Old School Scraper Sharpening

Richard King,
Your scraping class in MN this fall was great!
Thank you for allowing us to use your Glendo for sharpening.
I think you observed that it might possible to fab a scraper sharpener using a diamond wheel.

Question:
Historically what was used to sharpen scrapers before diamond wheels?
Were simple fixed stones used, with possibly a jig, such as is sometimes used to hold wood plane cutters?
An Arkansas stone would make sense for HSS, but not carbide.
I'm wondering if a diamond flat stone would work until I get my diamond wheel fab done.

Suggestions?


Thank you,
Daryl
MN

Daryl there so many threads on this already and I bet it you did a search above you could find the answer. But a simple answer is before Carbide blades were used, we used HHS blades and sharpened them on Medium Indian Stones that were either in a block of wood nailed to the bench or in a vise. It seemed as if we were sharpening 50% of the time and when it would not hold a sharp edge we would have to hardened it again. In recent years I use the Glendo and prior to the Glendo I used a Baldor double end tilting table grinder. I have not used HHS in 30 years I'm guessing. Tried it in classes for the fun of it, but not professionally.

Forrest have a good design home made unit and Matt in the Bridgeport forum made one as he has shown it on here someplace. Bob the Host of the KC class bought a cheap wood workers grinder and mounted cheap EBa engraving wheels he paid around 65.00 for a set of 3 different grades..... I have seen guys use diamond stones and they swore by them until they tried a slow moving lapper like the ones mentioned above. To me using some hand lap is a waste of time. You can pull out your Connelly book and in the chapters on hand-scraping and flaking you can see more info on hand sharpening. One great thing about this forum that the others don't have is the search library so before asking check it out. Rich

Think a diamond flat stone would take so much time to take perhaps .005 from carbide blade that would not be a good idea. Setting up a diamond wheel fab? Good to indicate in a diamond wheel for radial or face use with setting to an indicator (a shim under can protect the point.) with a paper shimming behind the flat wheel or snug and tap in with soft wood to get wheel .002 or so at start is good. Makes the grind better and at end of wheel they go out all the way around so not wasting wheel.
(tapping to the wood setting on the wheel..not tapping to the wheel and with the nut only snug so the wheel can move with light tapping so not harming the wheel. you would only tap a radial (OD) wheel with being sure there was clearance to the mount so the wheel cold move the needed way.. face wheel needs shimming not tapping.

A decent bench grinder could be used with radial or face wheel.. one could scrape in the wheel hub flange face for near zero run-out. If it was a loose hub a location mark would make sure it would be set to be set in same place at wheel installation..

Good to have a wet ability for grinding carbide with diamond.. use washing soda and water if needing a simple (home made) coolant. Wheel should be 120 grit or better ,320 is very good finish or 500 for mirror but slow stock removal..

Uglydog said:

Richard King,
<>
I'm wondering if a diamond flat stone would work until I get my diamond wheel fab done.

Suggestions?


Thank you,
Daryl
MN

Click to expand...

Would a diamond flat stone work to sharpen a scraper? Sure if you are willing to work. It can be done using the same motions that would be used to sharpen a HSS scraper on a conventional stone. But it may be somewhat slow. If a person used a green wheel on a simple bench grinder as a preliminary to remove the bulk of carbide---to establish the nose radius and maybe even get close to the roughly 100 degree angle on the vertical portion of the cutting edge, the rest could be finished in a half hour or so on a couple fo diamond stones--a fairly coarse (80-120) and moderately fine (400) stone would likely produce a very serviceable edge. I did sharpen a couple of carbide scrapers that way and finished the edge with a very simple flat aluminum lap charged with green diamond paste to produce a very sharp scraper edge. It is just a slower process than it is to use a powered device. This subject of sharpening was well discussed here in the past on a few threads. Here, for example, is a recent one: http://www.practicalmachinist.com/v...bros-carbide-scraper-blade-283498/index2.html however that one does not deal so much with non-powered methods. Here is another. http://www.practicalmachinist.com/v...you-using-sharpen-your-scraping-tools-286839/ As you will see, different folks use different methods to get to the same end result. The nice thing is you get to choose which one fits you personal inclinations, budget, and time constraints.

With respect to searching PM for relevant posts, I think Google or similar search engines work a lot better than the built-in search feature on PM. So I would just plug "Carbide scraper sharpening practicalmachinist" into google and you will get several hits. Slight variations will produce more/different hits.

Denis

Keep an eye on ebay for accu finish grinders, I picked up a series 1 and a series 2, and only paid $250 a piece for them. The series 2 also came with four wheels from 600 up to 3000 grit, but I find the 600 works well and rarely change it out. I understand it's unlikely deals like this will be available at any given time, I watched for about four months before I bought my two, patience pays off. I would never use anything else after having these.

In my experience if using conventional push scrapers, the issue wouldn't be so much the rate of removal, as quite coarse diamond bench stones are available, it would be in maintaining the correct angles while freehand sharpening the scraper.

It's also important to differentiate between sharpening to shape the carbide, normally a one-off task for a new blade, and honing to maintain an edge. I've never used a slow-speed diamond hone such as those above, but have no doubt they would be the best way to go. Nevertheless it's possible to get quite acceptable results from just facing up a disk of aluminium, cast iron, etc to fit your bench grinder, and impregnate that with diamond paste to hone your scrapers while using them. Make up a suitable rest, which can be as simple as a block of wood cut to the appropriate angle. If using a high speed grinder I find it best to run the carbide lengthwise while honing as the edges are easily chipped by any runout in the disk.

The point being that while many of these devices are definitely desirable, they're not essential to be able to start scraping, and the results can be every bit as accurate, though they may take much longer to get there. As Richard pointed out, until "relatively" recently, carbide wasn't used at all, and even high carbon steel can be used as a scraper if that's all you have. I don't think too many people would be wishing to go back to that era, as the carbide holds up so much longer, but you certainly don't HAVE to use it if you don't have any available for one reason or another.

This is a lapper I rigged up, it works pretty good.

The lowest tech carbide scraper sharpening aid

If a person were to try sharpening a hand scraper using a diamond bench stone or two and a diamond lap I would think progress might be more sure and faster if a simple sharpening jig were used after the bulk of the carbide was removed using a green wheel. This jig may seem almost laughable. But, I have found in sharpening plane irons and wood working chisels that I get an edge on the tool much quicker and more reliably if I have a jig to guide my my efforts and keep them on track. I know there are plenty of people who seem to do fine without a jig for various sharpening chores. It is just my preference to use one when possible. Same is true for a manually sharpening a carbide scraper. So I took a couple of pics of the simplest possible jig that might help someone if they were just trying to get a scraper sharpened without going to the trouble of making or buying a faster and more convenient motor driven lapping device. I think the pics are self-explanatory. I would slide the nose of the scraper along the long axis of the 400 grit diamond stone photographed keeping the distance from the upright board to the nose of the scraper the same throughout the length of each sharpening stroke. Shown with the last pic is a little diamond-paste-charged aluminum lap which is surprisingly effective at manually putting the final super sharp edge on a lap. obviously both the flat surface of the blade and the nose surface have to be sharpened using the diamond stones and, if desired, lapped with the aluminum lap.

I am not suggesting such a rig for the long term. Rather just as a means to get a sharp scraper for the guy who wants to just try scraping for the first time.

Periodically examining the edge being produced under high magnification (45X or so) will really provide a lot of useful information as you proceed to sharpen. The resulting edge should bite into your thumbnail at a very low angle--a few degrees. It should look shiny under magnification and should have no roll-off of the edge. Flat shiny nose should meet flat shiny broad bottom surface. The edge should easily shave little feathery spirals of thumbnail off when lightly drug over the nail.

Obviously this is not the fastest way to get to an edge, but it will help you get there. And the edge can be touched up to full sharpness in less than a minute as you scrape using the aluminum (or steel or iron) lap as shown. You should only have to do that every 30 to 60 minutes of vigorous hand scraping on cast iron.

Denis

Dennis, that is how I sharpen my scrapers. I did not think of the jig though, I sharpen mine freehand.

Thanks for posting pics!

ideally you want the sharpening grain perpendicular to edge. Using a stone, the manual way is scraper hand held straight up and down, drawn toward you over the stone so yo are sharpening the end (the sides having already been lapped)

you want to lap with fine diamond paste, 10-12 micron, and really a cast iron spinning disk is just about a requirement as you need to do this often.

here's mine made from a bench grinder. The wheels are on diy taper mounts, and the taper mounts were turned in situ after loctiting on the rotor so its very smooth with minimal vibration

Mcgyver how fast does the grinding wheel turn on your rig?

If you want the best that will last for years. I have the Glendo Accu-Finish Series 1 - 5" wheel and haven't done a thing to it 20 years accept replaced the wheels that are used 10 time more then the average user. I will bring mine with to the Houston Scraping class Swatkins is hosting. Bob the KC host made one out of a Griz VS wood lathe tool lapper he bought for $100.00 new and 5 diamond engraving wheels he bought on E-B. for $65.00 You can see it in the 1st picture of post 31 and if you look close on the right side or end is the thin engrving wheel he put on the end and the round barstock rest he used. http://www.practicalmachinist.com/v...eminar-texas-spring-2015-a-292947/index2.html

Accu-Finish® Machines | Accu-Finish
or you can buy a wheel
Diamond Wheels | Accu-Finish

Bottom line is there are several ways to skin a cat. Rich

swatkins said:

Mcgyver how fast does the grinding wheel turn on your rig?

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whatever a standard grinder is, 3400? I'll check next time i'm there. btw, that speed is fine with diamond and carbide. The slow speed diamond cutters are for hss or tool steel where high speed = high temp and the reputed absorption of the carbon (diamond) into the steel

Mcgyver said:

whatever a standard grinder is, 3400? I'll check next time i'm there. btw, that speed is fine with diamond and carbide. The slow speed diamond cutters are for hss or tool steel where high speed = high temp and the reputed absorption of the carbon (diamond) into the steel

Click to expand...

Mcgyver's grinder looks nice and probably works great, but he must not be like his TV show namesake and never tried a slow speed lapper like the ones everyone else uses, as the slow speed works super for sharpening carbide scraper blades, carbide tool bits, inserts touch up as it cuts like crazy. I have 3 wheels I use 260 for roughing, 600 for finish and 1200 for super sharp finish like a mirror. I also have dedicated blades at different radius's so all I need to use is the 1200 to touch up when scraping. One BIG advantage is on a tilt table like the Glendo you can sharpen different rakes to scrape iron, steel, Turcite in a flash. For years all I used was the 260 and 600, but after trying a 1200 grit after recommendations on here, I finish with it.

I have used high speed double end Baldor type 3400 rmp grinders with 300 grit and 600 grit wheels and they work great but heat up the carbide and you need to use a coolant or you can't hold the blade. With my slow Glendo the blade never gets hot. I can change the wheels in 20 seconds. On the home made grinder Bob made it took maybe 40 seconds to change the wheels as it had a wing nut that held on the wheel. It works great for sharpening my HSS spoon scrapers too by flipping it backwards and the wheel faces up at 90 deg's. if I had any HSS scraper blade I suppose it would work on them too with no heat. Rich

Now I know we have discussed what works best a few times, but as an alternative for the guys who dont need to sharpen scrapers every day would this tool work ok? It is variable speed and is something you could use everyday for other jobs but with the plated wheel it might be ok for scrapers also. Anyway it is just an idea and of course it doesnt really follow the question of "old school".

Tradesman DC Bench-Top Variable Speed Tool Grinder

Charles

Wow on edit I guess I should have looked down the page at the price....!

Richard King said:

Mcgyver's grinder looks nice and probably works great, but he must not be like his TV show namesake and never tried a slow speed lapper like the ones everyone else uses, as the slow speed works super for sharpening carbide scraper blades, carbide tool bits, inserts touch up as it cuts like crazy.

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The speed or heat is not an issue, that cutting speed is fine for diamond and carbide. Agreed you'd want a slow one for tool or hss

The heat may not effect the carbide but it does to my fingers....

I once saw a bench grinder with a small pulley second motor mounted behind.. the second motor would belt over the left grinding wheel to give a very slow RPM for finishing with the right side wheel of the bench grinder..

Scraper sharpening is high art! It has taken me many tens of hours to come to peace with what works for me, and I believe that what works is highly personal and is dependent upon individual technique.

The one rule that I have found to hold true is that the greater the difference between the hardness of the scraper material and the material being scraped the more obtuse (> 90°) the blade wants to be sharpened.

A couple simple things I've found about the Biax:

1) The ideal radius for the blade is defined by the holder. The pin in the slot defines the correct radius. (When you use a Biax blade holder as a sharpening fixture).


iu


2) The Biax will fill itself with tiny conductive scraper shavings until it destroys its filter capacitors and speed regulator. Mine did anyway. Periodic maintenance and cleaning is probably a good idea.

.

Richard King said:

The heat may not effect the carbide but it does to my fingers....

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lol, have you tried it, ie lapping at this speed vs the grinding you mentioned?

I'm sharpening bits of carbide silver soldered onto the scraping shaft, not enough heat gets to the shaft to really even feel it so it just hasn't been an issue. Are you referring to holding onto small bits of carbide directly? The sides of the carbide I lap to a mirror on a lapping plate with diamond before silver soldering on to the shaft, and yes, I would not want hold on to them on the lap I built above!