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Drilling using Tool Post

Mcgyver said:
It depends (imo) on the size of the drill. I've a few small lathes used for small holes with levers and agree, it is absolutely the way to. Easy to clear chips, more sensitive and faster. But they they lose their appeal as the drill size increases. I don't they'd be much fun over say 1/2"

For large drills, the DSG rig is (imo) the best. For punching a 1" through a length steel, the tailstock is obviously doable, but rapid retraction for chip removal, power feed and removing the chance a taper drill spinning in the tailstock quill would be nice The tool post gives some of these advantages, easier to retract, and power feed, but needs alignment and creates a moment around the tool post bolt. I've not used one so can't be certain, but wonder if that becomes an issue with large drills?
Click to expand...
Multifix, Aloris, and Dorian, all have anti-rotation pins, to allow for heavy cuts. Guys on YouTube with their compounds removed, make a locating part which butts up against the QCTP body to prevent rotation.

I've had a drill bit spin in my tail stock a couple times unfortunately. It was a 1 1/4" bit MT3-4. Since then, when drilling large holes, I'll put a dog drive around the drill bit with the tail resting on the compound.
 
Ok, as an experiment, I decided to try using the tool post to drill. Now, I do not have a QCTP. What I have is a four tool square post which I made years ago. I designed it to take 3/4" shank tools. In these photos, I have attached my drill chuck to my home made boring bar holder. And had align it so it is parallel with the ways. Then dialed it in for center. As you can see, I'm good front back (I always forget axis designations, Y?), but I'm about 0.005" too low. I wasn't about to redo everything to put a shim under the tool holder, so I proceeded.
 

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I then put a #4 countersink, and then a 1/4" drill bit. I attached a dial indicator onto the body of the drill chuck to see if there was any movement. Which there was a couple thou. I'm sure combination of the tool too low, plus I forgot to lock the cross slide. I used the power feed, it worked well no issues. I also tried manual, and you can still feel the cutting action. So sll in all I'm pretty satisfied that this can be advantageous if I had a QCTP, and a DRO. Some details: the bar i was drilling into was 2" diameter tool steel, HRC36, Albrecht drill chuck, 600rpm.
 

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Nice Experiment @thestelster

You said you ended up about 5 thou low. I would not have hesitated to use 2 pieces of paper to make up that small different. When it is torqued down I don't experience any loss of rigidity. A piece of aluminium pop can also works well.

A quick question - how did that small misalignment manifest itself in the drilling? Did the drill just bend and make a bit of a taper or did it start oscillating?

More important question - how are you gunna drill from now on?
 
Susquatch said:
Nice Experiment @thestelster

You said you ended up about 5 thou low. I would not have hesitated to use 2 pieces of paper to make up that small different. When it is torqued down I don't experience any loss of rigidity. A piece of aluminium pop can also works well.

A quick question - how did that small misalignment manifest itself in the drilling? Did the drill just bend and make a bit of a taper or did it start oscillating?

More important question - how are you gunna drill from now on?
Click to expand...
I have shims, thats no the problem, but because it took a while to get the alignment between the boring bar holder parallel with the lathe axis, I didn't want to take it all apart. I should have determined proper height first, then go to axis alignment.

There was no real issue with drilling. It probably acted a bit like a reamer, taking a bit off the the sides to fit. You could tell there was some rubbing by the slight squeal when retracting the drill bit. If the rpms were a lot higher, there would be heat issues, but I kept it relatively slow and used cutting oil.

I'll continue to use the tailstock, until I get a QCTP and DRO. Setting up the way I just did takes way too long, but knowing there's no deflection or chatter is promising.
 
thestelster said:
I have shims, thats no the problem, but because it took a while to get the alignment between the boring bar holder parallel with the lathe axis, I didn't want to take it all apart. I should have determined proper height first, then go to axis alignment.

There was no real issue with drilling. It probably acted a bit like a reamer, taking a bit off the the sides to fit. You could tell there was some rubbing by the slight squeal when retracting the drill bit. If the rpms were a lot higher, there would be heat issues, but I kept it relatively slow and used cutting oil.

I'll continue to use the tailstock, until I get a QCTP and DRO. Setting up the way I just did takes way too long, but knowing there's no deflection or chatter is promising.
Click to expand...

OK, I understand..

Reading your experience over again just now, I think I'd have to have a driving need before I tried to drill that way. How does that old saying go? If it ain't broke don't fix it.

This from the guy who is always looking at new ways to do things!!! LOL!
 
Here is photo my setup transferred over to the new lathe. 6.5mm end drilled into 3/8" AL rod, 700 holes to be done. Once everything is set, all the holes come out the same tolerance.

Note this is nor precision work and about 0.005 tolerance is acceptable.

1652359434699.jpeg
 
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