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  1. #21
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    What Machinery are you using? This is sort of self defeating unless we know. Lathe, Mill, Pencil sharpener, Potato peeler, Sinker EDM, fingernail trimmer?

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    Quote Originally Posted by litlerob1 View Post
    What Machinery are you using? This is sort of self defeating unless we know. Lathe, Mill, Pencil sharpener, Potato peeler, Sinker EDM, fingernail trimmer?
    A Haas Lathe (ST-10).

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    I'm begining to like the end mill thing more and more with what you just said.

    I thought that your big end was .916 diameter and the part was 6" long.

    I would think that you would use a .005 rad mill tho.
    I think that he was saying that even a sharp mill can leave a decent finish if you use small enough steps.
    Not that he was especially recommending to do it.

    ???


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    Think Snow Eh!
    Ox

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    Quote Originally Posted by Bendak View Post
    A Haas Lathe (ST-10).
    Quote Originally Posted by Ox View Post
    I'm begining to like the end mill thing more and more with what you just said.

    I thought that your big end was .916 diameter and the part was 6" long.

    I would think that you would use a .005 rad mill tho.
    I think that he was saying that even a sharp mill can leave a decent finish if you use small enough steps.
    Not that he was especially recommending to do it.

    ???


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    Ox
    The ST doesn't have live toys. But it does have 6000 RPM, so the OP could potentially use the same concept (endmill).

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    Drill thru
    finish straight ID and OD
    flip and finish taper id's and thread(?)

    Easy peasy cmon guys are we professionals or not

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    Farm it out to Tay.


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    Think Snow Eh!
    Ox

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    Quote Originally Posted by litlerob1 View Post
    The ST doesn't have live toys. But it does have 6000 RPM, so the OP could potentially use the same concept (endmill).
    We also have a VM-2 I could use for the end mill, but don’t you think the deflection would be excessive or not so much as a boring bar?

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    The end mill will be solid carbide.
    It will have 4 edges on it.
    It will cost much less than the bar.
    But more importantly - it will not likely chatter as much as the bar since it is not in contact as much, AND provided that you get a "variable flute" mill to help break up the harmonics.

    Get one with like a .005 corner rad.

    ... OK ... get 3 or more, but ...


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    Think Snow Eh!
    Ox

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    Quote Originally Posted by Ox View Post
    The end mill will be solid carbide.
    It will have 4 edges on it.
    It will cost much less than the bar.
    But more importantly - it will not likely chatter as much as the bar since it is not in contact as much, AND provided that you get a "variable flute" mill to help break up the harmonics.

    Get one with like a .005 corner rad.

    ... OK ... get 3 or more, but ...


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    Think Snow Eh!
    Ox
    Less contact means less bite or engagement with the stock so might it just glide over the surface. What DOC would you suggest?

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    drills.jpg


    This is a 6mm hole going down to a 1mm hole in 8mm OD stainess steel.

    Had the drills reground, it is a straight taper 6mm down to 1mm.

    About 25mm long taper step drilled first.

    Maybe drill then finish bore?

    Two drills shown short taper drill was for a different part.

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    Quote Originally Posted by Bendak View Post
    Less contact means less bite or engagement with the stock so might it just glide over the surface. What DOC would you suggest?
    I think that you are looking at that bass akwards?

    Less contact = more pressure per sqr inch of surface contact.

    Baby steps


    I'll let the mill guys recommend better.


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    Ox

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    Quote Originally Posted by Bendak View Post
    Sorry about the small print, I guess that's the largest the image will show in the browser. As for a verbal description, the largest ID at the far right is 0.259", staying straight for 0.926". The hole then tapers at 1° per side for 0.724" until the ID becomes 0.234". The final portion of the hole tapers at 3° per side for a distance 0.276" down to the final ID of 0.205". Overall, the hole is 1.925" long, 0.926" of it being straight, and 1" of it as two different tapers. The OD in the beginning is 0.375", leaving 0.058" of wall thickness.
    Eventually this part will be welded to a longer section of straight pipe with the same initial dimensions as in this drawing. It is essentially a hollow auger made for the purposes of retrieving core samples from trees wherein a serrated half-pipe extractor "spoon" slides in to remove the wood sample from the auger. The taper is there to compress the 0.205" diameter wood sample to the teeth on the extractor so that the end of the sample can latch onto the spoon and break from the rest of the tree beyond the end of the auger bit. I am essentially attempting to reverse engineer an already existing tool known as an increment borer. Is has been done all on my own time with the intention of eventually receiving credit on such a project given its unforeseen complexity and time spent research. Let's just say that I had no idea what I was getting into when I first set out to machine this (the external threads are an entirely different story finished beforehand) but ended up enjoying the machining process so much that I have decided to stick with it since October of 2017.
    I don't know if it would be wise to split the part as the difficulty in welding such a part at that point would add to expenses given its internal geometry, but perhaps worth a try if all ends up going sideways. I very much appreciate yours and everyone else's input.

    Jack Ruddat

    That's funny that it is for a tree auger... I have a 3 inch scar on my left hand from just such a device from working in the woods when I was an undergraduate. Worst job ever. Spent two months doing it, made $300 and got giardia from the water they gave us. But I digress.

    I do similar holes with an endmill on a mill. If you set it up vertically on a vee block, drill all the way through. Then do a helical bore toolpath down to where it starts to taper. Then do a flow line toolpath down to the bottom of the 3 degree, then another flow line down to the bottom of the 1 degree. You can use a straight endmill or better yet something with a little radius on it. The programming is pretty easy assuming you a decent CAM package. If you are running Mastercam, I can help you out with what the program should look like. {I could also do it on the lathe with little boring bars, or with a custom ground reamer, or by die sinking it with an EDM, or using tapered endmills}

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    QT[ I may resort to attempting to machine my own custom tapered D-Bit] likely a D bit as I see most D bits having one flute will be such a harsh cut that it will/may not penetrate the stock, perhaps stall a machine..Even the 4 flute taper reamer I suggested in post #16 might do this and need the OD flutes to be serrated like a roughing end mill, so taking smaller bites into the stock with clearance angle on OD 12 to 15* primary, secondary perhaps 25-35*.

    For a one or few up you might grind two taper reamers (out of the same standard reamer) So only buying one reamer and having two operations..likely drill through 13/64 first.

    What process do you plan...to do the ID first with plenty of OD strength, then finish the OD last..
    or finish the OD to size and the ID last..

    deep core sample: (tool $150 to about $300)

    YouTube

    YouTube

    Sharpen auger:
    YouTube

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    But just to further muddy the water... since I'm guessing I'm the only one dumb enough to have spent time using one of these core drills (just to bring everyone up to speed, it is a 24" long auger with a hollow shank. It is attached to a tee handle. You get it started into the tree and then twist in to the center of the tree. Then you drive in a "spoon" which is a 24" half tube. You then back out the auger, pull out the spoon, and count how many blisters you have to age the tree... not really, you count and measure the rings to age the tree and estimate growth patterns. We were doing this in the most remote part of Idaho and Montana with grizzlies around each corner. The end is sharp enough to auger into your hand if you do something stupid)

    But anyhows… I sincerely doubt you need the double taper in the inner bore. My guess is it would work just as well as the commercial units (which is shitty) if you just had a single taper of just about any angle. It just needs enough to leave room for the wood to expand into the hollow bore. When you reverse the rotation, it will shear off.

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    Goo does the large bore (.259) lead in first or the small bore (.205)?

    looks like the small leads in to give the extractor some clearance.
    if so why would a counter bore perhaps with a short taper of two diameters (perhaps .030-.050 a side) with a short taper to the small diameter not work?

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    Quote Originally Posted by G00 Proto View Post
    But just to further muddy the water... since I'm guessing I'm the only one dumb enough to have spent time using one of these core drills (just to bring everyone up to speed, it is a 24" long auger with a hollow shank. It is attached to a tee handle. You get it started into the tree and then twist in to the center of the tree. Then you drive in a "spoon" which is a 24" half tube. You then back out the auger, pull out the spoon, and count how many blisters you have to age the tree... not really, you count and measure the rings to age the tree and estimate growth patterns. We were doing this in the most remote part of Idaho and Montana with grizzlies around each corner. The end is sharp enough to auger into your hand if you do something stupid)

    But anyhows… I sincerely doubt you need the double taper in the inner bore. My guess is it would work just as well as the commercial units (which is shitty) if you just had a single taper of just about any angle. It just needs enough to leave room for the wood to expand into the hollow bore. When you reverse the rotation, it will shear off.
    I originally went for a straight taper, but then the extractor spoon did not fit, so I changed the hole geometry to match that of the spoon’s profile. I wish I could more accurately measure the geometry of a real borer without spending money on expensive telescope gauges, etc. It makes sense that the wood would automatically shear off after backing out, but I wonder if that would be reliable enough, especially in very dry or decaying hardwoods. I wonder how the company makes these tools, especially if they are one piece implying some sort of modified gundrill or back boring bar.

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    How sure are you on the material?

    Could the current models be made out of 1215 or 8620 and be case hardened?

    THEN the tapered drills (I still dissagree with reamer) would stand a much better chance of getting you what you want.


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    Think Snow Eh!
    Ox

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    Quote Originally Posted by Ox View Post
    How sure are you on the material?

    Could the current models be made out of 1215 or 8620 and be case hardened?

    THEN the tapered drills (I still dissagree with reamer) would stand a much better chance of getting you what you want.


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    Ox
    Not sure about the material by 4340 for the threads and 4130 for the pipe was my best guess.

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    Harvey has a boring bar that'll do it.

    Don't pack it up with chips, leave a reasonable amount to bite on on your finish pass (.01 maybe) and get your feeds and speeds right. Should be fine. I'd program it to bore a bit (quarter inchish), retract, stop so you can clear any accumulated chips or stringers, then go back at it.

    If it bores without chattering at the front of the hole, it should work just as well at the bottom. The bar doesn't know the difference unless you pack up or run dry.

    http://www.harveytool.com/ToolTechIn...Number=29180XL

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    Quote Originally Posted by Comatose View Post
    Harvey has a boring bar that'll do it.

    Don't pack it up with chips, leave a reasonable amount to bite on on your finish pass (.01 maybe) and get your feeds and speeds right. Should be fine. I'd program it to bore a bit (quarter inchish), retract, stop so you can clear any accumulated chips or stringers, then go back at it.

    If it bores without chattering at the front of the hole, it should work just as well at the bottom. The bar doesn't know the difference unless you pack up or run dry.

    http://www.harveytool.com/ToolTechIn...Number=29180XL
    That just so happens to be the first bar I tried machining it with, although I broke it on accident (hit the part during a rapid). The bar lost it's tip initially which I think may be due to too fast a surface speed (300SFM instead of perhaps something like 80SFM).


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