Hi guys, so I've been practicing some scraping and I've run into a few issues. Ive watched about 10 youtube videos on how to scrape so I do have a bit of understanding on what's going on.
Here's what I'm working with:
My scraper is a wood chisel, yes I know I should spring for a carbide scraper with a 60 degree radius. I was thinking I could grind the radius into my wood chisel and use that.
I'm scraping on steel since I don't have cast iron right now.
So first I did a roughing pass going in opposite ways at 45 degrees
Then I put the steel part in my surface plate and ran a dial test indicator. Appears the top half of the steel plate is about two thousandths high compared to the bottom half.
So I did another roughing pass on just the high area and brought the height from two thousandths to one thousandths.
Next I spread some prussian blue on my surface plate using a speedball roller, making sure not to use too much.
Then I slowly applied the steel plate on to my surface plate and used the hinge technique trying to see where the rotation was taking place.
But I noticed that the prussian blue would leave steaks of dye on my surface plate and the print on my part looked smugged.
Second what was more confusing the blue dye was inking the low side of my part the part that is one thousandth lower. I thought the dye went to the high spots.
So I cleaned the surface plate and my part with denatured alcohol to try again to get a good print.
This time I ran the part in a figure eight pattern with no pressure and light touch.
I noticed less streaking this time but again it was the low spots the were covered with dye and the high spots that were empty.
Only thing I can think of is either my surface plate is not flat or that some how the part is tilting and the low side is getting blued.
Here's what I'm working with:
My scraper is a wood chisel, yes I know I should spring for a carbide scraper with a 60 degree radius. I was thinking I could grind the radius into my wood chisel and use that.
I'm scraping on steel since I don't have cast iron right now.
So first I did a roughing pass going in opposite ways at 45 degrees
Then I put the steel part in my surface plate and ran a dial test indicator. Appears the top half of the steel plate is about two thousandths high compared to the bottom half.
So I did another roughing pass on just the high area and brought the height from two thousandths to one thousandths.
Next I spread some prussian blue on my surface plate using a speedball roller, making sure not to use too much.
Then I slowly applied the steel plate on to my surface plate and used the hinge technique trying to see where the rotation was taking place.
But I noticed that the prussian blue would leave steaks of dye on my surface plate and the print on my part looked smugged.
Second what was more confusing the blue dye was inking the low side of my part the part that is one thousandth lower. I thought the dye went to the high spots.
So I cleaned the surface plate and my part with denatured alcohol to try again to get a good print.
This time I ran the part in a figure eight pattern with no pressure and light touch.
I noticed less streaking this time but again it was the low spots the were covered with dye and the high spots that were empty.
Only thing I can think of is either my surface plate is not flat or that some how the part is tilting and the low side is getting blued.