anyone set up their manual lathe carriage for deep hole spade drilling?

[pmtool]

I have occasionally want to put deep holes 2" or 2.5" diameter though round work pieces 6 to 10 inches deep. I am thinking of making a tooling block to go in the place of my Aloris post that would hold a big spade drill and plumb it with an extra coolant pump I have.

Machine is a old Pratt and Whitney model c with a 7.5 hp motor. Pretty big and rigid for its size. (16 by 36) I want to power feed it.

This is just roughing work. I would like to have this drilling while I do something else.

Anyone have a setup like this? Based on my calculations 2.5 inches diameter may be a bit optimistic. Even 1.75 would be a good start.

Typically mild or alloy steels (1018, 8620, 4140)

Are modern insert drills more efficient horsepower wise than spades?

 

[Alex McGilton]

The tail stock is more ridged then the carriage assembly for inline forces.
https://www.youtube.com/watch?v=0sxZM2DTY6E

 

[sfriedberg]

pmtool, I've done a modest amount of spade drilling with the carriage on a 7.5HP 16x40, although IIRC only up to about 1.75". Have a 2.5" insert, but can't recall ever using it. I use either a 5C or a boring bar quick-change toolholder, depending on spade drill shank size. If you're planning to replace the QC toolpost for this operation, use any basic design suitable for a boring bar shank: split-clamped, cottered, etc.

Because these are almost always one-off starting holes to prepare for boring, I haven't looked into the benefits of insert drills.

If you have spade drill shanks with coolant holes, take the time to make a proper coolant hookup that works with whatever shank holder you build. Fluid at the cutting end makes a huge difference even for one-off holes. Chip clearance can be a problem.

I do prefer the known carriage power feed-per-rev to manually timing the handle cranking on the tailstock.

 

[Iridium77]

Ever seen the attachment Dean Smith and Grace made for drilling with the carriage, it mounted on the saddle and alllowed the use of mt #3 tooling.

 

[Joec@westminster]

Back when I ran manual lathes, we would drill and tap a 5/16-18 holes on the carriage casting and the base of the tail stock and screw in a shcs in each hole. We had made a bridge from a a piece of hot rolled u channel, milled a clearance slot in the flanges opposing one another. Insert drill in tail stock, back up the carriage to the tail stock and install the bridge and then crank up to the work piece and engage the feed.

Worked well.

 

[DMF_TomB]

I have occasionally want to put deep holes 2" or 2.5" diameter though round work pieces 6 to 10 inches deep. I am thinking of making a tooling block to go in the place of my Aloris post that would hold a big spade drill and plumb it with an extra coolant pump I have.

Machine is a old Pratt and Whitney model c with a 7.5 hp motor. Pretty big and rigid for its size. (16 by 36) I want to power feed it.

This is just roughing work. I would like to have this drilling while I do something else.

Anyone have a setup like this? Based on my calculations 2.5 inches diameter may be a bit optimistic. Even 1.75 would be a good start.

Typically mild or alloy steels (1018, 8620, 4140)

Are modern insert drills more efficient horsepower wise than spades?

.
i would use a pilot hole on a 2.5" dia drill. even if you have the hp you have to be able to hold it and i have seen parts slip in a chuck trying to hold on to a part during heavy cut
...... through spindle and through the tool coolant is messy. i have seen it spray easily 6 feet. i am not sure how well it would work on a open manual lathe

 

[HuFlungDung]

Insert drills won't last unless you are really prepared to rev up your machine. The centermost insert on any insert drill has a very low SFM and will chip if you run it too slow. The typical insert drill may also not have as much reach as you require. I did a bit of this on one of my manual lathes once: had to run a 1.5" insert drill at 1500 rpm to make the center insert last. This takes lots of coolant catching shielding. But, having said that, insert drills drill with very low thrust requirements. Centering is critical.

I would never use a tailstock for this unless it's heavy construction permitted it: it needs a massive drive key, many tailstocks have a simple pin that runs in the keyway in the spindle, and this could be twisted off very easily.

For another job, we fabbed up a spade drill holder about 2 feet long. I made a clamshell toolpost to hold this on the compound. Drilled a bunch of 416SS about 12" deep with it, starting at about 2.5" . It ran nicely, unattended. I use a simple air blast through the center of the drill. This will remove a lot of heat, and may be less mess than flood coolant. You don't need a roaring air flow either, just a nice flow (not too many decibels of racket).

 

[John Welden]

I think I would rather drill and tap the saddle or cross slide and mount a block to it. Then you could bore the block in place. Boom you're done, perfectly centered. I guess you could do it with your alloris but I'd think it would be pretty rinky dink.

 

[metalmaster10]

You can get MT holders for an Aloris post... But, for that heavy work I think I would do similar to what JOhn said... Mount a block drill or locate CL, hook up your coolant (and guards)... Drill holes.

I guess if you feed it too hard and it comes apart... You will DEFINITELY know!

 

[drewboyer]

You'll kill your carriage drilling much bigger than 1". A 2.5" spade requires around 4000 lbs of thrust. My 25" toolmex is only rated for around 2000 lbs and I tried with a 2" drill but I couldn't feed it as hard as you need to with a spade. Drilling with the tailstock I can drill things about twice as fast. I mounted a long flat bar to my tailstock hand wheel so I can get leverage and push the drill like I need to. In my experience spades don't last very long if they're fed too slow.

 

[metalmaster10]

You'll kill your carriage drilling much bigger than 1". A 2.5" spade requires around 4000 lbs of thrust. My 25" toolmex is only rated for around 2000 lbs and I tried with a 2" drill but I couldn't feed it as hard as you need to with a spade. Drilling with the tailstock I can drill things about twice as fast. I mounted a long flat bar to my tailstock hand wheel so I can get leverage and push the drill like I need to. In my experience spades don't last very long if they're fed too slow.

That technical data is sure worth thinking about!

 

[drewboyer]

That technical data is sure worth thinking about!

A few years ago allied had a product selector program which gives you the thrust required for the drills. Unfortunately they don't have it on the website anymore. I'm sure there's a way to copy the program I have, but I haven't figured it out yet.

 

[Gary E]

you need a 1 or 2A W&S Saddle type Turret lathe... one with as large a hole as you can find...

There's not an engine lathe built that will out perform a big old Turret Lathefor your work

 

[drewboyer]

I worked with this older guy who mainly did oil field work and he was telling me they used to chain the tailstock to the carriage on the hollow spindle machines and drill that way. Which sounds crazy but it was probably better than using a drill mounted to the carriage because of the high center height. Probably wasn't good for the tailstock but they never had to cut any critical ODs that long.

 

[Toms Wheels]

I did this to make a deep hole drill out of a 10" DR. Removed the compound and mounted a block to the crosslide. Added two more mounting bolt to secure a 7" x 10" block to the crosslide. On the rear of the block a guide rail with index holes to position block for each of four holes drilled into the front of the block, an MT-2 hole, a 1.25 with coolant, a 1" with coolant, and a .750 straight bore. Set screws in the top surface lock the drills in position.

This way Gun drills coolant feed and taper mount or others can be used. I regularly drill 4140 1.250 on the 10", only 3" deep, but have done 1" 18" with a gun drill. Slow feed high rpms. Photobucket does'nt work tonight or there would be photos.