9" x 1-1/4" hole drilled on a lathe

[Brian Kent]

What Forstner would you recommend?

I need to drill a 9" hole by 1-1/4" wide into walnut or sapele end grain. It is for a gun part for my brother-in-law.

I could get a Maxi bit with extender from Lee Valley. About $72 plus tax and shipping. Prefer not that much, but willing if I need to.

What other option is there for a difficult cut?

I also could do it in several steps, and/or from both ends with HSS.

Thoughts?

[Jamie Buxton]

Rip the blank down the middle. Mill channels up the middles of both halves. Glue back together. Turn the outside. No long bit required.
You can make the channels with a table saw, or a router.

[Brian Kent]

Brilliantly obvious.

[Rich Colvin]

Here's a great YouTube video of a guy doing just that.

https://youtu.be/NCrETz4RTyM

Rich

[John K Jordan]

I need to drill a 9" hole by 1-1/4" wide into walnut or sapele end grain....


If you do decide to drill I've had good success with deep holes by directing a stream of compressed air into the hole while drilling. Cools the bit, but more importantly, keeps the chips cleared out. I have a set of carbide Forstners I prefer for deep holes.

JKJ

[Paul Williams]

I start the hole with a forstner bit the desired size. Drill about 1/2 inch deep. Just deep enough to guide the bit by the sides. Then I use a 1 inch auger bit that is 12 inches long to get the depth. Then I go back to the original forstner bit with extensions to bore to final diameter. If the final hole is going to be much larger than 1 inch I use a forstner bit sized between 1 inch and the final size. Start that bit after the initial bit so that you will have sides to guide the bit after the auger bit. I have gone a foot deep with this method. Not sure how much the final bit wanders off center. In my case it didn't matter.

[David Delo]

Brian,

Not sure about the LV extender but the 6" extender I have with a 1 1/4" forstner bit would allow me to drill a hole just shy of 9.25" deep before the Jacobs chuck would hit the piece. If your just needing 9" and not any more, you should be okay. Just check out your dimensions beforehand.

I usually drill 10" to 13" deep holes in the vases I make and have gotten away from using extenders. Something always ended up spinning. Either the extender shaft spun in the chuck or the MT2 taper wanted to spin in the tailstock. Went to the Carter Strongbore system and never had a problem since. My pilot holes are 1 3/4" because I need that diameter to get the hollowing bar & cutter inside and have a little slop to manipulate the cutters. YMMV but works for me.
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[Kyle Iwamoto]

Does it have to be exactly in the center? A trick I learned is to drill the hole in the blank before turning to final thickness. Make a jam chuck to drive the piece, and put the other end back on the tail center. Centers the piece every time.
Irwin makes a ship auger bit that is real long. Start the hole with a sturdy bit and you have pretty good chance that the auger will be relatively straight.

[Marvin Hasenak]

Drill one end as deep as possible. Then take a 2x2x12 scrap blank and drill and tap for your lathe spindle, turn it to the diameter of the hole in the blank. This has to be an almost perfect fit, as close as possible. The blank with half the hole should fit on the shaft of the scrap spindle you made, then drill from the opposite end. If the bit length is too short, MLCS has a 5" extension that is reasonable.

[John K Jordan]

Drill one end as deep as possible. Then take a 2x2x12 scrap blank and drill and tap for your lathe spindle, turn it to the diameter of the hole in the blank. ...

I use that method a lot but instead of tapping I hold the wood with a chuck then turn it to fit.

I make jam chucks like that to use on the tailstock end too, but tap that 3/4"x10tpi. I fasten that piece on a live center, lock it with a piece of wire to keep it from spinning, and use it as a drive center to turn the jam piece. As Kyle mentioned, if you hold both ends this way then finish turn the outside, it will insure the outside is precisely concentric with the thru hole even if the hole was bored off axis. Good for kaleidoscopes!

JKJ

[Joe Meirhaeghe]

I us the Colt Maxi cut bit you mentioned mounted in my 1" diameter Advanced Lathe Tools boring bar to regularly drill 1 1/4" dia. end grain holes often 16" or so deep. Great drill bits, expensive yes but the best bit's I've ever used I often recommend them.

[robert baccus]

I guess I really am a cheapie. I do a lot of vases and urns in the 10" to 18" height and commonly use a Artisan 10" extension shaft and a 2" HF forstner bit for a pilot hole. Don't you just hate name droppers.

[Kyle Iwamoto]

I guess I really am a cheapie. I do a lot of vases and urns in the 10" to 18" height and commonly use a Artisan 10" extension shaft and a 2" HF forstner bit for a pilot hole. Don't you just hate name droppers.

Well, I use that aforementioned (not wanting to drop the name brand) Irwin ship auger bit to drill a deep pilot....... Gotta be cheaper than an extension shaft and a forstner. :) AND I have a 3 pack of them. I'm REALLY cheap. IF you do decide to use that auger bit, start with a cheap (1 buck for a clearance Home Depot set) spade bit the same size. If you start very slowly, even a spade bit can start fairly straight. In case you guys didn't already know, spade bits are really easy to sharpen.

[Thom Sturgill]

One tool not mentioned is a gun drill. While I doubt you find one that size, they drill a straight hole and might make a great starter hole to keep the bore straight.

[William C Rogers]

One tool not mentioned is a gun drill. While I doubt you find one that size, they drill a straight hole and might make a great starter hole to keep the bore straight.
Trent Bosch used a gun drill in his hollowing presentation at the symposium. He just used a 3/8"

[John K Jordan]

Trent Bosch used a gun drill in his hollowing presentation at the symposium. He just used a 3/8"

Did he describe the drill, type, brand, source? Specifically, was it a drill typically used for metal and used on wood without modification or one made for wood?

I've looked for one before but hate to spend the money just to experiment with something that may not work well with wood! Some are pretty expensive.

JKJ

[Marvin Hasenak]

Research "How to make a D style drill bit". It will take you to the world of bagpipes. I tried this years ago for making a flute, my results were mixed but were doable, but I can't imagine making one 1.25" diameter.

[William C Rogers]

Did he describe the drill, type, brand, source? Specifically, was it a drill typically used for metal and used on wood without modification or one made for wood?

I've looked for one before but hate to spend the money just to experiment with something that may not work well with wood! Some are pretty expensive.

JKJ

Trent said it was a 3/8 that he got off eBay for about $30. I don't remember anything about special sharpening. He put a handle on the end with a air quick connect. Didn't take long to make his starter hole.

[Brice Rogers]

Brian, the biggest risk IMHO when drilling a deep hole is that the Forstner will pull out of the extension when you try to back it out. That can be pretty well be mitigated by clearing the chips packing in behind the forstner every inch or so of drilling. I sometimes also squirt in WD40 on a clean hole to reduce the friction (and heat). Just take your time and keep clearing the chips and you should be in good shape.

[William C Rogers]

Brian, the biggest risk IMHO when drilling a deep hole is that the Forstner will pull out of the extension when you try to back it out. That can be pretty well be mitigated by clearing the chips packing in behind the forstner every inch or so of drilling. I sometimes also squirt in WD40 on a clean hole to reduce the friction (and heat). Just take your time and keep clearing the chips and you should be in good shape.

+1 on extension pulling out, don't ask why. When drilling deep I also put some wax on the bit

[John K Jordan]

Brian, the biggest risk IMHO when drilling a deep hole is that the Forstner will pull out of the extension when you try to back it out. That can be pretty well be mitigated by clearing the chips packing in behind the forstner every inch or so of drilling. I sometimes also squirt in WD40 on a clean hole to reduce the friction (and heat). Just take your time and keep clearing the chips and you should be in good shape.

Maybe try the compressed air method I mentioned. I use a long nozzle on the air gun which extends part way into the hole. I started using this method years ago and it keeps the chips clear and reduces friction. It may help with the extension problem you mention.

Although, my extensions have set screws to hold the bit.

JKJ

[Michael Schneider]

https://youtu.be/bPqZz-PDa4A. Take a peek at the 59 minute mark. Trent describes how hw converts a metal working gun drill for wood turning use.


Edit: fixed typo in tme mark, thanks JKJ
Michael

[John K Jordan]

https://youtu.be/bPqZz-PDa4A. Take a peek at the one hour 59 minute mark. Trent describes how hw converts a metal working gun drill for wood turning use.
Michael

I watched this (fast forwarded through most, actually), nice. Good ideas there.

In case someone else looks for the gun drill part I found it at the 59 minute mark instead of the 1:59 (which was the end of the video.)

JKJ

[Brian Kent]

Thank you everyone. I look forward to studying these responses when I am done with a work trip. I am leaning toward drilling instead of cutting and routing. I can see 2 basic options - adding strong extenders or a long-enough rod, or starting from both ends. Either way, I plan to leave as much material as possible on the sides, so that when the hole is drilled, I can turn between centers and get an even wall thickness.

[Brice Rogers]

I have had a couple of forstner bits pull out of the extender. I just had a lightbulb flash in my brain. The next time I do this (besides clearing the chips very frequently and maybe using a lube), I'm going to grind a "flat" on the forstner that lines up with the tightening screw. That would tend to minimize the bit pulling out.

[Dick Strauss]

Brice, take it one step further. Drill a small hole using your set screw holes as guides. Then enlarge the holes so that they are slightly larger than the set screw diameter. Once you do this there will be no chance of the bit pulling loose unless you missed the holes when tightening the set screws or the set screws vibrated loose!

[Brian Kent]

I ordered a long 3/4" drill bit for a starter hole to remove some material, a 1-1/4" forstner and a 6" extender. I have smaller forstners to step up in size if needed, and I know to start a 1/2" deep hole at final size to guide the forstner.


I do not have a source of compressed air to clear as I go.
I have never tried auger bits with lathe drilling, so I have no confident opinion on them.

[David Metzman]

I guess you are done but you could order on Amazon:
Century Drill and Tool 38112 12-Inch Ship Auger Drill Bit Extension, 3/8-Inch (about $17) - I have it and it works fine and also order a bit on Amazon as well.