Hook Scraping

I'm reading through "The Art Of Hand Scraping" on the archives, and towards the beginning he mentions the practice of hook scraping and how precise it can be compared to other scraping techniques (Writer claims up to a 50 millionths surface deviation.)

Now since this is a text, there are no pictures. Does anybody have pictures of a hook scraped finish, somebody practicing hook scraping, or better yet all the pictures in the book, or a text with pictures of the book?

I don't plan on learning hook scraping, as I am still learning push and pull scraping, but while I'm reading the book I might as well understand what I'm reading.

Thanks, all!

Umm. By hook scraping are they referring to that C-shaped stroke that Moore was famous for? Or is hook scraping a different tool with a hook? IIRC the claim made by Moore was that the technique produced a scoop that entered and exited cleanly so it didn't leave much of a burr. I've watched video of a guy doing it and I'm guessing that it was also used or developed to use more of the cutting edge - an important factor when scraping tools required frequent resharpening.

And by 50 millionths is that the difference between the high spots or is that the difference between high and low points.

TGTool said:

Umm. By hook scraping are they referring to that C-shaped stroke that Moore was famous for? Or is hook scraping a different tool with a hook? IIRC the claim made by Moore was that the technique produced a scoop that entered and exited cleanly so it didn't leave much of a burr. I've watched video of a guy doing it and I'm guessing that it was also used or developed to use more of the cutting edge - an important factor when scraping tools required frequent resharpening.

And by 50 millionths is that the difference between the high spots or is that the difference between high and low points.

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On the 50 millionths, I have no clue. I'd assume inclusive (high/low)

I don't know what the stroke was supposed to look like. He said start the cut with a light pressure and increase the DOC and twist. The stroke is 1" long roughing and about 3/8" for a finish cut/pass.
So I'd assume it would look like a C shape.

Hook scraping is another term for pull scraping. The scraper has a long handle with a gooseneck shaped end and a flat blade at its tip. The handle is placed on your shoulder and both hands are placed down about 4-6 inches from the cutting end and the cut is a pulling action. Your depth of cut is usually much less than push scraping, and the strokes are shorter. Most swiss machines are pull scraped, it's a beautiful checkerboard finish. I believe there are some threads on here about it.

I agree it is another term for pull scraping. There are a few ways to do it though. The shoulder method is just one, I have pull scraped the Inside bronze bushings of Barber & Colman Hob main spindle. The scraper was a round shaft of tool steel with a short 1/4" L or a hook on the end. We would heat it up, bend it, grind it, then heated it to cherry red, quenched it in oil and then honed it. I also worked with a Swiss Magerle Grinder Technician 30 years ago who was here in MN re-scraping 2 of their machines at a local shop. I found this picture showing how he pulled a small hook scraper with his arms. (Click on the picture to get to get it bigger) Studer Praises U.S. Performance at Annual Meeting

I was push scraping as he also did but he made his last few passes this way to get Magerle's Swiss "Signature" look. I have also made a round shaft and drilled and tapped a hole in one end and attached a BIAX Scraper Blade and pulled it. This method really works great on Turcite. I will show Turcite scraped to 60 points and .00005 / per 12" That is what is meant when someone wrote 50 millionths. Those are the spec's we use when scraping super precision machines like the Swiss made machines, straight-edges, surface plates, etc. We scraped the Turcite in a class in Taiwan. My assistant teacher Ted did it. I have also put on another thread where it shows him using the shoulder method on Turcite. Pull scraping, push scraping, BIAX power Scraping can all be used to scrape super precision surface and flat to .00005" / 12". I have seen students scrape 60 PPI with the BIAX Power Scraper and get an amazing checkerboard. Rich

ironsmith89 said:

Hook scraping is another term for pull scraping. The scraper has a long handle with a gooseneck shaped end and a flat blade at its tip. The handle is placed on your shoulder and both hands are placed down about 4-6 inches from the cutting end and the cut is a pulling action. Your depth of cut is usually much less than push scraping, and the strokes are shorter. Most swiss machines are pull scraped, it's a beautiful checkerboard finish. I believe there are some threads on here about it.

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I made a pull scraper, all it did was chatter unless it was dead sharp. Then a few strokes and it started to chatter again. I put hearing protection on and just lived with it. A you said it was much slower so I quit with it.
I will try making a smaller one to finish my angle plate off with, as a push scraper doesn't leave the best finish.

I would suggest you practice a bit more push scraping as it is easier and you can get a beautiful finish if you know how to do it correctly. I learned how to hand push scrape and have scraped several Sip, Moore, Pratt & Whitney Jig Bores, Hardinge lathes, surface plates, straight-edges, etc. to 40 PPI and .00005" flatness and it was a beautiful checkerboard finish. I will add a couple of pictures of my students results in 1 days training by hand. They may not all be 40 PPI, but they could have got it but I stopped them at 20 PPI. Rich

Well, going back to the text it sounds like they're describing what I think of as that characteristic Moore scraped surface. Rich has mentioned it in his class so I know he knows how to do it too. It might be slower than just the straight stroke or it might be harder to learn the coordinated movements required. Here's a video of a former Moore employee, Imants Gorbants, demonstrating it. https://www.youtube.com/watch?v=AkYyWcflMy8

This is what it looks like if anyone doesn't already have it burned in their memory. No disrespect for Swiss pull checkerboard finish scraping, but I think this is also just gorgeous.

Here's a video. Don Roberts at tge cutting edge:

https://www.youtube.com/watch?v=ikRO9yPgWD0

He's much more experienced and productive now.

One thing I noticed in that video is he runs a long string of continuous strokes, like if he were push flaking. In the book however you can see the strokes are laid down individually. I think the key to this technique is the radius of the blade must match the size crescent you are trying to produce, once you have that figured out its pretty simple if you choke up a little on your scraper, pretty strenuous though.

TGTool said:

Well, going back to the text it sounds like they're describing what I think of as that characteristic Moore scraped surface. Rich has mentioned it in his class so I know he knows how to do it too. It might be slower than just the straight stroke or it might be harder to learn the coordinated movements required. Here's a video of a former Moore employee, Imants Gorbants, demonstrating it. https://www.youtube.com/watch?v=AkYyWcflMy8

This is what it looks like if anyone doesn't already have it burned in their memory. No disrespect for Swiss pull checkerboard finish scraping, but I think this is also just gorgeous.

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Well I guess I learned something today. I have seen "Hook" scraping done, but never heard it called hook. I worked with the foreman at Garrett Aerospace several years ago out in Phoenix and he had apprenticed at Pratt & Whitney in Hartford, Connecticut (where I just realized is a coincidence where DAPRA is near). The Moore guy is demonstrating the pushing technique on Aluminum as he says you have to push 3 times harder in iron. Did you hear him say "it falls in" ? I also suspect he watched craftsmen do it as a supervisor, if he is teaching at Penn State he must be a Professor. And in the Moore book they scraper is aiming it as he scrapes. A real pain. I bet those guys has super sore hands after 40 hours / 52 days a year...lol.. of that compared to body push and lift scraping. That maybe why Rudy invented the BIAX because he needed to get a break from doing that...lol

I spent about 2 minutes trying it with the foreman watching and laughing...lol...Years ago while demonstrating the BIAX on a cast iron plate at the IMTS show a older guy walked into the booth and grabbed my Dad's Hand 1/2 moon Flaker that I was demonstrating the hand backwards bump flaking and this guy laid down a straight line of hook scrapes. He was the real deal. He and his buddies stayed and talked about the old days scraping that way.

I use the hook technique when scraping Rulon sometimes as I hate getting the fuzz when push and drag hand scraping it.
One great thing about it is the hook as well at the pull & lift and push & lift scraping has over the push and drag back is it doesn't leave the burr. The old (2nd one after the inventor of the BIAX, Rudy Wetzel) President of DAPRA a Swiss imagrant, Wolfred Meliert told me that Sip had done studies and tested the pull and lift method against the BIAX push and drag back and they found no difference in the results or the way the ways performed and lasted. The burr left over is stoned off. Stoning the correct way is key. All you want to do is stone off the burr and not the high spot. In the Old Dapra Catalog they mention how Sip uses the BIAX to scrape and i also observed some Sip Techs using them at John Deere.

They like many others use the BIAX to get 40 points and then finish by hand to get their "signature" look. Also if you notice on the demo the older guys scraper was an Anderson HSS blade and in the Moore Book the guy is using a Sanvik carbide tip. The pro's use carbide. Here in MPLS there is a company called Professional Instruments / Air Bearings Inc. and they had a very good co-op with Moore and their techs went to Moore to learn to scrape. I went out to demo the BIAX and give them a day's training. They ended up buying 2 BIAX.

As I have said there is several ways to skin a cat and if you are trained one method and not the next you need to adept as I have and scrape the method that works best in the right situation. As my Dad used to say. "When your done learning your dead". Rich

Forrest Addy said:

Here's a video. Don Roberts at tge cutting edge:

https://www.youtube.com/watch?v=ikRO9yPgWD0

He's much more experienced and productive now.

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Also I think Don was just demo-ing the technique as I bet he has a BIAX too and push scrapes by hand. The Sip guys that Don has worked with (I bet Don when doing that) press down a lot harder. No offense Don and Forrest, but what he is showing in the video is chicken scratching. Rich

Spyderedge said:

I made a pull scraper, all it did was chatter unless it was dead sharp. Then a few strokes and it started to chatter again. I put hearing protection on and just lived with it. A you said it was much slower so I quit with it.
I will try making a smaller one to finish my angle plate off with, as a push scraper doesn't leave the best finish.

Click to expand...

Can you post a pic of your scraper? I am guessing you are using steel; the guys here generally do as well for pull scrapers. You have to have a stone on the bench right next to the work and you hit it every couple of minutes or more. Just a few strokes on the stone and back to work. How wide is the cutting edge? Generally pull is used right at the end when you already have the bearing you want, it's really a finishing technique.

Screwmachine said:

Can you post a pic of your scraper? I am guessing you are using steel; the guys here generally do as well for pull scrapers. You have to have a stone on the bench right next to the work and you hit it every couple of minutes or more. Just a few strokes on the stone and back to work. How wide is the cutting edge? Generally pull is used right at the end when you already have the bearing you want, it's really a finishing technique.

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Here are some pictures. It looks uncomfortable, but really it's not. I scraped 8 passes last night on a face of an angle plate and it worked great. The edge is a 1/16 x .5 x 4.5" parting blade from HF. I didn't have to sharpen it, but I did anyway at the end of the night to have to ready for today. A lot better than the carbon steel scraper I made before that needed to be sharpened every pass.
I do have to make a wooden ball for the end of the handle, but that can wait a bit.







Thank you all very much for your replies, I think I will have to make a PROPER pull scraper now, with an adjustable head like the factory made one shown above. The one I made was way too positive and had some back rake. Bad!

To the others who are experienced scrapers be it a professional or Hobbyist who come to this forum because we want to share our experience. I encourage my students to pass on the knowledge of what I have taught them. I'm not exactly sure how to say this, but we were trained by professionals who were trained by professionals and we don't guess at what's the best tools. Practical Machinist has rules banning discussion on Hobbyist Chinese made machinery because they want us to discuss and work with professional Industrial machine tools. The Experienced Scrapers here show hand scrapers that we feel are professional tools, recommend where you can buy them or how to make them. Seeing these experimental home made scrapers made by someone just learning to scrape to me is like talking about Rung Fo's.

I love to see the Swiss members like Screwmachine where precision scraping is not a for-thought, it's a way of life, seeing our new member Ironsmith, old timers Nick, Cash, TG Tool, Forrest, Phil, Peter, RC, Dennis, Robert, I, (who am i forgetting?) etc. who are experts compared to many here, help and give advice learned from years of experience. I am sure when we see these experimental scrapers we "cringe" because we have been using professional tools that have been passed on to us or we made after a pro told us how.

I suppose I am pissing off a few people, but when this forum is packed full of Professionals, who can show and tell you how to scrape and make professional style scrapers, why experiment making home made tools? I know many tools are invented everyday and people come up with new idea's. But scraping is a skill that has been around for hundreds of years and most of us experienced scrapers have drawers full of tried and true tools alongside our experiments that failed. So please ask us how before making a homemade contraption that will fail. Happy Scraping, Rich

Richard, hear me out.

I'm 15, don't have a job yet. If I bought everything I have made I'd be broke.
Nobody I know knows much if anything about scraping or the process, let alone teach me anything I don't already know. I know how to make a surface flat, and I've done that. I'm just asking about a technique in a book, that's all.
Rich, you used to inspire me with your knowledge about scraping like Forrest, but you've really just disappointed me.

When new people get together and try to learn a new skill there will always be different ideas. To those who are already experienced they will know that to try a new technique might be a waste of time over more traditional ideas. That doesnt stop people from trying it just to see how it works out. As we share our knowledge we need to remember that sharing doesnt mean forcing one idea over another. I value the opinion of the "experts" but I hope they also remember that sometimes a person just has to learn the hard way. And it is sometimes better to let them try and fail, or let them try and succeed and we can all learn from that experience. Nothing can kill enthusiasm faster than trying to minimize that persons efforts in public.

Lets please try to keep our comments from sounding hurtful or patronizing.

Spyder, good luck with your efforts, I am sure of one thing, after working with your homemade tools when you do get a better one you will be amazed at how much easier things will be. But dont stop just because you dont have the right gear, the experience you will gain from trying will be useful. Just also try to remember that when you get criticism it is usually not meant to hurt but more often intended to be helpful.

Charles

Don't misinterpret Richard. While he can come across as pontifical and condescending, it's entirely unconscious and innocent. I don't think he knows any other way to write. He really is a good hearted man and he does love good equipment: he reccommends it to all who will listen. Most any of us can improve on the heavy and bulky Dapra hand scraper, the Anderson scraper really is a standard to emulate. I've seen postings over the years of DIY hand scrapers some of which would rival the best "professional" models.

You all have different budgets, preferred ways of doing things and some of us feel violated when criticised for DIY forced by circumstance.

Richard and I have bumped heads many times in the past over petty issues and probably will again in the future. You have to understand Richard is Richard and I will stick up for him and what he has to offer when it comes to precision scraping. Hhe has much to offer. If his written word causes backs to stiffen, take it with a grain of salt. He does have a good heart and a strong desire to nurture those wishing to learn what he has to offer.

BTW Richard, the "chicken scratching" you saw in the video was Don picking in the last few cuts in an almost completed surface. He was demonstrating how to cut spots down the middle and going slow for demonstration purposes. In three cuts he went from maybe 4 spots per square inch to maybe 16 IIRC over most of the surface. There were still a few holidays remaining.

Rich,

I'm struggling a little with the distinction between professional style scrapers and others. It seems to me a little like the aphorism that a weed is just a plant you haven't found a use for yet. A good scraper is one that works, a poor one is one that doesn't no matter where it came from. That can just be a matter of preference as easily as bad design or construction. Mike Morgan swears by the tubular scrapers because he thinks it gives him better control. I prefer several I've made because they have a little more spring. I've got long ones, short ones, one-sided thin ones to get into dovetails and any one of them could be a good tool or a bad tool on a specific task. And as for pull scrapers. I've seen photos of manufactured ones but haven't yet found one in a catalog in the US so if it's a pull scraper it's going to be made by me. Then it's going to be a good or bad one depending on whether it works for me or not. As it happens I have a bad one, but it might magically change if I figure out how to make it work for me. And no, I'm not planning on machining up a Biax.

Oh OH...I guess I should have reread my post before hitting "post"

I knew I would get in trouble writing that. I also think a couple of others mentioned "practice makes perfect" too. In the last class one of the students after 5 minutes of hand scraping said "I can't do this" I had no idea of your age and on here I would suspect not many are so young. I saw someone asking about hook scraping and showing a homemade version. Never thought about your age and I am sure the others who answered didn't either I congratulate you on your efforts at 15. I wanted to present my opinion on these many efforts on scraping and was hoping to present a short cut no matter what.

I encourage you to ask questions and maybe you did in other posts, all I saw was this one. I hope you ask more questions and I will gladly help anyway I can. Where in NY are you from? I have taught several places in NY over the years and maybe we can arrange for to meet an old student. Or tour a rebuilders shop or factory where they scrape. If we ever do a class near you and you can get permission from your parents You can come for free.

If I hurt your feeling...I am sorry.

I have said several times there are several ways to skin a cat and scrape. All I saw was a home made scraper that looked different...you mentioned getting chatter when using it and can't get straight lines.....

Forrest:
If we polled the students who have had Anderson Scrapers in all my classes I would bet 99% would say they wished they had not bought them. To stiff and no spring. No need to apologize for me Forrest I have heard plenty of things about you too.....lol... When I teach scraping I tell the student to scrape the same pressure down all the time. but change the blade radius, stroke, length of cut. Even when splitting a scrape mark in 1/2 should be scraped the same depth as the original scrape mark.
I have been scraping for a profession since 1972 when I was 22. Prior to that I worked part time scraping summers. I believe I was probably 12 or 13 when I pushed mt first scraper made from a file or may have been a Anderson. Now the Anderson is in the bottom of the tool box. Happy Scraping. Rich

PS:
TC: Please don't mention my name in the same sentence with MM....