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Scraping the 123 blocks

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  • Scraping the 123 blocks

    When Forrest has his training days for scraping how do the students gauge the project 123 blocks for squareness?

    Do they make three at a time and use the three plate method to make the sides square to one another as written about in Michael Morgans scraping book?

    Or do they use other gauging items to check how square the blocks are?

    I am looking at making up a set and wondering if the method I have devised is similar to the proper way to do it..
    Precision takes time.

  • #2
    Squareness is determined by using a granite knee with the surface plate. The vertical of the block are printed using the knee.

    Comment


    • #3
      You do understand that 1-2-3 blocks are mostly used for stand offs to raise the work off the table and seldom if ever used to test squareness of something. There are better tools for that. Having them ground as square as possible without going to extremes is good enough for what they do.

      If scraping them is an exercise to perfect a skill that is another matter and there are better things that need to be a near perfect square surface.
      It's only ink and paper

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      • #4
        I haven't been to one of his classes (but remain hopeful) so this is just speculation.

        Forrest has discussed on this forum the fact that squareness can be self-checking with a technique for checking squareness using surface plate, an indicator and parallels. And since the class would be intended to give participants the foundational mechanical and analytical skills to be able to apply to other situations, it would be to the point to make 1-2-3 blocks square even if not required for most everyday setup.
        .
        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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        • #5
          We used a knee block and surface block in the class I took. There were also instruments for checking parallelism.

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          • #6
            In the course at Savannah a couple of years ago, we had a granite knee, as I said above. Forrest Addy and Steve Thomas taught the course. But nobody got close to finishing the 123 blocks at the course. Folks were scraping lots of stuff they brought, including squares.

            As to using the knee, you can ink the surface plate or the knee. Inking the surface plate has the advantage that you can mark the part all the way to the edge, but this is not so on the knee as it has a rounded corner. But it is more difficult to handle the part when marking if you ink the surface plate. This is because you must hold the part against the knee firmly to insure that the face touching the knee is parallel to the knee surface during the marking.

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            • #7
              If your taking a course in scraping surfaces square it may be better to square up a small to medium angle plate. You would only have to deal with two surfaces rather than getting six side parallel and square.

              Why make a learning process difficult from the start?
              It's only ink and paper

              Comment


              • #8
                Originally posted by Carld
                If your taking a course in scraping surfaces square it may be better to square up a small to medium angle plate. You would only have to deal with two surfaces rather than getting six side parallel and square.

                Why make a learning process difficult from the start?
                You are never working with more than two surfaces at any time regardless of the number of faces in the given examples. I don't understand the problem but I do look forward to learning more about your curriculum and class schedules.

                Comment


                • #9
                  When I first worked out the course content for the scraping class I was hard pressed to cook up a project piece for the lab work. It had to fit several criteria: small, low in cost, easy to prepare, readily packed in luggage, represents several separable scraping problems, has a familiar and practical use when completed, and above all presents a challenge that is not overwhelming.

                  I hit on making a set of four 1-2-3 blocks. There was cast iron material available from DuraBar and its competitors. The raw material cost was not excessive. The material was easily machined into a 1.020" x 3.005" x 9"+/- bar of starting material. It presented a 3" wide x 9" long surface a neophyte could develop his skill on. When finally scraped to 8 spots per square inch the first surface served as the reference for the next step: scraping the opposite side parallel AND flat. At this point there was no attempt to work down to desired thickness; all we wanted at first was FLAT.

                  The next step was to scrape the second face FLAT and PARALLEL to the first face. We used dial indicating comparators to verify parallelism. At this point some excitement ensued when the students discovered they can "split tenths" with nothing more than a little work with a scraper and a good reference.

                  The next step was to make one edge FLAT and SQUARE. There are a number of ways to make stuff square but the simplest for the class I was preparing is to use a granite knee as a square reference. The knee remains unblued. The blue instead is applied to the surface plate, the work's face is applied to the square and slid down so the edge contacts the blue. We demontrated everal alternativee of ensuring squareness.

                  The next step is the second edge where the student scrapes it SQUARE to the wide face, PARALLEL to the opposite edge and of course FLAT. By this time the class was nearly over. The 1-2-3 blocks were only started on and people are packing up and exchanging addresses and finishing off flea market deals. The student understands he has to finish the blocks at home and had been taught the ways and means of doing this. The block is protected and sawed into 2" + lengths, then the ends are scraped square and parallel, all the faces scraped to dimension and a suitable storage box lined with green felt obtained to contain these treasures for posterity.

                  Thus the class draws to a close. It is not all about scraping. There are about 6 hours of supporting lecture, demonstrations of technique, an informal flea market devoted to home machine shop stuff, impromptu seminars on a variety of subjects, and assistance with projects brought from home. Most of all there is a meeting of like minds and friendly faces put at last to long established electronic associations.

                  Taking all the factors of time, cost, practicality, etc, I think the 1-2-3 block project is about perfect. While I'm glad I made a wise decision, the meet, greet, working together, and trade probably has greater benefit for the students than my babble.
                  Last edited by Forrest Addy; 05-24-2010, 12:19 AM.

                  Comment


                  • #10
                    Forrest:

                    I agree with your use of the 1-2-3 block for a class project. I attented your class a few years ago in Springfield, VT

                    It was probably one of the best and most enjoyable technical classes I have ever attented. I STRONGLY recommend it to anyone.

                    Pete Burne

                    Comment


                    • #11
                      Originally posted by Forrest Addy
                      I hit on making a set of four 1-2-3 blocks. There was cast iron material available from DuraBar and its competitors. The raw material cost was not excessive. The material was easily machined into a 1.020" x 3.005" x 9"+/- bar of starting material. It presented a 3" wide x 9" long surface a neophyte could develop his skill on.
                      Well I have hit a dead end... Rectangular or square cast iron bar is not available in this country....

                      It gives you the ****s the totally pathetic range of materials we have available here.... it seems to be limited to 1018, 4140 in rounds and extruded aluminium.
                      Precision takes time.

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                      • #12
                        Any help?

                        Any help Ringer?

                        http://www.google.com.au/#hl=en&sour...e43c1db0d92f02

                        I haven't tried any of them - I just Googled it to sse what might be there in OZ.

                        Comment


                        • #13
                          Forrest, that was interesting reading on why you selected 1-2-3 blocks for the learning process. I can see where it would be good for learning how to get two sides parallel and then learning how to make a side perpendicular.

                          I still would rather use a small, say 3"x3"x3" angle plate as a project if I were to take a course in scraping. To me the angle plate would be a more worth while project but there is always a difference in what tool a person values accuracy on and from what I read the class is not locked on using the 1-2-3 blocks.
                          It's only ink and paper

                          Comment


                          • #14
                            All squared away

                            Carl.

                            matched accurate sets of 1-2-3 (and upward) blocks are very useful, but given what is available I sure would not be making any.

                            Check out the normal and ultra accuracy unite here:
                            http://www.littlemachineshop.com/pro...Product+Search

                            I am more interested in accurate cylinder squares, angle plates and machinists squares:
                            http://www.littlemachineshop.com/pro...2742&category=

                            http://www.cdcotools.com and search for square
                            etc.

                            Comment


                            • #15
                              Originally posted by Ringer
                              Well I have hit a dead end... Rectangular or square cast iron bar is not available in this country....
                              Ringer, that would really surprise me. Continuously-cast iron (Dura-Bar and Versa-Bar here in the 'States) is a staple of industry.

                              I just did a quick Google search of "Continuously Cast Iron Australia", and there are a bunch of hits:

                              Flocast sounds promising:

                              http://www.flocast.com.au/

                              Manufacturers of:

                              * Continuous Cast Iron and SG (Ductile) Bar
                              * Centrifugally Cast Iron and SG (Ductile) Hollow Bar
                              * Continuous Cast Bronze Bar
                              * Centrifugally Cast Bronze Hollow Bar
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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