Gallery, Projects and General > How do I??

Very Deep Hole Drilling

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Jonny:
Missed this bit but for me to get any concentricity and runout after extending i do it my way.
Turn down the shank, often softish even morse tapers can be. I turn a stub of substantial length and fit to go in a drilled hole in a bit of steel round. Chamfer both pieces and either braze or silver solder, it will be man enough but no good for draw bars. If welding tack in 3 or 4 places round circumference to eliminate some of the warp/veering off.

No1_sonuk:
Thanks.

WRT feed length, mine is 2" (Chester DB7) I had thought about holding the bit in a boring bar holder on the carriage to get a longer travel.
I know it'd be a pain to centre, but any thoughts on how practical that might, or might not be otherwise.  I will be able to get at least 1/3 the blank into the spindle bore.

From my point of view, it's looking more and more like making a D-bit is the lesser of several evils.

Jonny:
Unless i am missing something, you are not going to be able to do it.
11" long, say 4" in chuck leaves approx 7" protruding.
Lathe centres only 12" minus chuck etc, probably only have 3 to 4" before tailstock and an 11" cutters got to go through!
May be able to nick some length by dismantling carriage etc but its not going to gain you 7" at best.
Will need at least on your set up about 19" centres.

Any way of mounting the part on carriage and drilling with the lathe chuck?
You could then drill in with normal standard drills then replace with the made up long ones which would be in the hole already done!

Stilldrillin:
Hasn`t an 11" long hole got 2 ends?  :scratch:

I make that 2 x 5.5" holes.....  :thumbup:

David D

No1_sonuk:
Good points.

Mounting it on the carriage is a possibility if I make a fixture for it.

Drilling one end, then the other would be problematic because of the short between-centres issues Jonny mentioned.  It can go in 1/3 of the way one way round, but not the other - probably about an inch or so.

Hmm.  It might be feasible to make it in 2 parts, though...  :scratch:

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