Author Topic: A Grubby Affair  (Read 313 times)

Offline Joules

  • Hero Member
  • *****
  • Posts: 867
  • Country: gb
A Grubby Affair
« on: November 12, 2017, 10:38:19 AM »
It all started late one night when I was all vulnerable like ...   :(

About to do some thread cutting and I couldn't get 2nd gear !!!!  Whaaaaa ?  1st and third appear to be fine.   No choice but to pull the cover off the headstock and investigate.   Yeah a "Private Investigation"  as I appeared to be in dire straits...

I had a big gap where second should be, and my third gear is actually my second gear engaging, just.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline Joules

  • Hero Member
  • *****
  • Posts: 867
  • Country: gb
Re: A Grubby Affair
« Reply #1 on: November 12, 2017, 10:48:24 AM »
The culprit, some Ace had decided to skip the grub screws that lock the black collar and it had undone letting the gear cluster slide left.  I consider it lucky the gears didn't crash or chip....   Email sent and as yet no response.   Time is ticking as I need to get these parts done, I retightened the collar and checked the gears.   Then I went fishing with a magnet to see if the grub screws happened to be at the bottom of the oil bath....   Nope, and looking at the collar in locked position no sign the thread ever had a screw bite onto it.

Break out the 8mm threaded rod and prepare to Grub thy Screw....

Be careful how you grip threaded rod as it is easy to crush the thread.  My preference is to use two nuts, the front one slit so it grips like a collet.  The rear nut just keeps the rod centred. Cut a small shoulder to clear the threads and another to clamp a copper disc down when we install the grub screw.  You might want some paper shim on the front nut to allow for it closing down and take the load of the rear of the jaws.  Bits of beer can work well too, both for shim or gripping the threaded rod directly.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline Joules

  • Hero Member
  • *****
  • Posts: 867
  • Country: gb
Re: A Grubby Affair
« Reply #2 on: November 12, 2017, 10:53:07 AM »
Something I have been meaning to try for a while is a, new to me way of slitting screw heads.  Mounting a hacksaw blade in the tool holder so I can draw it across the screw head to form the slot.

It worked pretty well and only took a few mins to do.   Not sure I would try it on harder materials though.



Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline Joules

  • Hero Member
  • *****
  • Posts: 867
  • Country: gb
Re: A Grubby Affair
« Reply #3 on: November 12, 2017, 10:58:16 AM »
Happy with my first screw, aye she was tight boys.....   :palm:    I made another and punched out the two copper discs.

Finally recheck the collar is tight, drop in the copper disc and install the grub screw, repeat on the other side and were done.

Workshop life back to normal, and that Grubby Affair is behind me without the missus ever finding out  :poke:
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline hermetic

  • Sr. Member
  • ****
  • Posts: 251
Re: A Grubby Affair
« Reply #4 on: November 12, 2017, 11:53:07 AM »
I changed the oil in my Colchester a couple of months ago, and found a selection of useful spare parts in the grunge at the bottom, including the original drain plug for the headstock. I thought the light alloy one I removed had a home made look about it. Even more frightening was the feed/sc gearbox, where I found a spacer and circlip which was missing from the geartrain, and another circlip which was partially jamming the locking rack. I took it off and rebuilt it, what a difference! Now I wonder which mischevious git wandered past and dropped them in there when no one was looking. :bugeye:

Offline akitene

  • Newbie
  • *
  • Posts: 4
  • Country: fr
Re: A Grubby Affair
« Reply #5 on: November 12, 2017, 02:03:19 PM »
Yeah a "Private Investigation"  as I appeared to be in dire straits...

-> Very fine joke, Joules. I'm glad for you the game didn't commence "for the usual fee plus expenses" as the missing grub screw could have ruined a couple of teeth on the other gears.
Christophe

Offline PK

  • Sr. Member
  • ****
  • Posts: 292
  • Country: au
Re: A Grubby Affair
« Reply #6 on: November 12, 2017, 03:20:59 PM »
it looks like there should be a spacer on that shaft to stop that cluster moving (or am I missing something?). If the grub screws don't do the trick (and your double declutching isn't up to scratch) then maybe make up a split collar to put in there.....

PK