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Tips for indicating drills in lathe turret?

I use Haimer coaxial indicator in the chuck and sweep the drill tip but i guess you can use a test indicator as well. If you haven't got your X offset for your boring bar/drill holder yet, sweep the holder bore first. Once you have your holder indicated and enter your X offset, insert the drill in the holder with the cutting edge at the tip parallel with the set screws on the holder (the set screws which you use to clamp on the sleeve or the collet chuck). Then, bring the drill to X0 and sweep the cutting edges. Read the highest point on each cutting edge and adjust the alignment with set screws on the holder. Once the drill is aligned, I can drill to size within 10um easily with a carbide drill and the tool life is much much better than a drill which isn't indicated.
 
One tip that no-one seems to have mentioned in this:

On a two fluted tool, chuck your tool up so's your tip diameter points (?) are in X.
Then you can offset that much of it spot on, and that way - any amount out of zero that the turret is radially*, will go into the flute area.

On a common twist drill, yeah - the flute will come around a bit later and rub, producing the taper that the OP was complaining about, but not normally quite as bad as if your flutes were turned the other way around.

If you are running a spade drill for instance, then the body would likely never rub at all.
If you are still producing the tapered hole doo to trailing flutes rubbing, you can take your tool over to the grinder and Jenny Craig those flutes. Or maybe you can git away with just wire wheeling those flutes to dull them down.


Radially*
This could be b/c your turret is out, but it also could just be that your holder is out. Many (most?) holders don't mount down in a manner that precludes that they are dead straight.


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Think Snow Eh!
Ox
 
I just run floating holders.
You guys can spend your days indicating if you prefer.
Interesting idea, are you using a proper floating reamer holder or will it work with floating tapping holders too (the type that can draw out slightly)?

One of my lathes (Emco Turn 325) is pretty limited on turret space so a floating reamer holder would most likely be far too big but I do have a load of PCM tapping collets that I can use in various sizes, other than having to grind some flats onto the shanks of the drills for the grub screws to grip is there any reason they wouldn't work?

 
Well you're not gunna put a spot drill in there!

But I have pushed up to 5/8" SMD's in a center drilled hole in 1200 series steel and it be right on size.

What I use seems to not be very available these days, so I would recommend that someone looking for their first, to look into what's out there today.

The ones that I use are able to be tightened or loosened as needed, where some others that I have (but likely not used yet) are rubber tensioned and are what they are.

TM Smith might be a good place to consider for basic floaters.


I think that Mari has a good holder out for not synch tapping tho.
I would look there first for a tapping holder.

I have old Hardinge TT style tap holders, and while the holder works fine, those TT collets absolutely suck!
I have some heads that just run one size tap shank b/c I can't git the tap out out!


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Think Snow Eh!
Ox
 
Well you're not gunna put a spot drill in there!

But I have pushed up to 5/8" SMD's in a center drilled hole in 1200 series steel and it be right on size.

What I use seems to not be very available these days, so I would recommend that someone looking for their first, to look into what's out there today.

The ones that I use are able to be tightened or loosened as needed, where some others that I have (but likely not used yet) are rubber tensioned and are what they are.

TM Smith might be a good place to consider for basic floaters.


I think that Mari has a good holder out for not synch tapping tho.
I would look there first for a tapping holder.

I have old Hardinge TT style tap holders, and while the holder works fine, those TT collets absolutely suck!
I have some heads that just run one size tap shank b/c I can't git the tap out out!


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Think Snow Eh!
Ox
Thank for the informative link.
 
As Orange Vise said, turning a straight diameter has nothing to do with turret alignment. If you turn a 5-6 inch long diameter and it is tapered, then your spindle needs aligning.

As already mentioned, mount the drill with the cutting edges parallel to the X-axis. I've often eyeballed a drill on center by using the hand wheel and making sure to the best of my ability that both cutting edges are cutting the same amount of material. This is usually good enough except for the below. I drill .010/.015 under size so one pass with a boring bar is all that is needed.

Many of our lathes are 30 years old or older. Crashed more than once. Turret alignments are bad enough that I've had to remove the locating pin to get them close to center. BUT that doesn't mean the drill is straight. Have to put a rod in and check along its length. Adjust to get reasonably straight. Then check center line again because I can guarantee the holder will need adjusting again. Rinse and repeat.

This is a time consuming process and hard on my back which is in bad shape. Oh to be 50 years younger. :)
 
Mark 1 eyeball is how I do it. Just make sure that your flutes are parallel with your X axis. Ears help tool. Drill it deep enough to get your flutes a bit past the face of the part, back it off a bit, then listen. If it is not centered, you can hear it rubbing. Move it in X until it is silent. This wont work if your turret is high or low, it will rub even if perfectly centered in X. I always laugh when I see someone using an indicator to center a drill.
 








 
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