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[Noteworthy] Scraping In A Precision Straight Edge

Discussion in 'MACHINE RESTORATION & WAY SCRAPING' started by Ulma Doctor, Apr 11, 2015.

  1. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Thank You Pete!
    i'm not sure when the class is going to happen, but i'm looking forward to it.
    i'm considering having my own party again and inviting guests....:grin:
     
  2. Uglydog

    Uglydog United States Active User H-M Supporter-Premium

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    Hmmm.
    I gonna have to look, where is Tracy California??......

    Daryl
    MN
     
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  3. tertiaryjim

    tertiaryjim Active User H-M Supporter-Premium

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    Ulma Doctor Hinging?
    I have noticed differing ways parts move when swinging ( rotating ) them to check that the centers aren't high.
    Never thought to do this on the blue. Will give it a try when possible.
    That may have sped things up a lot when scraping the gibbs flat before fitting them.
     
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  4. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hi Daryl,
    we are just about 60 miles inland, SE of San Francisco and 70 miles S of Sacramento- pretty much putting us in the middle of the state.
    https://en.wikipedia.org/wiki/Tracy,_California
     
  5. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hi Tertiayjim,
    hinging is a way of testing the bearing of the scraped piece on a surface plate.
    a properly hinged part will hinge at about a 1/3 from the end, on both ends.
    you won't really need to have blue on the plate to do it though, it can be hinged on a bare surface plate.
    another method i use, i learned form youtube video's is the-Tap,
    or Thump as i like to call it-
    you'll simply lay the intended scraping victim on the surface plate, and give a nice solid thump with your forefinger on the piece in the corners of the piece.
    if the part is flat all you will hear is the thump of your finger.
    if the part is not flat, in reference to your surface plate, there will be a slight ring that will be heard.

    i hope the info is helpful to someone :)
     
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  6. Primitive_Pete

    Primitive_Pete Active Member Active Member

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    well when you do, there will be at least two from sebastopol.
     
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  7. tertiaryjim

    tertiaryjim Active User H-M Supporter-Premium

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    Thanks Dr.
    Am learning from books, U-tube, the posts of others, and experience.
    I learn more from my mistakes than anything else. LOL
    Working on my china lathe has been easy in that even a poor job is far superior to the factory work.
    Components no longer rattle when tapped and rigidity is greatly increased.
    Machining gibbs has been a pain in the tookus. So much to learn...
     
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  8. vettebob

    vettebob United States Active User Active Member

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    Now that you have the first side roughed go ahead and rough in the dovetail side before finishing it as the first side will likely move after roughing in the second side. Also what is your scraping depth remember Rich's 2-4 tenths deep and percent contact rules Bob
     
  9. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Thanks for reading Bob!
    it's funny that you said to go to the dovetail next...
    i already started the dovetail but did not post any updates yet.
    my hand roughing scrapes may be a little deeper than 4 tenths, but thanks for the reminder!
    i haven't really started scraping for points yet, i'm just trying to achieve proper bearing and hinging first.
    all the pointers are greatly appreciated :)
     
  10. The Liberal Arts Garage

    The Liberal Arts Garage United States Active User H-M Supporter-Premium

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    Hinging? Never really thought about it, but in a lifetime of fitting things with
    files and grinders, I've been doing it for years. BLJHB.
     
  11. ericc

    ericc United States Active User Active Member

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    Hi Ulma Doctor. I'd love to look on if you have this workshop. I am in the bay area.
     
  12. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hi ericc,
    you would be welcome to the scrape off too!
    i'll make announcement nearer the date for all that would like to attend.
     
  13. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hello again,
    i got back on the scraping horse again
    i have some updated pictures.
    the thread lives on!!!!

    here's the top side, the bevel is facing the viewer

    2016-06-05.jpg
    here is the spine below
    2016-06-05.jpg
    the bevel is pictured next, it's still slightly high in the middle minimal distal edge contact
    2016-06-05.jpg

    here's the back of the straightedge, it's coming along very nicely
    2016-06-05.jpg
    it's time for me to get serious again about the straightedge , it's holding up other work.
    the only way to get there is to keep working at it, slowly and surely and maybe even a little surly :grin big:.
    as always thanks for reading!
     
    Last edited: Jun 5, 2016
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  14. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Mike,

    Looking good!!!
    Might scrape it a little hard in the middle a couple times on the bevel to get more spread on the markings. Be sure to go back and recheck the top and bottom to make sure they didn't move when finished working the bevel.
     
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  15. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Thanks Ken, :grin:
    the bevel is high in the middle, i'll do as you suggested and hit it hard in the middle!
    i have been trying real hard to scrape opposing faces to minimize warp.
    I've also been wringing the reference occasionally throughout the process too!
    i appreciate the pointers very much, Thank you,
    feel free to point away! :grin:
     
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  16. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    the thread lives on!



    Carpe Diem!
     
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  17. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    and the latest edition!
     
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  18. Flightmap

    Flightmap United States Active User H-M Supporter-Premium

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    I too am trying my hand at scraping! For my project, I have an acquaintance who likes to re-build lathes, and he had an old craftsman lathe bed that he was going to scrap. It has two flat ways and should make a great scraping project for a straight edge. The bed is "good iron," old iron, stable, and reasonably flat and straight. I just couldn't see scrapping this quality iron. Resource met need so now I have a project and the material.
     
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  19. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    An Atlas/Craftsman lathe would be a great starting point, have fun with it!!!:grin:
    thanks for looking!
     
  20. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    here is the latest installment, video 3
     
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  21. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Act 4, with bonus footage!
     
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  22. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Mike,

    Looking good and getting better at it.

    When you get finished there, I'll send you a compound and cross slide to my 15" lathe that needs some "touch up" scraping done to it.:D

    Ken
     
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  23. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hi Ken,
    thank you very much!!
    I'd be proud to touch up your compound and cross slide! :grin:
     
  24. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    I had a little helper join me for this cycle,
    installment # 5
     
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  25. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Those little helpers, always show up when you are doing something in the shop. My little helper is my 3 year old grand daughter. She gets into my mill tooling and starts putting the drills/endmills into all of the open holes she can find. Any loos screws, carbide inserts laying around go into those holes, too. She loves playing with the step blocks, at least the smaller ones, can't quite pick up the bigger one's. When that happens, it's time to put her to work! Ken
     
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  26. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hi Ken,
    my son is interested in all the shop tools and in the movie making process too!
    i hope some of it sticks, he could be really good starting as young as he is!
    thanks for watching!
     
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  27. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    here is a parallelism check performed on the straightedge :grin:
     
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  28. Dresden

    Dresden United States Iron Registered Member

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    You are holding your scraper at to high an angle and not putting enough pressure on the stroke, grind your blade to a flatter radius, 12cm and use shorter strokes, you should actually make cast iron dust when scraping.
     
  29. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    you can tell all that from a couple still pictures, wow you must be a master!


    for the record, the scraping in those first pictures was done with antique carbon steel scrapers.
    the old style scrapers are ground to a 0* end relief
    the radius on the scraper was already pre-formed by a much more experienced scraper than you or i. i just sharpened the tool and put it back to use.
     
    Last edited: Jul 1, 2017

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