Jam Chucks and profanity

[paulmann]

Hi All,

trying to make some progress as a beginner and decided to make a small box. All was going fairly well until I came to using a jam chuck !, the first attempt I thought was just right until I tapped the lid on and it split in half (ok back to the drawing board a little too tight ) the second box the lid went ok but i thought I had the base on the jam chuck just right, nice and tight and true but the moment I touched the base with a tool it flew off and made a large dent in it (hence the strange shaped box), everytime I thought it fitted the jam chuck perfectly the moment a side load (tool) was applied it flew off. The elderly lady next door to my workshop learned some words which she may not be too familiar with !!

I would be grateful for any thoughts or tips on where I am going wrong with the jam chuck as this is doing my blood pressure no good at all !

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hope pics work, best wishes to all.

 

[paulmann]

I'll try and sort the pics out asap.

 

[Bodrighy]

If the lid is too loose, a bit of wet tissue sometimes works. If too tight (you should be able to push on, not bang on) a little sanding...continiually testing...works.

Pete

 

[TEP]

Take heart Paul, you may have brightened up her day for her. :lol:

As to splitting the lid, it happens to the best of us As you have found out the fit has got to be just right. Tight enough to hold, but not to break, this will come with practice.

As to jam chucking the base, even with a good fit I ALWAYS bring up the tail stock with revolving centre to help support the work. If you are worried about the centre marking the wood too much make a wood cover with small tip to fit over the point.

Work on the base of the box leaving just as small a stub as possible where the point is, then sand the work. Finally remove the tail stock and gently remove the nub that is left, sand the last little bit and apply finish.

Also be careful which way you use the tool, when the work is unsupported always try to cut towards the head, not to the side or towards the tail. That way you are pushing the work onto the chuck. As when removing the last nub I always use the side of the tip of the tool in almost a draw cut fashion so as not to put any sidewards pressure on the work.

 

[paulmann]

 

[robo hippy]

When using a jam chuck on the base, I prefer compression to expansion. Make it so that it goes into a hole. Also, use a soft wood like cheap pine. It won't push back as hard as oak will. As far as the lid goes, it doesn't take much for the fit to go wrong. I use a skew chisel to get the fit just right, more of a negative rake scraper, and very gentle. A square chisel/scraper with a burr is too agressive. A parting tool isn't any better. If you have to force it at all, then it is too tight. If you get it just a tiny bit too loose, a tissue or two, or even just slightly wet the rim with water, and it will expand just a bit for a good grip. Getting it wet is preferable to me as it doesn't slip as much as dry wood can. It will shrink back down shortly, but you may need to pry the lid off. I do prefer for the fit of jamming the lid on to leave about 1/16 gap between the lid rim and the base. Then I can ease those edges a bit with sand paper, then trim up the spigot for a good fit after finishing the lid. This also gives you a slight opening if you have to pry the lid and base apart.
robo hippy

 

[PowerTool]

Beautiful looking box,Paul - finish looks good,and the timber itself looks fantastic

Andrew

 

[Jenx]

Agree.. the box is a little Gem !
I've "avoided" jam chucks for much the same reasons and experiences !

I wouldn't worry too much about the 'old dearie' .... she'll not only have HEARD it all before , but probably DONE 99% of it, as well !

Your box is a beaut Paul ... lovely work 8) 8) 8)

 

[John. B]

Well, despite the frofanity, you seem to have done a pretty good job.
A very nice box. Good shape, nice figuring.
But take heart, it happens to us all. Try to use soft wood for jam chucking, slightly loose then using some tissue push on not whack it on. then support it with the tailstock.

John. B

 

[stevebuk]

beautiful little box paul, i understand about jam chucks not working proporly, i tried making an ear ring stand and the bloody jam chuck wouldn't work so i left it.
keep trying mate, i will..

 

[Scrums]

Lidded pots are a pain in the backside......they'll always fly off just when you're on the very final stages !

Ultra sharp tools, tiny, tiny, light cuts and bring up the tool rest so the lid or base can't get enough room to fly off.

Use a revolving centre in the tailstock to make sure it stays where it should and take off that tiny little 'nipple' carefully when all's finished.....

Chris

 

[paulmann]

Thanks everyone, I like the tip of using the tailstock for support, stupidly I never thought of that, was too concerned with trying to get a perfect base.

Will have another go next week, making a box is certainly a challenge and has taught me a lot.

Best wishes all

 

[loz]

Sweet box Paul,

I always use tape, to secure a piece to a jam check, just a for added support, that and bring up the tail stock untill the very last moment !