Pull scraper??

Could anyone post a few pictures of a pull type scraper, and perhaps offer some basic dimensions?
I am working on an Aciera F4 mill that has this style, and I would like to try to keep it "similar".
Any info would be appreciated

Peter

I’d like to know how pull scraping differs in appearance on the finished work? Have only pull scraped turcite, not iron.

L7

This one was made by my friend Matt Critchley, it's called a Critch-build. I believe he will be selling these. It is a fine tool indeed. I have used it several times. The surface is flat when finished, so it doesn't have oil retention pockets, but a very nice reference surface. The overall length is 33 inches and it has a 5 degree negative carbide blade. I think the blade is 1/4" wide.

He is a member here, so I am sure the title of this thread will get his attention. Time to go to work Matt.

this is the best vid I've seen that shows Swiss type scraping and tools:

I have a question for other brother. Daryl do you put the scraper against your shoulder and pull to get the scraping action?

Sent from my SM-N950U using Tapatalk

Yes, that is exactly how it is used. I have a thick foam pad that slides over the shaft so my shoulder doesn't get sore. Matt spent a lot of time testing different spring amounts. The scraper feels well balanced too.

Here are some info on Pull scrapers.
Pic. of my assistant Ted in Taiwan, one is a aluminum bar with a drill and tapped hole on one end and a Biax blade bolted vertically to that end. The other one is he is using a regular scraper vertically. The pages were emailed to me by a Swiss Student, I have some more taken in Puerto Rico where a student made one.

Thanks all for the info!
if you look at my other thread you'll see some of wha I am up to.

Peter

Puerto Rico employee who made and used it until he used a Biax Power scraper, after that he left it in the bottom drawer of the tool box. They still make them commercially in Germany. I will contact Stefan and Franz in Austria who bought one last summer and get the info and price.

In reference to the first picture of Ted using the hand pull scraper (as distinct from shoulder - a mains vs a l'epaule). From my experience he's giving himself a disadvantage with the very long right angled tool extension. It takes some sensitivity to get the blade flat to the work, especially while you're pressing down and then pulling. If it's not flat, it's very easy to scratch with one corner or the other. A much shorter extension means less telegraphed leverage for off-square. Pictures of forged steel pull scrapers typically have closer to an inch or inch and a half turned at the end.

I duplicated an Agathon design from a picture for a scraper with an angle adjustable head. It can be set almost straight for shoulder scraping or closer to a right angle for hand pulling. I won't say I'm accomplished at pull scraping but I've explored the territory a little and stepped in holes here and there.

TGTool said:

In reference to the first picture of Ted using the hand pull scraper (as distinct from shoulder - a mains vs a l'epaule). From my experience he's giving himself a disadvantage with the very long right angled tool extension. It takes some sensitivity to get the blade flat to the work, especially while you're pressing down and then pulling. If it's not flat, it's very easy to scratch with one corner or the other. A much shorter extension means less telegraphed leverage for off-square. Pictures of forged steel pull scrapers typically have closer to an inch or inch and a half turned at the end.

I duplicated an Agathon design from a picture for a scraper with an angle adjustable head. It can be set almost straight for shoulder scraping or closer to a right angle for hand pulling. I won't say I'm accomplished at pull scraping but I've explored the territory a little and stepped in holes here and there.

Click to expand...

Ted is scraping Turcite and he got 60 points on the bar. The advantage of this technique, his eyes are directly above the scraping. I tried it and I liked it, IMHO it far exceeded the Swiss type on Turcite. We didn't try it on Iron. But the Puerto Rico student was so proud of his unit and showed me how wonderful it worked until we checked his depth and it was a only .0001" and he was killing himself in the heat. As I said once he used a Biax he never used the pull scraper again on a flat surface. I can see how in the saddle of a box way where it would be handy after you roughed it in with a Biax

Pull scraping is very labor intensive and is an art form in itself. With pull scraping there isn't any measurable depth of scrape marks for oil pockets because the blade is flat as opposed to a radius on a push scraper. With pull scraping I use my arms instead of my body as in push scraping and pull scraping tires me out quickly. I am much faster push scraping by hand than pull scraping but I like the look of a pull scraped surface.

I have only finished a few pull scraped cast iron projects so I am still learning. I have also tried making several pull scrapers but you will not be seeing any photos of my feeble attempts.

Daryl

Richard King said:

I will contact Stefan and Franz in Austria who bought one last summer and get the info and price.

Click to expand...

Look forward to hearing more Richard.

John

shapeaholic said:

Could anyone post a few pictures of a pull type scraper, and perhaps offer some basic dimensions?
I am working on an Aciera F4 mill that has this style, and I would like to try to keep it "similar".
Any info would be appreciated

Peter

Click to expand...

When i started to scrape one of my goals was to rescrape my Schaublin 70. I noticed it had a unique scraping style with little depth. A few years ago, member Screwmachine in Switzerland posted some photos of a pull scraper that he had made up and a small rotary table that he had scraped. His pattern looked very much like the scraping under the headstock on my Schaublin. Armed with this limited info i started to experiment with different configurations of a "pull scraper". My first attempt looked much like the commercially available Agathon, it was a bit to stiff but i could actually rough with it. The stiff configuration gave me a bit too much chatter.
I decided to abandon the large and stiff approach and emulate what Screwmachine built. I made several versions of varying stiffness's, widths, and edge conditions.
One of the most important considerations is the amount of castor built in between the centerline of the handle and cutting edge. After some time i added large wooden handles and that helped steer the cutting edge into being level. The built in castor also helps the blade land flat on the scraped surface. The biggest eureka moment was switching to spring steel for the flexable neck. There was a good learning curve on the proper hardening and tempering of the spring. The carbide insert is silver soldered into into a slot on the end of the neck. The difficult part of soldering on a tempered spring is to control temperature. I made up a set of copper chill blocks to keep the spring cool during soldering. The spring is 1/8" 1075 spring steel. The handle is a piece of Drill rod with a flat at 6 o'clock that the handles set screws lock onto. It is nice to be able to move the handles.
The configuration that i landed on is in the bottom photo.

The pull scraper produces a really neat checkerboard pattern with little depth. I really like the surface for tooling that will be in contact with an indicator tip.
I am not planing on selling pull scrapers but will happily help anyone with build details.

MCritchley,
Those are pretty cool.
I plan to have a go at this when I get back from a work assignment, next week.
The scraping pattern on my Aciera F4 is similar to your example, but slightly smaller and a bit more random. Definitely pull scraping though.

Stay tuned for some more questions...

Peter

Here is a photo of a finished pull scraped surface. The photo above is the first pass after milling.

Here you go:

YouTube

And...

YouTube

Pull scraping is a bit slower at first but more effective as you gain practice.

There is a persistent notion that pull scrapers are sharpened flat on the cutting edge. Not true. You can sharpen them any way you want. The depth of the scraping depends on the end radius of the scraper. Because the radius is poised at a 70 degree angle to the surface instead of 25 degrees, the pull scraper end radius has to be a bit more than double the radius of the push scraper for the same effect.

The objective properties (point count, depth, bearing quality) of pull scraping should not significantly differ from push scraping where the end radii are comparable in effect. However, body ergonomics and plain physics will result in unavoidable esthetic differences.

I prefer pull scraping in areas where fine control is necessary like working edges of oil and fastener holes, oil grooves, inside corners, etc. The scraping edge can be extended to the side beyond the shank of the scraper and 0.030 high (no more than a hook) to reach inside dovetails etc. Note how in the first video the scraper hand was picking off points on the narrow ends of an angle plate. Narrow surfaces can be tricky with push scraping where every stroke is essentially a lunge; pull scraping lends finer control thanks to body ergonomics and better visibility of the cutting edge.

Not all scraping takes place flat on a bench where the light is good and the scraper hand can stand comfortably. Some tasks are in cramped spaces, laborious, and hard to reach like under the ledge of floor mill runways, high on columns, or the tunnel dovetail of a surface grinder saddle. In these places pull scraping can work very well.

Reqardless, pull scraping should be practiced to gain skill. It's an effective alternative to push scraping that has niche advantages.

All that said, the third method (the Biax scraper) is far more productive once basic skill is developed. I can well believe Richard King's Puerto Rico student left his pull scrapers in his tool box to gather dust along with his push scrapers. However, don't toss them. Keep them handy and in good shape. The Biax can't do everything.

Forrest I had a fellow call me today who lives in a suburb next to Bremerton who want to learn to scrape. I told him you might help. I am going to message you his info. Rich