Richard Raffan on making and using jam chucks

hello I'm Richard Grafton this is a short video about Jam trucks Jam trucks are enormously useful if you want to turn off the bottom of an end grain box for instance you'll need a jam chuck if you've got a rounded Bowl the chances are it'll be safer to put it into a jam Chuck rather than over some Chuck Jaws so that's we're going to look at here I'm going to make a jam Chuck for this little box base and for that for Jam trucks I've got a lot of little odd blocks which have been left over from other jobs in Grand jobs so there's a little shoulder on there so that goes up against the Jaws helps it turn up nicely in the chuck then with these always peace it's all being going to be running slightly actually just screwed up just using a peeling cut for the there's a one inch skew chisel and that's pretty true on the top that's all right now I tend to do this by eye you could measure up the calipers but um uh I want a diameter slightly smaller than this now the idea is to cut a taper over which this fits and I'll hold it just firmly enough to get a small burnish mark but we've got to get down to that diameter first so I start with a bit of a taper now that doesn't fit deliberately so that I can show you what happens now if I keep the tool of that angle and take it on down the moment I've started cutting I've lost track with where I started so the trick here is to take that down to a cylinder so that still doesn't fit then keep the back of that where the pencil line is the same size and tilt that around still doesn't fit you take it down to another cylinder tilt it round this time it goes over I hold it very gently and there's a very slight burnish marker in fact there are two because I didn't hold the Box base on quite tight quite securely enough or straighten up that doesn't matter I work to between those two points because where you get the burnish Mark is where it fits where the other thing fits so what I want now is to have a very slight taper here think in terms of kind of half a degree and if it doesn't go right on Don't Whack It On very tempting but you split split things that way so there's a very slight burnish markup to the left of that pencil line take that away and on it goes and that's it and that's very secure it's also slightly out of whack it's better right so that's that now if you over cut that too loose just comes further on down for the taper you've got to be very careful holding unpolished wood up against unpolished wood because it tends to grab as it has just now very slight burnish Mark there so that's where it rubs is where it fits you want to keep this make sure this shoulder is true because that's where the top is going to fit up there you are so now's a um My Demo half box um so you can see how it fits in there so a very slight angle um and uh this flange here is is pretty well straight um so that just goes on to the very slow angle gets very slightly tighter as it goes on and then should stay on should stay on once it's there this time I've got a small bowl it's just under three inches diameter and it's narrowing all the way from the rim ideally when you're chucking anything like this you want it to get slightly wider inside the rim so we've got another or blank slightly loose this is also a bit of a branch so it's Center work [Music] now ideally I want that rim butting up to the shoulder so that just chews the whole thing up it's so much easier the shallower you can get this as an angle the near a half a degree rather than five degrees uh the better the grip you're going to get or in this case there might be a slope I have to match on the inside I'll see if I just rotate that around I get a very slight very slight burnish Mark around here together I'm going to keep that at an angle for the moment no little crunching sound is good it's getting tighter but in this case with a bowl there's probably this shoulder getting in the way so I'll just take away that and do that with the garage yeah from the shoulder it's just not quite down to the size and very cautiously here right so I'm going to leave it like that just a little tap on I don't really want to do anything with this bowl um other than maybe sand it but that'll be enough no it's not easy to get off if you want more security then you can use there's a little bit of MDF with a hole drilled in the middle and I can bring the tail Center up and just add that little level of security but I really don't think this bowl is going to need it because it needs Levering off now when you want to get it off and it won't go on much bigger versions what you do is is whack the um uh whack the actual Chuck but here I can probably do it with a ruler and that'll be that so once you get the hang of these jam Chucks they're very quick and easy to make and it allows you in a situation like this to get the piece on and really do anything you want to the outside if I want to put grooves in yes that's fine I can take the foot off sand it whatever so if you need to jam Chuck something like this bowl to get the base off then you need a a larger Chuck really with a hole in it and the idea is going to be just to get that in so you can turn the bottom off now that might stand but it could do it just being slightly larger and then I have to make sure there's enough room to accommodate the other part of the other part of the bowl so first thing I'm going to do is just uh take um on the bottom out and at the side here I don't need to take out very much so and I want this to get in it's got to be tapered narrowing very slightly on the way in any way dovetail you can get a bowl in there and can't get it out very frustrating right so that I've almost gone just a bit too far but what I'm after is that slight crunching sound or something probably this scraper it in and then you can do whatever you like to it I don't actually need to do anything to this because I'll just screw up the foot I definitely don't need to do this you can just see foreign whatever then you have to get the thing out and that can be a bit of a problem so um two ways of doing this one is to get something heavy uh like a heavy wrench ing it out buff it back in again you take it out of the chocolate and then hit it on the side of the lathe and as it comes

Channel: Richard Raffan

Views: 25,102

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Id: cKaZ3MS4SV0

Length: 11min 50sec (710 seconds)

Published: Wed Apr 26 2023