Tapered-shank drill bits in a tailstock - stupid question time
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  1. #1
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    Default Tapered-shank drill bits in a tailstock - stupid question time

    Just asking a question before I make a potentially bone-headed mistake. Maybe it's a stupid question, but given the stakes I figure I better ask it.

    Would it be good practice to seat a #3MT drill shank directly into my tailstock taper for a heavy 1" (or thereabouts) drilling operation? Or is there a better, safer way of holding a drill bit which will not risk damage to my tailstock if the tool were to bite in and spin? My tailstock taper is not keyed, nor does it have any sort of 'pawls' to interface with the drill shank's tang. A spun tool would ruin it's accuracy in a heartbeat.

    Go? No-go? Best practices?

    Be gentle, lol.

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    One of the old time forged tool companies (maybe Williams or Armstrong) made a socket for taper shank drills that had a long handle sticking out the side and a center hole that you could push with a tailstock center. I have never had one, but have seen pictures.

    Larry

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    Would a drive dog secured to the shank of the drill be a reasonable insurance policy against spinning?

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    you should be fine if you drive the drill into the tailstock.

    Tap it in with a soft faced hammer just to set it if you can.

    One spin is not going to ruin your tailstock. Make sure the socket is clean and the taper shank.

    if it spins, pull back on the tail stock ASAP.

    if it's a gummy material maybe not... brass, bronze it's a good idea to slightly blunt the leading edge of the drill bits edge. put flats on that scrape... that will avoid biting in and spinning.

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    If you're worried, put a lathe dog on the body of the drill in front of the taper and let it rest on a bar clamped in a toolholder on the cross slide. A long boring bar works pretty good for a rest for the lathe dog tail.

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    How big a lathe? What kind of toolpost? Can you get a 3MT holder for it? Not cheap, but comes with a free power feed.

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    You can remove the quill and drill and tap it for 2 set screws to catch the flats on the tang of the drill, a old idea that works...phil

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    13" South Bend. I've got a Multifix 'A' tool post on the way for it. I can get a holder up to MT2 for the 'A' size. 'B' or larger would be required for an MT3. Not an issue since I haven't purchased any tapered shank bits just yet.

    How does one center up a drill bit in the tool post precisely? There are three separate degrees of freedom which must be precisely aligned.

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    I put a drive dog on the drill and let it rest on a chunk of 2x4 sitting on the lathe bed. I cut the chunk to a length to suit my lathe and keep it by the lathe.

    Of course, with the price of lumber lately, the previously suggested boring bar might be a cheaper solution.

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    Quote Originally Posted by Just a Sparky View Post
    13" South Bend. I've got a Multifix 'A' tool post on the way for it. I can get a holder up to MT2 for the 'A' size. 'B' or larger would be required for an MT3. Not an issue since I haven't purchased any tapered shank bits just yet.

    How does one center up a drill bit in the tool post precisely? There are three separate degrees of freedom which must be precisely aligned.
    Turn a plug that you can chuck up and locate the drill holder onto and set a zero.
    Another vote for setscrews in the tailstock quill, works great, just be sure the screw can make it past to eject the drill/center etc.

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    You could also use a say MT4 or 5 taper shank by putting a dead center in the tailstock and using a drive dog to keep it from spinning.

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    I used TWO dogs - one on TS quill with the vee typical of grinding dogs and one plain bent tail dog on the drill. The set screw of the grinding dog sticks in the key way on bottom of TS quill ( not insubstantial on the 18 1/2" Monarch) and the bent tail dog sits in the "vee" of the grinding dog. Here is a set of grinding dogs with the "vee" feature

    dcp_0940.jpg

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    Well sticking a drill in it is what it’s for however, clean the oil out, clean the drill, stick it in, try shaking twisting etc to confirm seating, if good, stout thump on the tip of the drill with lead hammer ( my brother in law a doctor used to write pendulus plumbum on sick papers, aka swinging the lead)
    If good away you go, caution if backing off watch you don’t release the drill
    (Ask me how I know) when under pressure spinning is rare to never
    I found babying the thing did more damage,
    However there are no stupid questions so ask away, if you get a sarky answer ask someone else
    Mark

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    Quote Originally Posted by Just a Sparky View Post
    13" South Bend. I've got a Multifix 'A' tool post on the way for it. I can get a holder up to MT2 for the 'A' size. 'B' or larger would be required for an MT3. Not an issue since I haven't purchased any tapered shank bits just yet.

    How does one center up a drill bit in the tool post precisely? There are three separate degrees of freedom which must be precisely aligned.
    Just one, actually. A holder for drilling from the carriage doesn't have anything to do with "compound" nor toolpost, either one.

    A stout 4-Way directly mounted to the topslide, no compound even installed, "industrial style" can handle a drill. But hobby lathe users usually have a compound on the lathe even when they don't need it for a short taper.

    4-Way, Multifix or Aloris on a compound - even if pinned - just swivels the compound. SB easiest of all. Handy clamping system for the compound, SB's have. But nowhere NEAR as twist-resistant as an industrial lathe.

    Best of both world's?

    Dowel and screw a monoblock directly to the cross topslide rearward (away from the operator) and leave the compound on the lathe.

    Set a witness mark or arrange a shot-pin for that cross position.
    Finish bore, if not also drill (from the HS) the holder right on the lathe.

    When ready to drill, move the cross to the witness mark or drop the shot pin into position.

    Drill the hole.

    Since you line bored it ON the lathe? The height is dead-nuts already.

    No interference with the compound or toolpost at all.

    PS:

    Do NOT buy "any tapered shank drills just yet".

    Make the bore of that monobloc a straight cylinder, not a MT.
    Now it can hold a short ER or TG collet holder or an Ortleib tap holder on a straight tail.
    Cheap, cheerful, easy to afford more than one.

    Jacobs, Albrecht take up too much space. Even so, they can be had on straight tails, too.
    You don't want long body MT tail drills for a lathe anyway! Same reason.
    They eat too much long-axis daylight. ELSAE you are going to be into three sets right away, not just one or two.

    Also not cheap in all the varieties lathe work wants. Jobbers. Stub. longish Bell-hanger, centering. Spot. Reamers. Counterbores. Spot-facers, Countersinks. ... yadda, yadda. Cheaper in straight shank, every one of those

    You see the value of the shorty collet holder or the Jacobs or Albrecht?

    One cannot AFFORD to cover all that speciality stuff with MT tail goods ... even if you could FIND them made that way. And one cannot, actually.

    MT tail drills are for drillpresses. Plain-old ignorant HOLES.

    NOW "long" is all you need in MT tail. Only ONE of my three DP handles 5 MT "native". All-else I have reducers for. The two smaller DP have chucks. Drillpress doesn't HAVE to be limited to MT. It can mount all the other stuff, too.

    You know what a drillpress is, yah?

    A drillpress is the second machine you bought right after a general-purpose bench-grinder.

    Knowing in advance a mill makes a shitty drillpress and a lathe an even WORSE one.

    Drillpress sucks smelly orifices at being a lathe or mill, too, to be fair.

    "Horses for courses"


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    Quote Originally Posted by thermite View Post
    [...]

    [...]

    [...}

    You know what a drillpress is, yah?
    Hmm...

    img_20210224_203918701.jpgimg_20210224_203742619.jpg

    Variable speed no less. Can dial the revs and torque right down to zero. Perfect for power tapping in conjunction with instant reverse.

    And... I can store my tools under it.

    Something-something eating my cake and still having it.

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    You can always consider boring if you want to take it slow.

    If there is a jam, something has to give somewhere. If the drill chuck turns in the footstock, that would seem to be the least possibly damaging outcome.

    Tapers are pretty strong. I would expect the jaws of the chuck to let loose from the drill bit before the taper spun.

    When you set a taper, it just takes one light knock from a wooden mallet; don't pound on it.

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    Really I'm just looking for a drill bit big enough to be able to reach in there with a big 5/8" boring bar and start hogging out material. The biggest straight shank I've got is 1/2". I just figured it would put a lot less strain on my Jacob's chuck to use Morse-tapered drill bits directly for the purpose of drilling big 3/4" or 1" starter holes. I like the drive-dog and four-by-four idea. I think that will work well for my needs in conjunction with a couple of cheap $40-for-five flea-bay MT-shank drills.

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    You asked how to center up the drill precisely. If you are just drilling a starter hole for a boring bar then don't worry about it.

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    Just make a starter hole with a center drill . You might need a couple of drills in between but just drill the goddamn hole.
    You will figure out what your machine can and can't do very soon. ....it won't be mysterious.
    And the next time you won't have to ask.

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    Quote Originally Posted by Just a Sparky View Post
    Hmm...

    img_20210224_203918701.jpgimg_20210224_203742619.jpg

    Variable speed no less. Can dial the revs and torque right down to zero. Perfect for power tapping in conjunction with instant reverse.

    And... I can store my tools under it.

    Something-something eating my cake and still having it.
    LOL!

    - Electro-Mechano .. fears suffocation by twinned hostess twinkies

    - Walker-Turner .. nobody cares. Just make the F'n holes. Piece of cake.

    - Alzmetall AB5/s .. eats God's desert. Who wants to argue with a German?


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