Lapping plates

[Redmech]

What did he use to bond the pennies down to the aluminum?

 

[Hukshawn]

I didn't catch it. But I'm sure an epoxy or super glue would suffice.

What's the advantage of copper for lapping? Anyone?

 

[C-Bag]

I didn't catch it. But I'm sure an epoxy or super glue would suffice.

What's the advantage of copper for lapping? Anyone?

It's all about the plate being able to be "charged" which means the compound is able to embed itself in the plate so the part you are lapping isn't really touching the plate, it's riding on the abrasive compound. Cast iron is also good for this and it's why it's also used and why I went this route. Most of the stuff I do like the surface gage, is hard. The thing about the pennies was you had to use older than a certain date because after that they were just copper coated, and in using the penny you wouldn't have to cross cut the surface.

What I was going to do to cross cut was set up a simple v block piece of wood and like Tom did use a good carbide saw, but on my table saw. Yeah, it would be messy but it would be easier to control than the circular saw he used. I've cut aluminum on my table saw and compound saw, works fine. And now with my HF blade sharpener I can fix if they get dull.

 

[brino]

I never frown at making one yourself, but if you don't have the time, Lee Valley tools has a few lapping plates that are NOT ridiculously expensive.

This one has a 12x4-1/8' surface:
http://www.leevalley.com/en/wood/page.aspx?p=59752&cat=1,43072,59752
This one is 8x3":
http://www.leevalley.com/en/wood/page.aspx?p=69438&cat=1,43072
Either would be big enough for small tools.

They also have some diamond lapping plates and films.
-brino

 

[Mitch Alsup]

I've had an idea. To me, lapping plates seems like a poor man's way to surface grind.

One machines to 0.001
One surface grinds to 0.000,1
One laps to correct surface grind errors.

 

[Hukshawn]

I AM interested in making the plates myself. Food learning experience. But I have been trying to find a place to purchase the grits. Perfect.

 

[ThunderDog]

However. Its leading to soooo many projects.

Hukshawn, this is my life now.

Machining, metrology, etc., it's the ULTIMATE rabbit hole.

 

[Hukshawn]

Yeah well... I picked a terrible hobby to have while working two jobs regularly, a 2 year old at home, and a wife who works sporadic shifts.

 

[Redmech]

Watched Tom’s video. Making fllat lapping 4

He used Loctite 380
And pennies that are 1981 or older, or of course copper washers.

What would the advantage of copper be over using straight aluminum? Both are soft materials. I know the copper sort of becomes loaded with what ever grit you put into it versus cast iron you can clean and go to a different roughness/diamond dust, or at least that’s the way I understood it.

 

[C-Bag]

Watched Tom’s video. Making fllat lapping 4

He used Loctite 380
And pennies that are 1981 or older, or of course copper washers.

What would the advantage of copper be over using straight aluminum? Both are soft materials. I know the copper sort of becomes loaded with what ever grit you put into it versus cast iron you can clean and go to a different roughness/diamond dust, or at least that’s the way I understood it.

If I was like Tom and had several lapping plates and could devote a plate to different compounds I think more about copper. And maybe if I really get into this I can explore that. I don't remember the rational, but AL doesn't seem to be used. There could be a lot of what I call historical engineering(just the way we've always done it). I don't have as much time as I'd like to devote to this circular rabbit hole of metrology>grinding>lapping>metrology and the other, machine scraping. I'm doing it in steps with projects that need to get done like repair and try not to let me OCD get the best of me.