Measuring a complex part without a surface plate

[Mayhem]

I often see people using DTIs or DIs to measure parts and they almost always do so with the part being measured and the indicator stand on a surface plate. So, what options are there for those of us without surface plates?

I haven't got a good example in mind right now but I'm thinking of parts where using a mic isn't an option.

[Sunset Machine]

I use a machine table.

[PixMan]

Yeah, use the table from your Kondia. You'll need a good square angle iron, some clamps (I know you've got plenty), a 14mm pin and a long 16mm pin, and perhaps make a custom pin that fits 8.5mm x 10.5mm countebored holes.

For the unknowing, he has to measure the heights and centerlines of the broken feed trip/engagement bracket from his Kondia and the one I made for him because IT DOESN'T FIT. We suspect the print that Kondia sent him wasn't the same part as was on his machine. My gut feeling is that they probably have the correct part sitting on a shelf ready to be shipped, but Kondia doesn't have a clue.

[Mayhem]

I hadn't thought about using the table! I'll have to make up some pins but it shouldn't be too difficult and will be good practice in turning to a tight tolerance.

I wasn't going to say what it was for Ken...

[PixMan]

No worries on that Darren. We both know it was a matter of Kondia having either sent the wrong print for the part or perhaps the head is of a different vintage than the machine's base and associated serial number. We'll sort it out and if they can't supply the correct one I'll gladly make a corrected one. If that happens, it would make a good learning project for the next time you're here.

Or, I can swiftly make a new one now that I know the process, my machine's limitations, have the tooling and found a close-by source for material.

[kenne]

(07-21-2014, 07:22 AM)Mayhem Wrote: I often see people using DTIs or DIs to measure parts and they almost always do so with the part being measured and the indicator stand on a surface plate. So, what options are there for those of us without surface plates?

I haven't got a good example in mind right now but I'm thinking of parts where using a mic isn't an option.

I had a nice surface plate for a long time , but space and money caused me to part with it . I needed the space as it was 4'x4'x8" and weighed a lot more than I could pick up , and someone offered me the right amount of money for it .
Then i needed it the next day (as usual) , So I went to the countertop dealer in town and bought a piece of Granite about 2'x2'x2" and made a stand on wheels for it . It works just as well and cost very little , under $50 , as I remember . It is still in the shop at the test site , I plan to build another soon and take photo's of it this time .

[TomG]

Darren,

You can use any flat surface as a reference for part inspection, but keep in mind that if the base of your height gage or surface gage is sitting on even a small nick or bow in that surface, it may have a significant effect on the accuracy of your measurements. That mill table may seem flat, but compared to a surface plate that is flat to millionths of an inch, it may be more like the Rocky Mountains (or something equivalent down there).

I use a small 12" x 18" granite plate and it serves most of my needs. A plate like that would fit very well in a small suitcase.

Tom

[Sunset Machine]

Yes, stone the table first. I use a small, hard stone and it's easy to find dings and burrs. Some people use a file (ugh). It's not uncommon to use a machine table as a reference surface. Somewhere in Machine Tool Reconditioning is a blurb about making a decision on how many spots to achieve - the question is will the table be used as a reference, or just a clamping surface. Us poorboys do not have to go without.

[Mayhem]

(07-21-2014, 02:15 PM)TomG Wrote: ...I use a small 12" x 18" granite plate and it serves most of my needs. A plate like that would fit very well in a small suitcase.

Its not the size that is the problem it is the weight...

[TomG]

I don't know Darren, some of the luggage my wife has packed had the density of granite.