Post By L Vanice
Post By David Utidjian
Post By Forrest Addy
M2 blocks (drop) for hand scraper bits?
I have some pieces of M2 tool steel that were tossed in the scrap, maybe 7/8"x2"x3". Anyone try sawing/slitting off 1/8"-ish "slices", and toss them on the surface grinder to clean them up? Everywhere I have looked M2 tool blanks about the size need for scrapers seem kinda pricy.
IME the only way to cut hss not annealed is with an abrasive blade. Would be a PITA. Someone else might know more.
Excellent hand scraper blades can be made from old files. They are similar to 10100 or W-1 tool steel. Easy to anneal, forge, and heat treat with just a torch. Water quench and temper to straw color. Annealed HSS is a pain to heat treat and hardened HSS is a pain to cut up into little slices.
I am sure it would work fine as a scraper tip. But since cast iron is quite abrasive I would prefer carbide and, in fact, that is what I made mine with.
You may be practicing some false economy however... Enco lists 1/8" square by 2-1/2" M2 tool blanks at 95 cents each. Hard to get a cup of coffee that cheap these days. You also have to consider the cost of whatever you are using to slice up those drops. Most likely a far more expensive carbide slitting saw, or diamond, or grinder.
Enco currently lists 1/8" X 1/4" X 1" C2 carbide blanks for $2.19 each or you can get 1/8" X 12" square carbide stock for $18.75 (works out to about $1.60/inch.) Most people I have read or spoken to, amateur and pro, agree that carbide is the best way to go and cheaper because the carbide edge last 5X to 10X as long as a tool steel or HSS scraping edge does between touch ups.
If you want to save even more time and money Enco has 10" "machinist scrapers" for $5 each complete with handle and made of tool steel. I bought a bunch a while back and silver brazed some carbide tips on them.
I found some long spade drills rusting in a bucket. I ground off the tips and silver brazed some carbide tips, cut the shanks convenient lengths, added some comfortable wood handles. I like the flex and I made some a bit narrower for getting in to tight spots.
There are lots of ways to "go cheap" on hand scrapers but the cutting tip is not one of them. This is the 21st century and carbide is cheap and easy to find. You don't have to buy new blanks... I have seen scrapers that have old triangular turning inserts brazed on to the ends.
I would save those M2 drops to make form cutters for the lathe.
Allow me to hijack this thread for a most constructive reason: I wish to save neophytes a hell of a lot of time and work.
HSS is great stuff but cast iron is full of silicon which is like glass. HSS rapidly dulls when used as a scraper tip. HSS is not that much better than a re-purposed file for they are about the same hardness.
Here's the realities of HSS Vs carbide for the business end of scrapers.
The cutting edge is absolutely everything in scraping. It has to be razor keen; that is, the cutting edge has to be the intersection of two mirror surfaces. Lots of guys use re-purposed files, HSS, Starrett stock etc all hand ground or stoned or abrasive sheet lapped but the brutal fact remains: the half life of a steel based scraper used for precision hand scraping on cast iron is about one minute. In one minute you will have to work about twice as hard to remove a given amount of material as when the cutting edge was fresh. After three minutes it's time to re-sharpen. You can run but you cannot hide from that fact. You may think you can go longer between sharpenings but trust me, after three minutes you are past the point of diminishing returns.
OTH C2 carbide rectangles diamond lapped on the faces, silver brazed on the scraper shank, then ground to end radius and edge lapped to near mirror perfection lasts about 50 times longer than any kind of steel - even T-15 the primier hard HSS used for the most abrasion resistant applications. The silky smoothness of the diamond lapped cutting edge, its durability, and its ease of sharpening absolutely swamps steel edges of any kind.
The reason I assert this is hard experience. In early days I labored in my home shop for ten years breaking my heart with slow progress. I had to stop work every two minutes by the clock to touch up my scraper's edge. Eventually reality literally forced me to resort to carbide. Then after I got the technique of edge maintenence down I have been kicking my own butt ever since for wasting ten years of scraping the hard way.
Have I put it strong enough? Carbide because of its hardness is so far superior to carbon steel, tool steel, and HSS as a precision hand scraping edge there is literally no comparison - EXCEPT - on those materials carbide does not work well: soft steel for example.
Here are the equipment essentials for touching up carbide. If you are a good scrounger your can put it together for about $40. Buy new over the counter stuff you could spend $200.
Here is the carbide I prefer: Carbide Rectangular Strips - Rectangular Carbide Blanks | MSCDirect.com
If I haven't totally screwed up this link takes you to MSC import rectangular carbide C2 3/32 x 1/4 x 1 blanks. Work backwards through the MSC menu if you prefer other sizes.
The next item is a DIY diamond lap something like this second picture down: Shop Stuff: Scraping Class
Yes, that's a plain old 1/6 to 1/3 HP general purpose single phase motor. Any similar motor will do but 1750 RPM will be better. The wood base is as crude as it looks, the block used for a tool rest has a 5 degree angle cut on a miter saw. The lap itself is cast iron but any material will work including aluminum. However the softer the material the easier it will ding and gouge. The only requirement is the face has to run pretty true.
Third picture down is a Baldor grinder equipped with a face wheel. This is expensive but a real time saver. A nice to have.
The last item is 1 pc 5 gram Diamond Polishing Lapping Paste Compound Syringes 0.5 to 40 Micron | eBay
This is diamond lapping compound. Pick green 9-12 micron. The colors are an international standard for grit size. Note this is really cheap stuff and won't last very long. Better to buy the good stuff from a lapidary shop or McMaster-Carr. Expect to pay $30 for 5 grans but it's several year's supply.
OK the above is for lapping. Lapping square across raw new carbide scraper tips to a nice end radius will take lots of time but it can be done. A diamond face wheel on a Baldor 500 clone (referred to above) will be a lot quicker but that's major money.
Last edited by Forrest Addy; 06-18-2012 at 02:41 AM.
Looks like I need a little refresher on hardening M2 . I'll stick with A2 and W1, and old files. Which brings up another question, where can one find any kind of file blank?
I tried using some lathe cut-off bits but most of them have a concave side profile that makes them kinda tricky to put a nice radius on it.
I see a few guys mentioning using 1/8" or 1/4" square tool bits, I'm not sure how that works on a scraper, and tricky to get into small spaces.
I have a few carbide bits I ground, while they do last a long, long time, I find myself needing to touch up the scraper when finishing up a working, particularly making half-moons. I have honed the carbide bits with a piece of brass and some green diamond compound, I do prefer to use tool steel blades that I have stone when I'm in various different places and do not have immediate access to my tools. I have thought about making my own little grinding jig though for carbide.
I looked up Anderson's price on replacement blades (A&W Precision Inc. Manufacturers of Anderson Brothers Hand Scrapers and Static Balancing Ways in Rockford, IL) and it's about ten bucks for HSS, forty for carbide.
For Anderson models, are there any big advantages of the tubular vs the clip kind? What are the expert's preferences here, or do all experts make their own scrapers?
As long as I'm asking, what length is preferred? I'm 6'2, with very long arms.
I've been thinking about making a pull type scraper as shown in this video:
Originally Posted by bosleyjr
Le grattage Ó l'Úpaule - YouTube
When I took Forrest's scraping class back in 2007 there were two experts, Forrest and a guy who's name I can't remember at the moment... Forrest is in the neighborhood of 6'2, the other guy about 6'. In the class of about 10 students we ranged from 5'6 to 6'4 (I am 5'9 when I don't slouch.) Skinny and wiry to plump and stocky. Ages mid 30s to mid 60s. Pretty much everyone used the exact same scrapers made from the Enco machinist scrapers with a carbide tip brazed on. Forrest worked with hand scrapers and the Biax. From my limited experience it seems that "whatever works for you" is the rule to follow for size and style of scraper. Scraping can be very tiring work so I would experiment with different styles and lengths to find out what is comfortable to work with before I settled on a particular set of scrapers. I am still very much the novice and I am still figuring out what I like.
Forrest had a whole bunch of different tools for us to try including the flattened tube style you linked to which has a bit of flex in it. We also tried the Biax which is big and heavy but well balanced and remarkably smooth to operate. As I recall the thing I liked about the flattened tube style was the rounded sides. Very comfortable. No reason you can't make whatever tool you use comfy. The key thing is comfort and minimizing fatigue.