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Home made boring bars?

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  • htrantx
    replied
    This is a good one

    I have to say this is a darn good idea; could never though of that. I had been looking for one to do a 8.5 mm hole...

    Thanks...

    [QUOTE=Evan]I posted this some time ago so I guess Paul may have forgotten it or didn't see it.

    This boring bar is made from a 1/4" grade 8 bolt with a 1/8 hole drilled coaxially though the end and a broken length of 1/8 carbide milling cutter driven in the bar for rigidity. The insert holder is a split socket head cap screw that threads into the end of the bar and clamps the insert in the end as it tightens. It will fit in a 1/4" hole.
    Last edited by htrantx; 04-02-2010, 12:54 PM.

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  • Black_Moons
    replied
    Cute technique, I never thought of carbide cored boring bars before!

    Hot Bob: Ahh. that is solid carbide.. odd how it only says so on the catalog page and not the ordering page.
    Wonder how on earth they drilled/taped that hole? Or maybe if the tip is something more standard.

    Theres an idea for your own high quality boring bars. solid carbide round bar + nub of steel brazed on the tip for the insert holder.

    Or maybe just a nub of HSS brazed on and replaced as needed. giving you the awsome rigidity of a carbide shank with the sharpness of HSS.
    Last edited by Black_Moons; 02-24-2010, 01:28 PM.

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  • Evan
    replied
    I posted this some time ago so I guess Paul may have forgotten it or didn't see it.

    This boring bar is made from a 1/4" grade 8 bolt with a 1/8 hole drilled coaxially though the end and a broken length of 1/8 carbide milling cutter driven in the bar for rigidity. The insert holder is a split socket head cap screw that threads into the end of the bar and clamps the insert in the end as it tightens. It will fit in a 1/4" hole.







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  • Hot Bob
    replied
    Originally posted by Black_Moons
    $14 per insert for those tiny boring bars? sheesh! Sold in packs of 10, wonderful, $140+toolholder before you can bore your first hole.
    http://www.use-enco.com/CGI/INPDFF?P...PARTPG=INLMK32
    You can nearly buy solid carbide boring bars for that price ($17...) likey a little more sharpenable and those indexable holders will not be as rigid unless they are also made of solid carbide.. and I did'nt see em advertiseing that
    (Can you even make an insert holder outta solid carbide? well I mean, can you make TINY threaded holes in solid carbide?)

    Down to 0.05" min bore, gez! tiny things.
    Here's a link to a carbide boring bar made by Circle with a min. bore of .260.
    http://www.use-enco.com/CGI/INSRIT?P...PMAKA=317-3463
    Certainly not cheap. I have a little larger Circle boring bar and it is nice. You don't have to buy the full package qty of inserts but they're still expensive.

    Bob

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  • Sportandmiah
    replied
    After some consideration, I think I will take another look at HSS and other forms of home made boring bars. Granted, inserts are easier, but I've done a lot of reading the past few days both here and other sites and there are more options to grinding my own. That being said, any assistance in grinding boring bars is appreciated.

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  • Black_Moons
    replied
    $14 per insert for those tiny boring bars? sheesh! Sold in packs of 10, wonderful, $140+toolholder before you can bore your first hole.
    http://www.use-enco.com/CGI/INPDFF?P...PARTPG=INLMK32
    You can nearly buy solid carbide boring bars for that price ($17...) likey a little more sharpenable and those indexable holders will not be as rigid unless they are also made of solid carbide.. and I did'nt see em advertiseing that
    (Can you even make an insert holder outta solid carbide? well I mean, can you make TINY threaded holes in solid carbide?)

    Down to 0.05" min bore, gez! tiny things.

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  • Carld
    replied
    Sportandmiah, If you start on the page on this link and go to the next pages there are indexable boring bars that may do what you want. Grinding HSS is much cheaper than buying inserts and both get dull.

    http://www.use-enco.com/CGI/INPDFF?PMPAGE=227&PMCTLG=00

    It's your call.

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  • BobWarfield
    replied
    Ya'll need a little CNC lathe for those tiny wheels if you're making so many!

    Cheers,

    BW

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  • darryl
    replied
    Well then. I had a very similar problem. I was making wheels almost identical to what you show, same scale actually. All I had at the time for a lathe was the Unimat. I had a lot of chatter and it was slow. That's a lot of metal to remove. So what I ended up doing is turning some tubing for the rim and some solid bar for the hub, parting those off with a hacksaw and pressing it together. I bored the ID to leave a bit of a step for the hub disc to press into and up to, then remounted that to finish bore the inside of the hub and the ID of the rim, then faced the rim and deburred. I did several that way, then turned a plastic stub that I could press fit each wheel onto to finish turn the OD, and finally drill the center hole. I think I still have some of the leftovers around here somewhere- oh, yeah, here's some tids



    I played with nylon hub discs which you see on the rims, and aluminum hubs, which you see with the stub axles attached. There aren't any of the all aluminum completed wheels left here. Behind the wheel parts are two of the fixtures for holding the parts on the lathe. The solid one is what the wheel presses over to machine the od, and the hollow one (with the bit of string or something wrapped around it and crazy glued in place) takes the od of the wheel so I could machine the inside. Each of these was mounted, trued to size, then used for all wheels before the second op using the other holding jig. I see that both were made using bondo.

    Man, that was almost 30 yrs ago- holy cow

    If you look carefully at the wheel on the left, you can see the bit of a step I made in the ID for the disc hub to press up to. What I found with the all aluminum wheels was that once the disc was pressed into place, it was pretty much there for good, and I could turn out the id, including the step, without disturbing the discs position. These wheels measure .827 ID and .929 OD.
    Last edited by darryl; 02-22-2010, 12:39 AM.

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  • Sportandmiah
    replied
    It appears there is confusion as to what I am trying to accomplish. It's my fault because I haven't explained it well or explained it wrong, so here goes.

    1. I take a piece of 7/8" aluminum solid round bar, maybe 3/4" long.

    2. I chuck that piece in a three jaw chuck, face, rechuck, and face other end.

    3. I start the process by drilling a 3/32 axle hole completely through the entire piece of aluminum, and use a reamer accordingly.

    4. I use the largest drill that will fit into my sherline jacobs chuck, and drill into the aluminum. To me this cuts down on the actual boring bar process. I do not drill all the way through, but .333". (That amount is enough for me to place some wheel details like hubcaps into the wheel when it is done.)

    5. Now I use my pre-sharpened 1/4" HSS boring bar and bore the wheel .333" until I get the .042" as seen in the picture.

    6. Mission complete.

    After making 2 wheels using the above process, I've decided that I do not want to use HSS. I make alot of wheels, and I have absolutely no desire to sharpen the tools over and over. I do sharpen my HSS turning tools, but I would rather use an insert or carbide for this process.

    Regards

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  • Carld
    replied
    So, which hole are you boring or should I guess it's the one .333" deep by .826"-.084"=.742"

    I'll SWAG that it's that bore. Do I get a prize if I'm right?

    I'll take one of the little cars when it's done and thanks in advance.

    You can buy the indivual boring bars for the boring heads and get the small one and hold it in a holder with a V bottom for round bars.

    Probably best to grind your own from a square HSS cutter. I have a bunch that I ground, if you need a photo let me know.
    Last edited by Carld; 02-21-2010, 09:13 PM.

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  • darryl
    replied
    Just for the heck of it, I searched for carbide rod. I got a site that showed diameters from 1/8 and up, and lengths from 1-1/2 and up. Pricing wasn't bad, and in my favor at least, it's a Canadian business. Carbide.ca. But they don't do retail-

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  • Sportandmiah
    replied
    Thanks for input all. I really like Glenn's small bar! Just to clarify here's some pics with measurements of the wheel. I apologize for not supplying this earlier. I used a pre-sharpened HSS boring bar at first, but would like to try one with an insert. The hole in the very center is the axle hole, 3/32 reamed. That is NOT the hole I am talking about boring.







    This photo shows the distance from the edge to the inside of the wheel.

    Last edited by Sportandmiah; 02-21-2010, 07:25 PM.

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  • Glenn Wegman
    replied
    I knew I should have posted the pic of the little one.....but I couldn't find it

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  • J Tiers
    replied
    You can grind boring bars out of HSS cutter stock, although it can be a bit tedious.

    To buy small boring bars tends to get expensive, they are not so commonly available in the standard 'sheep's foot" bar, although the smallest common type is probably small enough for a 1/4" hole.

    Glen's photo is of a BIG boring bar!

    Yes, this IS a boring bar..... in a lantern post holder.....

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