Long Reach Drill

J

JPower6210

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Hi folks- I have a couple of holes I need to drill and then tap M4. The issue is that I can't get to the spot with a regular length drill bit- I need about 4 more inches. I can make the tap work, it's the drilling that is causing me the issues. I haven't found a bit extension that will work. So here is what I am thinking- take some rod, chuck it up in the lathe, maybe 1/4 or 3/8, drill as close to a slip fit as I can for the 3.3mm bit and then red locktite the bit in and make an extended bit. Opinions? Am I crazy to think this will work? Thanks!

JP
 
Being that thats a small drill size the red locktite might work. If that fails try some silver solder to hold the bit.
Sent from somewhere in East Texas Jake Parker
 
JP
I've extended many drill bits by pressing them into a larger diameter rod when there was no clearance issue.
The extension needs enough meat ( diameter ) to hold the bit without slipping. I suggest at least 11mm if possible.
The extended bit should be lightly clamped in your chuck by the flutes and spun to check for runout.
It needs to run true and keep feed light.Don't let chips clog the flutes when cutting.
 
I think it will work with red locktite. I have used JB Weld with good success. Rough the drill shank up a bit to give whatever you use some surface to bond to.
 
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You can purchase aircraft extension drills in common sizes in 6" and 12" lengths.

I have made extensions as you are suggesting using super glue for binding. I use this because it is fast. Just put a few drops in the socket and shove the drill in quickly. Give it fifteen or so minutes to set and it should be ready to go. For a more permanent join, brazing works. HSS can take the brazing temperature without draw its temper. Also silver solder.

I have had some for years and have yet to have one fail.
 
You could also use a setscrew to hold the bit in.
 
My vote would be against using a set setscrew.

1. A setscrew will require a much larger diameter shaft.
2. A setscrew does not provide adequate drive torque. This is evidenced in the pilot drills for hole saws and the extension shafts commonly used with woodworking drills. If used, a flat is required on the drill. The setscrew also galls the drill, making removal difficult should it need to be replaced.
3. Setscrew fastening is more difficult to execute, requiring drilling and tapping a cross hole instead of drilling a simple socket in the lathe.

Bob
 
Thanks all for the responses- I almost went with the setscrew idea just to do the machining part of it, but my lazy side won out and red loctite made the day. Broke one bit off in the rod drilling the hole, then turned the speed up and all worked well from there- And I figure better that than in the finish part.
 
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