Top-notch power scraping surface finish

[mecanicadeprecisio]

Hello !

A few days ago I started a thread called Special BIAX scraper to learn about a special Biax design used by SIP, @Richard King (thanks a lot!) posted a video from SIP (SIP scraping : The state-of-the-art) where the scraper can be seen being used in detail and I noticed the surface finish is quite curious, it looks to me (based on my limited understanding) there is some chatter. What do you think about it? Does anybody has detailed pictures of what should be considered a top-notch power scraping surface finish?

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[Bakafish]

This is a closeup of the scraping on a Japanese Grade 0 toolmakers inspection plate (150mm x 150mm) and you can see there are distinct striations to the pattern.



I do not believe that these are caused by chatter as they are so uniform, I also think the lines are parallel to the scrape travel. This means they are likely serrations on the blade edge themselves, and I believe they are intentional. My guesses are that they are aesthetic, functional or they change the feel (bite) of the blade (this is hand scraped), or its possible that they are just doing the initial grind to the carbide with a very coarse grit. Japanese are not very cut corner people though, especially with high end stuff like this (it's a $600 plate despite this tiny size) so I think there is a purpose for this, and my thinking is that it increases the individual bearing points without having to do a million micro passes.

 

[magisterFactotum]

The marks on the Japanese surface plate look almost certainly like toolmarks from the machining process, likely planing or coarse grinding. You can see two scraping passes in 90deg directions to break up the surface, and the original machined surface between them. The feathery appearance is from the surface finish where the scraper enters and exits the cut.

 

[TGTool]

The marks on the Japanese surface plate look almost certainly like toolmarks from the machining process, likely planing or coarse grinding. You can see two scraping passes in 90deg directions to break up the surface, and the original machined surface between them. The feathery appearance is from the surface finish where the scraper enters and exits the cut.

I would beg to differ. I don't think we see anything of the original machine surfacing. It does look consistent with the practice of those long hip scrapers using a wide blade and short stroke we see in some of the videos. This hadn't occurred to me before, but I expect it also means that there's very little depth between high and low spots with that technique.

 

[Bakafish]

The marks on the Japanese surface plate look almost certainly like toolmarks from the machining process, likely planing or coarse grinding. You can see two scraping passes in 90deg directions to break up the surface, and the original machined surface between them. The feathery appearance is from the surface finish where the scraper enters and exits the cut.

Taking pictures of scraping is always a challenge, and in the closeup above I was actually taking a picture of an unrelated object so I wasn't really trying to capture the scraping details. It just made a pretty backdrop and your request for scraped surfaces and the unusual line patterns made it an interesting data point. The base finish of the plate does have these lines as well, but I assure you the scrape marks have identical looking grooves parallel (maybe perpendicular, it's really hard to tell to be honest) to the scrape direction and is at an angle to the base finish. The simplest answer is likely the right one, that this is just artifacts of whatever blade sharpening process they have or is chatter and the lines have no real impact to the performance of the surface or visually integrate better with the lines of the base finish, so they just leave them.

Having watched that video a couple of times, I agree those marks on the SIP surface look like chatter. The first guy really seemed to be going at it, so maybe during the roughing they just go ham on the surface to remove as much as possible. The second guy seemed to be doing more dive bombing finishing work, although the blade seems pretty wide for that, he seemed to be able to just hit the spots he was aiming for.



Also with the second guy (Saverio), notice the different finishes and the small mark delimiting the areas between them, almost as if this footage was pulled from an internal training video. For all we know this was originally filmed to show employees what not to do and later repurposed by marketing people who were clueless...

 

[Richard King]

Hello !

A few days ago I started a thread called Special BIAX scraper to learn about a special Biax design used by SIP, @Richard King (thanks a lot!) posted a video from SIP (SIP scraping : The state-of-the-art) where the scraper can be seen being used in detail and I noticed the surface finish is quite curious, it looks to me (based on my limited understanding) there is some chatter. What do you think about it? Does anybody has detailed pictures of what should be considered a top-notch power scraping surface finish?

View attachment 396074​

View attachment 396075That scraping in a "static" scraped surface 75% to 80% percentage of scraping and not 50% way scraping. A hardened way or Linear way, screws to that surface. Biax at one time made a spring loaded blade holder so the blade lifted out because some customers like the Japanese would not buy power scrapers, just power flakers. I tried it when I worked the Dapra booth to the IMTS show several years ago. I was told it would not be continued as BIAX sent some of them to customers and no one like using them and just learned how to stone off the burr left at the front of the cut. I suspect this is what happed with the special Sip Scraper. I taught inside the BIAX factory and I saw the complete line. and we discussed blades that were useless like the twisted ones. They discontinued many blades as it cost money to make an inventory of blades. I have posted several photo's of 40 PPI scraping in many posts on PM and you can look back to see some. There is another power scraper made by a company called Renz. Some like them, I don't as I have been scraping with a BIAX sense 1972. I love them but hate the price. Stefan Gottswinter a famous German You Tuber once owned a Renz, but sold it and bought a new BIAX. I have tested about 3 Renze and they are far inferior to a lousy 50 year old Blue motor scraper.

From what BIAX wrote the Sip experiment did not fly and they only made a few as they were to expensive to make. Biax changes the Patient every 15 years or so by changing the scraper design just enough to "improve" on the scraper to get a new patient. I suspect the Hungarian models were made by Biax or they sold them a license to make some on there patient of the people in Hungary got sued and stop making them. I asked in Taiwan and China wwhen I taught and worked there that no one will ever copy a BIAX because they don't make more then 500 a year. Copiers want to sell millions not hundreds.

 

[Richard King]

Biax Scraper division is the smallest company of this BIGGER company that makes meat packing tools.
Biax is a product or the link below (smaller division of the bottom Link)

Home - BIAX

schmid-wezel.de

http://efa-germany.com/efa/impressum/index.php

 

[Peter.]

This is the best I can currently do with a Biax. I hope to improve on it with more practice. There is almost no depth to it as it's a gauge not a working surface but a 1 micron dial has barely perceptible movement along it's length.

 

[Richard King]

Not bragging, but Peter has taken 2 of my classes. One in Norway and he helped organize the UK class. Getting a good bearing take a lot of patience and practice. He is what I would consider a "natural" scraper and one of the best in the my 35,000 + students in my 30 + years of teaching. I show my students how to get 40 PPI and they have a good base to get that and more. Many of my students can scrape 60 PPI with a BIIAX Power Scraper.. Below is a straight edge scraped by my Austrian students who are now teaching the classes in Europe. They took 1 class in Germany and hosted 4 inside their shop in Austria. They use to be members here, but tired of the banned troll hassling them.

 

[eKretz]

I would beg to differ. I don't think we see anything of the original machine surfacing. It does look consistent with the practice of those long hip scrapers using a wide blade and short stroke we see in some of the videos. This hadn't occurred to me before, but I expect it also means that there's very little depth between high and low spots with that technique.

I think he is right. Those marks on the surface plate posted by Baka (in the very white areas of the image) are linear and perfectly parallel from one side of the image to the other, in lines far longer than the scraping marks. Almost certainly tool marks. I think perhaps that surface plate is flaked, not scraped.

Aside from that, do you know of anyone who scrapes with an edge that has that coarse a grind? It wouldn't work very well, not a keen enough edge - and would dull very quickly too.

 

[Bakafish]

I think he is right. Those marks on the surface plate posted by Baka (in the very white areas of the image) are linear and perfectly parallel from one side of the image to the other, in lines far longer than the scraping marks. Almost certainly tool marks. I think perhaps that surface plate is flaked, not scraped.

Yes, I examined it again several times, there is a clear base tooling pattern that shows up in that photo and on the plate. Also, 'flaking' is a better description of what they did as there is only a single set of passes over the surface. It's a tiny plate and if they get the initial grind or plane very accurate, there's little need to do anything other than break up the surface to reduce stiction.

That said, the flake marks do seem to have similar grooves and all of it seemed intentional and potentially related to the unusual examples shown in the OP video, which is why I posted it. When I first saw the plate I was struck by how unusual the appearance was, and the video had all those striations (not as pretty IMHO) which struck me as similar and so I wanted to add a possible data point.

I guess the question is, is a serrated scrape/flake potentially beneficial or just an artifact of poor workmanship or aesthetics?

 

[eKretz]

Yes, I examined it again several times, there is a clear base tooling pattern that shows up in that photo and on the plate. Also, 'flaking' is a better description of what they did as there is only a single set of passes over the surface. It's a tiny plate and if they get the initial grind or plane very accurate, there's little need to do anything other than break up the surface to reduce stiction.

That said, the flake marks do seem to have similar grooves and all of it seemed intentional and potentially related to the unusual examples shown in the OP video, which is why I posted it. When I first saw the plate I was struck by how unusual the appearance was, and the video had all those striations (not as pretty IMHO) which struck me as similar and so I wanted to add a possible data point.

I guess the question is, is a serrated scrape/flake potentially beneficial or just an artifact of poor workmanship or aesthetics?

I think in the SIP video it is probably just chatter. Happens to all of us now and again, I expect. We just don't all make videos and photos. The Japanese table may just be a coarse grind on the flaking tool in the interest of getting quick touchups to the scraper done frequently and easily. I don't think it reflects poorly, it's one of those instances of "not necessary" to go overboard with the scraper sharpening. A flaked surface is basically just creating airspace, nothing should ever be contacting it other than air or oil until it's worn pretty heavily.

 

[luke8888]

My knowledge about scraping is very limited, but you asked about good power scraped surface pictures so there you go.

This is a Polish made cast iron Surface plate 500x500mm (20x20''). These were mass produced and they were most certainly power scraped. I can't be sure when it was made, but when it came to me it had a 1998 calibration lab sticker. So I assume it hasn't seen a lot of use(or it wouldn't pass). The discoloration in the right corner is my fault...

Here are some pictures. There is definitely some sort of pattern visible.

 

[eKretz]

My knowledge about scraping is very limited, but you asked about good power scraped surface pictures so there you go.

This is a Polish made cast iron Surface plate 500x500mm (20x20''). These were mass produced and they were most certainly power scraped. I can't be sure when it was made, but when it came to me it had a 1998 calibration lab sticker. So I assume it hasn't seen a lot of use(or it wouldn't pass). The discoloration in the right corner is my fault...

Here are some pictures. There is definitely some sort of pattern visible.
View attachment 397054
View attachment 397052

I don't know if it's just the photo but that does not look great to my eye. The close up marks look like the scraper was not sharpened to a high level, and the far view shows what looks like a lot of non-random patterns, which don't bode well either. Take a look at Peter's image to see what a good scraped surface ought to look like.

 

[eKretz]

As an aside, I found this some time ago. Some of you may find it interesting. Scraping, automated!

Scraping｜Precision subtractive processing｜Advanced Manufacturing Business Unit and Next Generation Project Division, Nikon Corporation

This webpage introduces examples of scraping performed by Nikon's original metal subtractive processing machine.

ngpd.nikon.com

 

[luke8888]

I don't know if it's just the photo but that does not look great to my eye. The close up marks look like the scraper was not sharpened to a high level, and the far view shows what looks like a lot of non-random patterns, which don't bode well either. Take a look at Peter's image to see what a good scraped surface ought to look like.

To be fair I did choose an angle to show that pattern better, but the proof is in the use of that plate.

Peter's scraping looks nice, but does it have to be absolutely random like this? I seriously doubt a hint of a pattern that shows under certain lighting causes any issues. Also this is not a master plate. It is shop use plate with overall flatness of 8 microns(3tenths) or so if I remember correctly.

It did pass the calibration so it certainly was flat enough back then. I've been using it as my general use measuring surface plate. So I don't have to wear my granite AA grade plate when I don't need it. When I got it I checked flatness against a long knife edge (union jack pattern) and a light. No issues there. Also I slide my height gages across it's surface a lot and I have never found any unevenness, bad bearing surfaces, nothing catches etc.

So in my opinion it is a very good scraped surface. Techniques and equipment may vary, but what matters IMO is function. This plate performs its function adequately. Would it pass 1 micron across certification? Unlikely. I never saw any scraping that would, so as mentioned I may not be the best person to judge.

I suspect they did use a different technique to scrape these than let's say they used on machine ways. Other examples of this product I saw were scraped the same way. If I compare it with scraping on let's say my surface grinder's ways, the scraping on the ways is very different. A lot shallower and wider. This looks deeper and more point like. I wouldn't be surprised if it was a result of some special technique they used for these plates only.

Here is another one of these on a local auction site (you can just about see the same pattern there through that oil, unfortunately some clueless people wire wheel these (ouch!) and they loose this pattern, but it is visible if you look closely.).

 

[eKretz]

To be fair I did choose an angle to show that pattern better, but the proof is in the use of that plate.

Peter's scraping looks nice, but does it have to be absolutely random like this? I seriously doubt a hint of a pattern that shows under certain lighting causes any issues. Also this is not a master plate. It is shop use plate with overall flatness of 8 microns(3tenths) or so if I remember correctly.

It did pass the calibration so it certainly was flat enough back then. I've been using it as my general use measuring surface plate. So I don't have to wear my granite AA grade plate when I don't need it. When I got it I checked flatness against a long knife edge (union jack pattern) and a light. No issues there. Also I slide my height gages across it's surface a lot and I have never found any unevenness, bad bearing surfaces, nothing catches etc.

So in my opinion it is a very good scraped surface. Techniques and equipment may vary, but what matters IMO is function. This plate performs its function adequately. Would it pass 1 micron across certification? Unlikely. I never saw any scraping that would, so as mentioned I may not be the best person to judge.

I suspect they did use a different technique to scrape these than let's say they used on machine ways. Other examples of this product I saw were scraped the same way. If I compare it with scraping on let's say my surface grinder's ways, the scraping on the ways is very different. A lot shallower and wider. This looks deeper and more point like. I wouldn't be surprised if it was a result of some special technique they used for these plates only.

Here is another one of these on a local auction site (you can just about see the same pattern there through that oil, unfortunately some clueless people wire wheel these (ouch!) and they loose this pattern, but it is visible if you look closely.).


View attachment 397062

If it came like the one in that image, that may explain why it looks a bit dull. Did you have to clean rust from the surface like that one has? The patterns don't *have* to be completely random everywhere, but that's sort of the way it ends up with the progression of the scraping from start to finish. You hit less and less spots as you go, and in different directions. End result is that you don't usually see things like those multiple, large, regular square areas that were clearly done all at once, at the end. Doesn't necessarily mean it's not fairly flat, just looks like a quickie job if it is. I'd like to hear Rich's thoughts on this one, but he is apparently out of commission for a bit. Not sure if he's reading the posts here at the moment.

 

[luke8888]

If it came like the one in that image, that may explain why it looks a bit dull. Did you have to clean rust from the surface like that one has? The patterns don't *have* to be completely random everywhere, but that's sort of the way it ends up with the progression of the scraping from start to finish. You hit less and less spots as you go, and in different directions. End result is that you don't usually see things like those multiple, large, regular square areas that were clearly done all at once, at the end. Doesn't necessarily mean it's not fairly flat, just looks like a quickie job if it is. I'd like to hear Rich's thoughts on this one, but he is apparently out of commission for a bit. Not sure if he's reading the posts here at the moment.

It came pretty much as is now(minus the discoloration in right bottom corner which is burnt rosin - soldering flux).

That it was "a quickie job" I'm sure of :-)
These were made in a production line setting (not a one off) in a system where workers were told to do "150% of the norm" and those that did 200% got medals... But where it really mattered products were checked against norms and certified.

Still it is not a master, or a reference surface plate, in fact it's not even considered a measuring plate, but a "tracing plate". Measuring plates had product designation MLFa and MLFb (depending on size, not class, class was separate). This is MLFc, a tracing plate.

However, it is worth noting back in the day there was a law that actually made it illegal for a workshop to make certain things (such as surface plates, gages, anything on a list published) unless they were authorised to do it and the items were certified afterwards. This means only well tooled up establishments got to make gages, surface plates etc. Quality control for measuring equipment and tools was pretty good. I collect old stuff like this and I've yet to come across any shoddy work. Don't get me wrong. There was lots of shoddy work in the communist system, but it seems tools are one thing that was good (or only good ones survived?)

So what is the flatness standard for cast iron scrapped "tracing" plates? Idk I'm still looking for it.

 

[Richard King]

The last few years of my fulltime job of rebuilding precision machine tools I worked or Minnesota Grinding and they had several Studer Swiss made cylindrical grinders. Studer has developed a process that uses their own material with similar characteristics as Moglice Moly Epoxy. they cast the ways out of their materials on-top of vibration dampening epoxy granite bases. they cast the way surface or mold it. they cast small dimples or approximately 1/4'' dots that the cast iron slides run against to eliminate scraping. my math is a bit foggy today but if you have 1 sq inch divided into 1/4' squares divided by two. the dots are approx. .020'' high. i copied a link to a picture out of the Studer catalog showing them on the base that the table rides against. So 50% rides on the dimples and 50% is a low area where oil flows. my point is precision scraping is needed on the old style machine tool and test bars -straight edges or cast iron parts if its not made the new method Studer has patented i would think

https://pdf.directindustry.com/pdf/studer/s31/26168-975351-_10.html.