Musing about single chucking vs reverse chucking.

Hi Arch

Should be easy Arch.

Just some arbitrary sizes, OK, they can be changed to suit, and you might have to do some machining to get close fits.

Drill a 1 1/4" hole in your blank, and set aside.

Take a short piece of pipe that fits your 1 1/4" hole in your blank and is long enough to be clamped in your X/Y drill table vise, and stick out above it.(can be done in other vise also)

Now make a arbor that will fit inside the pipe on one side, and turn down to fit into drill chuck on the other end. (make the arbor long enough to overcome the distance difference between thickness of the blank and the drills quill travel ability)

Next put the arbor in the drill chuck and maneuver the pipe in the drill vise until the arbor goes straight into the pipe, clamp all down.

Take the arbor out of the drill chuck and replace with the drill to be used, place blank on the pipe in the drill vise and drill your other mortice.

Do I do it this way ??,.... NO. , works better on my late IMO.

And never say never, I find turning a bowl in one setup akward, harder to get a good form and cutting against the grain make for a worse surface, then there will be this time ................ like I said !!!

Have fun and take care Leo Van Der Loo

"Arch" wrote: (clip) I just want to know if and how it can be done. (clip) ^^^^^^^^^^^^^^^ Arch, you're being Leo'd to death here. Here's how I would do it. After drilling one side of your blank, secure a flat board to the drill press bed, and drill a hole in it also. Go to the lathe and turn a "dowel" that is a snug fit in the drilled hole. Insert in the hole in the board on the drill press, slip the hole in the blank over the exposed end of the "dowel," and drill into the other side of the blank.

Sure, do it on the lathe. That's how I do it. Not sure why you'd want to introduce the inaccuracies which would result from non-parallel faces. Doubt it'd save much time, either. Nice thing is, I finish the inside of the mortise before I reverse. If you're hot to trot to try some weird setup, make a 60 or 90 degree fence on a board which you clamp to your drill press. Tuck your round piece up into the corner so it's touching, mark across the piece and both legs of your centering jig fence. Bore your first hole.

Now drop the dicandpurpular from the reference marks, invert the piece, and align with the fence marks. Should be close, but don't know what you're after to determine if it'll be close enough. Other method is always on, of course.

Why do either of two bad things by trying a single mount? One is force yourself into weird angles to reach around the headstock , second, put yourself into the throw zone. Not to mention you're bucking for a dismount by cutting away from the chuck. Faceplates, back in the bad old days, yep, I did it single mount. Bought a chuck in about '85, and haven't done more than touch up from the rear since. You can bet I have the tailstock in play the whole time, though.

That means standing back and cutting away from yourself toward the chuck!

Arch I am not sure how I would drill the holes, but I would generally not bother so I am not much help. On the other hand I usually rough turn between centers, including the hollowing. For the final turning I use a glue block and finish turn from one fitting. It just seems easier to me and I do not have to worry about concentricity when remounting.

Well, in the "olden days" I never reverse-turned. I'd get one side of a blank flat by some means, glue it to a backer on a faceplate with some paper in between, turn the bowl, split off the joint, and sand off the paper scraps.

Before _that_ I just lived with 3 screw holes in the bottoms of my bowls, and learned to avoid making the bottom too thin.

Given various limitations of equipment and time, I've been known to still use a faceplate, though now that I've gotten to be better equipped for bigger chunks of log, I often reverse faceplate it (using the first mount to turn a flat spot for the second mounting), and I eschew the retained holes in favor of shaping most of it with a fat foot, then parting the foot mostly off and hollowing it up a bit by using all the space I can get at the back, followed by cutting the stub and using the

Things often move enough that reverse mounting means having to make a decision about where the new circle meets the old ellipse - while that should be no different with single mounting for the same movement, it does not usually feel that way, or at least you know that you are fighting wood movement rather than a lousy job of remounting.

Hi Leo, I was hoping for a really simple and easier method. I had thought about attaching a spring center (like a Steb center) in line with the drill's bit to seat in the indent made by the bit's tip in the first mortise. This should center the 'other side' over the drill bit, but with rough surfaces to sit on this wouldn't assure concentric mortise walls and bottoms. I could seat the blank in my scroll chuck to avoid the rough surfaces, but then I have to center the blind 'other side' and I'm back to your method or one more complicated? I know I've forgotten something, but isn't there an easier way with common sense, lasers and such?

Comments & other hole finding methods requested, laughter & derision acceptable if accompanied by a helpful adult. :)

Turn to Safety, Arch Fortiter

OK Arch

Simpler way, take drill press, position horizontally, call it lathe, clamp drill bit in lathe, hold blank and drill hole for woodworm screw, clamp woodworm screw and screw blank, drill or make the hole on the other side, DONE

Have fun and take care Leo Van Der Loo

I think I understand what you are asking. First, you drill a mortice on the top of the bowl blank. This is to secure the blank to the lathe with a chuck while you turn the outside of the bowl. This eliminates the need for a faceplate. You want a second mortice on the bottom to reverse it and then turn out the inside of the bowl. This is my standard method of bowl turning. For the mortice on the bottom, I mark with calipers (which are super glued in place) a circle that is the same size as my chuck jaws. I use a dovetail scraper to cut a mortice.The angle of the dovetail matches that of my chuck jaws. You just line up the scraper with the ways of your bed, and the angles will match.Remove everything inside the line, then for the last cut, make the mortice just a hair bigger than the line. The plunge cut used isn't plunge, and then move it over to match the dove tail, but plunge at the angle of the dove tail. At the bottom of the last cut, let the scraper rest there for a moment or 2, just barely touching. This will remove almost all uneveness, so that when you reverse it, it will run true. This will get you an almost perfectly centered mortice every time. I think that it would be impossible with a forstner bit. If I am trying to turn very thin, then sometimes the outside will need to be trued up. For utility bowls, there isn't enough difference to worry about, especially if you green turn to final thickness like I do. You can also clean up the mortice with a small spindle gouge, sand it and call it finished if you want. If you are coring, you just leave the chuck on, and never have to recenter anything. Also when I am coring, I will dovetail the top mortice when I reverse the bowl the first time, because it holds a lot better than straight walls with angled jaws. robo hippy

If you have one of those two-fanged thin parting tools, you can cut pretty well into the bottom. I even angle mine in anticipation of the final tail. Nice for those fuzzy woods like aspen or willow that don't respond well to the pointed gouge smoothing and undercutting. The fangs do a reasonable cut.

Nice thing about dovetails, unless you go dumb and leave fuzz sticking out or sawdust packed in, they'll get a piece as true as your chuck. Trick is to remember that, and if it doesn't mount perfectly, loosen and find out what's in the way. Even I sometimes just tighten instead of doing it properly.

SNIP

it can be done.

OK, here goes - and keep in mind that you're not concerned about the bowl's bottom:

Take a small-ish drill and bore the whole way through the blank. Then use that bore as a guide to center the Forstner on both sides. Hmmm?

In the 1st case, chuck the blank using the 1st hole, true the piece, than put a drill chuck in the tailstock and use the original bit to drill the 2nd hole..

Mac

Mac, I was looking for a way to drill both with the drill press one after the other. A.

Turn to Safety, Arch Fortiter

"Arch" skrev i melding news: snipped-for-privacy@storefull-3171.bay.webtv.net...

I reverseturn all my bowls and platters, every day.

The forstner bit only makes the first recess. I mount the piece, rough turn the bottom shape as far as to flattening the bottom surface, then I use my parting tool to cut the opposite recess the same size as the first.

It turns out exactly parallell and exactly centered, for all the natural reasons.

BjarteR

While all of you are trying to solve the multiple chuckig problem, what everyone is actually suggesting is multiple chucking to drill two holes. It doesn't matter that you do it on the lathe or a drill press, but the end-for-end work is exactly that.

Just turn the ends as needed for a given chuck and reverse when needed. All that work with dowels and jigs kind of defeats the advantages, don't you think?

Joe Fleming - San Diego

While all of you are trying to solve the multiple chuckig problem, what everyone is actually suggesting is multiple chucking to drill two holes. It doesn't matter that you do it on the lathe or a drill press, but the end-for-end work is exactly that.

Just turn the ends as needed for a given chuck and reverse when needed. All that work with dowels and jigs kind of defeats the advantages, don't you think?

Joe Fleming - San Diego

Thanks Derek and all respondents, Yep, the axis is the problem and of course you and the others who saw no reason for considering an inherently bad method are right. I hope thinking about problems, good or bad, interests a few of the group, otherwise my musings are nothing but trolls. Could be, I reckon. I am surprised that somebody didn't invoke the bylaws, since my question didn't advance the craft. Maybe just because I wanted to know if it could be done easily. Maybe because:

it's there, the impossible dream, ours not to reason why, the cutting edge, did it my way, followers can never lead, a better day is coming, the new science, the poor intelligence, the plagiary proof technique... Truth is, because I wasn't sure it couldn't work.

To coin a phrase, "perversus ego sum" or in English, I am a COC. :)

Turn to Safety, Arch Fortiter

That's what most of us do, Bjarte.... but this is ARCH asking.. *lol*

Mac

Thanks Derek & Mac, Don't encourage me! I'm thinking of asking your help in turning a 'Penrose Triangle' next, since all my parallel tool marks cross each other. :)

Turn to Safety, Arch Fortiter

not by my method:

Take a small-ish drill and bore the whole way through the blank. Then use that bore as a guide to center the Forstner on both sides. Hmmm?