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  1. #1
    Join Date
    Aug 2021
    Location
    Sydney
    Age
    46
    Posts
    116

    Default Improvised milling or routing spindle?

    I see many entry level and experimental CNC routers on social media, youtube etc.

    Apart from flimsy looking machines, I see a lot of flimsy looking spindles, or expensive looking flimsy spindles with small collets and small endmills attached.

    I also saw a pretty cool looking home-brew belt driven vertical spindle fitted to a horizontal milling machine in the US. The body was made of a large plumbing T piece, perhaps about 2.5" diameter or slightly more and bored to take taper roller bearings. I have been thinking for a little while about how I would make a better spindle for a home brew machine, (whether CNC or otherwise) if I was to ever build one. One thought was to use an old automotive hub with taper roller bearings, driven by a belt to a motor but there would likely not be sufficient ID in the setup to bore a hole for a drawbar, so would probably be stuck with one type of collet permanently fitted. Also would be too heavy for most lightweight/not very rigid home build CNC routers but might be ok for say a milling attachment that could be constructed to use on a more significant machine missing a vertical milling head.

    It's all probably a bit silly but the vertical milling attachment I saw recently on this very old horizontal mill looked promising. And the chippy at work wants someone to build him a big CNC router but if I am honest I don't really have the time.

    But anyone built something like this? Or have a simplified milling spindle/head that has been built using a small lathe and fairly humble materials?

  2. #2
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    The first steps for a big CNC router build are simple. Make them big ones in the opposite direction!!

    Assuming you only want a basic spindle for hobby work, you really need to decide what tools you want to run and materials you're going to cut. That will determine the RPM and (and to a lesser extent the rigidity and power it needs to handle) so you can choose suitable bearings. Most standard bearings have a higher rated RPM if run in oil - but grease is easier to seal etc.
    If using grease you only want a small amount in the bearings - don't pack them solid with grease or they will run hot/overheat.

    The other thing I'd try and do is to choose a bearing size/style that you can later replace with higher precision bearings.
    Ie you initially make the spindle with cheaper general bearings, but if it turns out well you can then cough up for a slightly higher spec bearing if the original bearings become a limitation.

    IMO, the simplest way would be to buy an ER parallel shank extension from the likes of aliexpress, bore a larger shaft to suit and to mount suitable bearings etc and press the ER extension into it. That gives you a reasonable taper which will be harder than your average mild steel etc so will last better.

    Yes, you could cut your own taper etc, but unless you start with a good material you'll have put a lot of work into it and still have a soft bore.
    The other thing to consider if cutting your own taper is that unless you've got the spindle bore capacity in the lathe to take the shaft, you're into using a steady to support the workpiece while you cut that taper. Not a show stopper, just something to consider.
    In comparison, pressing a bought ER extension into a bigger shaft means you can then mount a piece of accurate/ground stock in the ER collet and support the other end of the shaft with a center in the tailstock while you turn the bearing mount surfaces.

    FWIW you can buy bare spindles from the likes of Aliexpress for what I'd consider to be reasonable money.
    No idea on the bearing quality though - but likely have better tapers and runout than I could achieve with a lathe
    ER20 : https://www.aliexpress.com/item/32963410556.html
    BT40 : https://www.aliexpress.com/item/32963666282.html

    Good luck!!

    Steve

  3. #3
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,444

    Default

    Hi Guys,

    I was reading an article on the web about somebody That had made a universal mill using concrete castings with steel sleeves embedded to hold the horizontal arm and drive assembly. I vaguely recall that it looked a bit like a Bridgeport with a top mounted motor.
    Best Regards:
    Baron J.

  4. #4
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,185

    Default

    Quote Originally Posted by BaronJ View Post
    concrete castings with steel sleeves embedded
    Concrete? Must have been a prototype.
    Epoxy Granite is what the kids are using, these days!
    Nigel, from a cave FULL of unfinished projects and lost tools.

  5. #5
    Join Date
    Oct 2019
    Location
    Adelaide, SA
    Posts
    1,201

    Default

    Probably of not much interest to the OP and I should have posted this in the Marketplace section but I have reservations in doing so as there are people lurking the forums with commercial interests that I do not wish to explain further.

    There is a benchtop smallish Micro Proto HD/LE 2000 model with some good potential and accessories: https://lockwoodcompany.hibid.com/lo...-le-micro-mill

    Quality spindle and “Made in the USA”: MicroMill 2000

    Several other useful items are listed as well. Location is Vic.

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