Scraping a v-way without a relief groove

Hi Bob, What Robin does in this short video would have to be a similar hand movement to what we were taught but he is taking a very light cut. I saw Robin's video regarding the level restoration when it was published. He is a talented man without a doubt. Using just the hands would take weeks to move any amount of material such as what is found on a machine sent for rebuilding. Hence the use of the hip to push the tool. What Robin says about little to no burs left is the reason we cut using the "comma shape" cuts. Hard to explain but it is a combination of pushing forward with the hip and adding pressure with the forward hand then backing off the pressure and rolling the blade a bit as the cut is completed. Wish I could make a video but just too many back operations to make that a practical thing. (I'm fused with screws rods and what looks like Toyota parts from L3 to the pelvis, LOL) Lifting and twisting are things not on the allowed activity list)
 
Another help in reaching into the corners of dovetails is to bevel off the corners of the scraper insert to thin the edge at the corners. the corners must also be slightly radiused to prevent scoring when using the corner to reach into the dovetail; I keep one insert for this task; of course, it makes one side of the insert less usable for regular flat scraping.
 
Go to you tube and search "suburban tool rebuilding" In that show the scraper is scraping the comma technique. I have never heard it called that way. I use the term Moore Method or hook scrape. They also highlight 3 points, 2 color scraping, rubbing or bluing up. If you look at the lathe saddle you can see they relieved the corners of a box way. I did not link the show as Nelson told us not to. So I reference the show.

I was taught to push and lift the scraper and others were taught to hook scrape. My depth averages .0004" deep as the deeper the scrape mark the longer it wears. We call it "scraping a bearing" its a flat bearing, round bearings have balls that contact and we have high spots..

I'll keep looking for more photo's. Rich
 
Pictures of a flat straight groove cut in with what looks like a planner. There are all types of relief grooves. No special way, no special degree. Just cut in relief.
 
Richard: much more helpful. If you do add more pictures, could you show the tool you use to scrape into an oblique angle? Looking for size and geometry. If someone else has pics of their scrapers, I would also enjoy seeing what has worked for them. I have made two scraping tools so far, and as a result of those experiences I am cautious of making a scraper with a thin face. The rounded corners I think I understand. I Just don’t get how to avoid damaging one face or the other as the two faces of the dovetail are dressed (when a relief is not present).
 
I have a picture somewhere of the blade, but I have thousands of pictures. Look at your Connelly book pages 58, 59 and 60 and you will get the point (pun intended) The blade I would pick to scrape the groove on your power hack saw would be 3/4" wide carbide and it can be an insert or brazed on or just a HSS blade. I would grind the tip to a 5 deg. negative rake and a 90 mm / 3 1/2 " radius tip. Then on your grinder or lapper I would grind down the top outside corners of the insert at a 45 to 60 deg. Most Sanvik or Biax inserts are appox 1/16 thick so you grind the corner so it is approx. 1/64 thick at the corners tip. If I" am scraping a small dovetail like found on a Hardinge cross-slide I would use a 5/8" wide blade or insert. Grinding the tip completely from side to side a 45 deg and leaving a 1/64 thickness. You can only use one side of the blade. Next time im in the shop I will pull a couple of my blades to show you.

It isn't the difficult thing to do your making this. Many just use a regular blade and roll up the blade so it scrapes the groove on the outside radius of the blade and don't chamfer the corners of the bottom vertex of the dovetail triangle.
 
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