Scraping in a straight edge

[Richard King 2]

I sent you an Invoice for a HSB stick. I sell sticks and DVD's. on eBay, I am giving to a Hobby Machinist discount of about $20.00 off. I see you just paid it. I'll mail it today. Thanks It shows handscraping, Biax Power scraping and 1/2 moon oil pocket flaking. It's 60 minutes long.

 

[rabler]

@Richard King 2
As I've said, I'd love to be able to take one of your classes. But I deal with Crohn's disease, and traveling usually leads to ugly problems. I've paid your invoice and look forward to getting the copy of your scraping video. I appreciate your advice here and hope other's can benefit too.

Here's some of my rough scraping. Measuring the depth with an indicator shows I'm getting around .0005 depth.



Here's two consecutive bluings, fairly heavy, with dykem. Between these I step scraped from the left edge, two steps. Trying to pivot the face down toward the area not making contact. If you click these thumbnails open you can tell that the left edge just below center is still not making contact. (It still shows milling marks in the small area outlined in the second picture below. It hinges wide, only about two inches in from either end, so it's not convex.


Here's a little bit of light off the surface that gives some indication of the scraping. I'm scraping small scrapes near the front edge, so that appears to me more like a finished scraping. The central portion appears to have gotten over smoothed from several consecutive stonings. I think one mistake I made when milling this was to skim it just enough to clean off the surface, when I should have gone another .050 or so to get further from the surface hardening from cooling?


I'm guessing that in another roughing pass I'll have contact more or less over the full surface and be ready to move on to scraping for more PPI.

 

[Richard King 2]

Your scrape marks look to narrow. Almost looks like a blade corner scratch. But I see you have rounded your corners off a lot. Another way to get narrow scrapes is if your holding the back of the handle to high and your in the small radius of the blade. The Japanese video shows the right width cut and how close the handle is to the way. I would say 10 to 20 degrees is good. Also try to scrape cross hatch or X X scrapes. Stand at 45 degrees to the way, scrape from that position and then move you body so you scrape 90 degree's from the last position.

When I machined ways I used a fly cutter on my last pass to get a smooth finish. Another thing you need to do is when you blue up the first time and along one edge you see a "ridge" or it is hitting along the edge all the way along the way about 1/16 or 1/8" in. and it is hitting on the other surfaces of the way. Is to remove the ridge and don't scrape the rest of the way as you missed that ridge or on ways you didn't machine and just scraped, those are unworn original surfaces. There is a good example of this on a Lathe. On South Bend lathes it is called the "South-bend Ridge"

I say to measure the ridge and then file or scrape it off or if you scrape it and the rest of the blued ways, your changing the geometry and when you go to match fit it to the opposite way it runs against you have to change the original way angle to fit together. If I were you I would stop working on your machine and practice on a piece of scrap iron or on your straight edge. I am going to show you something else you need to do in the following post.

 

[rabler]

If I were you I would stop working on your machine and practice on a piece of scrap iron or on your straight edge.

All of this is on a straight edge, none of it is on a machine's ways. ??

 

[Richard King 2]

At 26.40 minutes he discovers the parallel has a hump in it. Rabler your ways look humped. You can use a gage block sideways to hinge it on the on the narrow width. In the beginning he shows how I taught him to use the Canode Yellow and Bluing. It's a good You Tube show.

Here is another show he does too:

 

[Richard King 2]

All of this is on a straight edge, none of it is on a machine's ways. ??

Your making some mistakes and I think you need to practice on something that isn't as important of the machine ways. so you don't make it worse. Less work on the good machine ways. How are you going to check the parallelism of the 2 ways?

 

[rabler]

Your making some mistakes and I think you need to practice on something that isn't as important of the machine ways. so you don't make it worse. Less work on the good machine ways. How are you going to check the parallelism of the 2 ways?

I am not scraping a machine. I don't understand where you got this idea. I am only scraping a straight edge. The pictures above are all of a straight edge cast by Dennis Foster (dgfoster on another forum). I realize you're trying to help but I don't know how to make this any more clear.

 

[Richard King 2]

You need to learn to not over stone it too. After you scrape it, clean off the old blue and then run your fingers over to feel the burrs, then stone it. I use a medium grit Indian stone. I press down and wipe the surface with the clean stone one time and then feel for the burrs, if they still are there, then stone again. Over stoning will eliminate the burr and the high spots. If you blue upand you se a number of - - thing marks those are burrs and you need to stone a bit more. I only wet stone it about every 5th stoning. Don't wet stone it every-time as that will increase the the percentage. You want 40 to 60% not 90 to 100%. I showed the % chart I give to my students in their orkbook.

Also here is another of my students and he shows some good drawing.
He shows a Renz scraper, but he now sold his Renz and has a BIAX.

 

[Richard King 2]

@Richard King 2
As I've said, I'd love to be able to take one of your classes. But I deal with Crohn's disease, and traveling usually leads to ugly problems. I've paid your invoice and look forward to getting the copy of your scraping video. I appreciate your advice here and hope other's can benefit too.

Here's some of my rough scraping. Measuring the depth with an indicator shows I'm getting around .0005 depth.

View attachment 425473

Here's two consecutive bluings, fairly heavy, with dykem. Between these I step scraped from the left edge, two steps. Trying to pivot the face down toward the area not making contact. If you click these thumbnails open you can tell that the left edge just below center is still not making contact. (It still shows milling marks in the small area outlined in the second picture below. It hinges wide, only about two inches in from either end, so it's not convex.

View attachment 425474View attachment 425475
Here's a little bit of light off the surface that gives some indication of the scraping. I'm scraping small scrapes near the front edge, so that appears to me more like a finished scraping. The central portion appears to have gotten over smoothed from several consecutive stonings. I think one mistake I made when milling this was to skim it just enough to clean off the surface, when I should have gone another .050 or so to get further from the surface hardening from cooling?
View attachment 425476

I'm guessing that in another roughing pass I'll have contact more or less over the full surface and be ready to move on to scraping for more PPI.

Oops. it looks like a dovetail way. oops...

 

[Richard King 2]

Be back later. I am going to go Vote absentee as I will be teaching a class in Oklahoma next week. Stefan's show above is a good one, showing his hand scraper like the one I use. With a pad on the end plus he talks about a HSS blade vs a Carbide blade as we discussed earlier in the thread.

I put your HSB stick in the envelope and will mail it when I go out. Flat rate 2 day - you should get it on Sat or Monday. Thanks.