Group Buy Proposal: We all need o-rings! (Warning: Long Post)
I suggest we assemble a “kit” containing almost every commonly used o-ring and have a single supplier assemble it and provide it to us at a fair price.
By the way, "the other forum" did in fact do just that years ago but they were principally interested in SureFire at the time and their Group Buy had only SAE sizes - not the Metric that we need. They had planned to get around to putting a Metric kit together but, to the best of my knowledge, never got around to it.
If a few detail-oriented people (with calipers or a very keen eye and a good ruler) will help by measuring some of their o-rings, I volunteer to create a spreadsheet listing as many flashlight models as possible along with their o-ring requirements.
Then I will create a list that includes a few of each of the sizes as seems practical so that we can solicit pricing for it. Kreisler’s source in Germany seems to have every size imaginable – 1000’s I think!
The proposed spreadsheet will yield multiple benefits – even if an individual doesn’t participate in the Group Deal:
1) First of all, when they need an o-ring for a particular flashlight, he (or she) will probably be able to refer to the spreadsheet to find out exactly what size(s) to get – no guesswork, no measuring (and how do you measure a broken o-ring anyway?). The alternative would often be a visit to the hardware store for some trial and error – that is IF they even have something that would be suitable. Note that most of the o-rings available in the US are SAE (in inches), not in millimeters (which is what we need for almost all of the lights we have).
Another way to look at this is that it would obviate the need for each of us to buy micrometers and remove all of our o-rings to see what we're using.
2) We will be able to assemble a kit specifically designed for flashlight collectors and arrange for a supplier to provide it to our specifications.
Some of mine have broken; some have worn out due to lack of lubrication; some are obviously the wrong size for the purpose (due to Chinese supplier neglect of what should be an important “detail”).
I’ve spent hours researching o-rings.
At first I was under the misimpression that I would be able to buy an appropriate kit at a good price and all the sizes I needed would be included – no such luck! There are tons of kits available from lots of sources. E1320 is certainly right that Amazon has a huge number listed. The problem is that the kits are all wrong for flashlight use.
Then there are the Chinese suppliers. DX does have a few useful o-rings. So does FocalPrice – but no one seems to have anything near the complete mix that we would need.
About the cost:
I agree with Kreisler that at first glance the cost appears a little high (if we use his source) – but after considering all of the useless kits – even the cheaper ones, we’d end up being reasonably close in price – but most important, we’d probably end up fulfilling 95%+ of people’s needs and at a very fair price (saving quite a lot because we’d be getting what we actually need) and without having to chase around, becoming frustrated like I’ve been for several days.
OK – How to proceed???
I would assemble the spreadsheet from information provided by a few of the members willing to help – either because they have a little time to do some simple measuring – or out of self-interest. It’s likely that a lot of people will simply want to make sure that their needs are met and that the final list of o-rings included for the kit includes what they want. I’ll help personally with the measuring but my collection is still quite limited.
What information would be useful and/or essential for the spreadsheet?
Please don’t get overwhelmed by what I’m about to discuss. It’s really all common sense and we’re not at risk of blowing up a rocket. There are only a few essential pieces of information. Keep in mind that if we guess wrong on some, the cost per o-ring is likely to be only $0.01 to $0.05.
[ESSENTIAL INFO] Manufacturer & Model Name/Number of the Flashlight
(Alternate Names for the same Light from Different Suppliers would make sense as well.)
[ESSENTIAL INFO] O-ring function or location on the flashlight in question
(Why – because the o-ring between the lens and the crown must be full size so that it’s not sticking out and obscuring the lens but the o-rings for the tubes should be slightly tight to stay in place.)
[HELPFUL BUT NOT ESSENTIAL] Note that the Budget Light Manufacturers/Suppliers we deal with do not always supply the optimum size for the intended use so it would be nice to know the size of the original o-ring along with information regarding whether it seems that, for example, a thicker o-ring would more effectively fill the channel/slot provided for it. (Channel depth and width are both factors influencing this.)
Measuring Parameters: (What Dimensions Do We Need?):
We really only need two (2) dimensions for each o-ring suggested:
[ESSENTIAL INFO] ID: This is the Inner Diameter. The only thing to make sure of is that you are measuring it when it is round. (If it insists on remaining oval, take the long measurement and the short measurement and average them.) Note that you can measure the OD instead of the ID if you find it easier. We’ll just have to subtract 2 x THICKNESS to determine the ID.
[ESSENTIAL INFO] THICKNESS or WIDTH: This is exactly what it says – the cross sectional thickness of the rubber (measured easily with a caliper if you make sure not to squeeze or deform it).
[ESSENTIAL INFO ONLY IF YOU CHOOSE TO MEASURE OD INSTEAD OF ID] OD, or Outer Diameter is simply 2xTHICKNESS plus ID and does not need to be measured unless you’d prefer to measure the OD and subtract 2 x THICKNESS to calculate the ID.
(Some size charts don’t even bother listing the OD but I’ll include it in the spreadsheet anyway.)
A Minor Complication:
O-rings that have been on a flashlight tend to stretch a little bit so it would be useful to know whether the measurements you’re providing are taken from a “virgin” o-ring or from one that has been on a flashlight and been stretched a little. I'm unsure about just how stretchable the o-rings are. In other words, just how much smaller should the o-ring be than the particular tube that we want to cover - or do we order the exact dimension? (probably not) I’ve done a little bit of experimentation here and it seems that a “virgin” 25mm o-ring is roughly one or two mm less in diameter than one that has been stretched. I’d love to get some additional input on this because it probably makes sense to order just slightly smaller than the particular tube so that we get a “snug” fit.
As already mentioned, another variation of this question relates to the o-ring that fits between the lens and the crown. Many of us know from experience that this one should be an exact fit or it is difficult to place in the appropriate position without some of it "sticking out" from under the crown.
About Prices:
The best supplier I’ve seen so far is the one that Kreisler mentioned. I am not “wedded” to them and would be happy to consider any other supplier that has what we need but here’s the link (I hope) and I think you’ll be amazed at the selection they offer:
http://www.ir-dichtungstechnik.de/shop/shopping_cart.php
Kreisler says they have a minimum order of 10 Euros and international shipping is an additional 4.1 Euros. There is a VAT (value added tax) in Germany but I’m hoping that it can be waived if the kits are exported. It would also be possible for two or more people in the US, for example, to share a “kit” because the shipping within the US would probably only be a dollar or two. By the way, although I didn’t see the option on their order form, Kreisler says they accept PayPal – important for cross-border transactions.
To those who feel that the cost is too high, consider that the kits at Amazon and elsewhere are close in price but almost useless. Also, our time has value and chasing around for a particular size of o-ring can use up a lot of that time – not to mention gas.
A Note about Materials:
NBR (otherwise called Nitrile or Buna-N) is probably what we need, NOT Silicon (which is too vulnerable to various chemicals/oils). NBR also has the advantage of being the most prevalent and the CHEAPEST of all of the alternatives. Prices should vary roughly from $.01 to $.05. Just as important, we should be able to fulfill almost ALL of our needs from only ONE SOURCE! - and not have to chase around.
PilotPTK is correct that Viton is a better material but it is A LOT more expensive and I think unnecessary for our purposes. The links that follow will take you to some general information about o-ring materials and their properties:
http://www.marcorubber.com/materialguide.htm
http://www.mcmaster.com/#catalog/118/3488/=h4iijj
The only other variable is Durometer hardness. It is usually either A70 or A90 but A70 is probably best for almost all of our needs.
LET'S DO THIS!
At the very least, we should assemble the spreadsheet.
A little more work to assemble a chart of needs for all the common lights and we can put together a very, very useful GROUP BUY - something that will save us all a lot of time and hassle (not to mention money). By the way, a GROUP BUY would not prevent each of us from ordering individually based on our own specific needs. The other people would simply not benefit from the package discount
COMMENTS AND SUGGESTIONS PLEASE!
