cost of hand scraping exercise

The 3 cornered scraper is used more for bearings or bur removal than for flat scraping. You want an end-cutting scraper, available in steel or carbide edge. Looks like a flat file, with the end ground to a very slight arc at 90 degrees or close to it. Some users make them from old files.

For sharpening, you'll need a bench grinder and an oilstone.

John Martin

Three cornered scrapers are used for scraping inside diameters, such as bushings, and for deburring. They are a favorite amongst machinists. The type scraper you're looking for would be a long, straight device (about 18" long or so), which could be either carbide or HSS on the end. The end, which does the scraping, has a slight curvature along its edge. Scrapers have a nice palm type handle on the opposite end.

Scraping, while possible on steel, is mostly accomplished on gray cast iron, which is the material of choice for machine tool construction because of its relatively low cost, but more importantly, because of its characteristics, which lend themselves extremely well to machine tools. Cast gray iron is a super bearing surface, and has very good damping characteristics, preventing, or minimizing chatter (vibration).

There are good books available that cover scraping. I'd suggest you do some research and invest in one, which would enlighten you as to procedures and proper equipment. You'll discover that a surface plate is essential for flat surfaces, a level alone won't hack it.

Scraping is not really the domain of the typical machinist. I worked in machine shops for almost my entire adult life and saw scraping done only once, that not by a machinist, but by a maintenance man, who restored a small Gorton mill which would otherwise had been worthless. With new screws and nuts, the machine turned out beautifully and was extremely accurate.

The home shop type seems to enjoy getting involved in scraping, which is likely a good idea because old worn machines can be refurbished enough to offer further life, a good thing for those of us on limited budgets.

Good luck with your venture!

Harold

This is a great book. Its subject is how to recondition machines. It assumes the reader already knows how to hand srape in a surface - very little in it on the actual scraping process.

Karl

Check out -

I bought my stuff directly from Dapra.

Steve.

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A 3 corner scraper is used to scrape or deburr internal holes (diameters). It is not used to scrape flat surfaces. For scraping flat surfaces, you need something that looks more like a paint scraper, except that the handle will be stronger and longer, and the cutter blade will be high speed steel or a tungsten carbide insert.

You can grind the end of an old file to the correct profile to make a cheap scraper, though the high carbon steel won't hold up as well as a carbide insert, and the file body may be too brittle to withstand the required pressure. You could also make a holder for a carbide insert, though that would require a bit more work. You can buy commercial scrapers, though it is a bit of a specialized tool and you may have to search a bit to find one.

Gary

I've read (but can't confirm from personal experience) that a carbide scraping blade is much preferred to a HSS blade. Apparently the HSS blades require *very* frequent sharpening. Perhaps someone here that does have experience with both carbide and HSS blades will chime in with their opinion.

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First purchase you might consider is a book or two on the subject. Do a search on hand scraping and you should find numerous articles from this forum on the subject. The standard text on the subject I believe is still " Machine Tool Reconditioning " by Edward F. Connelly. Check your local used book stores and online. A new one will set you back almost a $100. Also somewhere in this forum a person was writing and/or making a video tape on the subject. Google should have it archived. A little more homework is in order. :)

Keep plugging

Jim Vrzal Holiday,FL.

Allan Adler wrote:

Again, he should be aware that many modern files are case hardened. Grinding off the teeth will give a soft scraper. :(

The standard hand scrapers are sold inexpensively through McMaster Carr. That's where I got mine. The HSS blade is sharpenable on a regular pedestal grinder, the carbide one really requires a diamond wheel to do properly.

Another approach to life is to simply take a *large* HSS toolbit and mount to a piece of stock. That's what I did for my first foray into hand scraping. One advantage to a small scraper like that is you can get into the nooks and crannies:

It's tough to do small stuff with a large, wide scraper.

Jim

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Check out

I stumbled across it an hour or so after reading your post. Talk about synchronicity, eh?

chem

Allan Adler wrote:

Hi Allan:

There are several strata in scraping. It is possible to spend a very significant amount of money.

I would not proceed without a known reference - straight edge or surface plate. The often on sale 10x12 surface plates from Enco would not be a bad investment. I purchased a used DoAll surface plate, and an Enco. I had them certified and the Enco plate needed a bit of touching up to get back to grade 'B' - this after I used it for a poor man's surface grinder ala Guy Lautard's book. Even at that, grade 'B' surface plates are tight enough for scraping.

Cast iron is far easier to scrape than steel. That's what I would practice on.

Prussian blue works pretty good. I would add a rubber brayer to the tool list.

Enco makes an Anderson Bros' tubular scraper handle clone. They have replacable HSS inserts. HSS does require fairly constant maintenance, but carbide & the ability to grind it can be pretty spendy.

Books are good for some, but seeing the scraping action was an eye-opener. Just watching it happen made things easier to understand.

Having a reference on scraping, reading the spots and possibly more importantly, how to detect when you're not making progress, all help.

Scraping is addictive.

Oooh. Another widget. What's a 'brayer?'

Jim

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I believe it's a small rubber roller - Hobby Lobby sells them.

When I went thru the text, I didn't get the impression the author assumed the reader was experienced in scraping. Chapters 5 and 6 explained the tools and techniques to use them. Chapter 10 and 11 covers the markings and how to interpret them. While many of the chapters are specific to reworking machine surfaces, their are many tips and techniques a novice could gain knowledge or explain problems dispersed throughout the text. A dry read for sure, but the reader will come away from it with more than an understanding of just the hand scraping process.

My 2 cents

Jim Vrzal Holiday,FL.

Karl Townsend wrote:

To expand on Mikes answer ...

They are rubber rollers that are used in printing to spread ink on platens (I think that is the word).

They are great, though you need to get a good/expensive one. The cheap ones are not round (not a real issue) or straight (a problem).

V> > > >

Dapra sells them

Ah. Thanks guys.

I've been just carefully spreading the bluing on the surface plate with gloved hands.

Jim

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