Page 5 of 22 FirstFirst ... 3456715 ... LastLast
  1. #41
    I'm just looking at spindle design and A/c bearings so I'm intrigued if you know of a cheap type.

    im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them
    Do you mean rigid enough for milling Ali? If so be careful adding addition preload to a factory set tandem one as I believe you just end up un loading one side!!! if its a double row then lock it to the sharp end and fit a floating bearing at the other end.

    According to SKF the distance between the CL of the bearings should be 3 to 3.5 time the shaft dia, so 12mm shaft = 36 to 42mm so a 100mm shaft should be way long enough.

    The optimum design seems to be to use 2 opposing A/C bearings with a spring loaded pre-tensioner.

    Have you seen the "DIY spindle design" on here, or these?
    http://www.cnczone.com/forums/showth...t=12184&page=6
    http://www.cncathome.com/spindles.html

    It seems this has been done many times and the problems are mounting the motor to the spindle, the first link post no. 64 and 65 shows a flexible mount and water cooling for the motor.

    I also have an ER11 collet and a RC motor to power it but as its for machine No. 2 I haven't got around to doing anything with it yet. so I will be watching with interest.

    Good luck

  2. #42
    Quote Originally Posted by blackburn mark View Post
    Ah, im with you on the speed issue, i think i get you with the large motor to,, im guessing you would be fitting a rotory encoder for position feedback if you use the large DC motor ? (im no expert with these)
    Err I hadn't really thought about feedback. I was thinking something along the lines of using a stepper motor and the big brushless motor and switching between the two. For instance start by using the big motor for CNC lathe then switch to stepper motor to perform any milling on the part.
    It would be good to switch back and forth between the big motor and the stepper but that of course requires the motors to engage at precisely the same point. Maybe get the brushless motor to stop at a set position (doable) and have another solenoid push a pin in the shaft to engage the stepper (tricky) ... the best would be to just use a servo but that's very very expensive to get anywhere near the power of this brushless motor.

    Quote Originally Posted by blackburn mark View Post
    for the brake i would be looking at a motorcyle cluch plate maybe, im not sure youll get the force with electric solenoids to lock it for milling though but thats my guesstimation... id be tempted to consider an actual disk brake and caliper... the caliper would have to be beautfully fitted and have oposing pistons
    I'm not sure about the solenoids either, hence how I've milled spaces for several of them.
    Clutch plate... that looks promising.

    An actual brake disk and calliper would be very nice. Sounds expensive though. I don't know much about them - what would be required to actuate/use it? Are they available with small enough disks since the biggest disk I would want to use is realistically 6".

  3. #43
    I'm just looking at spindle design and A/c bearings so I'm intrigued if you know of a cheap type.
    "5200 zz z 2z ball bearing 10mm A/C" ebay aprox £16 for two... they might be to good to be true

    just end up un loading one side!!!
    och!! i hadnt thought of that... i hadnt decided if id just throw two in for good measure or pre-load them against each other
    iv decided now!! cheers ross

    According to SKF the distance between the CL of the bearings should be 3 to 3.5 time the shaft dia, so 12mm shaft = 36 to 42mm so a 100mm shaft should be way long enough.
    i think you misunderstand, jonathan has a motor that has a 100mm long body so with a 100mm shaft there is no room left to add an A/C bearing and housing


    yea iv seen those thread, they make interesing reading, one of those guys has his own ballancing machine!! to posh for me:)

  4. #44
    i thought a servo motor was just that "a motor with a rotary encoder" maybe somone can jump in and help us on that one

    you could make your own disk easy enough... the calipers would take to much effort compared to going to a bike breakers
    you need to look over some motorcycles and posh mountian bikes for inspiration :) im sure some of the mountain bike disk brakes are machanical,,, could be worth a look.. the hydraulic ones would need a cam and lots of torque to actuate

  5. #45
    Penis in pocket when around cnc machines is is a very good safety tip, no one wants to miss a tip :-)
    Sherline lathe, Chester DB11V lathe, Myford/ Rodney mill, CNC mill Isel/ home made, Sealy Hack Saw, Meddings Pillar drill.

  6. #46
    z3t4's Avatar
    Lives in Manchester, United Kingdom. Last Activity: 19-10-2017 Has been a member for 7-8 years. Has a total post count of 29.
    Quote Originally Posted by routercnc View Post
    Quickly sketched this ...
    Thanks for the explanation. It's good to have it presented so clearly.

  7. #47
    iv got some 8mm id A/C bearings but they are open (as apposed to sealed) so for now ill stick with the skate bearings
    it would be nice to seal the nose and have a nice light oil swishing around in there :)
    Click image for larger version. 

Name:	belleville washers.JPG 
Views:	258 
Size:	201.8 KB 
ID:	2570Click image for larger version. 

Name:	_MG_0257.JPG 
Views:	280 
Size:	149.2 KB 
ID:	2571Click image for larger version. 

Name:	_MG_0255.JPG 
Views:	249 
Size:	135.6 KB 
ID:	2572
    still a bit of work to do on this but it will give those that are interested an idea of what we have been on about

  8. #48
    My ER11 10mm shaft turned up,, nice tight fit.. i may loctite it when im happy
    Click image for larger version. 

Name:	_MG_0260.JPG 
Views:	309 
Size:	234.1 KB 
ID:	2616
    Iv decided on one double row A/C bearing for now... i left room in the housing for two just in case :)

    i ran it no load for ten mins... the bearing gives off more heat than the motor but nothing to drastic, if i remember correctly up tp 110 degrees is passable... it was nowhere near that
    Click image for larger version. 

Name:	_MG_0259.JPG 
Views:	287 
Size:	318.2 KB 
ID:	2617
    I tried to keep the housings 43mm but it wasnt really pactical
    i havnt fully decided on how to setup the small motor, iv considered inserting an engraving bit straight throgh the motor but im struggling to find engraving bits with enough length to allow for more bearings on the nose... i may modifiy a needle vise....
    anyway the engraving motor is not overly inportant to me but Its killing time while i wait for parts for the main build

    just got to hope they will work as well as they look :)

  9. #49

  10. Quote Originally Posted by z3t4 View Post
    Yes please!

    There was an article in MEW (Feb 2008 issue, No 135 ) about making outrunner motors but there wasn't much about how to power them. I'm guessing that the 'servo tester' provides a PWM pulsetrain and the speed controller (is this aka an 'ESC'?) sees the pulsetrain and uses electromagick to provide a 3-phase supply to the motor.

    John
    Quote Originally Posted by routercnc View Post
    Quickly sketched this to show aircraft vs cnc application for those interested:

    (You could probably delete the 4.8V supply if using a BEC ESC)
    1/ Whats the PWM signal characteristics?

    2/ 'Servo Tester' sounds an expensive beast

    3/ Surely you'd want a 0-10v input so you could control spindle speed from MACH3?

Page 5 of 22 FirstFirst ... 3456715 ... LastLast

Similar Threads

  1. laser cutting ally plate
    By i2i in forum Tool & Tooling Technology
    Replies: 12
    Last Post: 21-02-2013, 08:47 AM
  2. FOR SALE: 45 by 90 ally profile
    By johngoodrich in forum Items For Sale
    Replies: 5
    Last Post: 13-09-2011, 06:45 PM
  3. RFQ: anyone wanna quote me to cut some ally?! and....
    By robmurf in forum Projects, Jobs & Requests
    Replies: 2
    Last Post: 01-09-2010, 01:16 PM
  4. NEW MEMBER: anyone wanna quote me to cut some ally?! and....
    By robmurf in forum New Member Introductions
    Replies: 2
    Last Post: 01-09-2010, 10:31 AM
  5. Model Engineering Exhibition @ Ally Pally
    By irving2008 in forum General Discussion
    Replies: 6
    Last Post: 18-01-2009, 10:15 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •