Boring a hole to a bigger size and tap?

[Badasssapper67]

Got an arbor that's Brown & Sharpe #10 that's sized 1/2-13 for the draw bar. My draw bar is 5/8-11. I know this because I ran taps into the new arbor and one that I know works.
Doesn't seem like there'd be too much trouble but wanted to make sure, B&S #10 aren't cheap arbors.
Let me know what you think.

 

[sreeb]

I think a lot of collets are hardened...

 

[matt_i]

An arbor is likely thru hardened and no-va as far as tapping it.

Why not just make a new drawbar...while not fancy even a piece of threaded rod with a nut welded to it would work just fine. You could do a little better than that and make a copy of existing with your 1/2-13, but if pressed for time, see above.

Depending on the OD of existing drawbar, use of a black oxide setscrew is a fast solution to getting a high carbon, rolled thread in a fast manner. This will outlast a low carbon single pointed thread in my opinion. Simply tap the new drawbar shaft 1/2-13 and loctite in the setscrew...

 

[mowkep]

What sort of machine is the tooling for?

 

[Badasssapper67]

What sort of machine is the tooling for?

It's a Cincinnati No. 1-1/2 horizontal mill. Very old. I havent been able to date it yet but by the construction, I wouldnt be surpprized if it was made in the teens.

If I could figure out how to post pics on here I would make a thread about bringing her back to life.

 

[Badasssapper67]

An arbor is likely thru hardened and no-va as far as tapping it.

Why not just make a new drawbar...while not fancy even a piece of threaded rod with a nut welded to it would work just fine. You could do a little better than that and make a copy of existing with your 1/2-13, but if pressed for time, see above.

Depending on the OD of existing drawbar, use of a black oxide setscrew is a fast solution to getting a high carbon, rolled thread in a fast manner. This will outlast a low carbon single pointed thread in my opinion. Simply tap the new drawbar shaft 1/2-13 and loctite in the setscrew...

The only problem is my rack that holds tooling is behind the mill and up close to the lathe. The draw bar wont come all the way out unless I move a bunch of stuff.
I may end up having to cut a big hole in my shelving...... if I can figure a way so it doesnt look like a mickey mouse trailer park mod I'd modify the cabnnets but was hoping I could just tap the arbor.

 

[454ragtop]

Check to see how hard the tapered end of the arbor is with a file on the very end. I suspect you will find it's not that hard, and you should be able to tap it. Taper shank drills are fairly soft in the area of the taper, your arbor may be made the same way. Pretty sure they make the arbor softer than the spindle to help protect the spindle.

 

[Badasssapper67]

Check to see how hard the tapered end of the arbor is with a file on the very end. I suspect you will find it's not that hard, and you should be able to tap it. Taper shank drills are fairly soft in the area of the taper, your arbor may be made the same way. Pretty sure they make the arbor softer than the spindle to help protect the spindle.

Thanks!

 

[mowkep]

I typed in your machine type and there was some info on the No. 2s. I was reading one blog where the guy converted the B&S taper to a 50 taper. I'm pretty sure all of the tool holders I have from 50 to CAT 45 to CAT 40 to 40 to Anderson 300 are all hardened. There are plenty of machine tool dealers that have used tooling for decent prices.

 

[Badasssapper67]

I pulled the arbor out and gave it the file test The draw-bar area was not hardened so I decided to do the mod.
Dont know what the heck I was thinking, I got flustered trying to find a 17/32 drill bit. After stomping around in the heat I said "Screw it, I'll just buy another one", Then it hit me they're not only $19.00 it'll take a couple days to get here.
Realizing that 9/16 is 18/32 I decided to just go for it. Now this whole time Im flustered and worried and I grab my 9/16 drill bit and my cordless drill and keep asking myself if Im sure I want to risk ruining this arbor. Keep in mind that it's very hot and I dont do well in the heat. Deciding to go for it I pull the trigger and start drilling.
Im checking to make sure the drill is straight to the work and keep checking my progress when it dawns on me...... I have a lathe. Wow. Haha.
Took off the 4 jaw put on the 3 jaw, ran the arbor in tightened her down and drilled out the old threads.
Then I put a 5/8-11 tap in the drill chuck, set the old lathe on her slowest pully engaged the back gears and ran the tap into it, Presto! (ok it was a little more than that...)
Cleaned it all up reel well, insert the arbor, tighten the draw-bar and it works! I LOVE having the right tool for the job!
Then I ganged three cutters on the arbor and made some test cuts on a piece of steal Im making T nuts with, so far so good.