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MT drill drivers for tailstock

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petertha

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#1
I have a set of progressive bits from 0.5 to 1.0" all have .5" shank. I use these basically as roughing 'opening up' tools. As much as I try to avert tougher service conditions, the odd time I have experienced them slipping in the chuck jaws. Usually its gummier alloys or taking too bit a bite or rpm/feed not quite right. I keep my older chuck for this & my good chuck for precision work, but I still would prefer not to bugger up the jaws. Do you think a tanged MT driver would assist? I would just need to get one bore size (0.5") and it would fit my MT tail stock.
 

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Chipper5783

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#2
No. Set up a drill chuck for the tool post. That will give you power feed, quick pecking - it works great. Big drills in the tailstock are not good, there is the issue of spinning in the taper (which would be sorted if you use a drive tang - but not all tailstocks have the slot for the drive tang). Also, the tailstock is generally secured against rotation by a small key / key way and it is not good to put a bunch of torque on it. You can get drill sockets with a handle to take the torque (or make one). However, drilling from the tool post works very slick.
 

petertha

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#3
My MT3 drill chuck arbor has the rear tang to prevent rotation in the tailstock barrel. (Pic is not my chuck but same principle). I was thinking the same tang in drill driver insert would provide the same thing? It also has a slot for tool (drill shank) removal if I understand correctly.
 

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benmychree

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#4
Only one lathe that I have had experience with had a tailstock with a tang driver, that, an American Pacemaker; Technically, the tang is not so much as a driver, but a means of removing a taper tool from a spindle. It is not a good policy to drill using the tailstock, there is a very high probability of spinning the tool in the taper, destroying its accuracy for turning operations. It is a much better policy to use the tailstock for strictly turning operations and use the carriage with a compound rest mounted drill holder for drilling operations; this is best accomplished using a Morse taper tool block for QC tool holders such as Aloris. It is faster in drilling with power feed, and faster in tool changes from drilling, reaming, and tapping, etc. There is no downside to it as I see it.
 

petertha

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#5
Well you learn something every day. I'm going to have to look into the drill tool block. I know exactly what you mean, I have a 1" ID bore dovetail block for clamping boring bars. I always assumed these (or their taper hole or pre-mounted chuck) cousins would be perpetually fiddly to find lateral center with the cross feed on parts whereas the tail stock is always on center.

Actually I despise the big bits for the most part. Its just a means of opening up sufficient depth to start using insert boring bars which I prefer. I don't do a lot of rough work. Its a 14x40 lathe & the (Taiwan) drill chuck that came with it is actually pretty decent.
 

benmychree

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#6
The reality is that there is nothing fiddily about getting the cutting tools on center when using a carriage mounted drilling block; just try it and just do it!
 

petertha

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#7
So how do you do it? I know from past experience when my tailstock had drifted out over time about 0.003" I was experiencing chattering bits & even breaking the odd carbide center drill (talking small diameter stuff here). Once it was back to 0.000" problems melted away.

Once you have the drill block mounted in the tool post, now what? How do you establish work center accurately?
 

Chipper5783

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#8
For small holes, just use the tailstock drill chuck. Then to open that hole, use the larger drill from the tool post (chuck or taper shank). The height only needs to be set once. For the lateral setting, I don't sweat it - eye ball, and adjust until the drill is cutting nice and following the pilot hole. It takes longer to describe than to do (after all drilling is a roughing operation).
 

Cadillac

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#9
One way to center with Accuracy is mount chuck in block put it on qctp. Then put a good dowel in chuck. Then mount dial indicator in chuck. Dial in the dowel and lock adjustment down. Done deal!
 

benmychree

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#10
I have been using the Aloris for drilling for perhaps the better part of 50 years, and centering is not a problem; if you are using a center drill to get things started, you just (very lightly) push it against the rotating work so that it makes a light trace, if it obviously making a circle, you move laterally or vertically until the impression is in the center of the circle, then "go for it". The smaller the center drill is, the more likely it can be broken, so I avoid using a center drill that is smaller than necessary. Some folks do not use center drills for starting holes, but instead use spotting drills, which are quite short and ground like a split point drill; this is the best way to do it without the breakage problem experienced with center drills. I have not made a general practice of doing it that way myself, except in the turret lathe.
 

Silverbullet

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#11
The adapter you have pictured have been in use for over fifty years the work , some require flats on the drill shaft. Others use a set screw like on a mill. I have several I used over the years . Using the compound has plusses and minuses . With large drills it's iffy either way.
 
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