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  1. #1
    Join Date
    Nov 2004
    Location
    Eastern Suburbs Melbourne
    Posts
    218

    Default Make a camlock on a 9 x 20

    For some time I've wanted to rebuild the camlock on my woodlathe's tailstock. I did manage to convert the tailstock on my metal lathe to a camlock but that was only a very small amount of bar that needed to be turned for the cam. On my woodlathe it requires approx 200 mm to be turned eccentrically. I packed one of the jaws on the 3 jaw chuck slightly and dimpled the other end a little off-centre so that it could be turned b/w centres. After a hour, I did not make much progress, the lathe vibrates and I can only take a little off at a time, also when running the cross-slide along the bed, the cutter would not be equidistant from the work. This suggests that there is a tapering effect but how do you turn a cam b/w centres? Starting to think that this job might be beyond a lathe of this size, what do you think?

  2. #2
    Dave J Guest

    Default

    Hi,
    It sounds like your tail stock is off centre. For a quick check put a centre in both the head stock and the tail stock and bring them together with a 150mm rule horizontally in between. If the rule sits square to the ways it's pretty good.
    The other way to get it exact is to machine a bar both ends between centres at around the length you need. Take a cut on one end set the dial on the cross slide to zero then take a cut on the other end to zero as well, then measure both ends of the bar and adjust as necessary.
    Sharp HSS would be the best thing to use on a small lathe, also what material are you using.
    If the lathe is vibrating, I think you have it going too fast. With steel slower is better.
    Dave

  3. #3
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    If you are trying to turn an eccentric on your lathe,you could try the offset method that you have described,but if you are useing a tailstock to support the outer end you will have trouble.

    The main reason being that with the centre in the lathe will want to turn parallel.

    Unless you have the same offset at the chuck end as you do at the tailstock it will cut a taper.

    If you can for ease of machining turn the whole job between centres and not with chuck and tailstock.

    You will have to mark 2 centre holes in the end of your stock.

    One for the concentric section and one for the eccentric.

    Machine your concentric diameters first the move your job to the eccentric centres.

    There should be no reason why even the smallest of lathes would not achieve a result.

    The ridgidity of your machine may limit you to small cuts but that will be all.

  4. #4
    Join Date
    Nov 2004
    Location
    Eastern Suburbs Melbourne
    Posts
    218

    Default

    Hi Dave and Pipeclay,
    Tailstock pretty much lines up with headstock. Am cutting just mild steel.
    Pipeclay, I went for the chuck method as I thought it was more secure than just turning b/w centres. You lost me there with the 2 marking points, what do you mean concentric and then eccentric, I thought that only 1 point was needed on each end.

  5. #5
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    First how much experience do you have.

    I have never seen it done (BUT I KNOW IT IS DONE WITH THE CHUCK OFFSET IN A 3 JAW),making a cam with a 3 jaw.

    I assume you are trying to make a piece of material which is parallel over part of its length and then on the same piece of material another full or partial diameter offset to the first diameter.

    Think of a crankshaft,the bearing journals are parallel but the throw is offset to the bearing journals.
    Unless this a fabricated crank you would find that there would be 2 centre drill holes in each end,1 for the bearing area and 1 for the throw.

    You would be better off useing a 4 jaw chuck rather than the 3 .

    When you mark the shaft find centre first then set what ever method of marking you are going to use to suit the amount of offset you require,you would then drill the 2 centres in each end on the bench drill.

    Of course you would use a suitable sized centre drill for the application

  6. #6
    Join Date
    Aug 2008
    Location
    Charlestown NSW
    Age
    65
    Posts
    1,669

    Default

    Tigar
    have a look at this website, has a good description of eccentric turning, with diagrams.

    Eccentric Turning

    bollie7

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