Sharpening Anderson Bros Carbide Scraper Blade

So I have the smallest width Anderson Bros carbide scraper (the solid shank and not the tube) which comes with a flat square edge. I've used it like that successfully for removing rust, etc. But now its time for some actual scraping practice. I would like to put the radius and 5 deg negative angle on it.

My thoughts are to get a green wheel for my grinder and set the tool rest to -5 deg or so and simply hand-grind the radius. I recall lapping the edge of a HSS scraper on a cast iron rotating disk charged with diamond lapping paste....does the carbide edge need this treatment as well? I don't yet own a green wheel, so I'm not sure whether the finish from the wheel will be ready to go...my guess is its not as I see 120 grit as the finest wheel I can get from McMaster Carr, but I wanted to confirm that.

Thanks in advance.

Part of the scraping process done right is bright "scrapes" and these come from mirror finished edges achieved by the green diamond compound. Your green wheel will come no where near this finish, won't last long at all and will never be able to make "bright" scrapes. You can expect dull gray ones.

All has to do with quality of light reflection.

Green wheel strictly for rough shaping

matt_isserstedt said:

So I have the smallest width Anderson Bros carbide scraper (the solid shank and not the tube) which comes with a flat square edge. I've used it like that successfully for removing rust, etc. But now its time for some actual scraping practice. I would like to put the radius and 5 deg negative angle on it.

My thoughts are to get a green wheel for my grinder and set the tool rest to -5 deg or so and simply hand-grind the radius. I recall lapping the edge of a HSS scraper on a cast iron rotating disk charged with diamond lapping paste....does the carbide edge need this treatment as well? I don't yet own a green wheel, so I'm not sure whether the finish from the wheel will be ready to go...my guess is its not as I see 120 grit as the finest wheel I can get from McMaster Carr, but I wanted to confirm that.

Thanks in advance.

Click to expand...

good luck with the green wheel. how thick is the blank?

i use this to rough out the shape:

Of course you can do it yourself with a lot of work and the right equipment.

Maybe better by years and tens of thousands of dollars to find a real saw or tool shop that does sharpening.

They should be able to take it down to 600 grit by stages with diamond wheels.

Matt-

It will be difficult to shape an edge with a green wheel that does not have micro fracturing back into the "sharp" corner far enough that lapping it out becomes a time consuming exercise. If possible, acquire a diamond face wheel for your surface grinder or other spindle, in the 180 - 220 grit range. Density not critical though i tend to find 100% most economical given I use diamond wheels for other grinding apps on the surface grinders and T & C. You can probably find an adequate diamond wheel for what a green face wheel costs these days anyway.

That said, there is a way to proceed with the green wheel.
60 or 80 is fine enough. Shape the end of the scraper freehand as you describe. At this point don't even try to make a bevel. Try to make the end square from face to face, with whatever arc you decide is good for you across the width. Alternate which face is up as the arc is shaped, so you get a good perspective on where square is in section.

Now use a *good* pocket diamond hone, 220, with some oil, and polish and refine the edge. At this point, you will be "trying to keep the edge section square, without dubbing the opposite face", as you work the arc'd edge of both faces alternately. This will lead to a ~3° bevel Be sure the faces of the carbide are flat.

Now if you have a surface grinder you can make some CI, mild steel, or copper laps by rolling in red diamond paste, and one with green diamond paste. Use them with oil. I find mild steel (A36 in my case) works about as well as copper. My laps are about 2" x 3" which is a comfortable size to palm, and an easy size to make.

Polish the faces of the carbide with the red lap, then work the bevel. Again, the idea is to just clear the opposite face. You will get a ~3 - 5° bevel without trying. If you try, it can easily become greater.

After the red, lap with the green.

If you don't want to make a good set of hand laps, or are more interested in seeing progress first time around, you can use MDF (fine dense particle board) as the lap substrate. It will be more difficult to keep the lap flat over time, and there is less conservation of the lapping compound due to that, but they will sharpen agressively so long as the surface is not continued in use when it starts to dub the scraper edges.

When using carbide, including or perhaps especially when using the Biax; I use a good 220 commercial hand hone followed by the red and green shop made hand laps, to save running back and forth to a pedestal grinder (e.g.) when working on a machine. (I stamp an "R" or a "G" on the back and file the raised metal before surface grinding the working face) After there is a shaped edge on a scraper, so long as the carbide is not a great thick lump (which is counter productive anyway) it is easy to keep the edge shaped up and honed just with hand laps. IME & IMO, it is considerably faster, too.

FWIW, I only use the smallest size scraper for small slides and dovetails. One has the top beveled for clearance in dovetails, and only has one thin working edge.

smt

Thanks all, I do intend this small scraper for the inner slide work. I have a Sandvik 30mm scraper which comes with awesome mirror finished insert-blades, albeit at some extra cost. Dapra sells insert replacements, even with 4 edges over the original Sandvik 2, on the same blank. However that would mean a new scraper body, and I already have everything in the Anderson except the radiused and beveled edge.

Stephen, the hand lap you describe, is it basically a round/rectangular puck with a grooved/cross-hatched surface? Or do you just grind it dead flat?

Any idea what would happen if the diamond-charged rotating lap-wheel (from HSS) was used on the shaped carbide edge?

Buy one of these, make a hub and put it on your cheapo bench grinder. This is what I use to shape carbide blades, then a diamond lap to put a mirror edge on them.

4" inch 100mm THK Diamond Coated Concave Grit 600 Grinding Wheel Bench Grinder | eBay

Now the best bit is, if you buy two but use just one, it'll wear until there's very little diamond left and put progressively finer and finer finishes on your blade, approaching the quality of the lap but without having to charge it. This is time to mount the unused one on the other end of the grinder and have a roughing and a finishing wheel. Still can't beat the lap but it's not too shabby at all.

If you want to quit screwing around and start scraping, buy an Accu-finish. It doesn't matter what you cobbled together, once you use an Accu-Finish all previous sharpening stuff will go in your junk pile.

I have used a 80grit green wheel to rough out the shape of a scraper and then lapped it using a 1X6" aluminum lap on a bench grinder charged charged with green diamond paste. Main reason I used the green wheel is I already had it. (Be careful of the dust from a green wheel as it is nastier than ordinary grinding wheel dust. I wear a good respirator) I do not doubt that a diamond wheel would be a lot nicer. Just saying a green wheel is a workable solution for the time-being.

It did not take very long to curve the leading edge to a radius of around 60mm though there is a range of curves suggested as has been pointed out in other thread related to this. Lapping should only take a few minutes on the wheel. Do also pay attention to the bottom surface as your edge can only be as good as the least smooth surface. It should be good and flat or very close to flat. Again it is not hard to shine it up using a diamond bench stone and then for the best edge possible (for me) I used a piece of aluminum charged with 1 micron diamond past to finish up the bevel and the bottom. Again, the whole process can be completed in a half hour. Inspect your edge with the best magnifier you have---one of those cheap pocket microscopes will tell you a lot about your edge. Pocket Microscope 45x Magnification with Dual LED Lamp | 360-500

Once you are there, only occasional touch-ups will be needed. I think I touch-up about every half hour or hour when scraping cast iron. Never timed it though. When you have a good edge you will be able to raise a fair bit of shaving with each scrape and you will soon recognize when the scraper is settling in and cutting without forcing it. That alone is part of the pleasure of scraping for me.

Denis

gbent said:

If you want to quit screwing around and start scraping, buy an Accu-finish. It doesn't matter what you cobbled together, once you use an Accu-Finish all previous sharpening stuff will go in your junk pile.

Click to expand...

Once I got my Leonard cool-grind oscillating grinder, I stopped using my Baldor carbide grinder. Once I got my Accu-Finish, I stopped using the Leonard. I have several assorted grit diamond wheels for the Accu-Finish, and they are easy to change, so I seldom use the green wheel.

I resharpen my scrapers frequently while working, so there is no way I would send them out for sharpening. I have a Sandvik scraper with the carbide insert, and, with the Accu-Finish, one insert will last a lifetime.

Larry

Stephen, the hand lap you describe, is it basically a round/rectangular puck with a grooved/cross-hatched surface? Or do you just grind it dead flat?

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Matt- just rectangles 2" x 3", ground flat on one side, with the grit rolled in with a stick that has a ballbearing on one end. Very similar to what people use to roll the paste into powered round laps.
The commercial course grit (220, e.g.) hand lap/"sharpening stone" does the bulk of the material removal and shaping; the homemade fine laps polish.

Not sure why, but I would stick to CI for a powered lap. And of course if you have it, it may or may not be "better" for a hand lap. The idea for a hand lap is a substrate soft and gummy enough to embed the little diamond particles. Al is probably good as someone else mentioned. I thought copper would be ideal, but do not find it superior to the mild A36 steel. Do use lube. Olive oil would be traditional, but i just give a squirt with whatever oily product is near by at the time and place of use. Cutting oil, spindle oil, mineral oil from the woodworking honing stones, etc.

smt

Caveat: everything I know about scraping I learned in two days from Forrest and Don at the most recent PNW scraping class.
That said, Forrest showed us how to make a simple cast iron lap like this one http://www.practicalmachinist.com/vb/general-archive/sharpening-carbide-scraper-blades-79788/

I made one, and it works great to keep the edge honed once you have the basic curve in place.

There is a good response to carbide scraper lapping in Richard King's scraping jamboree thread.

Start looking around post #73

http://www.practicalmachinist.com/vb/general/scraping-jamboree-nw-2014-a-275498/index3.html

The others are SO right....

The accu-finish is THE item.... Good wheels, nice settable table, what's not to like?

The finish is extremely good, and it shows in the scraping job. Recommended.

I originally used hand held diamond hones, but while they worked, they were a pain and a nuisance, took a longer time, and obviously were not nearly as consistent.

Here's from a previous rant on the topic of sharpening scrapers:

Most scraping we home shop types get into is on cast iron and there I've found the best iincluded edge angle to be 90 to 100 degrees. With this angle double ground you can scrape with both sides of the scraper.

The best scraping edge is one that's dead keen; one that has an edge comprised of two mirror smooth surfaces intersecting at a cutting edge. There is no way a keen edge like this can be obtained with a coarse grinding wheel. A grinding wheel is used to shape the scraping edge and a hone or lap is used to maintain its keen edge.

Here's a bald statement: carbide cannot be sharpened to a keen edge by any abrasive media but diamond. It may be worn away with green silicon carbide and appear sharp but magnification of the cutting edge will show it as having an appearance of a broken stone with micro-cracks leading some distance back into the body of the carbide. So resign yourself to the expense of a plated diamond face wheel for the initial shaping of your carbide scrapers.

If you're patient, those cheap Harbor Freight diamond hand stones work well for shaping carbide. Carbide has a low energy of rupture and diamond will plain eat it up unlike most any other abrasive which simple skates off. Build a little wood fixture and you can do as nice a job shaping a carbide scraper as you can with a fancy diamond face wheel grinder. It will just take longer.

Carbide may be lapped with most any metal wheel configured to suit your face wheel grinder. Make the lap of any convenient metal that does not rust. Brass, copper, aluminum; whatever will hold diamond.

A 1/4 HP 1750 RPM cheapo motor mounted on a hunk of plywood is a hell of a start. Install the lap on the motor shaft dial in and mark the face and OD error. Remove the lap and chuck it on the lathe. Using the error readings, dial in the face and OD and take a cut to remove the error. Make the back face parallel to it to perfect intrinsic balance. Re-install. If the error is less than 0.003" use it. here's a picture:

Shop Stuff: Scraping Class (Second imaqage dorn)

Apply diamond "paste" (It's lapping compound guys! Come on!) roll it into the metal with a ball bearing rolling in a slotted handle. Diamond is to most metals as metal chips are to bar soap.

Fab up a rest at your favorite lapping angle. 3 to 5 degrees works for me. Lap the cutting edges of your scrapers to mirror bright surfaces.

HSS may be ground with any good aluminum oxide wheel. It may be honed with most any aluminum oxide slip stone or hard Arkansas. However do not grind HSS with diamond. Diamond and any iron alloy is like Superman and Kryptonite.

For what its worth. Carbide scrapers outlasts HSS by 50 to 1 in cast iron. I get about an hour’s tine scraping with carbide and about a minute with HSS before I have to touch up the cutting edge. Yes, you can scrape longer but sooner or later your arms feel like they're going to fall off and you're making rub marks in the work not cutting actual chips.

A scraper used for precision scraping has an end radius. I prefer a radius about like a coffee can lid for most work. The finer the scraping - the more points per square inch - the smaller the radius. I got a rough formua if anyone is interested.

Finally, scraping is a means of controlled stock removal just like any machining operation. Don't just rub off the blue. Make. Chips. They should look like coffee grounds when rough scraping and pepper when you're finishing.

Matt I will be bringing my 20 + year Accu-Finish 1 grinder used by hundreds if not 1000's of students over the years to the Kalamazoo Scraping class and you can use it and see what it's like. You can screw around making one if you have the time and want to hassle with the compounds., The One Forrest shows you how to make works good as one of the Nowata OK class students (sorry forgot your handle again, and we just talked, sorry) had one he made and it worked super. I have had other students recently make them from engraving plates purchased on Ebay and putting them in the lathe and they swear by them..cost them under $50,00...as the other guy said...check out the Jamboree thread. I was told that a used Accufinish sold last week on Ebay for $354.00 I think. Matt your coming to the MI class next month aren't you?

There are lots of options now-a-days....make them or order them...

I will be will be Priority mailing the DVD's to the students tomorrow and in it I show the Accu-finish 1. I'm down in MO at my lake place recuperating from a job I just did in Joplin. Those emergency jobs are getting harder and harder to scrape..... Rich

PS: found this on You-Tube shows it...but this is a newer model 2. but about the same. https://www.youtube.com/watch?v=CG--HJ6FGD4

A bit off subject, but I saw something pretty cool last week while on the Saddle / Cross-slide repair. The machine had a long skinny gib and we needed to scrape the Rulon we had just installed. I had one student who was a combo machinist maintenance man to make a gib holder...I left mine at home and it's pretty easy to make one....he came up with these clamp screws and he put them on his Bridgeport table diagonally It worked slick as hell. I plan on buying a set or see if I can buy at least 2 of them.

I was hoping to take some pictures on that job, but the plant had so many rules it made your head spin. I had to first watch a "Safety DVD" and sign a confidentially agreement, wear a hard hat, steel toed shoes, safety glasses 100% of the time accept breaks. No knifes on property unless it was a special approved one (small 1" blade) No soda or food in the shop, no camera's, no guns on the property, had to park your car facing out in the parking lot, etc. etc. Here s a link to these Mini-Mite Clamps. They are on a cam. I bet they work slick on clamping on the sides of parts too. Fixturing Clamp Sets | MSCDirect.com

johnoder said:

Part of the scraping process done right is bright "scrapes" and these come from mirror finished edges achieved by the green diamond compound. Your green wheel will come no where near this finish, won't last long at all and will never be able to make "bright" scrapes. You can expect dull gray ones.

All has to do with quality of light reflection.

Green wheel strictly for rough shaping

Click to expand...

John I have never heard it described like this and hope you will like the look of the straight-edge we will be scraping for you in the MI class. I will be using a BIAX 7ELM and the small drawn back to using it, it has small chatter marks in the scrape marks and I consider this "done right . I suppose I could hand scrape the final couple of passes by hand if you would prefer to remove the chatter. To me it doesn't affect the use of the Straight-Edge. But it might cost you a bit more, time is money you know.....lol Rich

Richard, the "bright scrapes" John refers to is a by-product of the keen-ness of the scraping edge. Its handsome effect is secondary to seeking an efficient aggressive cutting edge. I regard the flash adsparkle of the scraped surface as indicative of the condition of the scraper's edge. When the sparkle fades it's probably time to touch up the scraper. It's more reliable than noting physical effort to acheive a unit of progress. Your muscles become accustomed to the increasing effort and you may scrape beyond time te sharpen. Noobs whose skills have yet to develop are particularly vulnerable to sweating through their shirts before it dawns on them to sharpen their scrapers. The sparkle of the scraped surface is right there to see; if it fades to gray... OTH, maybe a kitchen timer.

You can't always count on "flash and sparkle." Different cast iron alloys when scraped may produce a brigher or duller appearance with the same technique and equipment. Look back over the area recently scraped and eyeball the difference.

Don and I supply our students with scrapers whose end radius is ground on a 220 grit diamond. Sometime in the first hour or so, it's time to resharpen. About this time Don or I take station on the diamond lap for show and tell. Each one or two get a few minues of instruction as they lap their end raddii. There are often audible exclamations ("Wow! This is like night and day," was my favorite) over the agressiveness and efficiency of a dead keen scraping edge Vs one ground on a 220 grit diamond face wheel. It drives home the lesson ragarding keeping the scraper properly sharpened.

I know you, Richard, prefer the Glendo and the Accu-Finish. Both produce keen edges, and you have spoken well of the diamond lap I prefer. I've never had the opportunity to test which produces the better scraping edge under impartial hands; the Glendo, the Accu-Finish, or my budget-driven lap. Does a 600 grit finish or a lap finish make a difference? Probably nothing significant but the best edge conveniently attainable is what really matters.

Adding: When I short stroke scrape (make that past tense, I can no longer scrape efficienty because of eye and balance problems) I noticed a little "chatter" (looked more like ripple to me) but as long as I moved right along so no two strokes were in the same spot, chatter was never a problem.

In 1985 or so at a class in PSNS I learned from Richard King a "float and tap" (my term, I think) method when finish power scraping. Hover the running scraper over the work and tap it on the blue spots: cut a trough right out of the middle of them little blue suckers with a single stroke. A little practice leads you to two or three taps (spots) a second. You can scoot right along. Three taps a second times eight spots per square inch works out to 6 - 7 minutes per square foot.

Figure the way area of the machine and all the funny inside corners, edges, holes, oil grooves - Oh! My stars and garters! It doesn't bear thinking about!

Nah! Get in the zone. Do the work and it will get done quicker than you think in spite of ornerous complications and dire calculations. Precison scraping is boreing but requires attention so quality doesn't suffer.

It's like driving a car: a perfect recipe for the "Zone" where the subconscious (superior at task-minding) takes over so the drifty, fickle conscious mind is free to wander. "Zen" is another way to look at it.

I sharpen on diamond wheels in an Agathon grinder, 15 micron to finish (about 600 grit). If I'm doing final scraping that will be the remaining finish I might use a 9 micron wheel (about 1200 grit). It does produce a nicer finish; but the 15 micron sharpened scrapers hold up very well in the work leading up to the final passes.