Drill Bit In A Boring Toolholder?

[cdhknives]

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!

 

[JimDawson]

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.

 

[randyc]

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 !

 

[gt40]

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...

 

[Wreck™Wreck]

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.

 

[kd4gij]

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

 

[randyc]

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)

 

[LEEQ]

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.

 

[randyc]

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.

 

[juiceclone]

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.