the fixturing/gauging to the customer, either in whole or in part.

I have had some success in doing this in the past, especially when a customer comes up with a new requirement (not related to a detected failure in my process).

There are a number of ways to measure a bore, depending on what your customer needs and what you are capable of doing. If you would like to discuss with me further, feel free to PM me.

[Sue]

Al, I haven't been able to find this gage on ebay - the range needed is 568-978. There was one with a larger range there however, so I will keep looking. Have added it to my "Favorites"

Ron, in a way this is a new requirement. We made a very similar part for this company for a number of years, but they recently made a design change. It was through the PPAP and control plan that they realized we use a plug gage for the ID, which we do for most parts since the ID is a tool dimension. I rather doubt they will absorb the cost at this stage, but it is a consideration if they insist on it.

Wes, this is in part their explanation for the use of a "digital" gage - nothing to do with uploading the SPC data. We don't have the capability to do that regardless.


The reason I suggested digital is resolution. I have never seen an analog metric gage with 0.001mm resolution; the most I have seen is 0.01mm. A vernier IntraMic probably has more, but they are difficult to use and read, have limited range, and are not really inexpensive.


The reason resolution is important is: if you take your natural process variation on the bore, which on your submitted capability study looks like 0.033mm at the most, an analog gage would give you three different measurements. Three possible values is not enough; a rule of thumb is to measure with a gage that has resolution at least 1/10th of your process variation. The reason is that the data most of interest in a study is in the tails of the distribution, which would not be visible in a data set with only three classes; and even the mean is hard to estimate with only three classes of data. The gage I suggested has 0.001mm resolution (by the way, the discrimination of a gage will be less than the resolution) which would give 30 possible different measurements which would work well sorted into 10 classes for analysis. I did notice that the capability study you submitted has only three classes of data, although I only got the graph, so I don’t know what your data resolution was.


The reason I suggested that particular gage is: flexibility: it has a one inch range, and more heads can be purchased to extend that; ease of use: the way the three contacts work make it difficult to get a bad measurement; and considering that it comes with the set rings, it really isn’t all that expensive.

Thanks for the help you've provided,
Sue

[Al Rosen]

In Reply to Parent Post by Sue

Al, I haven't been able to find this gage on ebay - the range needed is 568-978. There was one with a larger range there however, so I will keep looking. Have added it to my "Favorites"

Did you leave out a decimalpoint somewhere?

[Sue]

Hi Al,

It is listed as 568 series:
568-978 25.4-50.8mm (1-2")
Our spec for this part is 1.4911/1.4971.

Sue

[Wes Bucey]

Is this the picture? Neat deal. The set is about $3,000 USD, BEFORE adding the SPC hot wire.

Comment:
If I was willing to spend this much, I'd consider an air gage