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Thread: Drilling and tapping shaper table for accessories: How to?

  1. #16
    Join Date
    Oct 2007
    Falls Church, VA
    Blog Entries
    I was taught (back in 1974) to always machine cast iron dry. The instructor said something about oil making the iron harder. Iíve never had any problems because the stuff machines really easy. But I always wondered why.

  2. #17
    Join Date
    Dec 2008
    Quote Originally Posted by Roger Feeley View Post
    I was taught (back in 1974) to always machine cast iron dry. The instructor said something about oil making the iron harder. I’ve never had any problems because the stuff machines really easy. But I always wondered why.
    Cast iron machines so well dry because of high graphite content formed in the casting process.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  3. #18
    Join Date
    Feb 2014
    Lake Gaston, Henrico, NC
    Here's the 1" threaded hole in the tractor block. It originally was 3/4". It got messed up when the 3/4" bolt sheared off in it. On the other side, I was able to get by with one step up to 7/8".

    Below those big holes were originally 5/8" threaded holes. I was able to clean up one of them, but the other three had to be upsized to 3/4".

    Cutting the 1" threads, I used a 24" 1/2" drive breaker bar. It was pretty hard to cut. I'm not sure if the oil mattered, or not, but I was scared to try it without it. It still took quite a bit of effort. The 7/8" hole was noticeably easier, and the 3/4" threads cut like butter.

    Here's the 1" hole. It came out perfect. I think it just has stuff in it in the picture.

    That tractor would have been almost useless, if I hadn't been able to get the sheared bolts out, and remount the loader.

    I bought that magnetic drill press just for that job. We tried drilling them with a 3/4" drill motor, but bent bits. I bought the drill press off ebay for about half the cost of a new one. I figured I could resell it, when I got through with it, for about what I had in it. I like it so much, that I decided to keep it. It's a monster tool!!
    Attached Images Attached Images

  4. #19
    Thanks for all the excellent advice so far. The suggestion to simply bolt on the feeder makes sense--as luck would have it, there is a rib in the general vicinity but I'm hopeful I can work around it. I think I will tap for the guards as they'll need to come on and off and I don't relish the idea of an arrangement where I've got to get inside under the hood to access the nuts.

  5. #20
    Join Date
    Feb 2014
    Lake Gaston, Henrico, NC
    I bought sets of individual sizes of taps, used off ebay, and only older, made in the USA brands. They all worked just fine.

    At first, I only bought the large sizes that I needed for that tractor work. I liked them so much, that I went back, and bought sets of three in every size from 1/4", up. I had the standard set of taps, and dies, but didn't have the plugging, and bottoming taps. I didn't get a single set off ebay that wasn't ready to use.

  6. #21
    Join Date
    Mar 2008
    Lots of good advice already given. I've drilled and tapped dozens of holes for various machines over the years and will tell you once you've done the first one.... your realize theres not much to it. While I'm sure specialty equipment may be handy in certain situations, it's not worth it here IMHO. If I have to drill and tap a shaper top for example, grab the feeder base, mark out the holes and use a punch to get a nice precise starting point. Then I grab my cordless Makita to drill the holes and use my taps, (of unknown Asian origin), to tap them and done. You can use oil to tap but don't need it and it just makes it messier IMO. Cast iron is just really easy to drill and tap.

    As for top thickness, my machines were generally of substantial size so usually no worries about top thickness..... though it is a good thing to keep in mind. Through bolts can work if needed, but its a lot quicker and easier if your top is thick enough to do without. I had through bolts for my table saw feeder and that was always a royal PITA to get setup

    good luck,

  7. #22
    Yep. Agree with Jeff. Some never notice how soft the tops are .....but just wonder why dropping the the wrench on the
    table always leaves dents !!

  8. #23
    Join Date
    Apr 2017
    Let's back up to your layout. I would do a careful layout on paper. Maybe with drafting tools, maybe with CAD. This will work better than just trying to lay out on the cast iron. Tape the paper in place and center punch.

    Now for the drilling and tapping, like so many other things, practice really helps. You might even practice your layout. The second one should come out better and you can overlay them to see if they are the same.

    I like the idea of a separate plate underneath with nuts welded on so you don't have to tap anything and the strain on the top is minimized.

    If you decide too bolt thru, and you have the table off, you can fill some areas with auto body filler so your bolts or plate have good bearing.

  9. #24
    No need to overthink this task. No tool rental required. As has been mentioned use the feeder base to layout your holes, avoiding ribbing. I make size on centre punches but you don't need to be that accurate as the bolts are undersized. Good centre punch to get started. Use your tap drill bit to drill through a square block of wood, say 2" thick. Now you have a guide to keep you square. Drill holes. Use your guide to start your tap, no lube needed in cast iron, it drills and taps like a dream. You'll be done before you know it.

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