Retaining Key

[Martin W]

Hello all,my drill has two slots in the column. One is for using the drift to remove drills and sleeves. From what I’ve been told the other is for a retaining key to keep tools locked in I want to make a Morse taper #4 boring bar to bore some parts for bushings. Does someone have a picture of how this key works? I need some way to hold this in like a draw bar would.
Cheers
Martin

 

[benmychree]

That is what is called a draw key, unless you can adapt a G&L Davis draw key, the key usually consists of two keys, both tapered, driven into the slot to pull the tool into the taper, the slot in the tool must be located properly to allow this to work, the setup is most commonly used on horizontal boring mills with MT spindle tapers, but also on larger drilling machines.

 

[Martin W]

Thanks
I did a search for Davis Key

http://www.scott-bakerco.com/files/GL_D440_94.pdf

i Wonder if I could make a wedge type drift with a retaining collar to keep it in place?

 

[Martin W]

I found this on the net. I believe this is what I need to make to keep the taper locked in.
cheers
martin

 

[benmychree]

Yes, that would work, if it fits your spindle, or you could make one. The solid ones just drive in, no retainer needed, sometimes necessary to shim them to fit tight.

 

[Martin W]

This is where I’m at now. I still need to broach a hole for the cutter, make a bearing retainer for the end and the retaining key.
cheers
martin

 

[benmychree]

you might want to extend the key slot further upwards; usually, the slot is showing about 1/16 or more at the top and sunk about the same amount below the spindle slot. What kind od drilling machine is that? I once used a boring bar in my 21" Canedy Otto upright drill with #4 taper, it had no retaining slot, I just whacked the bar in good and tight and it stayed put, the bar had a bearing in the center of the table, got the job done ---

 

[Martin W]

I will extend the key slot as you suggest. It’s an old Mas radial drill. I have an old Case dozer loader that’s wanting new loader arm bushings.
Cheers
Martin

 

[Martin W]

Finally had some time to work on my boring bar. Made a key like the picture above. I just used an old pillow block bearing and turned a bushing to act as a sliding arbor support. It actually works pretty well
The only issue is ,my drills feed rate is just a little too fast even on the slowest setting, but still works pretty well.
the piece I am boring is just a piece of scrap with a flame cut hole. Pretty hard to bore until you get thru that hard bit of slag.
Cheers
Martin

 

[NCjeeper]

What design of draw key did you end up making?