A few questions about scraping
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    Default A few questions about scraping

    Hey!
    I am learning scraping on my own. I researched a lot of information on the internet about this and read the chapters on scraping in Connelly's book and also bought and watched Richard King's DVDs several times.
    Now I am actively practicing and I have several questions to which I cannot find answers:

    1. Connelly's book says that the part must be placed on the surface plate in the same position in order to get a permanent imprint. Nobody talked about it anymore. Is this the right advice?
    2. In the documentation for Biax it is written after each pass it is necessary to rotate the part 90 degrees and start the pass from a new side so that the part rotates constantly if it is possible. In many videos, people simply change directions without turning the part every time.
    3. How to correctly count spots in a square. I see a few large spots, but I can also see that these large spots can be made up of smaller spots. There are also spots that have just touched the top of the paint, but are still at the very bottom.
    What spots should be counted?
    Here's an example of my square:
    2021-06-15-22-46-57.jpg2021-06-15-22-47-03.jpg2021-06-15-22-47-11.jpg

    Now I have gotten a more or less even distribution of spots on my training surface, but it seems to me that I have not yet reached 50-70 percent coverage. Is that enough or is it worth working more?
    2021-06-15-22-46-45.jpg

    When I made a rough pass, I got this result. This is normal?
    2021-06-06-22-13-11.jpg

    Thanks in advance to everyone for their help and advice.
    Nick

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    That's some very nice work you're doing there !

    1. Don't worry about it.
    2. That'd be impossible in many situations.
    3. Count it as TWO if you feel it can be split without effort.
    4. Well, it depends what you want to use the surface for.
    5. Yes, it's pretty normal. ( you will notice I did not say what the reason is... )

    I like your work but everything needs (lots of ) refinement starting probably with sharpening the scraper blade PROPERLY and (!) right for the kind of scraping you do - there are basically four flavors. Maybe five. I suggest you look for posts by Forrest Addy on this forum. Forrest was ( is ) a very smart and profoundly experienced individual and his advice is 2nd to none. Tons to learn from his posts. There are also two other members who actually worked as scraper hands for SIP - I'll try see if I can put you in touch with one of them. Always good to pick up the minds and experience of people who scraped the sub-micron jig borers : lots of nifty tricks.

    Anyway, best of luck with your efforts and drop a PM if anything else I could help.

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    It's late. I will comment on your work tomorrow. If you contact Forrest ask him who taught him to scrape. Yours truely.

    Come Join my scraping and rebuilding forum on Facebook, King-Way Scraping Consultants, we have 6 pro's and over 700 members. Also look on You Tube under "Richard King scraping" many of my students have down some great shows. Stefan Gottswinter and NYC CNC - John Saunders and Jan Sverre Haugjord have some good ones.

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    Here is what I think and teach.

    Quote Originally Posted by Nickki View Post
    Hey!
    I am learning scraping on my own. I researched a lot of information on the internet about this and read the chapters on scraping in Connelly's book and also bought and watched Richard King's DVDs several times.
    Now I am actively practicing and I have several questions to which I cannot find answers:

    1. Connelly's book says that the part must be placed on the surface plate in the same position in order to get a permanent imprint. Nobody talked about it anymore. Is this the right advice?

    This means in the old days when Connelly organized the book (1950's) surface plates were not as consistent as they are today. Not as many granite places and most scrapers were using scraped cast iron that isn't as accurate as a A or AA grade granite is today and if you set it in various spots you may bet different readings. They wanted you to use the same area to blue your part up to get the same reading every time from that same spot. A simple method to compare how accurate the plat is , is to move the plate around the plate and "hinge" the part and if the plate is good your plate or straight-edge should "hinge" and blue up the same. "hinge is what I call it when you pivot the training plate to be sure it is flat. A flat plate hinges approx. 30% in from each end. I show that in my DVD you purchased.

    2. In the documentation for Biax it is written after each pass it is necessary to rotate the part 90 degrees and start the pass from a new side so that the part rotates constantly if it is possible. In many videos, people simply change directions without turning the part every time.

    Most of the time we move our body from one side of the part to get the "Checker booard" Look on the parts, whether it is the training plate or machine part. I did a class at KingsBury Babbitt Company : https://www.kingsbury.com/pdf/R-S_Brochure.pdf
    Page 2 and 5 show the scraping techs. Kingsbury had huge rotating air tables the would use to rotate the parts to get the 90degress swings. In the majority of parts I scrape I move my body or switch hands to come in at 90 degs as again I show in my DVD or now I have HSB sticks.

    3. How to correctly count spots in a square. I see a few large spots, but I can also see that these large spots can be made up of smaller spots. There are also spots that have just touched the top of the paint, but are still at the very bottom. Your square counts to about 12 to 15 PPI (Points per 1 inch) and if you were to split the big ones up you could easily have 20 to 25. Your percentage looks like about 40 to 50%.

    What spots should be counted? You can use less bluing too as there are small smears on the training part that cause the merging of the high spots. Another method on the 3rd section of my of my DVD is where I have you rub the blued (red ink) rub the part of a non inked surface and shine up the part. This will highlight the highest points, as this makes the very highest points shine like a mirror. When your going for 40 PPI that is used on surface plates, straight-edges and super precision machines.

    Here's an example of my square:
    2021-06-15-22-46-57.jpg2021-06-15-22-47-03.jpg2021-06-15-22-47-11.jpg

    Now I have gotten a more or less even distribution of spots on my training surface, but it seems to me that I have not yet reached 50-70 percent coverage. Is that enough or is it worth working more?
    2021-06-15-22-46-45.jpg

    When I made a rough pass, I got this result. This is normal?
    2021-06-06-22-13-11.jpg

    Thanks in advance to everyone for their help and advice.
    Nick

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    The 2 bottom pic's have holes in them where you marked them with a sharpie. Those look great, but as most rookies do, they start scraping to good to soon. You should continue to rough scrape until you can lay the control gage (you 3 D printed one on every part of the plate and have 5 PPI in the square. Once you have eliminated the open no blued areas, then you start to scrape the higher PPI. Again you can split the large areas up to get more PPI. Also your depth of the cut looks good. In picture 2 I show how we check the Depth or the difference from the top of the high spot to the bottom of the low spot that will eventually be an oil pocket. 0.0051 mm to 0.0012mm The drawing of the hgh spots came from Sip in Switzerland and BIAX and this is how we evaluate the PPI. The 2nd line down is what we use to machines and parts. 20 PPI to 40 PPI with 40 to 60% contact. Picture 1 is a ground stone that works great to stone super flat scraping parts. The photo was taken in Austria.

    20171201_101415.jpg20200222_173339_resized.jpg20191022_112958.jpg20170201_142032.jpg20170114_095048.jpg

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    Sorry for the duplicate. I tried to delete this one.

    If your in Europe you can buy my DVD from BIAX Germany Scraper - BIAX and here in the USA from DAPRA https://www.dapra.com/biax/scraper-training or buy it directly from me or on eBay.
    One of our Members who attended one f the Austrian classes is Ballen standing next to our Austrian host Franz.

    Machine Scraping | Cottage Grove, MN 20160703_144737-1-.jpg20171030_091919.jpg20171030_091940.jpg20181114_145452.jpg20170201_142101.jpg

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    If your in Europe you can buy my DVD from BIAX Germany Scraper - BIAX and here in the USA from DAPRA https://www.dapra.com/biax/scraper-training or buy it directly from me or on eBay.
    One of our Members who attended one f the Austrian classes is Ballen standing next to our Austrian host Franz Lutfinger. and some more charts I pass out at my classes. The sales manager at BIAX Germany is from Russia too. y I also added another GREAT book "The Foundations of Mechanical Accuracy that can be purchased from Moore Special Tool Jig Grinders | Jig Grinder Remanufacturing | Precision Manufacturing



    Machine Scraping | Cottage Grove, MN 20160703_144737-1-.jpg20171030_091919.jpg20171030_091940.jpg20181114_145452.jpg20170201_142101.jpg

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    Thanks for such a detailed answer Richard!
    I will be consistent
    Quote Originally Posted by Richard King View Post
    What spots should be counted? You can use less bluing too as there are small smears on the training part that cause the merging of the high spots. Another method on the 3rd section of my of my DVD is where I have you rub the blued (red ink) rub the part of a non inked surface and shine up the part. This will highlight the highest points, as this makes the very highest points shine like a mirror. When your going for 40 PPI that is used on surface plates, straight-edges and super precision machines.
    I took a few photos with notes of different variants of counting the spots.
    One photo is clean and on the rest I showed with numbers what places I can count as a spot. Which of these photos am I on the right track?
    cute.jpg cute-3.jpg cute-1.jpg cute-2.jpg
    Quote Originally Posted by Richard King View Post
    Also look on You Tube under "Richard King scraping" many of my students have down some great shows. Stefan Gottswinter and NYC CNC - John Saunders and Jan Sverre Haugjord have some good ones.
    I watched all these videos as well as the channel Abom79. I found a lot of useful information there and thanks to this I began to make my first successes.

    Quote Originally Posted by Richard King View Post
    The 2 bottom pic's have holes in them where you marked them with a sharpie. Those look great, but as most rookies do, they start scraping to good to soon. You should continue to rough scrape until you can lay the control gage (you 3 D printed one on every part of the plate and have 5 PPI in the square. Once you have eliminated the open no blued areas, then you start to scrape the higher PPI. Again you can split the large areas up to get more PPI. Also your depth of the cut looks good. In picture 2 I show how we check the Depth or the difference from the top of the high spot to the bottom of the low spot that will eventually be an oil pocket. 0.0051 mm to 0.0012mm The drawing of the hgh spots came from Sip in Switzerland and BIAX and this is how we evaluate the PPI. The 2nd line down is what we use to machines and parts. 20 PPI to 40 PPI with 40 to 60% contact. Picture 1 is a ground stone that works great to stone super flat scraping parts. The photo was taken in Austria.
    I try to learn how to do a good quality rough scraping. I realized how important this is.
    I also try to work out the correct movements with the scraper. I remember the Richard King's 4 Rules and develop the habit of following them.
    So far, I have not been able to get a stable result with rough scraping. My spots change location frequently. I still cannot understand the reason for this.
    I am working with a carbid plate with a radius of 90 and a negative angle of 5 degrees. I do the strokes 3/8-1/2".
    I also measure the depth of cut. It fits into the range you specified and sometimes even a little more.
    The cleaning stone you are talking about, I will now order. So far I am using an old and not very smooth aluminum oxide stone.
    I took a photo with a lot of spots when I decided to try it. It was interesting for me to experiment. I reduced the stroke length in half and got this result.
    I'll go back to the rough scraping again to perfect my craft.

    Quote Originally Posted by Richard King View Post
    If your in Europe you can buy my DVD from BIAX Germany Scraper - BIAX and here in the USA from DAPRA https://www.dapra.com/biax/scraper-training or buy it directly from me or on eBay.
    One of our Members who attended one f the Austrian classes is Ballen standing next to our Austrian host Franz Lutfinger. and some more charts I pass out at my classes. The sales manager at BIAX Germany is from Russia too. y I also added another GREAT book "The Foundations of Mechanical Accuracy that can be purchased from Moore Special Tool
    I have already established contact with BIAX in Europe and received a lot of useful information for myself from them.
    The Foundations of Mechanical Accuracy is a very good book. I already found it on the Internet and got acquainted with the content. I will study it gradually.

    My problem now is the quality of the strokes. I can't make strokes of the same length with the same distance between them.
    I try to do "tap tap" but it is not always convenient for me, so I start to do the movements that pattern "Z" gives.
    I also do not understand how to make very short strokes when finishing scraping 1/8-1/16". It seems to me that the scraper is very difficult to control. I guess I still have very little practice.

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    That thing Richard King said about scraping too good too soon really is the truth. I found it hard to avoid at first, and I'm still no expert.

    But I have found that if you rough scrape for overall contact, and you vary your direction of scraping strokes on every pass, so as to come from all angles, then when you are ready to refine the spots, you start splitting spots and suddenly it starts to come in very rapidly. It sometimes seems like magic. As things get better, shorter strokes, yes. Higher angle helps there, and also not using all arm movement. Body movement seems to be more controllable, and best if the work is at a height wher you can brace against your hip.

    It seems that if you do arm movement, it is too easy to overshoot the stroke length when the initial cutting resistance is gone. With your weight behind the stroke, the scraper just moves regardless of resistance, so no extra force, and less risk of overshoots.

    Of course, mostly I am not doing reference surfaces, but sliding surfaces, so 15 spots is generally fine for me, maybe 20. It takes more passes of shorter strokes and the scraper at a higher angle, to get reference surface quality.

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    You need to learn how to Bump Scrape....scroll up to 5:27 min..bump scraping richard king - Bing video


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