Bits for deep boring

[Brian Holcombe]

You'll be using as a drill and it IS center cutting and can go ~9-10". You'd have to drill and retract many times to clear the chips - - because of the length of cut.

I'd have to disassemble the entire setup to retract that bit to clear chips. I appreciate the thought but I think there may be a better solution out there. $250 is also more than I would like to spend in order to solve this issue.

[Malcolm McLeod]

I'd have to disassemble the entire setup to retract that bit to clear chips. ....

Whatever bit you select, keep in mind that a Bridgeport knee mill will allow you to use the full quill travel, plus the vertical travel of the knee. Combined, it should eliminate the need to disassemble. I've seen machinists reach into seemingly impossible places with a well thought out setup. - - Hope it helps.

[Prashun Patel]

Can you bore the hole as deep without the extension.
Then use an extension to drill a smaller diameter hole through to final depth.
Finally, attach your original bit to the extension and ream out the hole to final width.



I use this method when drilling dog holes in my bench - not because I'm afraid of deflection, but because it makes it SO easy and resistance-less to drill to deep depths. The reduction in resistance might (my theory) reduce the desire of the bit to deflect.

[Brian Holcombe]

Malcolm, I'll continue to keep that in mind, as I have for the past 14 years that I've worked with this machine.

Fixturing to the machine is not the issue. I was looking for specific types of woodworking bits best known to minimize deflection and maximize chip evacuation. I assumed Forster but was looking to double check unless there was something significantly better.

Maximum underhead is 16" and the piece will likely end up at 10-12"~. Which is why I expected to need to cut then drop the longer bit in to finish the cut.

[Malcolm McLeod]

I have come to know you as 'The SMC Neander Guy'; had no clue of your metallic skill set. I'll shut up now.

[Prashun Patel]

...and don't try to school him on scotch either, Malcolm

[Malcolm McLeod]

...and don't try to school him on scotch either, Malcolm

The gauntlet has been thrown..... it's on!!

[Brian Holcombe]

Hahaha! Ok, we may as well steer this one well off the rails. I'm an Islay man and I like long walks on the beach (the second part is a lie )

Bunnahabhain 18 and Lagavulin 16 are my go-to's.

[Malcolm McLeod]

We're all allowed some claim to fame...
Ian.jpg
...my cousin. And not a sassenach.

Anybody else?

And anybody who likes the Lagavulin is welcome in my home ... with a bottle in his pocket!!

[Brian Holcombe]

Awesome! That's got to have some good benefits. Also, good to know that I'm in good company on this board.

[Grant Wilkinson]

I've read that flute makers use gun drills for deep, straight bores.Would that work for you?

[Roger Nair]

To be on point with the O.P. and the derailment, consider the Scotch eyed tee auger, still available from the UK.

As a former timber framer, I would layout drawbored peg holes and drilled the holes before cutting the joints. I used several bit types and achieved predictable results, namely twin spurred solid center Irwin bits, single spur ship auger bits from various sources and triple spur Wood Owl bits. Lengths from 12 to 18 inches. Sharp spurs are, imo, one absolute key getting a clean bore. Other key are directional control and boring through perpendicular to tangential grain. I used drill frames of two types and several jigs to focus the bit. The simplest is a block five or six inches thick with a perfect bore through the block. Layout the bore on both sides and center punch. Insert bit through the bore in the block, find the centered punch hole with the feed screw and clamp the block to the workpiece. Drill halfway through and flip the stock and repeat process. Accuracy depends on crisp layout and regular surfaces. Or one could just bore through with a block clamped of the side where the bit comes through. to prevent blow out.

[andrew whicker]

https://www.mcmaster.com/#standard-drill-bits/=172fyd9

?

Not sure if a drill bit on your mill would be good enough.

[Brian Holcombe]

Thanks for the insights.