Archive for the lubrication Category

Flashlight O rings and Grease

Posted in light, lubrication, technology with tags , , , on November 30, 2010 by marksun

O rings are used in most state of the art, high tech flashlights – the kind with the aircraft aluminum precision machined bodies.

The purpose of the o-rings are to form a tight, smooth fit for parts of the light that must move smoothly past each other, and to form a waterproof seal.  To have a reliable and smoothly functioning light,  keep the threads and o-rings clean and free of lint, dirt and moisture, and use the small amounts of grease on o-rings and threads.

Virtually all o-rings used in lights are made of synthetic rubber.  O rings for lights are seldom made of natural rubber (cost and durability) or silicone (cost and/or not the right mechanical properties).

  1. Virtually any silicone based grease or lubricant with or without PTFEs (or teflon) are safe on flashlight o-rings.
  2. Petroleum and mineral based greases are deemed to be less suitable because some synthetic and natural rubber o-rings are attacked by some petroleum based products.  carry risk in this application.  Manufacturers mainly recommend silicone based lubricants.
  3. WD-40 is petroleum based, is too light for this application, and may dry out the o-ring.

I use a couple of greases that I have in my collection of lubes:

  • Lube Gel – silicone grease with PTFE from Radio Shack (oem from a SYNCO).  This tube should last me about 40 years.
  • “Green Slime”,  a silicone PTFE grease used for RC car shock absorbers left over from my RC days.

In the short term, just about any grease will seem to work just fine.  The reason to consider what you use is that greases  tend to stick around for the long haul.  You don’t want the grease to melt down the o-ring to a gummy mess, since the time you discover it will be the time you will need your light the most.

Reference:  “Comprehensive Grease and Lube Thread” on the Candlepower Forum (CPF).


A shredder in the house

Posted in house tech, lubrication with tags , , on March 21, 2009 by marksun

After going through my dad’s filing cabinet, I decided that it is worthwhile plunking down money for a shredder. I still think these are luxury commodities that take up space and cost money, but in return they save time in the chore of mincing sensitive documents into unreadable bits.  As a reluctant security specialist, I have to concede that many household documents pose a security threat. While the threat is often exagerated it is not zero in our society. Thus, I am on my third shredder working my way up the cost chain to $129 at OfficeMax on a mid-priced Fellowes model (which is cheaper at Costco btw). The cheapest on sale models are proof of the “you get what you pay for” theory. The thin flimsy blades get jammed with paper under normal use quickly and cleaning is very time consuming and hazardous.  Overload the shredder just once, and the blades bend, and that permanently voids the warranty because overloading violates the “abuse” clause of the guarantee.  It may still work, but the loud mechanical noise tells the story.  We’ll see how this Fellowes works out. (it does by the way).

Shredders need “shredder oil”.  Naturally you can just buy shredder oil, but that would be too easy.  Why not concoct my own cheap lube?  So why is there such a thing as “shredder oil”, and why the specific warning against wd-40 and 3-in-one?   Lets work the problem.   Why oil in the first place.  The purpose of oil is lubrication, keeping the blades clean by releasing paper fragments and dust from the blades.  Oil reduces friction which would overload and cause overheating in  the electric motor.  But why do you need special oils?

If you do a google search on “paper shredder fire” the answer comes clear.  Paper shredders under conditions of overuse heat up to the point of ignition!  As it turns out, electric paper shredders, while convenient, can become a fire hazard. WD40 sprayed into a smoldering shredder becomes a blowtorch and so will canned air!  Adding oils that are highly flammable increases the chance of fire.  Thus for liability purposes, the shredder manufacturers specify the use of oils that they know will not contribute to the fire hazard.

Let’s have a look at the flash point of certain oils.

  • WD 40 flash point is 110 deg F. 
  • Mineral oil 275 deg F.  
  • 3-in-one  305 deg F.
  • Mobile-1 (synthetic) > 430 deg F

On the other hand most  common vegetable oil  flash points  including canola, corn, safflower, and peanut oils are 600 deg F or greater.  From what I see on the internet, canola oil is a good choice because it is least likely to reek.

The flash point of paper, if you remember from Ray Bradbury’s famous novel is Farenheight 451, so the vegetable oil flash points are higher than paper.

This more or less settles it.  Although the lubrication qualities of machine oils are likely to be excellent and probably better than vegetable oils, the vegetable oils are much safer to use.  

Being humans means that we will abuse our shredder.  The shredder manufacturers are aware of this and the rule that the customer is always right.  They are caught between the inevitable stupidity of the customer and their need for that very customer to buy the product. To compromise, they build heat sensors and timers into their shredders, increasing their cost, but preventing as much as they can the possibility of fire.  They don’t want to come out and say that their shredders can burn down your house, but this is what they are trying to prevent – that and liablity lawsuits.

I didn’t know there was so much to say about the paper shredder.  The main thing is do not overheat a shredder because they can and do catch fire.  And do not add fuel to the fire by using machine oil for lubrication just because it is cheap.