Making a Grumbine chuck......question

[Odie]

I am currently putting the pieces together to make a Grumbine chuck for natural edge bowls.

My Lathe capacity is 16", but, I have a feeling that it might be overkill, if I make the chuck the maximum size I can make it......

Am I right, or wrong about the above assumption.....?????

From what you've seen, what is the general size of natural edged bowls? Do you see many with a diameter of.....say.....12"......more, or less?

What size should I make the Grumbine chuck?

Thanks for your comments, thought, and general input.....:cool2:

ooc

The following photos, I grabbed off the internet a few years ago.....can't remember where I got them, off hand.

 

[Odie]

OK.....maybe this seems like a naive question for some of you, but here's a little revelation for you.......

......I have never seen anybody else's natural edge bowl, except in photographs. I don't have much conception of the size these bowl are, but most of them look to be fairly small.

I could make a Grumbine chuck that would handle a natural edge bowl to about 15" in diameter, but it seems like that might be a wasted effort. If I'm probably not going to need that size of chuck, then I'd rather not have that big of a spinning contraption on my lathe.....unless I really have a need for it.

For those of you who have seen and/or done quite a few natural edge bowls, all I'm interested in is getting a general idea of the average diameters these bowls are, so that I may plan accordingly.

thanks

ooc

 

[Vaughn]

Odie, in my experience with this type of chucks, I've found it useful to make the back plate as big as the lathe will allow (within a 1/2" or so), then make a variety of rings with different sizes of holes in each. I tend to make the rings as I need them, then save them for the next time I need one that size. I understand your consideration about having something that big spinning on the lathe, but it's almost as sure as sunshine that as soon as you make a 12" chuck you'll end up turning a 13" bowl.

To answer your other question, the natural edge bowls I've done have generally been between 10" and 18" in the longest dimension. My average is probably somewhere around 14". But that's just me. Other guys will have a different range they like to do.

 

[MichaelMouse]

Sort of like the old saw - you can turn small stuff on a big lathe, but not big stuff on a small. Make the main plate(s) it as large as possible.

People with access to urban trees can find wood in great dimension. In the woods things grow slow, and a hardwood tree over 16-18" is probably rotted on the stump. To make a near circular 15" bark up requires a tree of 18 or better.

Then there are these kind. http://i35.photobucket.com/albums/d160/GoodOnesGone/Third-Bite-Beech-Upright.jpg Don't work well in the donut, so the bottom's finished before they're hollowed.

 

[Joe Greiner]

Largest possible at the outset. And tailstock assistance until the last cut.

For natural-edge bowls, cut groove(s) in the back plate to accept standoff(s) of newsprint core or pvc pipe. Newsprint cores are generally about 24" long minimum and standard diameter, so you can cut many different lengths of standoff. Similar with pvc pipe. Non-staining foam cushion for either at the bowl end. For something really long, add a steady rest for the front plate.

For the front plate, add a slit piece of clear vinyl tubing to the rim of the hole.

You can even make natural-edge funnels this way.

 

[john lucas]

While your at it make several of the doughnut plates so you can accomodate bowls of different shapes. I use to use these a lot but now I just bring the tailstock up, turn the base and cut off the little nub left.

 

[hockenbery]

I do what john does for bowls and hollow forms.

Alan Lacer had an article on this chuck in the AAW journal about a year ago.
He called it the Straka chuck. Alan gives a bit of the history

It is a great holding device for balls and other objects.
I use one for my Ball in a Ball. It also gives access to the bottom of a bowl to do some intricate work you can't do with the tail stock in place.
take the time to get the front plate paralell to the back plate. an invers cone ton the oneway center makes it easy. I also lay calipers on the tool and meaure from the back to front for even all the way around.

I don't think there is any size limit. I hold mine with a 4 jaw chuck and it needs to be wide enough for the bolts to clear the chuck.

pylwood can delaminate so be sure you dont use it in any manner where the hold is just with the glue bond and plys.

I usually reverse turn a natural edge bowls. I put them over a block of wood with a pad and bring the tail stock up. The wood in the bottom of the bowl is pressed against the jam chuck and a pad. No danger of damaging the rim and it is virtually impossible to put too much pressure on the tail stock.



happy turning,
Al

 

[Richard Baker]

I have two sizes and several "doughnuts" for each size. The smaller size is just handier for smaller workpieces. The "faceplate" piece is 5/8 or 3/4 particle board (also serves as a friction chuck), and the doughnuts are cut from scrap 1/2 OSB. Thin padding on the faceplate and ample padding on the doughnuts.

 

[Robert Manning]

RIng Chuck

Odie, for a ring chuck:

1) I would recommend building a fixture like this on a heavy duty face plate like those from Oneway to minimize the flexing that translates to chatter.

2) Consider laminating two sheets of 3/4" or 5/8" plywood for the base portion face to face to counter natural warping. Baltic or Russian birch plywood available in 5' x 5' sheets is an excellent choice. True it up with your scraper. Today's price for 3/4" x 5' x 5' Baltic Birch is $32.30 a sheet.

3) Cut the hole in the ring on your lathe so it bears evenly on your piece and rout it with a rounover bit. Pad it with leather.

It looks like you have the three carriage bolts properly placed for safety's sake.

 

[Odie]

Thanks for all the responses, comments, and advice...........

I have a few comments of my own, but the main thing is to acknowledge that I'm taking the advice here and making the largest Grumbine chuck my lathe will accommodate. 16" swing, minus allowance for the bolt pattern should give me somewhere in the neighborhood of 14" maximum bowl diameter.

(BTW: Vaughn and Robert Manning......I checked out your bowls in the contest results. Very creative use of dyes and laminations.......nice job, to both of you! :cool2: )

Vaughn: You aren't the only one who suggests multiple "donut" plates to accommodate different bowl feet......I'm adding that to the list, but will probably make only one for starters.

MM: Often times, you are one that makes great common sense......yep, it will be as big as possible. That example you show a pic of.......looks like it includes the pith.....am I correct in assuming there is an element of luck that you seem to have avoided cracking?

Joe: Already purchased the PVC for an interior brace.....was planning on using a child's rubber play ball on top of that....should provide some cushion to it, but don't want it too spongy. Might cover it with leather.

John: Yes.....different donut plates. One to start me going. At this point, I prefer to have clear access to the base......sort of what my Mega Jumbo Jaws give me. Really have gotten to like the freedom of movement around the base without that tailstock being in the way.......!

Al Hockenbery: I've been wondering how the best way to true up the bowl and donut plate so that the bowl base runs true. I have ordered a #2 MT to 1 1/4x8tpi adaptor from csusa.....plan to use it for this purpose. Hope that helps keep things running true, once the chuck is installed.

Texian: I have purchased some 3/4" particle board for this purpose. I'm having some doubts about the strength, but I know particle board is very resistant to warping over time. I might laminate two pieces for the base plate, and use a single thickness for the donut........still, mulling that over right now.......

Robert: I have some thin Baltic Birch plywood, and I know you are correct that it would be a great material for this purpose. I've already got the particle board and plan to use that......but, if it's a "no-go", I may have to re-think...... Good idea of using leather for the donut hole. I had planned on using a piece of rubber, but leather is probably a better non-marring choice.

thanks to all......hope to get this chuck in the works this weekend, but have some other obligations that may require a delay......hope not, because I'm anxious to finally make this chuck a reality........

ooc

 

[Robert Manning]

Odie,

First let me say thanks for the compliment on Desert Flower. Desert Flower has been juried in to Against the Grain, a woodworking show at Cypress College. One of my kayaks and Ponderosa Radiata will also be exhibited with works by Sam Maloof and John Cederquist. The show opens February 4, 2010.

Regarding your ring chuck, if you laminate your thin Baltic Birch plywood to each side of your particle board, it will be much stiffer than the particle board alone. I would use Titebond II or Weldwood powdered plastic resin glue for laminating.

Thanks again,

Robert

 

[george morris]

Jamb chuck

Hi Odie I just turned 6 cherry natural edge bowls. I jambed chucked all of them. I use my vicmark chuck mounted on the lathe then take a 4" piece of PVC pipe with a foam ring around top and expand the chuck to hold the pipe . Compress the natural edge on the foam and bring up the tail stock to compress the bowl. I cut off the nub and sand flush. Quick and easy!! George

 

[Mike Peace]

The largest NE I have turned =19". It was a square edge winged bowl that was about 12 X14 but 19" diagonally. My typical NE is probably 6" if round but I do a few rectangular winged bowls because I like the look. And you get a bigger piece than doing one round. This one for example is 4"X5" but about 6 1/2" on the diagonal.

I looked at making a Staka chuck but decided I would get more use from a vacuum chuck that cost a few more dollars to build but probably did not take a lot more effort and I felt would be more versatile in the long run.

 

[Bill Grumbine]

Since my name has been invoked here...

Odie, I take no credit for that chuck, although I am honored that you would associate me with it. I learned about it from my mentor, Dave Hardy. You won't see him posting here, but he taught me lots about turning. That style chuck works well for finished rim bowls, but as has been mentioned by some others, a friction chuck, pinching the bowl between centers, is fast and easy, especially with natural edged bowls. I use it all the time.

A friction chuck can be like that pictured in one of the responses, or I do ones as simple as a piece of foam sanding material slapped up against the chuck. Good luck with whatever you decide.

Oh yeah, I have turned natural edged pieces anywhere from 3" in diameter up to 25" in diameter. But bowls in the 8"-12" range are most common.

 

[Vaughn]

Odie, a couple tricks for the rings that you may or may not have thought of...

I use a router with an offset base and anchor pin to cut several ring blank circles out of a single piece of plywood. That way I have a few blanks in stock. To cut the centers out of a ring, I bolt the blank to the back plate (just as I would a ring) with a scrap wood spacer between the two, and spin it up on the lathe. Then I just use a bowl gouge or parting tool to cut the appropriate-sized hole in the middle. By cutting the hole on the lathe with the ring mounted on the back plate, you're assured of a centered hole. Note: Use the tailstock to keep the center of the ring in place. Otherwise, when it lets loose it has a tendency to fly like a sideways Frisbee. The results can look like this. (The window is directly behind me when I'm standing at the lathe. I have good reflexes.)



That all said, Like others here have mentioned, for NE bowls I tend to use the tailstock and a friction chuck (leaving a little nub to trim away off the lathe) or a vacuum chuck. And when I do use a donut chuck, I also keep the tailstock in place until the last possible moment. Things just seem to stay in place better that way for me.

 

[Gil Jones]

I reckon I do not care what a Donut Chuck is called, but the one I made works great. For bowls, or other things with an odd shaped or fragile rim, here a few pics of my workaround to that problem. In this case it is a piece of 6" PVC pipe, 9" long and padded on both ends with rubber sheet that looks like an inner tube.
It was turned from a green, very gnarly and misshapen, chunk of Live Oak Burl. The dimensions are 228.6mm (9") high by 266.7mm (10.5") diameter.
I am building a vacuum chuck system, but in this instance it would not have worked.
Gil

 

[Joe Greiner]

To give credit where credit is due, Gil was my source for the notion of tubing at the rim. But I think clear tubing would be more universally non-staining. I've used colored craft foam (about 1/8" thick) at the standoff, and it stained the inside bottom of my first NE form; laborious hand sanding cleaned it up. Use white from now on, or test beforehand.

 

[Odie]

Donut Chuck

Progress report.......

I got up in the wee hours of the morning and worked on the Donut Chuck.

The faceplate is a huge 8" one that I probably haven't used since the 1980's.....will leave it permanently mounted.....It's perfect for this purpose.

Plan to use different lengths of 2" PVC to accommodate different height needs.

I'll get different lengths of carriage bolts to suit the needs of the moment.....will not have those dangerous exposed threaded shanks, but this is what I have at the moment.

I got that orange play ball at Target store. It might work out ok, but if not....there are plenty of other sized balls that can be had.

Bill.......I've been storing those pictures in the original post for several years. Wherever I got them, I can't remember, but I believe the chuck was called the "Grumbine Chuck" by the person who took those photos. Why your name is associated with it is a mystery to me.

Thanks for additional comments from everyone......I read everything, and many suggestions are used.....Whether I put everything to use, or not, all advice and suggestions are certainly appreciated, and give me a better perspective! :cool2:

Here are some photos of work in progress......so far, so good, everything running true and looks like this Donut chuck is something I'll probably use. Still have to use some leather padding where necessary, get some various length bolts, various length PVC piping, and whatnot.......

I do NOT intend to do very many NE bowls.....just something different for me once in a while.......just to add a little variety to my turning. My main thrust will remain the same......it's what turns me on!

Thank you

ooc

 

[Bill Grumbine]

Bill.......I've been storing those pictures in the original post for several years. Wherever I got them, I can't remember, but I believe the chuck was called the "Grumbine Chuck" by the person who took those photos. Why your name is associated with it is a mystery to me.

Odie, I can help with some of that mystery. Those photos are of my Vicmarc mini lathe, and go way back in time to the days of the Badger Pond woodworking forum. I took them in 1999 - I can tell by the background - long story and not important. I had an article on my website for many years about how to make this chuck, and I am sure it has been stored on at least three or four computers.

 

[Joe Greiner]

Odie, before you invest a king's ransom in a lot of long carriage bolts, consider using a few shorter lengths with coupler nuts and a collection of all-thread rods, similar to what Gil uses. Jam nuts at the couplers can lock them against vibration. There's less nut-running this way too, although the wing nuts help. Two-inch increments should be adequate, and the all-thread has many other uses around the shop.

The whole kit deserves its own storage place. Surplus food containers are ideal; best would be pasta jars, if available in plastic, not glass. If glass is necessary, wrap them with clear packing tape. It won't prevent breakage, but the pieces will be easier to find when (not if) it hits the floor.

 

[Odie]

Odie, before you invest a king's ransom in a lot of long carriage bolts, consider using a few shorter lengths with coupler nuts and a collection of all-thread rods, similar to what Gil uses. Jam nuts at the couplers can lock them against vibration. There's less nut-running this way too, although the wing nuts help. Two-inch increments should be adequate, and the all-thread has many other uses around the shop.

The whole kit deserves its own storage place. Surplus food containers are ideal; best would be pasta jars, if available in plastic, not glass. If glass is necessary, wrap them with clear packing tape. It won't prevent breakage, but the pieces will be easier to find when (not if) it hits the floor.

Great suggestions, Joe.....

I'm going to look for the "all-thread" and coupler nuts. Matter of fact, I might cut off those three carriage bolts I have and connect the excess cut off pieces with the couplers!

I'm also going to take your advice on storage.....there will be extra parts and various lengths of PVC pipe. I've got some big plastic coffee cans that might work well for this purpose.

There is one reason why I have chosen to use Carriage Bolts. I will be using them because the head is domed. To my way of thinking, this is a safety issue, and having those rounded carriage bolt heads facing toward me while I work will be a little insurance against the possibility of my paying a big price for doing something stupid! (I wish I could say I've never, ever, let my concentration for what I'm doing, overcome alertness to safety issues, but it has happened!......I'll bet almost all of us can relate to that! )

thank you

ooc

 

[Odie]

Odie, I can help with some of that mystery. Those photos are of my Vicmarc mini lathe, and go way back in time to the days of the Badger Pond woodworking forum. I took them in 1999 - I can tell by the background - long story and not important. I had an article on my website for many years about how to make this chuck, and I am sure it has been stored on at least three or four computers.

OK, thanks Bill.......I don't believe I got those photos from your web site......I think I got them from someone else, who probably got them from your web site......funny how some things get distributed on the web. Those two photos will probably live on for many years to come!

ooc