# Large Forstner bits on a lathe?



## Darkmoor (Jan 26, 2013)

I'm wondering what the max size is for practical use on a Jet 1640 lathe. I would like 5 or 6 inches but I'm having trouble finding them in that size.. the object is cookie/candy jars with the bark left on..


----------



## BigJoe16 (Feb 20, 2012)

That might be a but big. I haven't seem them that big but if you found them, I would think you would have to start much smaller and move up in size. 

I would for see a problem with the drill chuck in the tail stock spinning. With that much force and torque coming from the headstock and piece of wood, it would spin the bit with the wood. You would really need to lock it in there and go really slow. 

You could get a smaller, say 3" bit and cut the rest out with a chisel. 

Do you want to cut out the end grain or make a natural edge bowl? What kind of wood?


----------



## knika (Jan 15, 2012)

I don't know how big you can find but I am sure that they would be very expensive. Why not just use s bowl gouge?

Jack


----------



## Lilty (Dec 20, 2006)

I agree a bowl gougewould be the better way to go.


----------



## Darkmoor (Jan 26, 2013)

knika said:


> I don't know how big you can find but I am sure that they would be very expensive. Why not just use s bowl gouge?
> 
> Jack


Time factor.. I have some very nice bowl gouges but would like to bore the jars out as large as possible, first.. the largest I see in a quality Forstner is about 3.5 inches

Darkmoor is a business and this will be production work


----------



## duncsuss (Aug 21, 2009)

Darkmoor said:


> Time factor.. I have some very nice bowl gouges but would like to bore the jars out as large as possible, first.. the largest I see in a quality Forstner is about 3.5 inches
> 
> Darkmoor is a business and this will be production work


Have you considered metal-work style boring bars or fly cutters?

They'd require a starter hole and multiple passes, but would probably be faster than using a hand-held gouge.

Or maybe one of the many articulated-arm hollowing systems?


----------



## Bob Willing (Jul 4, 2008)

These people http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/forsbit.htm carry a 4" but chucking would present a problem. If you could remove it from the lathe and than bore on a drill press that would be ideal. You would want to run at very low rpm's.


----------



## sawdustfactory (Jan 30, 2011)

You're going to spend almost as much time backing out that bit, clearing the waste, and letting the bit cool; not to mention that you'll probably have to do this at a much slower speed than you would if you just turned it.


----------



## Darkmoor (Jan 26, 2013)

Good info, thanks guys.. maybe a combo of Forstners followed by a bowl gouge.. bigjoe, the plan is to use 8 to 10 inch diameter sections of tree trunks with the bark left on, and end bored, for 'bark on" cookie jars, for retail sale. Have much redwood, honey locust, birch, alder curing 

Also larger "bark on" redwood planters after we get the smaller process worked out


----------



## jimmyjames (Nov 23, 2012)

i hope you have a gigantic and powerful lathe, trying to use a 4" plus forstner bit takes ALOT of power.....


----------



## Darkmoor (Jan 26, 2013)

jimmyjames said:


> i hope you have a gigantic and powerful lathe, trying to use a 4" plus forstner bit takes ALOT of power.....


Only a Jet 1642 so far, about to try it 













jet 1642 so far, about to try it..


----------



## john lucas (Sep 18, 2007)

The gouge is really fast if you cut across the grain. Drill a hole 2" or so to get rid of as much of the end grain as you can down to about the depth you need to do. Then cut from the center out with a bowl gouge. I prefer to go a little deep and then cut out at an angle so I'm cutting across the grain at an angle. 
The flute should be about 45 degrees or about 10:30. Make a bunch of cuts leaving the edge just a little thicker than you need. Go down about 1 1/2" or so and then cut straight down from the lip and thin this area to the final dimension. Don't go back, this area is done. Cut another inch or so and then cut down trying to blend the previous stop line. Shear scraping works well for this if your gouge technique isn't that good. 
When you have about 3" left you an just go ahead and hollow it all the way and then do the last finishing cuts.
Guys who thin really large and thin pieces like lamp shades often use a really thick straight coring cutter to core out a cone shape. This makes it go faster but probably isn't necessary for what your doing.


----------



## Alan Sweet (Aug 16, 2013)

*Quest ..*

I think that we are talking a maximum thickness of 5-6". Is that right?

If so maybe just use a Forster Bit say up to 2".

The use carbide square insert tools to widen hole say 1/4-3/8" at a time. Come straight in from the end grain. Should not take too long.

You really have to be tight at the chuck. Seems that the size of the hole would be limited by strength of the wood, how thin, does it have checks, how dry?

I have made hollow columns that 4" long and 5" diameter in such manner.

Alan


----------



## Darkmoor (Jan 26, 2013)

Alan Sweet said:


> I think that we are talking a maximum thickness of 5-6". Is that right?
> 
> If so maybe just use a Forster Bit say up to 2".
> 
> ...



You got it, just trying to speed up the process a bit.. makes sense to me, thanks

Will be relatively thick walls, solid dry woods, birch, sequoia, alder, maple, etc


----------



## jimmyjames (Nov 23, 2012)

Bob Willing said:


> These people http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/forsbit.htm carry a 4" but chucking would present a problem. If you could remove it from the lathe and than bore on a drill press that would be ideal. You would want to run at very low rpm's.


Not too mention a large drill press to spin it, a harbor freight belt driven jobber wouldn't do it.....


----------



## Darkmoor (Jan 26, 2013)

jimmyjames said:


> Not too mention a large drill press to spin it, a harbor freight belt driven jobber wouldn't do it.....



I have a chuck fitting for the Jet lathe.. hope that will get the job done


----------

