Drill Bit In A Boring Toolholder?

[kd4gij]

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 .

 

[cdhknives]

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...

 

[Wreck™Wreck]

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.

 

[randyc]

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

 

[Wreck™Wreck]

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.

 

[randyc]

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.

 

[uberlinuxgeek]

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.