Jam chick timber, what's being used and where do you get it from?

[Redbeard]

Title says it all really. I'm making bowls of many different sizes, up to about 300mm, and I'd like to use jam chucks for finishing the bottoms. What timber are folks using and where do you get it from?

Thanks
Redbeard

[Mobyturns]

I use whatever is at hand and preferably free. The only things to be mindful of is that the timber is sound and does not split easily when it is attached to a face plate with screws. If you are using a scroll chuck to mount the jamb chucks be sure to use an appropriately sized recess but more preferably a tenon.

Its also handy if the timber doesn't have any knots or hard spots in the area that will be the mating surface to your bowl and that it is relatively soft compared to the timber in the bowls.


Most turners use Cole jaws or a vacuum chuck if they can afford the gear. Some use a ply face plate with an interface pad of foam with tailstock support.

[mick661]

I find pine is good for jamb chucks its generally softer than the timber you have turn hence less chance of marking or scratching the bowl

[Old Croc]

I don't know why Nubsnstubs has not chimed in, but he uses MDF very successfully. I am a cheapskate, so I use Northern Silky Oak because I have lots of it and it's dimensionally stable.
Rgds,
Crocy.

[mick661]

MDF is not a good thing to turn it can also fail.
Not a choice I would make.
Cheers mick

[Redbeard]

Jam chicks, jamb chucks, potayto, potahto...

Cheap is good, free is even better. Soft pine is nice, I've made a few chucks out of radiata from bunnos with varying success, mostly smaller ones for cups and goblets. Something bigger for a 250mm bowl is what I'm thinking of, wrapped with some of the rubber drawer lining mat to provide some grip and protection. Just need to source a bigger lump to start with.

MDF does not appeal, nasty stuff with lots of inherent risks, not the least is the whole carcinogenic side of the dust.

I'm going to give a large round ply disk a go, just have to swing a mounting. I've got some M30x3.5 nuts here, just have to come up with some ideas.

Cheers
Redbeard

[Nubsnstubs]

MDF is not a good thing to turn it can also fail.
Not a choice I would make.
Cheers mick

It all depends on how you are using it. If it's between centers, how can it fail? Anything you put on a lathe CAN fail. It's how you put it on the lathe that determines success.

I see people condemning the use of plywood as a glue block. Granted, without some type of stabilizer, it isn't a good thing to use. But, with a few screws going through it, it's better than any solid piece of wood you have. Some people thread their own small 3" diameter wooden face plates using glue to attach their work onto. To me, that seems more unsafe than using a piece of MDF between centers.

Mr. Beard, if you are making a jam chuck using a very snug fit to hold the piece, are you going to use your tailstock to assist while removing the tenon? Also, how are you going to hold in your chuck?

Several years ago, Stewart Batty demo'd at our club here in Tucson. He used a jam chuck like what I think you are wanting to use. It works, but unless you have something to apply pressure to keep your piece between centers, one day you will lose one. I've found that you must always cut towards towards the headstock in order to keep the piece on the lathe.

Back in 2009, I started turning. Complete novice with no one to teach me. Within one year, after losing 3 out of 10 pieces while removing tenons, I made a donut chuck. That lasted about one year, before it exploded and put a gash on my side. It took me another 6 months or so to invent a tool that I named The Tail Stock Steady. Since the first prototype, in 2012, I lost 2 pieces when I first tried it out. Too much pressure on one piece, not enough on the other. Since then, about 800 pieces later, not one loss. I had several pieces split, or break up while removing the tenon, but not because how it was held. It was because of the type of crappy wood I like turning.

Go to this site https://www.woodturningonline.com/ . In the April issue, scroll down until you find "New and Hot" items for woodturning. You will see a picture of my invention. Go to my website, Wood Turning Tools | Tucson | WoodTurners WorkHolding Solutions (http://www.woodturnerstools.com) , and check it out. There are a couple videos. If you click on the youtube icon at the bottom of the video, it will take you to Youtube. When you get there, in the Youtube search box, put in Nubsnstubs. More of my videos there. You will also see how the MDF is used. Pretty stable stuff in my opinion.

Thanks Croc, for the mention. You dry out yet???............ Jerry (in Tucson)

[Dalboy]

I use any cheap soft wood that is stable. Soft wood will do less damage to the bowl being turned I also use a router mat over the jam chuck

[Old Croc]

I was not quite ready to post any pictures yet as I will do a feature of this later on. Here is one of the multiple step jam chucks I use just setup for this photo. The bowl is not finished, but this is how I remove the tenon. That's one of Nubsnstubs (Jerry's) tailstock steadys in use. Because I use a 108mm/4 1/4" tenon that suits the middle set of the multi jaws from the blue lathe manufacturers, I had to add a 14mm/ 9/16" spacer under the wheels as the PCD of Jerry's design was the same as the tenon.
I have done about 20 odd bowls/plates now with this steady and I love this setup way better than my Longworth chuck. Only other thing I had to do was make the pictured toolrest as my usual ones copied from Retired would not get into the space between the wheels.
Jerry uses individual jam chucks out of very thick MDF, very strong, but I am very space limited so I made 3 multi step chucks from real small up to very large.
As with anything in woodturning there are multiple ways to skin a cat, but I have settled on this setup.
Rgds,
Crocy.

[Nubsnstubs]

I was not quite ready to post any pictures yet as I will do a feature of this later on. Here is one of the multiple step jam chucks I use just setup for this photo. The bowl is not finished, but this is how I remove the tenon. That's one of Nubsnstubs (Jerry's) tailstock steadys in use. Because I use a 108mm/4 1/4" tenon that suits the middle set of the multi jaws from the blue lathe manufacturers, I had to add a 14mm/ 9/16" spacer under the wheels as the PCD of Jerry's design was the same as the tenon.
I have done about 20 odd bowls/plates now with this steady and I love this setup way better than my Longworth chuck. Only other thing I had to do was make the pictured toolrest as my usual ones copied from Retired would not get into the space between the wheels.
Jerry uses individual jam chucks out of very thick MDF, very strong, but I am very space limited so I made 3 multi step chucks from real small up to very large.
As with anything in woodturning there are multiple ways to skin a cat, but I have settled on this setup.
Rgds,
Crocy.

Thanks, Richard. I'm happy to hear that my Tail Stock Steady is working out for you. You could also use your Longworth chuck, and using both would absolutely guarantee success....... It looks like you have a lot more space that I do. Jerry (in Tucson)USA
m

[TTIT]

. . . . . That's one of Nubsnstubs (Jerry's) tailstock steadys in use.
. . . . . .
Rgds,
Crocy.


Hmmm!?!? Interesting little creature - Haven't seen one of these before - I either haven't been on here enough lately or somebodies keeping secrets from me! :oo:
Looks like another job for the mini-metal lathe santa got me :U

[Mobyturns]

Several years ago, Stewart Batty demo'd at our club here in Tucson. He used a jam chuck like what I think you are wanting to use. It works, but unless you have something to apply pressure to keep your piece between centers, one day you will lose one. I've found that you must always cut towards towards the headstock in order to keep the piece on the lathe.

Thanks Croc, for the mention. You dry out yet???............ Jerry (in Tucson)

Jerry - very good advice all up.

Many turners do not understand the forces involved "cutting" on the wood lathe. There are tangential and axial forces created. Most understand the tangential forces - the "push back" against the tool and the downwards force on the tool rest but very few realize the strength of the axial forces.

The feed rate of the tools cutting tip actually works somewhat similar to a screw thread and will exert a force along the lathes axis, either forcing the blank / workpiece towards or away from the headstock. This is best illustrated in the spiral track created in a skew chisel catch where the blank is "constrained" with the tool free to move.

When using a friction jamb chuck in either spindle or faceplate (bowl) turning it is very important not to create an outwards acting axial force that is greater than the frictional force holding the work piece - i.e. use light delicate cuts! If the tool is "constrained" and the work piece free to move then you create a UFO - an unintended flying object.

The presentation angle of the tool and the sequence of cuts is very important for tasks such as refining the base of a bowl held in a jamb chuck or in fine spindle turning (ie delicate finials & trembleurs) to reduce the destructive effect of those forces.

[Nubsnstubs]

Hmmm!?!? Interesting little creature - Haven't seen one of these before - I either haven't been on here enough lately or somebodies keeping secrets from me! :oo:
Looks like another job for the mini-metal lathe santa got me :U

There are only two of those critters in Australia. I invented it in 2012, and received my patent in2016. If you want to make one, do it in aluminum. I used steel as I thought it was needed, but now am of the opinion that aluminum would have work as well. It might cost a few cents more for the Aluminum, but I believe it would be as sturdy. When you make one, please be sure to post it. If you want to see more, go to youtube, and put in Nubsnstubs. That's my channel. You will see more of it in use......... Jerry (in Tucson)USA

[NeilS]

I either haven't been on here enough lately or somebodies keeping secrets from me!


Your absence was noted...:U