Drilling from compound QUESTION

silver star · Dec 9, 2016

I have a SB Heavy 10”, 4 ½ ‘ bed.
I am toying with an idea that I have no reference of how it would be done.
So can this be done?
Can I install a power drill of some sort on my compound…or somewhere so I can drill the straightest 15/64” hole possible into a 1” round stock of titanium 3 ½” long?
Due to rubbing and work hardening I feel I need to make the hole size needed in one pass.
That distance with that small of a bit is hard to make a straight hole.
It is my understanding that if the stock is turning one direction and the drill is turning the other direction that my hole should be straight.
Thoughts or references most welcome.
Michael

gadget73 · Dec 9, 2016

Any reason for not just chucking the drill bit in the tailstock? Thats what I do when I need to drill the middle of a piece of stock. Center drill it to start, pilot drill of appropriate size, then the final size. Add steps in between as needed depending on final size of hole and how difficult the material is to drill.

iwananew10K · Dec 9, 2016

ok, just me a hobby guy so no production.

I drilled lots of Ti with just high quality HSS drills and sulpher based cutting oil.

I would spot drill with the tailstock, then switch to one of those handy dandy AXA drill chuck holders, line it up and peck drill as needed feeding with the carriage handwheel.

Bob Wright(aametalmaster) has a post on here somewhere of his carriage mounted arrangement that he powered with a hand drill.

maybe he will chime in.

IME tailstocks generally suck for drilling at any real depth, too slow to get in and out, really bad in Ti as you need to get out FAST... Not to mention at his depth would require resetting of the tailstock due to not enough travel

gzig5 · Dec 9, 2016

I don't see how a powered drill is going to change anything other than not having to run the lathe spindle as fast. Plus you add a more complex alignment and the crappy drill bearings to the equation. Twist drills drift off center because of their design or ground tip. Look into a gun drill bit and either buy or make one. Pre-drill and single point bore the hole to get the bit started straight. Don't know it gun drill geometry is compatible with titanium, but that is how you drill a long, straight hole.

silver star · Dec 9, 2016

Well I have done that twice.
Starting with pilot hole, short 35 degree split tip bit, reset tail stock for longer bit, using with coolant, peck drilling, reset tail stock due to length and still have quite a bit of drift from one end to the other.
I am faced with drilling hole thru stock best I can and then set up on centers to finish project.
Project would be centered on my center line hole but wish I could get center line hole much better.

silver star · Dec 9, 2016

gzig5 said:
I don't see how a powered drill is going to change anything other than not having to run the lathe spindle as fast. Plus you add a more complex alignment and the crappy drill bearings to the equation.

That may answer my question, I thought if stock was turning and drill was turning opposite direction it would have to go straight.
I will look into gun drill bits.
Thanks

stephen thomas · Dec 9, 2016

What are you holding the work in/with?

IOW is the drill wandering for some reason, or is the work presented askew and the drill is following the rotational centerline correctly? I don't seem to have much trouble drilling in collets with the TS 4" or so deep. As mentioned and as you state, do center pop the hole with a center drill first.

I have no Ti experience. In other materials when it matters that the holes come out well aligned, I drill in to center from both ends, drill through with the pre-reamer size, then ream through. My understanding is that this would not be a problem in Ti if the tools are sharp & fed appropriately to cut not rub (don't dwell in the cut).

smt

TDegenhart · Dec 9, 2016

I agree with thomas. Sharp drill, coolant, frequent pecks to clear the chips, constant and uniform feed. Unless this is either a really fun and learning project, I would forget about gun drill. They, with all of the support equipment, are expensive. If you truly need a straight hole, I would edm sink it.

Tom

silver star · Dec 12, 2016

stephen thomas said:
What are you holding the work in/with?

IOW is the drill wandering for some reason, or is the work presented askew and the drill is following the rotational centerline correctly? I don't seem to have much trouble drilling in collets with the TS 4" or so deep. As mentioned and as you state, do center pop the hole with a center drill first.

I have no Ti experience. In other materials when it matters that the holes come out well aligned, I drill in to center from both ends, drill through with the pre-reamer size, then ream through. My understanding is that this would not be a problem in Ti if the tools are sharp & fed appropriately to cut not rub (don't dwell in the cut).

smt

Holding with 4 jaw chuck.
Drill bit in tail stock.
Start with centering bit, then short drill bit as far as I can, then longer drill bit.
Using coolant at beginning of hole and coolant on top of project but I do not have coolant thru bits.
I may could pull out and clean more often.
However, the further the bit goes the more the rest of the bit rubs in the hole causing work hardening. Thus making target sized hole necessary on my first pass. Reaming that distance and that diameter seems non productive.
Thanks for your input and please forgive my reply.
Looks like drilling thru then setting up my work on centers and a dog is as good as I can get it.

onecut · Dec 12, 2016

What your doing sounds good to me only thing have you clocked the tailstock in?,If its even slightly off it could give you problems.Of course that decent material your working with if your tailstock was slightly out even with a center drill it could be the problem.You could be using a poor drill try another then you know its not the drill,you have tried HSS so get yourself a carbide masonary drill might not work but I would give it a go.Gun drills can sail thro Titanium but shouldnt be neccessary and cost an arm and a leg and need resharpened regular so unless your a millionaire and can afford the drill and the grinder to sharpen them.Dont understand why you want the job and drill both revolving not saying this is not correct but when I have drilled this stuff on deep hole drillers often 10ft long the job was static,only the drill revolved we would on average sharpen the drill every 2jobs but if you hit a hard spot you had to get out quick .The speed should be very slow .Coolant is essential that could be your problem its not getting to the point of cutting

Monarchist · Dec 12, 2016

silver star said:
I have a SB Heavy 10”, 4 ½ ‘ bed.
I am toying with an idea that I have no reference of how it would be done.
So can this be done?
Can I install a power drill of some sort on my compound…or somewhere so I can drill the straightest 15/64” hole possible into a 1” round stock of titanium 3 ½” long?
Due to rubbing and work hardening I feel I need to make the hole size needed in one pass.
That distance with that small of a bit is hard to make a straight hole.
It is my understanding that if the stock is turning one direction and the drill is turning the other direction that my hole should be straight.
Thoughts or references most welcome.
Michael

Cheap and cheerful is probably going to be really GOOD drils and held in a fixture directly on the cross-slide in place of the compound rest.

Biggest immediate advantage is twofold:

- better control over centering than a worn TS on a featherweight lathe can offer.

- much faster and more frequent clearing of chips or 'pecking'.

Having reversible power feed available is another plus.

Try that.

Forget the drill-motor.

Price, do not BUY powered or 'live' tooling for such drilling - often with "TG" family collets, and you'll get a hint as to relative worth of their substance and spindle bearings vs a hand drill-motor & Jacobs chuck.

"Night and Day" cometh to mind..

Bill

stephen thomas · Dec 12, 2016

If the TS is off, drilling with the carriage may help.

I have an AXA holder for #2MT and stick taper shank drills in directly, or a 2MT shank Jacobs drill chuck.
As Bill notes, that will allow the possibility of vertical and horizontal alignment more or less easily. Drill some scrap to dial in and verify. While drilling the scrap, make sure that not only the travel of the drill, but the alignment is spot on.

This is the trouble with drilling from the compound. There are practically 4 alignments to make. Drill must align parallel with travel vertically and horizontally. Horizontal it "easy" over a few iterations - rotate the toolpost until correct. Vertically could be more difficult - face or shim top of slide or compound until tool post does not tilt.

When drill is perfectly aligned with Z axis, next it can be dialed in on center with the cross slide or compound, and vertically by adjusting the depth nut on the holder.

Once everything is perfect and tested, on a small lathe if you feed too fast either manually or under power, the TP or the compound may rotate.

But it does work well if that is the final tweak you need. Worth a try. As i said, I have the option and sometimes use it. For quick work it is easier to use the TS.

smt

Monarchist · Dec 12, 2016

stephen thomas said:
This is the trouble with drilling from the compound. There are practically 4 alignments to make. Drill must align parallel with travel vertically and horizontally. Horizontal it "easy" over a few iterations - rotate the toolpost until correct. Vertically could be more difficult - face or shim top of slide or compound until tool post does not tilt.

When drill is perfectly aligned with Z axis, next it can be dialed in on center with the cross slide or compound, and vertically by adjusting the depth nut on the holder.

Once everything is perfect and tested, on a small lathe if you feed too fast either manually or under power, the TP or the compound may rotate. But it does work well if that is the final tweak you need. Worth a try.
smt

And there yah are.

When you are trying to hold a drill off a QCTP or even a 4-Way. so long as either is still perched atop the wiggliness of the average light lathe's compound?

Too damned much stuff moves.

By fabbing a monoblock that fits to where the compound has been REMOVED, vertical height and axis of travel remain nailed. Horizontal is the only one you have to adjust.

Good to have an "ER", better-yet "TG" ("Tight Grip", and they damned well are. Or CAN be) collet to fit the monobloc.

Discover the gripping capability of bespoke size / 'limited collapse' collets and your pet Albrecht or Jacobs chuck's are sent back to where the drillpressen live.

Bill

abarnsley · Dec 13, 2016

Use a 5C collet chuck to hold work. Have your 4 jaw chuck jaws ever been trued??? They can be off axially. Or jaws and chuck slots can be well worn...

Most QC toolposts have a locking pin hole underneath... so they can be fixed to compound... No rotation problems...

A Lever tailstock saves a lot of time di*king around with that standard, feather weight, no decent length of travel tailstock. Not greatest for larger size drills though..

http://operatormanuals.tpub.com/TM-9-3416-235-14-P/TM-9-3416-235-14-P0059.htm

Non Gun drills suck at holding straightness and diameter.

Many objects shaped like that in the firearms muzzle attachment arena, have ~ .040 clearance between hole and moving part.

Why ??? Because of difficulty/cost drilling straight enough holes, and no need for tighter clearance, to perform well...

LKeithR · Dec 13, 2016

I generally consider a drill to be "starter" for a boring operation--they're really not very accurate--but with a small hole and a dia. to length ratio like this boring is pretty much out of the picture. On the odd occasion that I've needed to get a hole right down the centre-line of a piece of stock I use a trick an old machinist showed me many years ago. Start with some oversize material; drill and ream your hole as accurately as possible then set the workpiece up between centres in the lathe and turn the OD to whatever diam. you want. Works a charm...

stephen thomas · Dec 13, 2016

Also, FWIW, if the drill is in a holder on the compound or the cross slide; instead of feeding by means of the carriage hand wheel, you can put a 1/2" round bar in the TS chuck, and push straight behind the holder with that for feeding. The carriage mount permits "perfect" alignment as described by several above. Pushing directly on axis (assuming flat back such as Aloris type) on the toolholder avoids torque that might turn it. OD skim cuts (boring) and pecking can still be made with the carriage.

smt

silver star · Dec 13, 2016

monarchist said:
cheap and cheerful is probably going to be really good drils and held in a fixture directly on the cross-slide in place of the compound rest.

Biggest immediate advantage is twofold:

- better control over centering than a worn ts on a featherweight lathe can offer.

- much faster and more frequent clearing of chips or 'pecking'.

Having reversible power feed available is another plus.

Try that.

Forget the drill-motor.

Price, do not buy powered or 'live' tooling for such drilling - often with "tg" family collets, and you'll get a hint as to relative worth of their substance and spindle bearings vs a hand drill-motor & jacobs chuck.

"night and day" cometh to mind..

bill

boom !!
Boom !! Again. Wow!

silver star · Dec 13, 2016

Guy's...I feel like I have been parking my car for years in such a way so I could get out of my parking spot on my return.
Now you tell me my car has a "REVERSE".
Bill's post and everything that follows is requiring me to process and think about what has been said.
So give me some time before I try to reply but please know a very big THANK YOU goes out to you all.
Michael

Monarchist · Dec 13, 2016

LKeithR said:
On the odd occasion that I've needed to get a hole right down the centre-line of a piece of stock I use a trick an old machinist showed me many years ago. Start with some oversize material; drill and ream your hole as accurately as possible then set the workpiece up between centres in the lathe and turn the OD to whatever diam. you want. Works a charm...

+1 From another "OLD machinist"!

Side-step the problem entirely.

Guess wot? If you happen to have a decent drillpress, that initial hole and reaming can be made faster and with less gritting of teeth than if drilled on a lathe.

DP's are more easily given lube. A vertically rotating drill, stationary work lifts chips better than horizontal rotating work, stationary drill. Gravity exists, and it is 'off centre, downward'. The ease of backing out fast and often clears chips better.

Drillpress makes a lousy substitute for a lathe. Or for a mill.

Lathes are best at turning and BORING. They make a lousy substitute for a drillpress.

Mill ain't all that great for punching ignorant 'basic' holes, either.

One needs ALL THREE machine-tools for a well-rounded shop.

Bill

LKeithR · Dec 17, 2016

Monarchist said:
+1 From another "OLD machinist"!

Funny you should mention that...since I turned 70 in April I guess I'm an OLD machinist as well. When I was shown that trick I was in my mid twenties.

When I was first starting my welding business there was a machine shop a couple miles down the road. The guy that owned it was from somewhere in Ohio--I never did find out how he ended up in our neck of the woods. I spent many an hour in his shop (especially in the winter time, his shop was heated, mine wasn't) looking over his shoulder and paying attention while he explained how and why he did things. He never let me run any of the equipment and it was 15 years or more before I got into machining myself but when I did a lot of the knowledge he had shared came back to me. By that time he had passed on but in those early years I often felt like he was standing there looking over my shoulder...and if he was there I'm sure there were numerous times when he cringed at what I was doing... :eek:

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