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I Need Some Magic - Scrapping a Master

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  • I Need Some Magic - Scrapping a Master

    Yes, I said "scrapping". As in, "lets throw the master out the window and find a new way of doing it" (Forrest will probably go ape-sh*t on my newb ass for asking this ... )

    As most of you know, I've got a couple of "project" machines on my plate but I can only work on them during the "holiday breaks". I've got free time during Thanksgiving, Christmas and then "spring break" but my machines seem to be scattered all over the midwest, which makes this whole restoring-machines-gambit a little challenging.

    Anyhow, I've started working on the shaper project again and I wanted to touch up the ways on the vertical height adjustment mechanism. I refer to this as the head of the shaper, although this may not be the correct term.

    I don't have a master for the dovetails so I was wondering how you folks would go about making sure everything is flat/parallel etc without a master for the dovetails.

    I've been reading Connelly's book but it seems like it's pretty tough to do what I want to do with out a master. I also made a new gib for the head, since the old one was broken. Before I scrape the gib, I wanted to touch up the ways - "to correct for wear" (Forrest's words from an older post) but without a master ... how do I do this??

    I can get the flat part of the bearing surfaces easily with a surface plate, but the angled part and the mating dovetail are a little bit tougher...

    And an obligatory picture of the machine in question. Unfortunately, I don't have any good pics of the parts, so this is essentially a meaningless picture in the context of the thread ... but I think it's purty so I'm putting it up

    Last edited by Fasttrack; 12-19-2009, 01:01 AM.

  • #2

    I'm glad you got Ahab's harpoon out of her before you posted a picture!


    • #3
      Originally posted by Hollowbuilt
      I'm glad you got Ahab's harpoon out of her before you posted a picture!

      LOL - well I suppose beauty is in the eye of the beholder. She's a whale, alright ... tips the scales at about 7500 lbs, IIRC. In that pictures, she just had about 20 years of bird filth hosed off. That's what the puddles are from


      • #4
        Originally posted by Fasttrack

        I don't have a master for the dovetails so I was wondering how you folks would go about making sure everything is flat/parallel etc without a master for the dovetails.
        the short answer is you can't.....but that dovetail doesn't look very long. A master is easily made once you get a suitable hunk of cast iron.

        you can either scrape one surface (spotting on a surface plate) of something flat with an acute enough angle to fit in the dovetails and then you use a shorter scraped angle block to check each end.....or make a shorter female angle block and scrape two sides of the master so the master gets things both flat and at the right angle (the later is more time upfront toolmaking, less time time later on)....or make a road trip and use one of mine

        ...but its one of the two...scraping only works by gettng surfaces flat via comparison to a master
        Last edited by Mcgyver; 12-19-2009, 01:22 AM.


        • #5
          No bat debris here. And you don't really need a fancy camel back straight edge with a scraped angle on it for a short slide like on the tool post slide of your shaper. That shaper is a whopper.

          Like McGyver says, small scraping masters for dovetails are not hard to make. Take a hunk of any old kind of metal of suitable sze, get a dovetail angle on it somehow then scrape it to suit the two intersecting flats represented by the male dovetal. Use the existing least worn part of the dovetail for an angle reference and the surface plate for a flatness reference. Go back and forth and eventually you get a good angle at the interection of two flat surfaces of your new scraped reference resulting in an angled straightedge you can use.

          Naturally, cast iron is preferred but for a one-use tool, brass or aluminum will work so long as it's about dovetail length and you are careful not to ding it during scraping or use.

          You will have to file a small flat along the edge of the straight edge you made so it doesn't hang up in the unscraped part of the shaper's dovetail deep in the inside corner. You will also have to be careful to scrape a little relief in the tool post slide so a high ridge does't develop as youy scrape. This is a famous trap for the unwary. The straight edge will hang up and suddenly you get no more indications from the straight edge on the work. Only a little blue line way deep in the dovetail and some intermittant marks on the outer edge. elieve the inside way surfacce deep in the corner and the indications will come right back.

          It's tedious but if you keep at it you will whip it. You will learn a lot about scraping in that slide and once the DT matches and blues in, then fitting the gib. The Connelly book gives pretty good instructions on how to scrape dovetails back into factory original geometry. If you hit a snag and need a push in the right drection PM me and I'll send you a phone number; we can talk about it.
          Last edited by Forrest Addy; 12-19-2009, 08:22 AM.


          • #6
            Thanks Mcgyver and Forrest! I figured this would be a good project to start learning the ropes, so to speak. We'll see how I get along in the next week or so and if I run into any trouble, I'll be sure to PM you, Forrest. I sure appreciate that.

            I actually just got back from buying a bunch of used tools/scrap iron from a fellow in Chicago. In the boxes of stuff, there was an old scraper (I made one earlier with some help from Lazlo and PCarpenter but this one is bit "schnazzier" than mine ) and I also got a bunch of cast iron parts that I plan on practicing with. I've got a whole bunch of tiny compounds - but only the top slides!

            Anyhow, sounds like I'll be making a master. I'll have to see if I can find a chunk of CI to work. How about a piece of steel? I hear that it can be a real bear to scrape, though...