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Thread: Making Boring Bars for Hollowing on a Lathe

  1. #1
    Join Date
    Oct 2006
    Location
    ABQ NM
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    30,020

    Making Boring Bars for Hollowing on a Lathe

    I had a boring weekend in the shop. Boring bars, that is.

    I really like the 3/4" stainless steel boring bars that came with my Monster hollowing rig. However, they're limited to working through a 7/8" or larger hole, and I wanted to be able to go smaller. Over a year ago, I bought a set of Don Pencil "Stinger" 7/16" boring bars. They were a nice size, but I never did like the round bar cutting tips that came with them. Plus, the set screws to hold the cutters were tiny, and they stripped out way too easily (or my hex wrenches twisted because they were so thin).

    After reading about several guys recently making their own boring bars and Oland tools, I figured I should give it a shot myself. I wanted 1/2" bars that were capable of holding the 1/4" cutters that I already had for the Monster rig.

    Saturday, I picked up a 3' piece of 1/2" cold rolled steel bar and a few set screws at the local hardware store. The first three bars went so well, I went out Sunday and bought another 3' piece of steel and made a few more. Here are a few progress pics...

    First, I had to figure out how to drill a hole in the end of a 1/2" steel bar. I took a wooden screw clamp, and drilled a 7/16" hole between the two halves of the clamp.

    Attachment 30144 Attachment 30145

    That allowed me to hold the bar vertically and drill a pilot hole...

    Attachment 30146

    And then the final hole. (I don't know what size it is...I just experimented around until I found a hole size the 1/4" square HSS bits would fit in.)

    Attachment 30147 Attachment 30148

    Then, to hold the cutting tip in place, I needed a tapped hole for the setscrew. I ended up using a 10-24 screw, so the pilot hole was a #25 bit...

    Attachment 30151

    I also wanted to make a bar with an angled cutter, so I ground an angled flat spot on the end of a bar and drilled a hole to fit the cutting tip...

    Attachment 30149 Attachment 30150

    The angled bar also got a setscrew, but I didn't get any pics of that operation.

    I also made three different bent bars (with a little help from my propane torch), but didn't take any pics of the bending process.

    More in the next post...
    Attached Thumbnails Attached Thumbnails Boring Bars 01 - 800.jpg   Boring Bars 02 - 800.jpg   Boring Bars 03 - 800.jpg   Boring Bars 04 - 800.jpg   Boring Bars 05 - 800.jpg  

    Boring Bars 06 - 800.jpg   Boring Bars 07 - 800.jpg   Boring Bars 08 - 800.jpg  
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  2. #2
    Join Date
    Oct 2006
    Location
    ABQ NM
    Posts
    30,020
    And here are the results...

    Attachment 30152

    Here are the three bent bars. I'll probably make more after I see how these perform...

    Attachment 30153

    And here are the three straight bars. One is truly straight, one has an angled bit, and I ground one of them down to accept a scraper bit from the Monster gear.

    Attachment 30154

    Here's a detail shot of the angled bit...

    Attachment 30155

    And the scraper bit...

    Attachment 30156

    And as an added bonus, all of them (except the scraper bar) will accept my Hunter carbide insert...

    Attachment 30157

    All told, including steel bar material and setscrews, I spent under $20 to make these. Given my choice, I would have preferred to buy them from Randy at Monster Tools (assuming I could talk him into making 1/2" bars for me). Randy uses much better steel, and his tools are machined instead of hacked and ground. Unfortunately, being laid off, my tool fund ain't what it used to be, so these will have to do until I can afford to buy some better ones.
    Attached Thumbnails Attached Thumbnails Boring Bars 09 - 800.jpg   Boring Bars 10 - 800.jpg   Boring Bars 11 - 800.jpg   Boring Bars 12 - 800.jpg   Boring Bars 13 - 800.jpg  

    Boring Bars 14 - 800.jpg  
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

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