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Thread: Advanced Fettling 404

  1. #1
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    Advanced Fettling 404

    This post will be linked at the end of the original Fettling old metal planes in the Neanderthal wisdom/FAQs Sticky.

    Occasionally, the threads in the base of a plane may get stripped. Cast iron is funny that way. For repairs, I have used JB Weld since that is what is on hand. It has worked for me. Like many products, it is probably best to let it harden for at least as long as the directions suggest.

    Other Creekers have suggested some products that one may choose to use, Form A Thread from Locktite and another called Belzona which has different formulations for different metals. My experience is limited to JB Weld. If these other products are better than JB Weld, then they will be awesome.

    The hole was cleaned using Q-tips and lacquer thinner. The cut off nail in the picture was used to push the mixture into the hole. A layer of tape was used to get the diameter close to the drill size, #17. The tape was not overlapped. In my case, since there just happens to be some in the shop, teflon tape was used. Regular clear tape should be good enough. It may not really be needed.

    Drilling.jpg

    The tap is a 12-20 which is available from Victor Machinery Exchange (victornet dot com). They have a minimum order of $25 so I bought 3 taps and ground the tip off of one to make a bottoming tap. The current list price on the tap is $9.50. It is listed under HS Special Thread Taps.

    WARNING WILL ROBINSON WARNING!!! If you like machine tools and such, avoid this site, you may be tempted by their close outs or other deals, DAMHINT.

    Tapping.jpg

    The hole only has enough depth for about four or five threads. It is probably a good idea to count how many turns you are making with the tap so you do not go too far and pull out all the new threads. Also, a starting tap will not be able to go the full depth. That is why a bottoming tap is needed. For one of those, you will need to make one from an extra tap.

    After forming the threads, the oil and chips need to be cleaned from the hole and the tote bolt installed. If the threads on the tote bolt are bad, you will need to find a way to repair them before installing the bolt. I have used the multi-piece adjustable 1/4-20 dies with good results. Be careful to not over tighten the tote bolt. My method is to lightly wiggle the bolt while tightening. When the bolt doesn't wiggle any more, if it is firm in its position, then that is where I stop. I also pay attention to how many turns it has been given. The goal is to engage as many threads as possible without damaging them.

    Mount Bolt.jpg

    When assembling a plane, it is easiest to instal the tote before the frog.

    After the plane has been assembled, it is time to test it out. Oops, this plane is making shavings left and right, but not center.

    No Middle Shaving.jpg

    That means the sole is convex laterally and needs to be lapped. After one fresh strip of 80 grit abrasive, the shavings are showing an improvement. They are shown as they came from the blade, left to right. There is still almost a thousandths of an inch difference in the center shaving, so more lapping is needed, but not tonight.


    Getting Better.jpg

    If you have never tapped threads before, this would not be a good first project. You should at least get a little instruction in the proper way to use a tap. Tapping threads also requires oil. I have used regular motor oil when tapping oil was not available, but the right oil for the job is always best.

    jim
    Last edited by Jim Koepke; 02-10-2010 at 2:02 PM.
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  2. #2
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    Thanks Jim
    always enjoy your pictorials and unpresuming manner

  3. #3
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    Good info Jim........ thank you!

  4. #4
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    or those of us just learning all of this stuff

    Thank You!!!

    Randy...

  5. #5
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    Glad to hear others find this useful.

    As I read this again, it seems a few things were overlooked.

    When drilling the hole, use a low speed and make sure you are at the correct angle. I used another plane sole as a guide and had the body in the vise so the hole would be straight up and down. Originally, I was thinking of using the drill press, but that seemed like too much set up work.

    The through taps come with some starting threads and do not fully form threads all the way to the tip. A bottoming tap does not have a pointed tip. To make one from a regular tap the tip has to be ground off. Be very careful doing this as heat will soften the tap and the threading area on a tap is sharp and if there is a slip when sharpening you may need band aids or worse. The metal is also brittle and it is easy to break off some of the cutting pieces.

    jim
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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