Showing posts with label KHM. Show all posts
Showing posts with label KHM. Show all posts

Saturday 22 October 2011

KHM: tab problem solved

The grime inside isn't doing any harm - it has taken 74 years to build up. I reckon that's part of its heritage and I'm positive I'd do more damage removing it than leaving it alone

I have figured out the solution to the sticky tab illustrated in my previous post

Removing the left-hand rear dust cover reveals the motor and what I'd originally thought was a retaining collar for the clockwork motor's spindle. At second glance (and in better light) I spotted a worm gear. A drop of oil and a trial and error turn in both directions and voila! No more sticky tabs and enough pulling power wound into the spring for the carriage to move briskly along to the set tab. If I hadn't had all the covers off again for a more thorough cleaning of the paintwork, I'd probably never have spotted that worm gear.  

I hope this is of help to any other Royalists (aristocrats? typocrats?) with sluggish carriages. This fix took two full rotations of the motor spindle to load the spring sufficiently. To save straining yourself with heavy carriage returns or stressing any parts, slightly over-wind the spring first and then gradually slacken it off until there's just enough tension.

Friday 21 October 2011

Sticky tab


Though the rock-hard platen is the perfect paper perforator - confetti of little 'o's fly off the type heads - the Royal KHM's almost running perfectly. 

But there's a problem with the tab brake. Unlike some older machines, this machine has a cork brake pad which slows the carriage down as it disengages the escapement to rattle down the rails to meet up with its set tab. It is actually a pretty sophisticated solution! 

Trouble is that pressing the keyboard tab button actuates the brake a bit too fiercely. It brakes the carriage's motion to the extent that it never actually arrives at its station. You can see the surface which the cork pad actuates on in the photos. The pad itself is hidden away in the campanology department. A problem like cycling AND braking at the same time.

The video below shows what happens when the space-bar is used, then the tab button. You can see the problem when I press the space-bar a few times, then the tab, then repeat. No tabs are set. Any advice on how to overcome this would be extremely welcome!

PS: Yep, I cleaned the friction surface the pad bears on

PPS: UPDATE - problem now solved! See next post.


Thursday 20 October 2011

Royal KHM - answers



Well, I have dusted, polished and oiled this old Royal and in the process found out a few things:
  • Why's it so heavy? That's a cast iron body!
  • Typewriter covers are sort of OK, but not as effective at keeping the dust out as a proper box. Good reason to stick with portables?
  • Adwoa: the cover is one-piece alloy with hinged ribbon tops (re-coined 'bongos' from now on). Not hinged but bolted on. And I honestly don't have space for this typewriter either...
  • Mike: thanks for the pointers. The ribbon advance is actually driven by the clockwork motor. Incredible, ingenious! Disconnecting the carriage strap and pulling and releasing it you can watch the ribbon inch its way along.
  • Richard: soft lighting hides a multitude of defects. The paintwork isn't up to usual Royal standards. The front plate especially has a slight 'orange peel' look about it - not dead flat.
  • Matt: the top left lever is to enable free-spooling from left to right - it disengages the ribbon drive. This will help when re-spooling fresh ribbon.
  • MLG told me about the cunning key tension control knob and indicator - nice touch.
  • The Royal KHM is an amazingly well-designed and built bit of pre-WW2 machinery.
Most things started to work once the dust was cleared out of the segment and the carriage tracks were hosed down. But there's stuff that still needs attention, like the strap tension. Can't figure out how to adjust it - any advice welcome - or I could just wrap the strap around the drum twice? It is good enough to advance the carriage during normal typing but not strong enough for tabulating. The fiddly bell-ringing trigger is only sort of half-working - a solution'll come to me though. And one side panel's been backed into by something - needs careful bending so it lies flush.

Back story on this one is that my friend had it getting on for forty years after his dad brought it home from a place he'd been working. It was used for essays and college work but was forsaken by a switch to a Selectric when he went into fanzine production in the '80s. Needless to say, the ribbon works but badly needs replacing. Lowercase 'o' punches holes in it from time to time - interesting effect but that's some serious ribbon fatigue.

The bigger picture
    [Addendum: I get questions about the ribbon advance and why it might not be working. Yes, half inch ribbon is fine but you do need spools as illustrated showing top and bottom views. Unlike most other typewriters, the advance is not connected to the ribbon vibrator but to the travel of the carriage.]