Author Topic: Machining brake drums  (Read 1727 times)

0 Members and 1 Guest are viewing this topic.

Offline vmxrider

  • A-Grade
  • ****
  • Posts: 366
    • View Profile
Machining brake drums
« on: July 16, 2014, 08:32:32 pm »

Offline pokey

  • Legend
  • *****
  • Posts: 1454
  • Arse .. Elbow. Know the difference
    • View Profile
    • FB
Re: Machining brake drums
« Reply #1 on: July 16, 2014, 08:52:14 pm »
That's novel. a fuel line for the band.  Can just see the safety officers draw drop if he seen that one but I like the ingenuity.

Offline KTM47

  • Legend
  • *****
  • Posts: 1412
    • View Profile
Re: Machining brake drums
« Reply #2 on: July 17, 2014, 08:16:36 am »
If anyone wants to know why it is being done like that?  It is because the wheel is running on it's wheel bearings so is true to the wheel bearings.  Any other way could be slightly out.  You could use a face plate and two centres with a drive pin also. 

Also after that is done you then hold the backing plate in the lathe with oversize brake shoes in.  Put some shims in hold the shoes out a little bit from the cam.  Then machine the shoes to the exact size of the hub.  Full contact on shoes straight away.
MAICOS RULE DESPITE THE FOOLS

1999 KTM 200, 1976/77 KTM 400,1981 Maico 490

Offline Gippslander

  • A-Grade
  • ****
  • Posts: 467
  • Google "Ancient Greek Sculpture for Kids" 2C more
    • View Profile
Re: Machining brake drums
« Reply #3 on: July 17, 2014, 09:33:36 am »
The other reason for that method could be that the false axle that the wheel is turning on is (must be) held up and out from the normal centreline of the lathe because the wheel is of too large a diameter to be spun in the lathe chuck.

So the method simply solves two problems 1st how to ensure the machined hub is true to the wheel bearings and 2nd how to spin a 21 inch rim in a 16 inch capacity lathe.   

Offline KTM47

  • Legend
  • *****
  • Posts: 1412
    • View Profile
Re: Machining brake drums
« Reply #4 on: July 17, 2014, 03:40:44 pm »
Yes you are right.  After looking at it closer I can see that the wheel is not running in line with chuck.  It would take a bit of work to set that up, but if you have a few to do probably worth it.  Or get a lathe with a gap bed.
MAICOS RULE DESPITE THE FOOLS

1999 KTM 200, 1976/77 KTM 400,1981 Maico 490