My mini repeat-o-meter

[Peter.]

so what about the angular movement? is the forward foot flat?

Yes all the feet are flat Angular movement is unimortant because 1. The gauge directly reads the vertical movement of the front foot and 2. It's a comparator so even if there is a tiny error it's unimportant, it's comparative results that you look for.

[Paul Alciatore]

Your second link does not work. I assume that you kept your hand on the repeat-o-meter for 15 or 20 minutes while not moving it and the meter either did not move or just moved a little.

I have to say that if at least two different manufacturers of these devices both use handles to minimize the effects of body heat, then it is probably a very good idea. I can easily see the rear section bowing from heat at the top and the would push the probe end down. And the reverse would occur when the heat source (hand) is removed.

I think I would even use wood or plastic studs to attach them to the body of the repeat-o-meter.

Repeat-o-meter in action.

https://www.dropbox.com/s/i5l51b8qjg...meter.mp4?dl=0

The comments about hand heat afffecting the reading made me wonder about it so I made this 3 minute video - speeded up x8:

https://www.dropbox.com/s/zbiymvzmqm...0heat.mp4?dl=0

[Peter.]

I don't know how it got deleted Paul, but I have restored it now. Must have been a slip of the keyboard.

Half a micron in 3 minutes of solid gripping doesn't fill me with dread but the most important thing is it swung the wrong way for it to be heat input - I think it was just my arm getting tired. You can affect the reading by varying the pressure whch I think is likely part of the reason for the spindly handle on the factory ones - to stop you resting on the tool. Either way, it's a comparator not so just like clocking in a part in the chuck you read the difference not the absolute value. It still works exactly the same.

Anyway, didn't you guys notice I was wearing a glove when I was using it?

[Paul Alciatore]

I did notice the glove. And I find it puzzling that it went down instead of up.

You said it is made from a slab of CI. I wonder if there could be some internal stresses that cause it to move in an unexpected direction with a moderate application of heat.

[JRouche]

repeat-o-meter

Are you guys still repeatometering? Cool..

Wasnt that thing I showed you guys the kind of a repeated kind of meter you needed? Three nice drop indicators.

I figured out the granite plate after messing with it. Was to synch them in, sorta calibrating them. Nice granite block fyi.

Three point all already calibrated on a nice lil granite surface plate. That happens to come from some place that does that lol Granite cutting board would work well as a working plate.

So that three prong re-peat-o meter? LOL.. No,,,, It is some kind of devise. I am still looking JR

[dian]

Yes all the feet are flat Angular movement is unimortant because 1. The gauge directly reads the vertical movement of the front foot and 2. It's a comparator so even if there is a tiny error it's unimportant, it's comparative results that you look for.

why look for comparative results? you want to know how much the plate is off, no? of course the error is small, but its there.

[Peter.]

why look for comparative results? you want to know how much the plate is off, no? of course the error is small, but its there.

You don't have much choice really. The whole of the device sits on the plate so all you can do is compare the height of one bit to another. If you wanted absolute measurements the body would have to stand on a known good flat surface and the reading end on the surface being measured.

[JoeLee]

Well thank you.

Yes the shoe falls under it's own weight until it closes the gap both directions. It actually has a little 'down' spring caused I think by the clamping of the blade.

I think I will put in those flutes just to save it slipping from my hand, thanks for the good idea.

I forgot to say that I had to surface grind a spacer for the gap in order to grind the four feet all on the same plane. With the spacer in there and the part inverted on the mag chuck, the weight of the shoe was enough to keep the whole lot flat.

Very nice work and some clever ideas that you've incorporated into it.

Any thoughts of some sort of a locking devise to secure the two halves together so the shoe doesn't drop when you pick it up??

I was thinking a long screw that would go straight down through the top and into the shoe.
Thread straight through the top and into the top of the shoe so the threads line up. The screw would prevent the shoe from dropping, or moving up when your handling it. When you set it on the surface plate remove the screw. Good safety feature.

How about a finish for it?? a nice black wrinkle finish would look professional.

JL........

[Peter.]

Repeat-o-meter in action.

https://www.dropbox.com/s/i5l51b8qjg...meter.mp4?dl=0

Just to follow this up, I made a hardened roller, re-purposed an iron plate for a lapping plate, got some diamond dust and lapped that knackered old plate (from 45secs in the above video) flat. Pics show lapping progress butnot the finished article there were a few more rounds after the last pic.







https://www.dropbox.com/s/r5n3akvad9...%2001.mp4?dl=0

[dian]

i wonder if you could see any difference if you map it out with a (sturdier) surface gage.

[Peter.]

i wonder if could see any difference if you map it out with a (sturdier) surface gage.

Can't see why it would. If anything I could do with a gauge with better resolution but you can extrapolate half-marks on it easily enough. If I had one crticism it's the narrowness of it - it could do with being a little more stable on it's feet and sometimes wants to tip when swiping sideways especially if the plate surface is a bit grabby. I made this one small for a purpose though and I will as I said make a larger one, for larger plates.

Anyway, now that I have got the surface of this plate flat locally and globally to (the equivalent of) grade AA I am going to work on my much larger one. That one will be a challenge with a small lap and also given that if you draw a line across the diagonal one half is grade A flat and the other has a mountain range along one edge.

[Peter.]

This 24" square plate needs a bit of work...