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View Full Version : Jet Mini gets a Longworth



chrisb691
11th June 2007, 06:36 PM
I finally got a Longworth chuck made, for the Jet Mini. Attempt 1 failed due to inaccurate markout, and a crappy El Cheapo 1/4 router bit. I bought a 1/4 CMT spiral upcut bit, and got the markup right. I've never used a GOOD bit before, and now I know the difference one will make. To say it's chalk and cheese, is a total understatement.

Anyway, mk2 was duly finished and mounted on the Jet. Wearing a full face mask (some of the pics on the forum have got me rattled), and standing well out of line, I switched on. Bloody perfect.......for 30 seconds.

Pic 1 demonstrates why Corian was not a good choice of material to use. It must have had a hairline crack (I guess), and exploded with a hell of a bang. Definitely needed a change of knickers.

Pic 2 mk3. Finally got it right!!! and learnt a few more things along the way. A very happy chappy.

Pic 3 Used 'Rubber pin buffers' from Bunnings, with 6 X 50 brass connector bolts. I think Skew Chidamn posted about using the connector bolts, and the combination of these, with the pin buffers, works very well. Made a slight change to the design, in that I've got the front plate located by a 32mm tenon. which gives it very smooth action. The faceplate is also located by a spigot, so that I can remove it to use elsewhere, and get it back to the exact centre again.

WOODbTURNER
11th June 2007, 07:07 PM
Hello Chris
Great looking set of jaws.
I was just about to make a set also using an old Corian bench top about 400mm dia. but you might have changed my mind. Hate to think of the damage shattered hard Corian would do.
Chris, any chance of a few pics showing how you set up your 32mm tenon and f/plate spigot? Would come in handy when I make mine. Ta
I will be utilising my existing stoppers off my Vicmarc bowl jaws.
Jeff

chrisb691
11th June 2007, 08:36 PM
HI WT,

pic4. is the faceplate alignment spigot. I rough cut a piece of pine, on the bandsaw. Then put it between centres, and tuned a 4mm high spigot (tenon?) so that it's a snug fit into the faceplate. It actually needs a 1/4 turn of the faceplate to 'screw' it on. Screw on the faceplate, 4 screws, and turn the od to size. You need to watch that it's not so long as to interfere with the headstock shaft. I've only got the one faceplate, and I can swap it between the chuck and the disk sander, and still spin true when I put it back. The hole through the middle of the spigot, was used for a 10mm dowel that I used to locate the chuck plates onto the faceplate assembly.

pic5. Is the 32mm tenon at the front. I rough cut the 2 disks on the bandsaw, and held them together with 4 small screws. Then I drilled a 10mm hole in the rear of the back plate, and fitted a short 10mm dowel. The plates were the glued to the faceplate assembly, using the dowel to get centre, and the tailstock as a clamp.

Left it all clamped under pressure overnight, and the turned the od of the plate assembly true. Now use a parting tool, to turn out a socket that is a sliding fit onto the tenon that you have prepared earlier. Remove the front plate, and glue the tenon into the rear plate, using the tailstock as a clamp. When the glue is set, you refit the front plate and screw it back on. Face off the excess tenon, and run the tailstock centre into it so that you get a centred dimple. This dimple is then used for layout, using a pair of compesses and a ruler as per normal.

scooter
11th June 2007, 08:57 PM
Great job Chris, thanks for sharing.

I'd like to see more piccies too, disassembled maybe?


Cheers.................Sean

bitingmidge
11th June 2007, 09:05 PM
Well done Chris,

It answers a couple of questions for me, like how many tracks will fit in the mini diameter for instance, I was going to have a crack at five or six.

I don't know if odd numbers will work better or not. How has it performed thus far? It really looks the part!

What is the thickness of the ply?

cheers,

P

chrisb691
11th June 2007, 09:29 PM
Well done Chris,

It answers a couple of questions for me, like how many tracks will fit in the mini diameter for instance, I was going to have a crack at five or six.

Mine is 245mm dia, which is just about maximum for the Jet Mini, and I got 8 in with no problem (so far). I don't think it would be possible to get any more in.

I don't know if odd numbers will work better or not. How has it performed thus far? It really looks the part!

I'm currently building everything I'll need to have a go at segmented turning. So it'll be a while yet before I actually try it out. But in the meantime....it looks good. :D

What is the thickness of the ply?

The back plate is made of a piece of 12mm mdf, sandwiched between 2 pieces of 4mm 3 ply. The front plate is 2 pieces of 4mm 3 ply.


cheers,

P

WOODbTURNER
11th June 2007, 10:11 PM
Thanks Chris. Good stuff.
Jeff

ziggles
11th June 2007, 11:38 PM
:) Thinking of buying a JET lathe and prefer the mini with the bigger motor and sizes to the midi. How long have u had it? Was it a good purchase?:?

chrisb691
11th June 2007, 11:54 PM
It's a brilliant piece of gear, and I have zero regrets.

TTIT
12th June 2007, 09:27 AM
OK, so I'm gonna have to be the wet blanket here :shrug: Looks like you'll have the same problem I had with the first one I made Chris - when you try and use it at the smaller diameter, you won't be able to tighten the wingnuts because of the block you screw the faceplate to.
When I made my 2nd one, I turned up the doo-dad (pictured) so that the wingnuts would spin in the gap allowing me to close the chuck right down to hold about 50mm diameter pieces. (easy if you've got access to a metal lathe :- )

Rance
12th June 2007, 11:14 AM
OK Chris, I'll ask the newbie question (I qualify, I AM still a newbie).

So how do you use this chuck? I'm guessing that you loosen all the bolts, then twist the two plates to bring the bolts in or out to fit your piece. Do the bolts naturally move along the grooves when you do this or do you have to help them along? It seems that if you had to help them along, then you'd have questionable results with the chuck.

Another thing, did you use plans for this or just wing it? Thanks. An impressive work BTW.

Rance

TTIT
12th June 2007, 03:24 PM
OK Chris, I'll ask the newbie question (I qualify, I AM still a newbie).

So how do you use this chuck? I'm guessing that you loosen all the bolts, then twist the two plates to bring the bolts in or out to fit your piece. Do the bolts naturally move along the grooves when you do this or do you have to help them along? It seems that if you had to help them along, then you'd have questionable results with the chuck.

Another thing, did you use plans for this or just wing it? Thanks. An impressive work BTW.

RanceRance mate, you would be amazed at how easily the bolts follow their tracks - provided the bolts are loose of course! Google will find you more 'how to's' on building a Longworth than you can poke a stick at.:2tsup:
Hmmm - maybe we need one (a how-to) permanently packed on the forum - volunteers???:;

chrisb691
12th June 2007, 07:26 PM
OK Chris, I'll ask the newbie question (I qualify, I AM still a newbie).

So how do you use this chuck? I'm guessing that you loosen all the bolts, then twist the two plates to bring the bolts in or out to fit your piece. Do the bolts naturally move along the grooves when you do this or do you have to help them along? It seems that if you had to help them along, then you'd have questionable results with the chuck.

Another thing, did you use plans for this or just wing it? Thanks. An impressive work BTW.

Rance

Hi Rance.

Your guess is quite correct, you counter rotate the two disks and the jaws move in/out. Additionally, they are self centreing.

Apart from the addition of the spigots (tenons?), I used the imformation I got from here (http://www.fholder.com/Woodturning/lwc-wtm.htm), and took notice of other posts on the forum.

chrisb691
12th June 2007, 07:42 PM
OK, so I'm gonna have to be the wet blanket here :shrug: Looks like you'll have the same problem I had with the first one I made Chris - when you try and use it at the smaller diameter, you won't be able to tighten the wingnuts because of the block you screw the faceplate to.
When I made my 2nd one, I turned up the doo-dad (pictured) so that the wingnuts would spin in the gap allowing me to close the chuck right down to hold about 50mm diameter pieces. (easy if you've got access to a metal lathe :- )

Hi TTIT,

Not a wet blanket at all, just a realist. I'd already worked out the limitation, and have been cosidering my options. I don't have a metal lathe, but am considering getting some 80 dia aluminium bar and test turning it in the Jet, using an HSS tool. If that works, then all I need is a 1" X 10 tap, and I'm in business. Mind you, to close the jaws up more, I'd have to remove 4 of them.

cedar n silky
12th June 2007, 08:58 PM
Thanks for that Chris. And TTIT!:2tsup: I think thats my next addition to the lathe accessories!:D

La truciolara
14th June 2007, 08:13 PM
Congratulation Chris
You did very well and it is very useful for each one of us. Thanks.
Can I draw attention of those who want to make one?
Personaly I would not have carved so much with the rooter. You might have some vibrations on large pieces for the little wood left near the junction of your curves.
See picture which explains much better what I mean
http://www.la-truciolara.com/forum/Longworth5b.jpg

The problem can be easyly resolved buy doing curves with a larger radius, thus enabeling to take small pieces while keeping more wood between curves.

TTIT
14th June 2007, 11:01 PM
................. You might have some vibrations on large pieces for the little wood left near the junction of your curves.
.............Well spotted Claude - this is the main reason I stuck with just 4 buttons on my chucks - didn't want to weaken anything more than necessary. :shrug: