Resusitating Some Chinese Iron

I'm not going to argue over 3 deg. I've always set mine for 5 deg tilt in to the grinding wheel. Of course, back in the day, the only thing I available was some worn out 6" OD diamond grinding wheels that were worn down to the aluminum in places. And I hand ground the radius tilting the hand scraper as needed to get the negative angle needed on the face of the carbide. Scraped a tone of cast iron that way. When I got a T & C grinder, used the same wheel, but had the all angle vise set up to the angle needed.

Boy, we are getting off topic here... IT's all good!!!
 
How far out of whack is my relief angle, I just off hand ground the thing to what a picture looked like, what I have found is all the masters talk about how to do it but never actually show good pictures of the blades up close, in a way that's easy for the super noob to understand what is going on. My blade cuts but I ruined the temper grinding the radius
 
something i tried when i was using a file for a scraper, i'd make the file radius on the end and no relief to the cutting edge.
it cut much better than a relieved blade, but it does need to be resharpened frequently.
it was a little harder to push, but it could remove a lot of metal in a single pass.
 
I'm really enjoying the conversation on sharpening. I have been replacing carpet with a new hard surface floor in one of the bedrooms. I received a brayer, red and blue canode ink, and an Anderson hollow scraper handle with a HSS blade while I was otherwise occupied. I will eventually get a carbide blade, but I need to build my diamond hone first. Is 150rpm too slow?

I need to get the HSS blade profiled and sharpened so I can scrape something. I've seen that 600 grit diamond is fine for carbide, but what grit do I need for final pass on HSS?
 
Don't use diamond on HSS, that is meant to sharpen carbide. They sell CBN wheels for HSS that are specifically for HSS. And 150 RPM is about where you want to be, 350 RPM max. The Glendo units run at about 250 RPM, about a 7:1 ratio with a 1725 RPM motor. My old Lenard Grind O Lap runs at about 200 RPM.
 
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Using diamond on HSS (or any steel) is OK if the process has a low surface speed. Diamond dissolves in HOT steel but cuts COLD steel perfectly well. WHen I say 'hot' I mean as in 'sparks'. If there are no sparks its not going to disolve the diamond.

By the way, scraping with HSS or a file is VERY tedius. You spend 1/4 of your time sharpening or fighting with a blunt edge. Go straight to a fine grained carbide and sharpen every 2-4 hours scraping....
 
I am well aware of the reputation of HSS for being tedious, but then scraping is tedious. I'm not sure that I have the personality of patience to scrape. I could get by lapping off the machining peaks, or even putting the mill back together 'as machined' and have it work. That is essentially what Seig did when they manufactured it. So, if after some practice pieces, it turns out I'm just way too bored to deal with a scraping project, then I won't have wasted my money setting up to scrape with carbide. I am cheap enough that I would kick myself for not getting that co-ax gauge I've been wanting instead. On the other hand, if scraping is cool, I can set up for carbide and relegate my HSS blade to softer metals. Aluminum bronze gibs come to mind.

My suspicions about diamond wheels was that there would be little migration of carbon at low speed, especially with some coolant. Iron has some interesting phase changes as temperature goes up, so figuring solid solubility and doping levels for carbon into iron is way more than I want to deal with. We had books of diffusion graphs back when I still worked in a silicon foundry, so we didn't even go through the pain of calculation then.

I started sharpening my scraper last night. Connelly talks about polishing off the pits on the side of the blade. I didn't understand where the pits came from until I looked at the commercial HSS blade. It looks like it was sand cast. My previous experience with HSS tools were with ground ones. I would have been happy to pay another dollar or two to have gotten a ground blade. I don't have a course bench stone, so I had to order one. Polishing the flats on my Arkansas stones is painful. I am still wondering how fine a grit I need for honing the HSS cutting edge.
 
I got my course/fine india stone yesterday and spent an hour or so working on the flats of the blade. They aren't as nice as I would like, but the pitting is off the cutting edge. A surface grinder would be nice for times like this, so I'll add it to the 'some day' list. I put a 3" radius on the blade and honed a secondary bevel at about 5 degrees. It cuts fingernails. It even cuts cast iron.

So I couldn't resist trying it out. I cleaned up everything on the bench and sqeezed a drop out of the blue canode. Except that the nozzle was clogged. After cleaning a quarter oz of ink off the plate, I was able to spread a thin layer and ink up the block plane. I forgot to take a picture of the first impression, so this is the second.
Plane1.jpg
I'm having trouble controlling the blade, and it is hard to tell just where it is going to cut. I think that a smaller radius would work better, but maybe I just need way more practice. I forgot to stone between impressions for the first few goes. Things started improving when I remembered. This is where I stopped for the night. Contact is growing.
Plane2.jpg
 
I'm hooked on scraping now, it does appear that your cutting edge is not good, looks like it is scratching in a few spots, over in the potd I posted a pic of an initial rough scrape, insane how much better the sandvik carbide blanks are over the file I sharpened, although the radius is huge on them, they need to be shaped. I'll be following you progress.
I seen someone put a mark on the cutting edge so they could have better sight of where it's going to cut.
Maybe you said already but what kind of scraper handle are you using? My sandvik is pretty stiff, I may thin it out so it has a little flex to it.
 
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