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  1. #1
    Join Date
    Jul 2016
    Location
    Melbourne
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    35
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    1,522

    Default Replacing the CVA compound

    I hope this is on interest to someone. After all the hassle with replacing the spindle bearings, and using the CVA a few times, i have decided the compound slide can go. with the taper turning attachment and the ability to chamfer under power there is no need for it.

    I am going to replace it with a solid block and a really too large for the machine qctp ( it wont reduce my swing at all but might make getting up to the tailstock with the LH toolholder hard)

    I didnt have any suitably sized cast iron or steel of the right size (5" x 6" x 1.75"), but did have some 5018 aluminium hanging about I hope this doesnt chatter too badly. I dont know what its static rigidity is like but we shall see, worst case ill remake it.

    Here are some photos of squaring the block up, I had to use an unorthodox rig to hold it on the long axis with two cheapo grinding vices.

    20180817_220142.jpg20180817_220131.jpg20180823_200125.jpg20180831_222551.jpg

    I then had to do the terrible deed, tap holes in the cross slide, there wasnt a lot of meat in there and due to some features on the underside the pattern wasn't a square but more of a trapezoid, the front two holes are 5/16 and the rear are 1/2 both BSF. No going back now.

    20180831_222344.jpg

    I didnt get any shots of drilling for clearance and counterboring in the top piece but here it all is mocked up

    IMG_20180912_201521.jpg

    I then started on the bolt to hold the two together (there is also an anti rotation pin yet to be bored) the only piece of stock I had to hand of the right size was 316 stainless which is pretty horrible to work with so making this took a fair old while. This is the first part i have made on it and i was very happy, super smooth and no lack of power.

    IMG_20181002_143812.jpg

    I then started boring the through hole for the bolt, im not yet sure how im going the fix the bolt into the bottom bolt, im thinking about milling a slot into the bottom of the block for a 1/2" or so pin that goes through the pin and resists both turning and upward force, worried about the small contact area on soft ali though.

  2. #2
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    Quote Originally Posted by caskwarrior View Post
    ...After all the hassle with replacing the spindle bearings, and using the CVA a few times, i have decided the compound slide can go. with the taper turning attachment and the ability to chamfer under power there is no need for it.
    Chamfering is even easier if you just grind a tool to cut it directly (that is, a tool with a 90 degree included angle). However, keep the compound because you may find it handy in some circumstances. I seem to most often use it when thread cutting. I plunge cut the thread but if I need to adjust the tool position because I've removed the part from the chuck for example I will realign tool to thread by adjusting the compound.

    Michael

  3. #3
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
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    Default

    Oh no im absolutely keeping it, and i havent altered anything that would prevent me using it, but i dont think itll be on often unless this really doesn't work out, I do have ground chamfer tools but i find its really handy having both feeds engageable because it saves me a tool holder.

  4. #4
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Neat setup with the pair of grinding vices Ralph. I was toying with the idea of springing for a modular vice but your demonstration could suggest the purchase of a pair of cheapo vices might be a more versatile and far more economical option.

    BT

  5. #5
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Ralph,

    I don't understand why you want an anti rotation pin under the tool holder ?

    I can understand why you need a cross pin in the mounting bolt. A round pin through the bolt sat in a groove machined with a ball end cutter would work well.

    Whilst my lathe is a lot smaller, there is a grub screw, forming a scotch pin locating and securing the toolpost bolt on mine. Remove the grubscrew and the bolt just pushes out.
    Best Regards:
    Baron J.

  6. #6
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Ralph,
    How is this mod working? I'd like to do something similar on my Hercus 260. Do you think it was worthwhile?
    Chris

  7. #7
    Join Date
    Jul 2016
    Location
    Melbourne
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    35
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    Default

    Hi Jack, sorry I haven't had a chance to really use it, I just finished it and then had to go to Japan, as soon as im back I'll let you know. I definitely think I'll have to swap down to a smaller toolpost

    I did add one more feature, I put in two blind pockets so the compound retaining bolts could stay where they were avoiding the need to remove the entire cross slide.

    IMG_20181007_180608.jpgIMG_20181007_173725.jpg
    IMG_20181007_173712.jpg
    IMG_20181007_173604.jpg
    IMG_20181007_153121.jpg

    Sorry if they are the wrong way round, can't get to a computer right now to fix them. Have some random Japan photos as an apology.

    IMG_20181017_193046.jpg
    These little motocompo scooters we designed to fit in the boot of the Honda City.

    IMG_20181016_143215.jpg

  8. #8
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Thanks Ralph. Please let us know if you see an improvement in rigidity in your machine when you've had a chance to use it.
    Chris

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