Results 1 to 14 of 14
  1. #1
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

    Default Disc brake for lathe - best location?

    I own a Metalmaster 12 x 36 circa 2007 - same as an AL 335 - you know, same lathe different brand and had a rush of excrement to the brain about fitting a disc brake.

    In terms of efficiency, where is the best location to fit such a disc brake?

    The disc is about 150 mm diameter and originates from a step through cycle. I also have the hand brake master cylinder assembly from the same cycle.Those parts gave been sitting around for 7 or 8 years.

    I am favoring the pulley off the motor location as I think that may be the easiest to mount. The question in my mind is how efficient is that location?

    I have heard of locations behind the chuck and also at the change gear box. Can anyone speak to the advantages and disadvantages of mounting in these places?

    If members have some experience and insight over such a project on their lathe I would lathe to hear about it.

    I have the lathe and drill press to do this work with ,but don't own a mill but can get access to one with some difficulty.

    Any advice ,opinion and relative information is most welcome.

    Thanks

    Grahame

  2. #2
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Grahame the motor would be a good spot, motor braking with a vfd works well. A mounting bracket for the caliper should be pretty straight forward and bolted to the motor mounting bolts

  3. #3
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Motor pulley is where I put mine.
    On a AL 335 that's the shaft that's spinning fastest.

    Behind the chuck would mean no "worry" about the load on the gears. But you will need more brake pressure as the chuck is always at a lower rpm.
    I had wondered about belt slip but I haven't had an issue. Though mine setup is a cable operated brake off a monkey bike. You might have more stopping power.

    It might come down to just how fast you want the brake to stop the lathe. Mine as currently setup stop so the lathe a lot faster, but if you are after "almost instantaneous"

    Can't see how you would easily fit a rotor on a camloc spindle. Unless you really do mean "chuck" which would mean a rotor on each chuck??

    QCGB never entered my mind. I would be worried about the gears in that case. Besides, there is a lever on the front of the headstock that would make your brake ineffective.

    Had to cut a slot in the cover for the rotor and a hole in the side for the caliper.

    Pretty sure I did a thread. I will have a look.

  4. #4
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    I guess the short answer is that you can mount it anywhere you like. However, as the idea is to stop the chuck quickly, ideally it will be on the spindle. Any further along the power train and there is the added inertia of the train to consider.
    The other thing is that if it is the other side of say a V belt. If the belt breaks then the brake is useless, so preferably there are only rigid couplings between the brake and the chuck.

    Michael

  5. #5
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Found the thread but the pictures are gone.
    Here is a video, stopping without and with brake.
    https://www.youtube.com/watch?v=CmTeDUAPceg

    Quote Originally Posted by Michael G View Post
    Any further along the power train and there is the added inertia of the train to consider.
    You sure? brake has to stop all inertia where ever you put it.
    With a AL335 the motor is doing 1440rpm, the chuck might only be spinning at 75rpm, so you'd need 20ish times the braking force(yeah the total energy is the same)to stop in the same time.

    Quote Originally Posted by Michael G View Post
    The other thing is that if it is the other side of say a V belt. If the belt breaks then the brake is useless,
    AL335 has twin belts. So I put it down to "damn you have to be unlucky to lose a belt the time you really needed it. How unlucky would you have to be to lose them both? and even then it will coast to a stop like 99% of the lathes out there, so no worse off"
    Now there are some threading practices where that might not fly.

  6. #6
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

    Default

    Quote Originally Posted by Stustoys View Post
    Motor pulley is where I put mine.
    On a AL 335 that's the shaft that's spinning fastest.

    Had to cut a slot in the cover for the rotor and a hole in the side for the caliper.

    Pretty sure I did a thread. I will have a look.

    Me,being old and lazy ,the motor end is where it looks to be the easiest point of attachment. I have never broken a belts to date, but having said that , fresh belts will be on the agenda along with the mod.
    You responded to my same inquiry in 2011 on the WW side but no pics from then . Sorry, I had forgotten completely.
    Still I do need to find out as much as I can before starting.

    Thanks for the replies so far.

    Grahame

  7. #7
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

    Default

    Fellas ,
    Agree to disagree , by all means, but please do have a barney over it on my account.
    OK?

    What instigated this whole thing is that we are having a cleaning up of shed and garage. I blame you racingtadpole.

    She who must be obeyed surely has noticed your post about the tidy up of your place, (but I still want the gooseneck please). Now I have to justify each piece my treasury of carefully collected and curated engineering items, lest they be consigned to the tip.

    I am not allowed to go to the tip unaccompanied as I tend bring stuff back from the recycle shop

    Grahame

  8. #8
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Quote Originally Posted by Grahame Collins View Post
    You responded to my same inquiry in 2011 on the WW side but no pics from then . Sorry, I had forgotten completely.
    You say that like I don't have stuff on my "todo" list from back then lol


    Quote Originally Posted by Grahame Collins View Post
    Fellas ,
    Agree to disagree , by all means, but please do have a barney over it on my account.
    OK?
    Me? I hope it didn't come across as a barney. Sorry if it did. Was asking a question and or explaining why I made the decisions I made. I think on the spindle is the place for it, if 1. you want instantaneous stop. 2. you can find somewhere to mount it. 3. you supply the force required(which is no real issue if you have room for a car rotor and caliper. I see I only posted half my thought earlier "It might come down to just how fast you want the brake to stop the lathe. Mine as currently setup stop so the lathe a lot faster, but if you are after "almost instantaneous" " (I had meant to add something like) " you might have to come up with something else" ).

    The date of the thread lets me find the pictures. Here it is almost finished.
    If any other pictures sound like they are worth seeing let me know and I will dig them out.
    Attached Images Attached Images

  9. #9
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Quote Originally Posted by Stustoys View Post
    so you'd need 20ish times the braking force(yeah the total energy is the same)to stop in the same time.
    If the rotor is the same size.

  10. #10
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    4,779

    Default

    I'd have to agree with Stu. Braking systems remove energy from a system. This is done by generating heat. The spindle, gearbox, motor system is a coupled system and can be approximated by a single moving mass. Different parts of that mass may be moving at different speeds but the overall energy of the system is the same. Identical braking systems placed either at the spindle or the motor would absorb the same energy from the system and therefore heat up the same amount in order to bring the system to rest. From this POV there is nothing to be lost or gained in choosing one location over the other.

    Gear backlash, breaking belts, ease of mounting the parts etc. are another argument all together and may perswade you to choose one location over the other.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  11. #11
    Join Date
    Mar 2011
    Location
    Southern Flinders Ranges
    Posts
    1,536

    Default

    Quote Originally Posted by Grahame Collins View Post
    What instigated this whole thing is that we are having a cleaning up of shed and garage. I blame you racingtadpole.

    She who must be obeyed surely has noticed your post about the tidy up of your place, (but I still want the gooseneck please).
    My work here is done.... bahahahahahaha
    I’ll update my clean up and organisational thread in the next few days, it’s been something of an evolution in the few months since it was last updated...

  12. #12
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Exclamation DC Injection !

    Hi Guys,

    A guy that I used to know, used a rectifier and a big capacitor, of about 350 Mf charged from the mains and a two pole relay to disconnect the supply voltage and dump the capacitor charge into the motor windings. The motor didn't stop instantly but did within a couple of revolutions. I have the circuit details somewhere.

    Unfortunately he is not around any more having got wasted and wrecking his bike. He did like his beer though !
    His workshop was disposed of via his local MES members auction.
    Best Regards:
    Baron J.

  13. #13
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
    Posts
    1,894

    Default

    Just to mention, the brake on a Harrison M300 lathe is a V-shaped block that acts upon a pulley.
    It is all mechanical, rod-operated from a foot pedal.
    The lathe is still in production.

    That's how brakes were on old motorbikes.
    I installed such a device on a 1924 motorcycle with belt transmission, making the block out of hardwood - good enough for around the paddock.
    Attached Images Attached Images

  14. #14
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    930

    Default

    The brake on my Harrison M250 is a disk, spring applied with electro-release, on the outboard side of the motor.
    Removed as I do not like putting a strain on all the headstock gearing when an emergency stop is initiated.
    The lathe has a VFD, and will get a braking resistor sized to reduce deceleration time as much as practicable.

    Note that the electro-release was wired directly across the motor terminals when the lathe acquired.
    This meant the spindle was locked whenever the motor was not energized.
    Must have been a real pain to operate.
    If I do re-commission, I would add an independent on/off switch to enable spindle rotation by hand when needed.

    Keep well,
    John.

Similar Threads

  1. Tungsten carbide disc brake rotors
    By bob ward in forum GENERAL DISCUSSION / OFF TOPIC
    Replies: 16
    Last Post: 12th Jul 2020, 02:56 PM
  2. Useful ? Circular lathe mounted filing disc
    By steamingbill in forum METALWORK GENERAL
    Replies: 24
    Last Post: 21st Mar 2019, 09:44 PM
  3. Lathe Brake
    By Stustoys in forum METALWORK GENERAL
    Replies: 29
    Last Post: 10th Apr 2011, 08:17 PM
  4. Brake disc removal
    By Sterob in forum METALWORK GENERAL
    Replies: 5
    Last Post: 5th Mar 2011, 05:48 PM
  5. Lathe brake
    By Grahame Collins in forum METALWORK GENERAL
    Replies: 14
    Last Post: 15th Jan 2011, 10:30 PM

Posting Permissions

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