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Hi all,
i have been doing some spindle work lately and as I was hollowing our the end of a piece of hard maple to make a “cup” for a fat candle, it occurred to me that I could use a forstener bit or even a hole saw to do a lot of the work and then clean it up. I have a drill bit chuck for the tailstock. Then it occurred to me that this could be dangerous or problematic in ways I am unaware. Any advice appreciated.
Thanks!
I use Forstner bits regularly to help create hollows. But a Hole Saw will not remove anything except the ring where the saw cust and the center drill bit. Use Forstner bits and a scraper afterwards to clean out the point at the bottom. Or get 2 bits of the same size and grind out the center point of one. Start with the unaltered, and follow with the altered one. DONE.
I also use Forstner bits on hollow forms. There are some concerns. Slow the lathe down for drilling. Pull the bit out frequently to clear the shavings (carefully as it is possible that the taper might pull out of the tail-stock leaving the chuck flying around). If you fail to clear the shavings, it is possible (likely?) that the drill bit will end up stuck in the blank and foul up your day.
I don't know why you would use a hole saw but it should work at slow speed.
Many people use Forstner bits for that. I recommend directing compressed air towards the back of the bit to clear chips while drilling.Quote:
Originally Posted by Dan Gaylin
Another option I learned from Rudy Lopez - a 1" taper shank twist drill. He used one in a demo to clear out some wood when turning a goblet. Taper shank bits fit directly into the tailstock so you don't need to use a Jacobs chuck. Since then, I've acquired a number of taper shank bits and use them almost exclusively to drill holes on the lathe, except where I want a large diameter hole such as 2-1/16" for a chuck recess, or a shallow, flat-bottomed hole.
Attachment 407594
The larger bits are #2 Morse Taper which fit the tailstock taper. The smaller are #1MT which require an inexpensive adapter to fit.
Rudy cut a 1" down to a stub and resharpened it, perfect for relatively shallow holes on the lathe. I haven't done that yet but plan to.
JKJ
I know a lot of people use forstner bits but I use spade bits. They don't go as large but they are cheap and are easy to sharpen. I grind away the center point and the wings on the outside edge so they bore a flat hole. Most of the forstner bits that I can buy locally have removable wood screw for the guide. You have to be a little careful starting the hole as the bit can flex a bit. But I can easily bore to within an 1/8" of the final depth.
This is great stuff. Thanks for all the helpful replies. My thought with the hole saw is that they are relatively cheap at the larger sizes (a 3” hole saw doesn’t cost much). True it won’t remove the plug but you will have straight sides cut out and a center hole. If you used a larger bit to make the center hole bigger you’d end up only having a small ring of wood to hollow out, no?
I also use a spade bit as Alex does, but I use a Forstner to drill holes that need to be "nice" and centered. For me, spades seem to wander all over. And they don't cut as well. Pre drilling with a spade a size smaller makes the expensive Forstner work much less. Easy to sharpen up spades.
One thing I've been doing with taps and bits and such that might get stuck and twist or pull out of the tailstock is put a small vice grip clamp on the shaft and rest it against the toolrest positioned parallel to the bed. If any taper loosens in the tailstock it can spin, and spinning is the thing I dread the most since it can scar up both surfaces in the taper. When backing out a bit I can use the vise grips to help pull the bit. If it jams I stop the lathe and work it out manually. If the bit has flats like a tap I grip with a wrench instead of the vise grips.Quote:
Originally Posted by Dennis Ford
But I found if I use the compressed air method I mentioned earlier the chips stay clear and the bit never jams (and the bit stays cooler too).
And I forgot to mention earlier - for the Forstner bits I use a lot I mount them in an end mill holder instead of holding with a Jacobs chuck. The holder is compact and light weight so if it does come out of the tailstock it's not so traumatic. The end mill holder grips the bit with a couple of set screws. Of course, it only works with bits with round shafts - most of my Forstner bits have 3/8" round shafts.
I got this one:
https://www.amazon.com/gp/product/B01MXSP25W
Attachment 407659
JKJ
All the above is good advice--might buy an air nozzle extendable gadget from HF. Allows air clearing of chips without withdrawing your bit--I do a lot of vases/urns that get deep.
I've used forstner bits; the cut quality with a hole saw or spade bit would be so poor that I wouldn't use it, even on the inside of a piece. Since the point of using a drill would typically be to leave a specific dimension of hole it wouldn't work very well to then have to make finish cuts.
As for just removing material, I think it's way faster to hog it out with a gouge than set up the drilling rig. That equation would change if you were doing production work and could do many of the same item with one setup.
I user forstner bits, too, but to get around the pilot divot in the middle, I use a 1/4" MDF spacer. I know many have two forstner bits of the same size, and grind the centre prong off one of them. You start the hole with the "normal", and as soon as you have a shoulder cut, you switch to the other bit. That way, the second bit is guided by the shoulder and it removes the centre divot created by the first bit. I have some larger forstner bits that have a long centre prong and for pieces that I am drilling to make a recess for my chuck, I don't drill deep enough with the second bit to completely remove the divot. So, I hot melt glue a piece of 1/4" MDF to the bottom. I drill into that with the normal bit, then use the shoulder on it to guide the second bit. This way, the centre prong barely penetrates the bowl and I can remove it with the second bit even if I am drilling for a shallow recess.
I do similarly but start with a forester then change to a Spade bit which is ground round on the end to finish the hole to final depth.Quote:
Originally Posted by Alex Zeller