Vintage Cast iron surface plate, is it worth the effort?

[Janderso]

The plate is hinging perfectly. I’ve used .0015 feeler gauges to make sure I’m not high in the center.
After 2 hours of scraping and printing, I feel very close.
The blueing is coming out much better. Maybe a few more dive bombs on the high points.

 

[ddickey]

Is it on three points? If not is not a surface plate but a bench plate. Could be why is was blanchard ground and not scraped in.

 

[Janderso]

Is it on three points? If not is not a surface plate but a bench plate. Could be why is was blanchard ground and not scraped in.

Well done!!
I didn't know there was such a thing as a bench plate.
No, there are not three points of contact.
Well, I have made my bench plate more accurate!!
Considering it's a bench plate, I can quit while I'm ahead

 

[Janderso]

Is it on three points? If not is not a surface plate but a bench plate. Could be why is was blanchard ground and not scraped in.

What would one do with a bench plate? Back in the day?
It would make a great sanding plate. You know, tape or stick emory/sand paper

 

[Janderso]

What a small world! Did the person that gave it to you say anything about how he got it? Maybe from the Concord flea market about 35 years ago?

I need more please.
I got it from a 90 year old machinist up in Lake Almanor.
I bought my B&S Micromaster from him. He threw it in. I also got a Rhodes shaper and a Baldor tool room grinder.

 

[matthewsx]

I have a small cast iron lapping plate, I expect your bench plate could be used for same. Or, layout, especially when you wanted to use magnets to hold stuff down.

John

 

[Janderso]

Is it on three points? If not is not a surface plate but a bench plate. Could be why is was blanchard ground and not scraped in.

Interesting, there are no company logos or marks of any kind. There is “LP1” on the underside in the casting. That’s it.
It also has the two bosses on the sides usually for pivot points.
Absent are the three points as Mr. Ddickey pointed out.

 

[ddickey]

On the Busch Precision website they state their ground bench plates are flat within .0005" Pretty darn good I think.
Their scraped cast iron surface plates are stated to be within .0002".

 

[hudstr]

I have a 18" x 15" that also has "LP1" on the bottom. I tried looking it up but the only results I got back were old listings and sales for similar plates. It has 6 contact feet and its top surface thickness is thinner than the other cast iron surface plates I have. As for bench plate vs surface plate it seems surface plates have thicker top surfaces. However I just saw a small plate branded with Metro that must have been 1 1/2" thick everywhere but it had 4 feet, one for each corner.

 

[Janderso]

I have a 18" x 15" that also has "LP1" on the bottom. I tried looking it up but the only results I got back were old listings and sales for similar plates. It has 6 contact feet and its top surface thickness is thinner than the other cast iron surface plates I have. As for bench plate vs surface plate it seems surface plates have thicker top surfaces. However I just saw a small plate branded with Metro that must have been 1 1/2" thick everywhere but it had 4 feet, one for each corner.
View attachment 466257

Interesting. =LP1
Yeah, good point, this one has 1/2" thick plate. Pretty thin.
The flats on the bottom must be machined for the three points of presure.