Thread: Drill Holder For Lathe

From my lack of experience I would think that the type of setup with the parallel section with internal M/T would be suited to a lathe that may have either no M/T in there tailstock or if a M/T drill 2 sizes above the tailstock taper was to be used.

I have used a lathe dog attached to a M/T drill to give better drive when drilling large holes when a smaller than desired pilot is used.( So the drill does not spin in the tail stock taper.)

Cant comment on why a boring bar would not be used except for the common reasons.

On jobs with a deep hole of say around 13-16mm diameter I've found boring bars flex too much. When using a drill, providing you use a centre drill and drill slowly to the shoulder, there is minimal flex.

Originally Posted by Michael G

http://www.machineryhouse.com.au/D401

Michael

The tool that H & F sell can be bought much cheaper on Ebay $20 --$30

Originally Posted by DSEL74

I assume the only reason to do this is if the drills taper or shank doesn't match the tails stock ie is larger. Looks a bit dangerous to me, same as the Americans' idea of holding a piece of stock by hand and drilling against those morse taper Vee blocks in the tailstock.

When we see some setups the first thoughts are that it could be a bit dangerous. The method shown above is a recognised method of holding/driving a drill in a lathe and is still shown in most text books. Here is a page from an old text book explaning how it does work with safety even on through holes. Hope it helps. All these old NSWGR Apprentice text books come in handy at times!! Worth looking for them at flea markets.

Originally Posted by sacc51

On jobs with a deep hole of say around 13-16mm diameter I've found boring bars flex too much. When using a drill, providing you use a centre drill and drill slowly to the shoulder, there is minimal flex.

But we would seem to be dealing with drills much larger than 16mm and at least the one in the picture is not what I would call a deep hole

Originally Posted by OldRustyToolie

The method shown above is a recognised method of holding/driving a drill in a lathe and is still shown in most text books.

You do notice there is an important part in the sketch that is missing in the above picture?

Stuart

Originally Posted by Stustoys

But we would seem to be dealing with drills much larger than 16mm and at least the one in the picture is not what I would call a deep hole


You do notice there is an important part in the sketch that is missing in the above picture?

Stuart

What part would that be to save us from a guessing competition?!

He is probably talking about the forcing bar ... however you could use the saddle (crossslide and toolholder/post) to provide a rearward force.

I'm guessing the lantern tool post is supposed to be acting as the forcing bar??

Whether this setup is adequately safe or not it still looks like it has a margin for error greater than having a drill in the chuck or using a boring bar. So I can only assume it is a speed thing??

Originally Posted by Vernonv

He is probably talking about the forcing bar ...

He is.

Originally Posted by Vernonv

however you could use the saddle (crossslide and toolholder/post) to provide a rearward force.

Maybe you could, you could do a lot of things.. but that's not what the picture is showing.

Originally Posted by DSEL74

I'm guessing the lantern tool post is supposed to be acting as the forcing bar??

Then it could be argued its in the wrong place. If it is being used as a force bar, why the bar/rest parallel to the bed?

Originally Posted by DSEL74

So I can only assume it is a speed thing??

So far thats my best guess. Though I have to assume you're making a lot of them and you dont have a (large)drill press.(which is fine, we don't all that camel backs... I'm just trying to find out why someone would use such a setup...... hey I might even be talked into using it myself)

Thinking about it a little more step drilling with this setup could be out(I would think) as starting the drill could be some what tricky in a large hole. Could be wrong though.

Stuart

p.s just because its in a book doesn't make it a great idea. One of my books says to get the hardest possible result quench tools in Mercury.

Originally Posted by DSEL74

I'm guessing the lantern tool post is supposed to be acting as the forcing bar???

Yes, that's what I was getting at also.

Originally Posted by Stustoys

Then it could be argued its in the wrong place. If it is being used as a force bar, why the bar/rest parallel to the bed?

No, the actual lantern post provides the rearward pressure, not the bar in the lantern post ... you would do so by manually holding the saddle handwheel so that the lantern post is being pushed towards the tailstock. Pressure would have to be adjusted as the tailstock is extended.

It would provide the same function as the forcing bar, however if it was me I would have the lantern post closer to the drill holder.

Originally Posted by Stustoys

Then it could be argued its in the wrong place.

Originally Posted by Vernonv

No, the actual lantern post provides the rearward pressure

Originally Posted by Vernonv

however if it was me I would have the lantern post closer to the drill holder.

It would seem we agree IF the lantern post is being used in place of the forcing bar then it is indeed in the wrong place.

The reason I say IF is because my guess as to why the long flat bar is being held in the lantern holder is that the carriage isn't being moved.
If you move the lantern in you're then supporting the bar in the wrong place.................at least so says the sketch.

Stuart

Originally Posted by Stustoys

It would seem we agree IF the lantern post is being used in place of the forcing bar then it is indeed in the wrong place.

It would now appear so ... the only difference being you say "wrong", I say "less than ideal".