Monroe electromechanical calculators

Tony Duell ard at p850ug1.demon.co.uk
Fri Jun 17 19:18:50 CDT 2005


> > Serondly, do not spray it with Wanton Destruction 40, or anything else 
> > for that matter. You will do a lot more harm than good...
> 
> I've been using sewing machine oil so far (which is the lightest stuff

I normally use clock oil (or watch oil if it's a very fine mechanism). 
H.S. Walsh in London sell it, for example.

> I've got). I just wonder if leaving it in a (slowly circulating /
> filtered?) bath of oil for a week or so would be useful for freeing
> stuff up and getting all the dirt out...

No!. That is a sure way to get oil where you don't want it (like between 
parts that are designed to slide over each other), and gum things up.

There is a bodger's trick of putting the whole machine (minus keytops,
rubber parts, and if possible the motor) in a solvent bath to clean out
the old lubricant and dirt, and then re-lubricating everything with a
suitable oiler tool. Everything meaning bearings, etc. 

SOmewhaere I have a copy of a service manual for a hand-cranked 
mechanical calculator (I think a friend found it on a web site). It makes 
it _very_ clear that this is not the right thing to do, and that you 
should take it all apart, clean each part separately and put it back 
together again. Of course it's a lot easier to do that if you have the 
service manual...

> > Most of the time, that's due to tracking across the impregnated fibre 
> > insulators used in things like the automatic on/off swtich. 
> 
> Aha, well I can isolate and test easy enough there without any severe
> dismantling of things. Can anything be done to fix the problem (short of
> making new insulators)?  

Clean off any oil (and especially graphited lubricants :-)). If you see 
visible tracking, scrape it off, if necessary cut into the insulator. 
Maybe bake the parts in a cool-ish oven.

-tony




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