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  1. #21
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    Quote Originally Posted by Kevin T View Post
    Did anyone make a tool to cut with RCMT inserts? Is there anything that needs to be shared that might help me in that pursuit?

    The Witte RKD1 device mentioned earlier is one that benifits from round inserts because of its design

    Peter

  2. #22
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    I built a really cheap-and-dirty version a little while ago. Mounts right onto the compound slide and looks like this:

    p1080281.jpg

    p1080289.jpg

    p1080290.jpg

    Loosen up the compound lock screws a tiny bit and just swivel the whole compound around.

    The upside (besides the price tag and the simplicity) is that I can control the diameter of the ball with the stock compound knob. And I can control the depth of cut with the cross slide knob.

    The downside is that the size of ball I can produce is limited to about an inch max. That has not been a deal breaker to date. Other down side is that if I have to sharpen the cutter, I'll need to reset the tool height. Pretty much like any other ground HSS cutter whose cutting edge changes height when sharpened.

    Oh, and it's a little fiddly to grab the compound and swivel it around by hand. Would be nice to have a longer handle on it for better control, but not nice enough for me to take the time to put one on.

    You can use something like this to build yourself a nicer one.

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  4. #23
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    Quote Originally Posted by Kevin T View Post
    Is there anything that needs to be shared that might help me in that pursuit?
    Pretty cool thread. Some clever ideas as well. Caught the thread late as I'm catching up on reading.

    Saw you had some questions along the way, which you might have figured out already.

    One problem with ball turning, as mentioned, is running into the chuck or work if using the normal 9 oclock centerline. With Jim Rozen's idea centerline is 12 oclock. By being at 12 oclock you dont use compound or rest to feed. You use the adjuster on boring head to feed straight down.

    Boring heads usually are attached to a short shank just like a drill chuck. And many drill chucks the shank is a taper like mt3, mt4 etc. Many boring heads might be R8 shank which fits Bridgeport mills. R8's are easy and cheap to come by, but you would need an adapter for your Aloris 1.25 holder. Or find a straight shank and make a sleeve or something. An example of a straight shank:
    APT Offset Boring Head BH34A (3/4" Shank) | eBay

    The boring heads are meant for the round type boring bars. Those boring bars can be 3/8, 1/2, 3/4 etc on the shank diameter. Also boring heads have different reach, 2", 3" etc from the bottom mountings. So knowing which boring bar diameter, and which reach you want, plus shank would be things to search when buying. The cool thing with boring heads is you have multiple options for where to mount the boring bar. I would think a 2" boring head would serve most of what you want, 2" being the furthest reach if mounting the bar from the bottom.

    An example of a decent priced R8 kit,1/2" boring bars:
    2'' PRECISION ADJUSTABLE BORING HEAD WITH R8 Shank & 9pcs carbide boring bars | eBay

    Besides holding the boring head, working out how to stop in and out thrust and still rotate in Aloris holder will take some planning.

  5. #24
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    Not much planning - the boring head I used was threaded, and I made a half inch dia shank to thead into it - with a larger flange that serves as a thust bearing on the oilite bearing installed in the QC tool holder. End float is set by sliding the ultra high tech v-belt pulley along the shank until it feels (technical term) 'just right' and then using the setscrews to lock it in place. Armstrong effort applied via a handle with fancy ball-end.

    The boring head has three locations for the cutting tool.

  6. #25
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    Adding a couple of level vials helps quite a bit when setting the tool up, especially if you need the center of the radius at a specific place.

    I also made a 3d printed jig to set a specific radius. It's not 0.001" class, but easily better than 0.01".

    Sent from my SM-G892A using Tapatalk

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  8. #26
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    one thing about those boring head ball turners is you need to think about how the cutting edge is oriented to the work. I like indexable tools, so I made a little bar to go in the boring head just for ball turning:
    img_6999.jpg

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  10. #27
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    This is sorta off topic. That's quite an interesting discussion and designs on how
    to make a ball. I'm afraid I personally would have to just rough a shape out, then
    use a sharp file to round it off. But I can certainly appreciate the quest to design and produce a smoothly rotating tool device.

    This got me thinking of a recent video I saw where a guy made an "8" ball out of a chunk of stainless steel. Maybe this can give you some ideas if you haven't seen it.

    Making the ball itself starts at around 4:28 if you want to skip the first part.
    As far as I can tell, it looks like this guy has a CNC lathe. As you'll see, he goes over
    to a mill to finish the shape. I have never seen a mill with a tilt-able table like that.
    Maybe it's a vise of some sort.

    Anyway, here it is:
    https://youtu.be/KKiHgBhW8UQ
    (There are a few ads to skip)

    Ingenious really! Sorry for being off-topic.

    PMc

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  12. #28
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    Quote Originally Posted by mcload View Post
    This is sorta off topic. That's quite an interesting discussion and designs on how
    to make a ball. I'm afraid I personally would have to just rough a shape out, then
    use a sharp file to round it off. But I can certainly appreciate the quest to design and produce a smoothly rotating tool device.

    This got me thinking of a recent video I saw where a guy made an "8" ball out of a chunk of stainless steel. Maybe this can give you some ideas if you haven't seen it.

    Making the ball itself starts at around 4:28 if you want to skip the first part.
    As far as I can tell, it looks like this guy has a CNC lathe. As you'll see, he goes over
    to a mill to finish the shape. I have never seen a mill with a tilt-able table like that.
    Maybe it's a vise of some sort.

    Anyway, here it is:
    https://youtu.be/KKiHgBhW8UQ
    (There are a few ads to skip)

    Ingenious really! Sorry for being off-topic.

    PMc
    OK - I am impressed............

  13. #29
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    I made a pivot type ball turner years ago to make some 2" dia. balls for a project.
    I used some 6" heavy wall pipe for the main pivot, 5" heavy wall for the inner pivot,cut in two and machined. The hardest part for me was broaching the square tool hole accurately.
    I cut the dovetail in the mount, and attached the pivot to the mount mechanically with dowels, screws, and then silver soldered. I machined the mount so the tool is exactly on center when sitting on the top of the compound.
    Light cuts and a properly ground tool gives me excellent results.
    I have attachments for it now that support the tool better out near the pivot point for smaller radii,and to cut concave radii.


    radius-turner-2.jpg
    radius-turner-3.jpg001.jpg

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  15. #30
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    you can even use them to turn wood Makes a huge bloody mess though..
    img_0042.jpg

  16. #31
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    Quote Originally Posted by Tool Junkie View Post
    I made a pivot type ball turner years ago to make some 2" dia. balls for a project.
    I used some 6" heavy wall pipe for the main pivot, 5" heavy wall for the inner pivot,cut in two and machined. The hardest part for me was broaching the square tool hole accurately.
    I cut the dovetail in the mount, and attached the pivot to the mount mechanically with dowels, screws, and then silver soldered. I machined the mount so the tool is exactly on center when sitting on the top of the compound.
    Light cuts and a properly ground tool gives me excellent results.
    I have attachments for it now that support the tool better out near the pivot point for smaller radii,and to cut concave radii.


    radius-turner-2.jpg
    radius-turner-3.jpg001.jpg
    This is the kind of setup I want. It would be great if Aloris would make this kind of thing. I could make the whole thing on my lathe except the female dovetail! I asked somewhere if anyone knew of bolt on dovetail sections that I could use to mate with the Aloris QCTP. Three inches long and I'm set. Drill and counterbore for some SHCS and bammo!

    ...so....

    anyone know of modular dovetail parts I can get my hands on?

  17. #32
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    I guess if you aren't set up to make the dovetail, you could just buy a tool holder of some description that fits your toolpost, and attach the outer pivot to that.

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    Quote Originally Posted by Tool Junkie View Post
    I guess if you aren't set up to make the dovetail, you could just buy a tool holder of some description that fits your toolpost, and attach the outer pivot to that.
    I was thinking the same. Maybe a cheap chinese holder and weld on to it. I know the Aloris holders are pretty hardened, not sure all the aftermarket stuff, might be difficult to machine with cutting tools. But if like Tool Junkie's type, could weld the large C to a holder.

    Out of curiosity for Tool Junkie, How free moving is the inner C ? Is there tension or resistance, or do you need to hang on for dear life ? Just thinking how I might control that if I were doing it.

  20. #34
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    I was careful when I made the pivot pins to make them TIGHT, so there is a little pretension, but they rotate freely. This kind of ball turner has to have light feeds and moderate speeds, so it doesn't get away from you. That said, I have had no issues with the tool at all, and have turned some large projects that barely fit inside the inner pivot.

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  22. #35
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    This is kind of cool. People say it works well

    Turnado - Turning System




    Sent from my iPhone using Tapatalk Pro

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