Scraping a cast iron surface plate

[Janderso]

Looking good, Braden, looks like you are doing the right thing. Too bad that Richard was forced off this site, he would have had a lot of good advice for you. I am in contact with him, and can refer questions that you may have for him.

Yeah, unfortunately Richard can only hang out on the dark side

 

[Janderso]

Started finish scraping. I’m using yellow acrylic paint diluted in way oil as the highlight. With ten random spots I have an average of 21ppi with a high of 28ppi and a low of 14ppi. The percent of contact is a bit low currently.View attachment 479668View attachment 479669

I did the same thing to mine. I found out it's a bench plate vs. a surface plate.
Do you have the three points on the underside?

 

[Firstram]

Yeah, unfortunately Richard can only hang out on the dark side

The dark side isn't nearly as dark anymore. They may have cleaned house or made some new rules.

 

[Braeden P]

I did the same thing to mine. I found out it's a bench plate vs. a surface plate.
Do you have the three points on the underside?

The manufacturer had machined three of the six bosses higher so it doesn’t need anything to be on three points. Good designing.

 

[Janderso]

The manufacturer had machined three of the six bosses higher so it doesn’t need anything to be on three points. Good designing.

What we found out was a cast iron surface plate has three significant points of contact and the plate itself was much thicker than a bench plate. The pics I found of the surface plate had three reinforced (more mass) points in the casting.
As far as I'm concerned both options are a valuable shop tool.
My bench plate is 18x18" but the plate is only 1/2" thick. and the base has a grid pattern with no three point contact in the design.

Please know, I am just passing on what I learned when I scraped my plate.