Hand Scraper Design

I'm monkeying around with making a scraper to repair the cross-slide on the 1440 and would appreciate some input from those that use them.
I'm attempting to do this with materials that I have on-hand. The lathe crapped out at very a inconvenient time.
I had to take a pass on a decent bit of side work because with the stick-slip, I messed up the first three pieces. So the budget is hurting.

Richard sent me a copy of Keith Rucker's design. (Thanks Richard!)
I have a couple of questions about the design.
I've got a few pieces of 3/4" Sqr. carbide inserts that I'm trying to make do with. I realize that they are really not wide enough, however it's all I've come up with.

On Keith's design on the insert extension piece, the flat on the end is at 2° positive.
Does anyone know why? I'm wondering if it can be 'straight'.
..........

Here's my first take on it using the 3/4" insert.
I'm making a couple of needed ergonomic / handling modifications to it.
I made up a mock-up out of a file and then played around with it trying to mimic the way I've seen people handle them in videos.
A problem/difficulty has cropped up from this, with my left hand tendons messed up from some medicine, gripping the scraper becomes uncomfortable after a bit.

With this first take, I've made a change on the handle end so that I can try out different size handles if needed. They will be screw on.

My Left-Handed/Right-Handed -ness is odd. I write left handed but do a number of other things right handed, it just depends.
I haven't figured out which way I'll hold a scraper yet.

If I'm holding the end with my left hand, 1.5"-2" DIA. feels best and lessens the discomfort.

Then I've also added a 'Grip' handle for holding the shank left handed.


Thanks,
_Dan

 

I made two of the Keith Rucker design scrapers from 1/8 X 1" hot rolled steel, and then surface ground all the parts flat and shiny. They are the lower two in the photo below. I also glued threaded inserts into the drilled ends of the store bought file handles to hold the push pads in the upper part of the photo. They are rubber sanding disc holders, 120mm (~5") in diameter, good for pushing the scraper with your body. There are lots of variations on push pads, some wood, some other materials. Whatever works for you. The scrapers turned out nice. They are still too stiff even after grinding about .020" of thickness off of them in making them. I will mill some shallow pockets into the flats of the long portions of them at some point to make them more flexible. They are copies of Biax hand scrapers, the 2 screw connection holds Biax scraper blades. The short extensions are designed to hold Sandvik 25x25 or 25x30mm carbide scraper inserts, which are mounted in the photo below. The other scraper in the photo is a very old Anderson scraper, bought it from Ulma Doctor some years ago.

Dan, it sounds like you have some issues that cause problems with pushing with your hands. Making some sort of arrangement so you can push with your body when scraping will let your hands only be responsible for holding the scraper in position, keeping the blade flat, and pushing downward so it will cut. Your body will do the harder work of pushing. Most commercial scraper hands use some kind of body push method when hand scraping.

You may have trouble with the square insert you are planning to use. Any thickness over about 2mm will just make the blade more difficult to keep sharp and the correct shape. The cutting edge needs to have a radius so the corners do not dig in. In my mind, the insert you are planning to use will just make using the scraper and learning how to scrape more difficult. I sure could be wrong, though. Any way I can be of help, please ask.

 

I made two of the Keith Rucker design scrapers from 1/8 X 1" hot rolled steel, and then surface ground all the parts flat and shiny. They are the lower two in the photo below. I also glued threaded inserts into the drilled ends of the store bought file handles to hold the push pads in the upper part of the photo. They are rubber sanding disc holders, 120mm (~5") in diameter, good for pushing the scraper with your body. There are lots of variations on push pads, some wood, some other materials. Whatever works for you. The scrapers turned out nice. They are still too stiff even after grinding about .020" of thickness off of them in making them. I will mill some shallow pockets into the flats of the long portions of them at some point to make them more flexible. They are copies of Biax hand scrapers, the 2 screw connection holds Biax scraper blades. The short extensions are designed to hold Sandvik 25x25 or 25x30mm carbide scraper inserts, which are mounted in the photo below. The other scraper in the photo is a very old Anderson scraper, bought it from Ulma Doctor some years ago.

Dan, it sounds like you have some issues that cause problems with pushing with your hands. Making some sort of arrangement so you can push with your body when scraping will let your hands only be responsible for holding the scraper in position, keeping the blade flat, and pushing downward so it will cut. Your body will do the harder work of pushing. Most commercial scraper hands use some kind of body push method when hand scraping.

You may have trouble with the square insert you are planning to use. Any thickness over about 2mm will just make the blade more difficult to keep sharp and the correct shape. The cutting edge needs to have a radius so the corners do not dig in. In my mind, the insert you are planning to use will just make using the scraper and learning how to scrape more difficult. I sure could be wrong, though. Any way I can be of help, please ask.

Thanks Bob.
Those are handsome. Those are the nice solid style of file handles, I haven't seen them for quite awhile. Surface ground? whoa...
I've watched several of those short videos showing the hip stance. I hazard to guess how long it takes to learn how to master that.
Can you imagine the gouges I'd end up with? (Wonder what type of music to play when doing it that way...)
I've actually already scrounged up some sander pads to use on the handle, at least those were something I could find in my clutter.

OK, so 1/8" is still to stiff? I've got a bar of 3/16" - guess I'll be thinning it down a tad, and redrawing the current design.
I've got this 'button' insert that's Ø1.44 x .19T", and I was thinking of grinding it down square, 25-27mm. It'll be quite a task with a green wheel but I may give it a go. Have to haul the grinder outside, I don't want to have to deal with all that carbide dust.

Once again I could have sworn I had some carbide 'strips' in my stash somewhere, but they haven't shown up yet.
I also thought I might have had an old style Anderson but that hasn't surfaced yet either. I've lost a couple of boxes of 'good' stuff during moves over the years.

 

I think Tom Lipton (youtube "oxtool") showed that you can used brazed-n C6 carbide tools (available cheap) tof make a finishing scraper quite easily... I can't remember the exact video, but I'll look for it in the next week.

 

I expect that the 2 degree angle on the drawing is to allow for "spring" when the insert is tightened, otherwise, the insert could wiggle around when it is in use. I quite agree with Bob about not trying to use other inserts, they are bound to be too thick and likely the wrong grade of carbide; what makes an insert right for most work (durability) makes the quality necessary for scraping be absent ( wear resistance). A green wheel will never produce the quality of finish necessary for scraping.

 

after sharpening with a green wheeel, it is possible to produce a great edge with acheap diamond hone or diamond sharpening plate. [top to save time and frustration] Grind the edge to just over 90 degrees (such as 93) and then hone it to 95. If you do 90 it takes alot of time and can wear on a cheap hone. Grind it all all the way to 95 and now you have to hone the entire flat, which wears it even more.

You only need to hone the edge for about .020 or .030 to make a great scraper.

 

Those are the nice solid style of file handles, I haven't seen them for quite awhile.

Believe it or not, I got those at Staples(!), Three at $4.89 each, no freight charges, pick up at the nearest Staples store. Mine is just over a mile away.
https://www.staples.com/Lutz-File-Long-Ferrule-File-Handle-Style-4-5-1-2-Length/product_701181
They have a lot of file handles, and a ton of other stuff you might never guess they have. Cheap, and quick free shipping.
https://www.staples.com/Lutz-File-Files-Handles/cat_CL166894/00ilu

Surface ground? whoa...

Because I could... The local metal store only had hot rolled, not cold rolled, so I ground them. I am sorry, they were made from 3/16 x 1" stock, not 1/8". I also measured one, now .180" thick, so I really did not take off that much. But yes, they are definitely too stiff as they are now for my preference.

I have not tried pushing the scraper with my body for more than a few minutes, and yes, it was awkward. Still, lots of full timers use that technique, so it is very likely worth the effort of trying if scraping is causing you pain or other problems. It is no doubt best to learn many techniques, which can serve you in difficult access situations, on smaller or bigger work, or whatever, maybe a temporary pain somewhere. Richard King talked about scraping laying on his back on BIG machines.

 

after sharpening with a green wheeel, it is possible to produce a great edge with acheap diamond hone or diamond sharpening plate. [top to save time and frustration] Grind the edge to just over 90 degrees (such as 93) and then hone it to 95. If you do 90 it takes alot of time and can wear on a cheap hone. Grind it all all the way to 95 and now you have to hone the entire flat, which wears it even more.

Agreed. I have never got a really decent edge with a green wheel alone. A diamond "file" or "credit card" is a good way to finish hone carbide, just go easy and let the diamonds do the work. 800 to 1000 grit will work. If you push too hard you will just tear the diamonds off the metal plate. We typically look for a -5 degree angle for the cutting edge (95 degree included angle, just the cutter cutting edge, not talking at all here about the angle of the scraping tool to the work. That number can change a bit depending on material being worked on or other things like the angle you hold the scraper to the work at. You should be cutting real chips, mostly thin ones. Cast iron is an exception, some chips and some dust.

 

I think Tom Lipton (youtube "oxtool") showed that you can used brazed-n C6 carbide tools (available cheap) tof make a finishing scraper quite easily... I can't remember the exact video, but I'll look for it in the next week.

Found it! Thanks!
around the 45:20 mark.

 

One of the cool things Tom Lipton was working on when we had the scraping class was a bump scraper, to make possible short and consistent length cuts with the thought of making precision scraping cuts exactly where needed. He brought one to demonstrate that was kinda' like a slide hammer, and in the discussion we talked about making bump scrapers with electric solenoid or air power. I don't know where that eventually went, but it is interesting. We did meet up with one of the class participants, Adam, at a Sturgeon's Mill tour, and he said he scraped in a tiny cast iron surface plate (about 2x2 inches) to 100 points per square inch with a homemade bump scraper -- just to see if he could do it. He was with his wife and a new baby, so we did not have time to talk about the scraper or techniques he used for that job. Richard showed us a way of bump scraping using the palm of the hand near the wrist to bump the end of the scraper handle, with the fingers supporting the scraper under the handle. I found it clumsy, or maybe it was just me not trying hard enough or long enough. Interesting stuff...