# Ghetto surface gauge



## Janderso (Aug 7, 2021)

I didn’t own a simple surface gauge. I’ve seen some YouTube videos where they have a simple Noga articulating arm mounted on a flat block.
Well, I had a cheap surface gauge that was awful. I found it wasn’t flat, it rocked a few thousands
I lapped the base with one of my new DIY lapping plates.
It doesn’t rock anymore and it hinges correctly.


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## rabler (Aug 7, 2021)

I think you've hit the true point of being a machinist, you make the tools to make the tools to make the ...   

Honestly, I'm impressed with your work!


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## Bi11Hudson (Aug 7, 2021)

I like the way you think, Sir. *Take what you got and make what you need*.  What else needs saying?


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## Janderso (Aug 7, 2021)

Thanks for the confidence.
What I didn’t say was I drilled and reamed the hole oversized to .3135.
The Noga shaft is .3135.
I placed the Noga in the freezer and the steel base in an oven at 325.
After about 20 minutes, they are now one. They aren’t coming apart.
I was thinking about a set screw but I really don’t think it’s necessary.


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## Janderso (Aug 7, 2021)

Not to beat a dead horse, I wanted this base to look like it was lapped.
I brought out the diamond paste and lapped for a few minutes.
Kingsford lighter fluid and 5 micron paste.
I was also frustrated as I was finding movement. About .0005”
I wiped the surface plate with my hand and the base, I slid it on the plate and the movement I was detecting was gone. It must have been dust. Have you noticed you can clean a plate, wait a minute, slide your hand and feel grit?
Where the heck is it coming from?
Also, the base would lift the lap off the table. It rings, wrings, to the surface plate as well. This is fun!
Don Bailey alway says, wipe and slide. I think he may be on to something.


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## projectnut (Aug 8, 2021)

Nice work.  That looks as nice as (actually better than) the Starrett ones I have.  I was cleaning one up a couple weeks ago and noticed they are not identical.  One looks like yours with 2 pins, the other has 4 pins


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## Richard King 2 (Aug 8, 2021)

Jeff who else taught you about wiping with you hand? hmmm?   Please explain to the members what "hinging the part" means?   Who taught you about hinging?   You wrote about "ringing" what does that mean?  Can you explain why machine way surfaces are not lapped?  Or why can't you just surface grind both sides of  machine ways, or where a saddle runs against a bed way.  Wouldn't lapping make a perfect fit?   

To the readers. Where does it (dirt) come from?  Next time your in a room and sunshine is shining in a window, look into it and look at all dust particles floating in the air.   If you have a dry clean surface, wipe it clean as good as you can with a red rag and then wipe it with your hands and see if you can feel and particles on the surface.  Jeff your doing a fine job, thanks for sharing what others have taught you, and pass it on!


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## Janderso (Aug 8, 2021)

Gee thanks Richard.
I could say, “If you want the answers to these questions and more, just take Richard King’s scraping class”
I learned lots of valuable skills during a week long course on scraping, we touched on machine tool rebuilding, alignment and a load of other good stuff.

”Hinging” a part is one way to help to determine if the part is flat. The part should swivel 30% of the way in from each end.
Lapping would make a perfect fit but it would not be good if the parts are intended to slide against each other.
Scraping introduces load bearing points and oil pockets. The high points carry the load and the low points hold oil. This allows the sliding parts to glide on a film of oil greatly increasing the life of the components.

Ringing or sticking, occurs when both parts are so flat there is a tendency to stick together.

The pic on the left is a scraped surface, the pic on the right shows a scraped angle plate and a surface ground plate.
It’s pretty clear that the scraped surface would be a better surface for a machine tool way. If the mating upper part is scraped and flaked, there would be a greater chance of improved lubrication.

Cheers,
Jeff


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