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  1. #1
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    Oval shaped lollipop cutters?

    I have an interior sidewall groove that needs to be rounded -- it's like a thread, but cut with a scoop instead of a vee shape. Luckily, it's in 6061 aluminum, so not very hard to cut.

    The lollipop cutters I can find all look like the left of this picture, but I need something that looks like the right. Ideally, 1/4" diameter, where "diameter" is the diameter of the round part, so the total width is more like 1/2" or whatever adding the center shaft will make it.

    Attachment 423116

    Where can I find a cutter like this?

    (The closest I've found is McMaster: https://www.mcmaster.com/2820a74 -- but ... 6 flutes? Not for aluminum, surely? Also, 3/4" shank is hard to get into the TTS holders I have, which top out at ER20 and 1/2" Weldon.)

  2. #2

    Re: Oval shaped lollipop cutters?

    Look for a fluting router bit in the radius that you want. They work great for what you are doing.

    https://www.amazon.com/Freud-99-030-...AJ3DF4A1WAP86K
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
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    Re: Oval shaped lollipop cutters?

    Quote Originally Posted by jwatte View Post
    I have an interior sidewall groove that needs to be rounded -- it's like a thread, but cut with a scoop instead of a vee shape. Luckily, it's in 6061 aluminum, so not very hard to cut.

    The lollipop cutters I can find all look like the left of this picture, but I need something that looks like the right. Ideally, 1/4" diameter, where "diameter" is the diameter of the round part, so the total width is more like 1/2" or whatever adding the center shaft will make it.




    Where can I find a cutter like this?

    (The closest I've found is McMaster: https://www.mcmaster.com/2820a74 -- but ... 6 flutes? Not for aluminum, surely? Also, 3/4" shank is hard to get into the TTS holders I have, which top out at ER20 and 1/2" Weldon.)
    I have used form cutters on the lathe, they need to be held close to the cutter or I would get chatter easily. I use sprutcam and I dont think I can program a negative contour in a waterline op, if I could maybe use a small slotting saw radius ground and use multiple passes.
    I have used a woodruff cutter to cut a groove in the bore of a part but it was a single pass, normal entry, and fake the diameter (negative stock) to get it to undercut the part.
    mike sr

  4. #4
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    Re: Oval shaped lollipop cutters?

    If I could grind my own, then yes, I actually longingly thought about that!

    Also, what's extra annoying is that the diameter of the bore I'm milling this groove in is 25mm, so a 1-1/4" radius cutter isn't going to fit. And it has a dead bottom, so a very small slitting disc won't fit, because the arbor tip would bump into the bottom of the bore.

    I'm going to look at wood router bits, because there's lots of forms to be had there! If I find something without a bearing on the tip, and go easy on the DOC I think that might work!

    This one is almost right, but too wide: https://www.amazon.com/Woodtek-92141...5&s=hi&sr=1-10
    Same thing with these: https://www.amazon.com/CMT-855-701-1...5&s=hi&sr=1-16
    I ended up finding one of these, which is too thin, but I think I can take multiple passes and get where I need to go: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    If I had 5D milling, I could do this good enough with a simple ball end mill. Looking with lust at that UM-750 that Saunders is showing off on his YouTube channel :-)

  5. #5
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    Re: Oval shaped lollipop cutters?

    Most of the wood working world call these fluting bits.

    Here is a sample from one company of bits without bearings. Never dealt with them, so I don't know if their products are well thought of or not, but should give you an idea what types of bits are available.

    Terry


    https://www.magnate.net/SearchResults.asp?Cat=510098
    Attached Thumbnails Attached Thumbnails fluting bit.jpg  

  6. #6
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    Re: Oval shaped lollipop cutters?

    Thanks! The main problem with all of those that I found (also known as "canoe joint bits" it seems) is that they are too wide -- my bore is 25mm, most bits are 1-1/4" or 1-1/2" which won't fit :-(

  7. #7
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    Re: Oval shaped lollipop cutters?

    Go look at convex cutters on the suncoast tool website. Ive used them on undercut rad work

  8. #8
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    Re: Oval shaped lollipop cutters?

    It looks like those Suncoast cutters are pretty close to what you need, if there is enough depth for your part.

    You mentioned earlier about the 3/4" shank on the mcmaster tool, I'm sure you know you can just put that in your mill's collet and skip the TTS. If your part is a one-off or you need just a couple you can zero the tool when you use it, of if you need repeatability, you can put a collar on the shank of the tool to measure from and it will be essentially a TTS tool.

    Terry

  9. #9
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    Re: Oval shaped lollipop cutters?

    Quote Originally Posted by jwatte View Post
    Thanks! The main problem with all of those that I found (also known as "canoe joint bits" it seems) is that they are too wide -- my bore is 25mm, most bits are 1-1/4" or 1-1/2" which won't fit :-(
    Pricey for a wood cutting bit but see https://www.amazon.ca/Amana-Tool-Car...dp/B000P4QDOS/ I haven't checked if they are on the Amazon US site.

    Use a collar or an ER32 TTS holder for the 3/4-inch shank cutters.

  10. #10
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    Re: Oval shaped lollipop cutters?

    Maybe a hand ground single lip form tool in a 3/4" boring bar??

    There are companies that will grind a tool as per your drawing.
    Is this a one off part?
    how deep is the slot in the bore?
    how deep is the slot?

    It has been my experience that a .5 radius cutter feeding straight in will be a recipe for chatter unless you can chuck it very close to the cutter and low rpm.
    Wood router bits may give you the shape you need but the shank on them I dont believe will be beefy enough.

    good luck.
    mike sr

  11. #11
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    Re: Oval shaped lollipop cutters?

    This is a prototype, so there will only be a few parts. (As prototypes go, there will surely be more than one, though :-)
    The groove is just under 3mm deep in the wall of the bore.
    The bore is 12mm deep, so just under two full grooves tall.
    The bore is 24mm wide. This is the biggest challenge -- 7/8 will "just fit" and I'm going to have to take shallow cuts to avoid packing it full of chips that can't get out.

    Thanks for all the advise! Knowing what to look for and what to compare is super helpful. I'm going to try this guy out: https://amzn.to/2XEArKG -- and run multiple passes of the thread milling program from Fusion to get to the required shape. Good news is, tolerances for smoothness are 5 thou, so I don't need 100 passes to get it good enough.

  12. #12
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    Re: Oval shaped lollipop cutters?

    Hi, how long is the groove......could you cut it from the end with a long slot drill?...…..a 150mm long slot drill from each end will give you 300mm length of cut and a clean up with a woodruff type cutter as previously shown.
    Ian.

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