Hows My Scraping Looking?

[bkcorwin]

OK, so I bought a camelback straight edge casting that popped up on craigslist. So I figured if I wanted to scrape it I should start learning on something less nice. So I bought this 15 dollar cast iron knee from enco and have been attempting to teach myself to scrape it in. Could someone offer feedback on the progress? I watched rich's scraping dvd and whatever I could find on youtube and kind of just went for it.

 

[Bob Korves]

For a novice it looks just great! Nice even coverage. For a static part that is fixed and does not slide, that piece looks done. Make sure it does not rock when you tap on the corners with it resting on the surface plate. Just looking at the photo, it looks like the high spots are pretty high and the low spots are pretty low, but that depends on the spotting. Try taking some light cuts just on the bright areas in the middle of the darker spots. I like to think of it as trying to cut them in two, leaving two slightly lower spots where there was one before. It also looks like you are cutting a bit too hard on the edges and corners. Just how my eyes see it, and I am not there and I am not any kind of expert. Those import angle blocks make nice practice pieces that are cheap yet quite useful when done. I have scraped them too.

 

[4GSR]

One thing Richard encourages his students to do is set up a tenths reading indicator and sweep the surface and measure the depth of your scrape marks. The non-bearing areas should be about around .0002-.0003 deep. Any deeper than this, your'e scraping too hard, too deep. Like Bob said, try to split those larger bearing spots in half to more bearing point per sq in. Takes lots of practice to get it right. Looks like your on the right path!

 

[bkcorwin]

Thanks everyone. I should post up a new print this evening. I went back and measured the high vs low spots, and I am actually right in line with a couple of tenths variation. I have seen a lot of people use what looks like way too much blue so I have been very cautious about the thickness of the marking fluid on the plate. I think that may be why the spots appear so deep. I also started cutting those spots. It seems like I need to make sure my strokes stay quite short as I try for more PPI

 

[middle.road]

(I'm not looking at scrapping posts, I'm not looking at scrapping posts, I'm not..., ah heck...)
That looks fine. Can I send over my Enco India Blocks - hehe.

...The non-bearing areas should be about around .0002-.0003 deep. Any deeper than this, your'e scraping too hard, too deep. Like Bob said, try to split those larger bearing spots in half to more bearing point per sq in. Takes lots of practice to get it right. Looks like your on the right path!

I like how one misses hints in youtube videos and then I pick up these tidbits in a post and it finally registers in the brain.
I am trying so hard NOT to get bit by the scrapping bug.

 

[Andre]

Looks very nice, however it looks to be like you might be using too much blue. You should be able to see the surface plate under the blued (or, redded? ) surface.

With less blue, you can more easily scrape to higher PPI's.

Are you checking squareness as you go?

 

[Bob Korves]

Thanks everyone. I should post up a new print this evening. I went back and measured the high vs low spots, and I am actually right in line with a couple of tenths variation. I have seen a lot of people use what looks like way too much blue so I have been very cautious about the thickness of the marking fluid on the plate. I think that may be why the spots appear so deep. I also started cutting those spots. It seems like I need to make sure my strokes stay quite short as I try for more PPI

The amount of blue looks just about right to me. As you get closer to finished you want less and less blue on the work. Toward the end it helps to rub on a very thin transparent coat of yellow dye over the whole surface before rubbing the blue on. It gives you better contrast so you can see the blue better.

 

[jjtgrinder]

What kind of scraper are you using and how do you sharpen it? I am also working on learning to scrape.

 

[4GSR]

I use the Sandvik style scraper tha has replaceable blades. I have a 150 grit diamond wheel I shape the cutting edge to. Then I have a slow speed lapping machine with about a 400-600 grit diamond lap I use to get the fine keen edge on it for scraping. Other people like the Anderson Brother's hand scraper. And a number of people make their own scraping tools. Personally I like using the Sandvik style myself. It's all I've ever used for the last 40 something years!

Edit: I notice that there is a thread on a scraping class being held n S. C.. If you have the money to attend, it would be a excellent class to learn "hands on" scraping.

 

[bkcorwin]

Heres the latest updates. I cut the points thinner. I made a lapping plate out of a big piece of aluminum and some diamond paste. I am having a really hard time getting consistent edges. I think I may just spring for the accufinish with the rough wheel and the 600 wheel.