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  1. #1
    I am thinking of buying a fly cutter to use on Aluminium but I'm in two minds

    is it better for the spindle to use a larger two flute cutter

    say a 30mm cutter as this is better balanced

    I would assume a fly cutter will generate a lot of unbalanced force on the spindle bearing
    and with a standard 2.2kw VDF the spindle would be spinning far to fast.

    I would like your views and comments on this before I buy a new cutter

    also advice on a new spindle collet nut

    I currently have a nut that came with the spindle but I want to buy a spare one or two

    But I can't find any that are balanced

    are these any good if not would you please point me in the right direction please

    James and Luke :feedback:

  2. #2
    I often use a fly cutter on my manual mill but, due to the large diameter, the speed has to be kept down. They can give a very good finish but I don't see much point in using one on a cnc machine.


  3. #3
    As you say, fly cutter is unbalanced which is bad for the spindle bearings, but more importantly because the fly cutter is such a large diameter it has to be run at a low rpm. I often use them on the mill when I want a nice finish, does take a long time. Used one on your ballnut mounts and possibly the motor mounts, can't remember. Anyway, I tried it once on my router, about 40mm diameter, just out of interest. It worked, but the finish wasn't consistent. The spindle doesn't have enough torque at such low rpm, so I switched to a 1/2" 2 flute endmill and that's much better. I wouldn't go above that size on aluminium. For wood, or surfacing the bed certainly use something bigger.

    Collet nut... I have emailed 5 different eBay sellers about those asking if they are balanced and therefore suitable for use an a 24,000rpm spindle. Asked about the standard nots and the ones with bearings in (though I doubt they're suitable) and only 3 replied. All said no they're not suitable. So I'm a bit stuck now :(
    The ones you linked to are type M, not type A which is what's used on the spindle:

    I didn't receive a reply from that eBay seller... so no idea! Can't see the drilled bit to balance them on the picture, but that's obviously inconclusive.

    I wonder if these are more expensive because they're balanced, or because they're sold in the USA:

  4. #4
    thank you Russell and Jonathan

    just as I thought



    I found a 27mm router cutter last night (new well used once to make a jig)

  5. #5
    Try cutwell tools they sell high quality Collet chuck nuts, both standard and balenced as well as slim line nuts. The balanced ones are the notched type thou and will require a matching wrench which they also sell.
    Don't know if they deal with public direct or you need an account. I have an account if you want one getting.?

    That said why would you want a spare nut.? In over 3yrs I've not come close to wearing out the nuts on these chinese spindles and I must have changed thousands of bits.
    If you make sure the inside where the collet seats is clean and clear of crud you'll never have a problem.

  6. The Following User Says Thank You to JAZZCNC For This Useful Post:

  7. #6
    Quote Originally Posted by JAZZCNC View Post
    That said why would you want a spare nut.? In over 3yrs I've not come close to wearing out the nuts on these chinese spindles and I must have changed thousands of bits.
    If you make sure the inside where the collet seats is clean and clear of crud you'll never have a problem.
    My collet nut wore out, so that's no doubt where luke11cnc got the idea. I also clean it out regularly. By worn out I mean it developed very poor runout. Luke11cnc kindly lent me his collet nut and the runout is fine with that.
    I have checked the runout of the spindle bore and that's fine.

  8. #7
    Surprised to hear that Jonathan.! unusual to develope runout unless seat not cleaned often or not tightened correctly allowing the collet to spin in it's seat. Thou over tightening is just as bad and will distort the nut.
    Must say thou I'm very carefull and blow out the nut an clean the taper every time I change a tool, I'm also carefull not to over tighten.

    I recently killed a spindle so have a spare nut if you don't find one, I don't really want to sell it but will gladly lend you it when James needs is nut back untill you find one.

  9. #8
    I clean it with the compressed air, or just wipe it. It's not too bad with aluminium though as the swarf is big chips and I've not cut wood for a long long time, except a quick bed surface.

    Granted I do do it up tight, but it's rated for 30-60Nm depending on cutter size (30 for <=6mm) if I recall correctly ... been using a high quality collet lately too because I got it for next to nothing.

    I may well take you up on the offer for nut, but it looks like I might have somehow killed the spindle anyway as you might have seen in my previous post. Why did yours break? Did you dismantle it out of interest? I know that's been done (CNCzone), but it would be interesting to see if the bearings vary.

  10. The Following User Says Thank You to Jonathan For This Useful Post:

  11. #9
    Killed mine by a silly mistake, I'd had it off the machine to test fit into a spindle mount I'd made for someone. When I replaced it didn't fasten a cable bracket and over a few weeks the cable flexing caused the wire to break inside the small crappy spindle connector causeing a big flash bang dead short. It killed the spindle instantly and blew a torque vector drive ABB ACS350. VFD faulted and wouldn't come out of reset.
    The new spindle is much better 8.5A instead of 7A with a much larger better quality 4 wire connector so one can be grounded to body.

    Yes I did strip it down heres some pics.
    I was very pleased with the build quality and the bearings were in very good condition even after nearly 3yrs use.
    Very easy to strip and I wouldn't hesitate to strip one down and replace the bearings. Basicly 30min job Max.
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  12. #10
    Yes see Jonathan tighten his nut up.

    and yes Jonathan this is where I got the idea from that the nut's wear out and need replacing from time to time

    with all the problems I've read about the Chinese spindles and VFD's I'm going to buy a spare one when I can get the money together.

    James and Luke

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