Drilling Deep Hole On Lathe

D

Deerslayer

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The pins I have been making for my backhoe need a hole in the center of them 7" or so deep, 1/4" or 5/16 is the ideal size. I drilled one today with 1/4" and got the full 7" depth but wow it was painfully slow. I would drill 1/4 or so, back the drill out clear chips, reoil and go again. Took me 45 minutes to drill that hole.

Btw drilling CRS with HSS
 
That is the way I do it and I make a lot of pins some times 10" deep .Out of 4140 I take it your drilling for grease fitting. I make pins, bushings, and sheaves for cranes . Here is a bushing.



0213150841.jpg
 
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kd4gij said:
That is the way I do it and I make a lot of pins some times 10" deep .Out of 4140 I take it your drilling for grease fitting. I make pins, bushings, and sheaves for cranes . Here is a bushing.



View attachment 120429
Click to expand...

Nice! Is that a solid piece your making that out of?

Yes it's for grease through the pin, so forever and slow is the only way to drill it?
 
The bronze we buy tub the size we need for the job the pic is 6" od 5" id. the stock is .060-.100 over and under. As for drilling the holes I run them on a 20x80 lathe the first 2" is just striate in then peck 1/4" at a time.
 
Deerslayer said:
The pins I have been making for my backhoe need a hole in the center of them 7" or so deep, 1/4" or 5/16 is the ideal size. I drilled one today with 1/4" and got the full 7" depth but wow it was painfully slow. I would drill 1/4 or so, back the drill out clear chips, reoil and go again. Took me 45 minutes to drill that hole.

Btw drilling CRS with HSS
Click to expand...

Well, it isn't that bad. Of course, use a drilling fluid (everyone will have their own favorite - mine is RapidTap) - then you don't have to clear chips quite as often. Also, I slide the tailstock back and forth (make sure bed is clean and oiled) - you get a certain rythum: slide forward, lock, crank one turn, release, slide back, slide forward, lock, . . . . If I had a lot of holes (that were pretty small), I'd get or make a lever attachment. Another approach is the hold the drill chuck in the toolpost (MT tool holder, or make up a straight shank for a regular thread on chuck - hold it in a boring bar holder), then you can simply crank the carriage back and forth, which is faster travel than cranking the TA quill.
 
If you're cranking the tailstock, it can definitely be a chore to drill deep hole. Here's a mod I made to my Grizzly 9x20. The "pin" on the hinge was originally a #10 screw, but I've now gone to ¼-20, with a bit of a notch to help it stay put in the T-slot of the carriage.
kHPIM2579.jpg kHPIM2581.jpg
You can't apply a huge amount of force this way, as there's a lot less leverage in the carriage wheel than in the tailstock crank, but if the available force is enough, this can greatly speed up the drilling and withdrawal/reinsertion operation. Of course, it's best to first use a center drill in the normal manner with the tailstock locked in place, just to establish the centering. You'll need to unlock the tailstock for this trick to work.
 
hman said:
If you're cranking the tailstock, it can definitely be a chore to drill deep hole. Here's a mod I made to my Grizzly 9x20. The "pin" on the hinge was originally a #10 screw, but I've now gone to ¼-20, with a bit of a notch to help it stay put in the T-slot of the carriage.
View attachment 120445 View attachment 120446
You can't apply a huge amount of force this way, as there's a lot less leverage in the carriage wheel than in the tailstock crank, but if the available force is enough, this can greatly speed up the drilling and withdrawal/reinsertion operation. Of course, it's best to first use a center drill in the normal manner with the tailstock locked in place, just to establish the centering. You'll need to unlock the tailstock for this trick to work.
Click to expand...

That's a great idea! Engage power feed and get er done! In all serious ness it's a great idea for most but I'm pretty tall and more comfortable at tail stock height.
 
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