# Drill Bit In A Boring Toolholder?



## cdhknives (Mar 5, 2015)

Can I use a boring bit toolholder in my QCTP to hold a drill bit and set the carriage feed to a appropriate feedrate to automate drill feeding?  I know there are some feedrate calculators for various materials and hole sizes...I would set it up appropriately and have to really work to square up the bit...but will it work?

I am trying to correct 2 issues, wallowing out the hole as I peck my way through 316 SS, and alignment issues with my tailstock chuck.

I also have just taken stitches out of my right hand, and cranking the handle on the tailstock gets old very fast!


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## JimDawson (Mar 5, 2015)

I have found that if you are going over about 3 drill diameters deep, that you have to peck to clear the chips.   You could mount a drill bit in the tool post and hand feed the carriage, I would be nervous about power feeding.


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## randyc (Mar 5, 2015)

I agree with Jim and frankly I've never seen an advantage in drilling from the tool post.  Intuition suggests that drilling pressure _might_ exert a certain amount of torque that _might_ slightly rotate the QC tool post, changing the drill alignment.  The only situation that MIGHT justify power feeding (without pecking) is enlarging a previously drilled hole.

But power feeding a drill is really not a good idea - hand feeding provides operator sensitivity to both the tool and the material so that if a problem arises, it is instantly sensed and corrective action can be applied.

A classic example would be drilling a work-hardening material ... as heat is generated from the cutting process, the material hardens, dulls the cutting edge of the drill which increases the heat which hardens the material more .... if the drill is power fed then the eventual result: disaster !


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## gt40 (Mar 6, 2015)

randyc said:


> I agree with Jim and frankly I've never seen an advantage in drilling from the tool post.  Intuition suggests that drilling pressure _might_ exert a certain amount of torque that _might_ slightly rotate the QC tool post, changing the drill alignment.  The only situation that MIGHT justify power feeding (without pecking) is enlarging a previously drilled hole.
> 
> But power feeding a drill is really not a good idea - hand feeding provides operator sensitivity to both the tool and the material so that if a problem arises, it is instantly sensed and corrective action can be applied.
> 
> A classic example would be drilling a work-hardening material ... as heat is generated from the cutting process, the material hardens, dulls the cutting edge of the drill which increases the heat which hardens the material more .... if the drill is power fed then the eventual result: disaster !


I agree with manual lathes.  

On the other hand, power drilling is standard with cnc, usually using a canned peck cycle like G73 - a high speed peck cycle for shallow holes.  There are actually a number of cnc drilling  cycles for lathes.   I use this frequently on my Jet 13x40 cnc lathe.  I have a cxa tool holder and use a 1" boring bar holder with a straight er32 1" collet holder holding the drill in it. 

I will take a pic sometime but it works awesome.   FYI the straight collet holders are also great for using really fine stock in a big chuck- my 6" Bison has a 1/4" hole fully closed and you can hold small pieces in it by first putting it the straight shank collet holder then putting that in the lathe chuck...


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## Wreck™Wreck (Mar 6, 2015)

If you have a QC post and a square tool holder with a V-groove on the bottom land clamp the shank of a drill bit in the groove, this is why it's there.
Power feeding a drill works a charm just do not forget to clear the chips and don't get greedy.


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## kd4gij (Mar 6, 2015)

I don't thing your QC54 is ridged enough. 316 ss can be tough,Also it work hardens quick.


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## randyc (Mar 6, 2015)

A programmed CNC drill/peck program isn't at all compatible with power feeding a manual lathe.

What would be the point of power feeding a manual lathe _when the feed has to be disengaged every ten seconds or so and the drill manually withdrawn to clear chips _?  Centering the drill with the spindle axis in a QC tool post is also problematic as is preventing the toolholder from rotating.  (Remember that of all operations performed by a lathe, drilling usually requires the greatest amount of thrust.)

I've power fed a drill before (I don't remember why, it's been decades ago) but I used the classic method of placing the slightly loosened tailstock in _front_ of the carriage, using the carriage to push the tailstock along the ways.  This technique keeps the drill aligned with the spindle and the drill axis can't be rotated like a QC toolholder hanging out three or four inches from the clamping stud.  But it still is a clumsy method because of the reasons listed in the first sentence of the second paragraph.

This is a _personal opinion _of course, but I think that this procedure doesn't really offer any significant advantage compared to standard tailstock drilling and might also be unsafe.  I just don't see any reason why it would be preferred over conventional practice (unless one prefers just standing beside the lathe drinking beer instead of cranking the tailstock handwheel)


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## LEEQ (Mar 6, 2015)

The OP is having alignment issues. Some folks shim their machines tail, and head stocks to fix it. Not the same lathe, but Gadgetbuilder has a nice write up on his site.


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## randyc (Mar 6, 2015)

Wreck™Wreck said:


> If you have a QC post and a square tool holder with a V-groove on the bottom land clamp the shank of a drill bit in the groove, this is why it's there...



I would differ with that statement.

A vee groove simply implies that a tool with a round shank can be accommodated, not specifically a twist drill.  I suggest that the tools that were envisioned when the vee groove was included in the holder were small boring tools and reamers, both of which are obvious candidates for power feeding.


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## juiceclone (Mar 6, 2015)

I have used a large drill bit in my axa boring bar holder a few times, and it was ..ok... I didn't use power feed and was careful (skeptical) about it.  Interesting enough. if you orient the cutting tip of the drill bit correctly, you can also use it as a boring bar, rather well actually. Takes a little tweaking for the correct angle and clearance.


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## kd4gij (Mar 6, 2015)

juiceclone said:


> I have used a large drill bit in my axa boring bar holder a few times, and it was ..ok... I didn't use power feed and was careful (skeptical) about it.  Interesting enough. if you orient the cutting tip of the drill bit correctly, you can also use it as a boring bar, rather well actually. Takes a little tweaking for the correct angle and clearance.


 


  I us endmills for boreing this way .


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## cdhknives (Mar 7, 2015)

juiceclone said:


> if you orient the cutting tip of the drill bit correctly, you can also use it as a boring bar, rather well actually. Takes a little tweaking for the correct angle and clearance.



...and when your tailstock chuck holds drill bits out of line, they inadvertently wallow out your hole during every pecking cycle...leading to my search for alternatives!  Aren't old machines fun...


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## Wreck™Wreck (Mar 7, 2015)

randyc said:


> I would differ with that statement.
> 
> A vee groove simply implies that a tool with a round shank can be accommodated, not specifically a twist drill.  I suggest that the tools that were envisioned when the vee groove was included in the holder were small boring tools and reamers, both of which are obvious candidates for power feeding.





A straight twist drill is a boring tool with a round shank which is perfectly suited for use in a tool holder. As with any other tool excessive feed rate will cause problems. I use QC tool blocks with MT bores to hold taper drills and drill chucks for power feed drilling on lathes up to 1 3/4" diameter drills with no problems. Would use a larger drill but we don't have a holder for that size MT shank.


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## randyc (Mar 7, 2015)

We'll have to disagree again.  A twist drill is not a boring tool, it is a pair of chisels offset from a common axis although one can also characterize a boring tool as another form of chisel.  All cutting tools (not abrasives) are derived from a chisel configuration, at least that's my opinion.

Those large drills to which you refer are clearly used to open up a previously drilled hole where chip clearing is unnecessary, not for starting and drilling a hole by themselves, right ?  And, as I noted previously, it would be the only time I'd ever use power feed for drilling.  However I don't get to choose how other people use their machinery


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## Wreck™Wreck (Mar 8, 2015)

randyc said:


> We'll have to disagree again.  A twist drill is not a boring tool, it is a pair of chisels offset from a common axis although one can also characterize a boring tool as another form of chisel.  All cutting tools (not abrasives) are derived from a chisel configuration, at least that's my opinion.
> 
> Those large drills to which you refer are clearly used to open up a previously drilled hole where chip clearing is unnecessary, not for starting and drilling a hole by themselves, right ?  And, as I noted previously, it would be the only time I'd ever use power feed for drilling.



By definition a "hole" through a part is a "bore" regardless of the tool used to make it, be it a twist drill, core drill, trepanning tool, WEDM,  flame or plasma cutting, Etc.

Actually  I push large drills through stock without a pilot hole or center drill spotting for roughing operations. If the machine has the power and rigidity for it you can do whatever works. I do the big stuff in a Warner & Swasey #5 turret lathe that is "break any tool" powerful.


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## randyc (Mar 8, 2015)

I'm sure that this is beginning to "bore" everyone but I differ with your definition.  Would you refer to a hole punched in a beer can as a "bore" ?  Or a hole in a length of pipe, or a piece of garden hose, or the sound hole in a guitar or countless other examples that don't fit the definition that you chose.  (As an example, the holes in loose-leaf notebook paper are "drilled" but are they called "bores" ?)

(Incidentally, you left out the last sentence in my post: "However I don't get to choose how other people use their machinery "  Which is sort of significant since the implication is that whatever works for you is fine with me.)

I worked at Westinghouse Marine Division for three years (think forty foot VBMs, lathes fifty feet long, gear hobbers in environmentally controlled rooms as big as a two-story home) and never saw anyone try to force a really big drill without a pilot hole.  The rule of thumb I was taught was to use a starter drill just slightly larger than the chisel point of the next larger drill intended to enlarge the hole.

After all, why would one would want to apply hundreds to thousands of PSI creating a lot of heat and dulling the twist drill in the process not to mention stressing the drive drain of the feed mechanism.  Whether or not the efficiency of the metal removal process is better or worse, well I suppose that would depend on individual circumstances and, as you noted, the size and horsepower of the machine.

Of course there are drills with forced coolant passages that ARE designed to make large holes without pilot drilling and frequent re-sharpening but it's unlikely that any of us on this forum own any, right ?  I may be off base here but I believe that gundrilling machines, for example, don't use geared feed mechanisms because of the stress on the feed train - I think most use hydraulic feed.

Anyway, we have drifted way off topic at this point and for my contribution to that, I apologize.  I think that everyone that wants to has provided an opinion regarding power feeding a drill from a QC toolholder on the carriage.


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## uberlinuxgeek (Mar 9, 2015)

Not to get in the middle, but Aloris and Dorian both make a tool holder for this that I use. It has a Jacobs chuck to place your bit in. So using a boring bar holder is in line with it. What I do is keep the holder unlocked and tool post loose with a peice of drill rod on the chuck and run it into the lathe chuck and slowly tighten the chuck while lining up the tool post to match. Eventually every thing is locked down and in line with center. I do this with mild steel, plastic and al so it can be done successfully. I do this manually and with cnc and with cnc I make the program work the same as peck drilling. Just passing along my experience and that tool holders are made just for this too.


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