Repeat Reading Gage - DIYSwede's "Cheap-O-Meter"

[tonyfoale]

Johan,

I have just seen this. Great job.
your frying pan may tell you that a giant sphere is actually flat, but I doubt that would be a problem with a surface plate though. Assuming that a plate was made to its grade tolerances then any future lack of flatness will likely be a result of wear (some users take less care than I do) and your frying pan should work pretty good for that.

I too, have considered making a 'repeat o meter' but I know that I have no use for it. My plate is a grade A inspection quality and I know that it is not worn. I use it only for measuring and never for lapping.

[DIYSwede]

Thanks Tony for pitching in (in both threads).
My only problem (sic!) was that I found a plate with totally unknown pedigree,
having the oddest of dimensions (nowhere else to be found, even less bought),
no maker's brand and not even glue residue from any calibration sticker.

So I just winged together a few DIYed measuring tools to get me in the ball park,
and checked for magnitude of its deviations, that would be plenty good for me.

Then I kludged the Cheap-O-Meter together on a zero budget from scrap pieces,
really just for the heck of it, as I got PO of the Rahn prize tag.
I still think that the Rahn is a ghastly over-prized, badly designed and poorly machined piece of tooling,
but then that's just me, and I guess I won't use the C-O-M very often in eventual coming years...

I'd personally never use my (freebie) lab grade plate for anything but measuring and dying in stuff for scraping.
I use plate glass and cast iron (found, scraped old lab stands*) for lapping.

Cheers

Johan

A few 7 x 10" by 3/4" thick and free lab foot stands is enough for my small needs.

[DIYSwede]

-Ah, heck - why not delve further down into the rabbit hole of Surface Plate Inspection & Lapping?
20 minutes of "Full frontal nerdity"...
Courtesy of Adam Booth (Abom79)

[Toolmaker51]

-Ah, heck - why not delve further down into the rabbit hole of Surface Plate Inspection & Lapping?
20 minutes of "Full frontal nerdity"...
Courtesy of Adam Booth (Abom79)

As one with a bit of granite acreage to get checked.....OK! Here I go >>>> v,

[tonyfoale]

Through the years I've used this motto professionally to rather successfully un-promote my career:
-"People without humor shan't be taken seriously - but be seen as pure threats!"

Cheers
Johan, ( "Ex-Whiz Kid, previously "young and talented")

I have never seen the humourless as a threat, I do feel sorry for them though.

Cheers
Tony (Left it too late to become a Whiz Kid, previously "young only"

[tonyfoale]

This must be my favourite HMT tool. Somehow I have avoided putting a copy into metal, although that has long been my intent. However a new machine tool project is underway and might just be the motivation to get up off my ass and do something.

[DIYSwede]

Thanks, Tony for your reply.
I haven't been around here much lately, as I've finally retired from work last year and having a few other projects/ duties to sort out.
I've got a few HMT projects on the back burner, which will turn up here eventually.
Just a few personal considerations/ experiences from my build:
1) Keep the probe arm as long as possible (minimizing angular error), and the base footprint length/ width as small as practical for your purpose.
2) My feet have probably a bit too big dia, smaller would be preferred just to smooth out the surface noise.
3) The differential screw makes adjustments much more easy and repeatable/ consistent than a coarse thread could ever do.
4) Use a handle of low thermal conductivity.

Keep up the good work and good luck!
Cheers & ATB
Johan

[tonyfoale]

Thanks, Tony for your reply.
I haven't been around here much lately, as I've finally retired from work last year and having a few other projects/ duties to sort out.
I've got a few HMT projects on the back burner, which will turn up here eventually.
Just a few personal considerations/ experiences from my build:
1) Keep the probe arm as long as possible (minimizing angular error), and the base footprint length/ width as small as practical for your purpose.
2) My feet have probably a bit too big dia, smaller would be preferred just to smooth out the surface noise.
3) The differential screw makes adjustments much more easy and repeatable/ consistent than a coarse thread could ever do.
4) Use a handle of low thermal conductivity.

Keep up the good work and good luck!
Cheers & ATB
Johan

Retired? That will eat into your free time. One problem with retirement is that one usually becomes old before experiencing it.
Thanks for the tips. Nos. 3 & 4 were on my list, 1 Maybe?, 2 No I would not have considered that.