Vacuum chucking for Revo 1836

[Bill Dempsey]

Oops, another slide down the vortex. I've replaced a delta midi with Revo 1836, sort of a retirement gift to myself. Got her together and started a couple of pepper mills. But bowel turning is next frontier, so thinking about vacuum chucking after looking through the alternatives.

Occasional hobby use alternatives seem to be holdfast, frugal vacuum chucking, or the Laguna vac generator option. As a newbie to bowels, am I missing other alternatives? Any and all suggestions welcome. To date I've taken a bowel course at Woodcraft and turned a few glued up 2x8 into something vaguely looking like a bowel.

Any and all suggestions welcome...

[Steve Eure]

I have the 1836 and started out with a HoldFast chuck on my midi before going to the 1836. I wound up making my own headstock insert with a piece of wood with 2 ball bearings embedded on each end. I took a 5/8" brass mpt plumbing fixture that had a hose barb on it, ground it down to press fit into the bearing. On the other end that attaches to the hose, I took a brass hose barb, ground off enough to fit into that bearing. This allowed me to screw it into the headstock, similar to the Laguna offering. Works very well with no leaks.
I did make a few chucks from ideas from watching Youtube and also bought a hub that I could swap out different size pvc couplings with.

https://jtturningtools.com/vacuum-chuck-hubs (https://jtturningtools.com/vacuum-chuck-hubs)

That would be the route I would consider if I were to do it over again. I like the Holdfast chucks, but on light wood, they sometimes tend to leave black marks that have to be lightly sanded to remove. Not a big deal. just annoying.

[William C Rogers]

The easiest is to buy the vacuum adapter from Laguna. It is about $90 and screws into the hand wheel. I then made PVC chucks. I had made adapters for my previous lathe, but decided it wasn't worth the hassle.

[John K Jordan]

Oops, another slide down the vortex. I've replaced a delta midi with Revo 1836, sort of a retirement gift to myself. Got her together and started a couple of pepper mills. But bowel turning is next frontier, so thinking about vacuum chucking after looking through the alternatives.

Bill, this might be an interesting read: https://www.joewoodworker.com/veneering/vacuumchucking.htm
Even if you don't want to go the do-it-yourself route, the education on vacuum chucking is useful. Joe sells the components at very reasonable prices if you do decide to build or build part of the system.


As a newbie to bowels, am I missing other alternatives? Any and all suggestions welcome. To date I've taken a bowel course at Woodcraft and turned a few glued up 2x8 into something vaguely looking like a bowel.


My first bowl was on the world's worst lathe from a stack of 4/4 red oak on a faceplate, finishing the bottom by hand. My advice is to run far away and take up another hobby unless you want to end up like many of us here. (me, five lathes and a new shop later and a king's ransom in tools and turning wood, teaching and driving around doing demos! Get out while you can. :))

I don't turn a lot of bowls these days (prefer making other things) but when I do I generally hold the work by the top (screw chuck, scroll chuck, etc), shape the outside, then reverse and turn the inside (held by recess or tenon - sometimes with a waste block glued on the bottom). Then reverse again and finish the bottom if necessary.

Even if you get a great vacuum system it's worth getting experience with other methods in case you can't use the vacuum chuck on a piece. (voids in wood, natural edge bowls, warped bowls, broken vacuum chuck, turning away from your shop...)

Some ways I've used and know of to hold the bowl by the top to finish the bottom:

- Jam chuck. Time honored method, cheap, easy, very effective. Turn a profile on a block of wood held in a scroll chuck or face plate so the inside of the bowl fits tightly. If the jam block is accidentally turned a tiny bit too small you can sometimes use some paper towel to make it tight. If turning the bowl from green wood, you might have to work fast or keep the bowl damp to keep it from warping too much to jam effectively. I sometimes add strips/loops of tape to help secure the bowl. Further secure the bowl with the tailstock as long as possible (can even leave a small stub in the middle and remove it by hand off the lathe). Make gentle cuts primarily down the axis of the lathe. Professional turners/demonstrators often use a jam chuck even for large bowls, then turn may even make another bowl from the large temporary chunk.

- Commercial Cole jaws/jumbo jaws. These grab the bowl by the rim with soft "buttons", etc. If the rim is suitable in size and shape these work very well. For rims that turn in at the top the jaws can often be used in the expansion mode.

- Home made methods - cole-type jaws, Longworth chuck, donut chucks. This book by Doc Green covers some methods and how to make what's needed - great book to have in your library if you are a reader.

- Old method. Finish the bottom by hand. It used to be common to glue a waste block to the flattened bottom before turning with paper between, then split the waste block off. Or part off the waste block (or the tenon). Then finish the bottom with chisels, sanding disks, etc. It's nice, of course, to slightly dish the bottom so the bowl doesn't rock on the table if it warps slightly.


There is another, simpler way I often use - simply eliminate the final reversing to clean up the bottom! When initially turning the outside/bottom I make a shallow recess in the bottom, use it to turn the top/inside, and leave the recess in the final piece. I'm using this more lately, people I give pieces to often comment on how much the like the look, and some turner friends who were initially strongly against the method are starting to use it themselves after seeing and holding the pieces.

When initially turning the bottom (always from dry wood, of course) I usually smooth, sand, and even apply finish to the bottom before reversing to hollow out the inside of the piece so after smoothing and finishing the top the piece is done.

I use this method exclusively in these small "squarish" dished platters:
410477 410478 410481 410484 410482

I show this method when demonstrating since this design won't always fit in Cole jaws and because lots of people don't have a vacuum system. Another advantage is automatic and perfect registration without frustrating alignment.

I use it often in other pieces:
410483 410479 410480

The recess doesn't have to be real deep. I make most 1/8" deep or so. The recess in the last one on a 20" platter consists of the three arcs on the inside of the three sort-of curved triangles, just outside the central dome. (This is my variation on Frank Penta's multi-axis base technique.)

I have used recesses as shallow as about 1/16" but a bit deeper is probably better. The wood does have to be good - no punky wood, voids, cracks in the base. The amount of wood outside the recess needs to be sufficient to be strong - don't try this with a 2" recess in a 2.5" diameter foot! Also, with dovetailed jaws it is important to not angle the dovetail in the wood too much - the jaws need to contact only at the bottom of the recess.

I like the look when the bottom is turned to decorate around and inside the recess. The small flat ring also makes a place to sign the work, sort of like a little shadowbox.

JKJ

[Bill Dempsey]

Thanks Steve and William. JKJ, always amazed at your level of knowledge, and down to earth advise, mucho thanks for sharing. And...yeah I tried to run away, but to no avail..

[Brice Rogers]

Some advice: there are a variety of different bearing types. I found out the hard way that not all sealed bearings are the same. Some are contact type sealed bearings (that is what you want) and there are some "sealed bearings" that are non-contact. That latter ones leak badly and it is hard to pull more than 7 or 8 inches. I ended up buying my bearings from Frugalvacuumchuck. They are very good.

[Jack Lilley]

I have an 1836 with the vacuum setup from Laguna, it works great, I'm very happy with it. I have had a vacuum pump setup on two other lathes and find the one from Laguna works just as good but you do need a decent air supply for it. My chucks are homemade.