How much moisture control for expansible dowel pins?

[Michael Gramm]

When it comes to expansible dowel pins and long term storage (they'll be used every now and then, but I'm talking about a large enough supply that will last for a while), to what lengths should one go to keep them away from moisture?

Is it enough to simply put them in a tight container? Or should they be accompanied by silica gel (or some other dessicant) as well?

I don't know how sensitive they are - especially for long term storage, but given how they are designed to work, I felt the need to ask.

[Jamie Buxton]

Of course it depends on what the atmospheric humidity range is in your shop. However, for an example, assume that the EMC of your dowels ranges from 6% to 9%, and that you have 1/4" diameter maple dowels. The diameter change due to the EMC change will be about three thousandths of an inch. That's pretty imperceptible.

Bruce Hoadley's book Understanding Wood is a good place to learn about the physics of wood.

[Tom Esh]

I keep mine in sealed food storage containers in ziplocs, but that alone usually isn't enough for more than a few months once the package has been opened. I also toss in a couple of these
http://www.leevalley.com/garden/page.aspx?c=2&p=53896&cat=2,2260
They work great - as long as you remember to check / rejuvinate them occassionally. I've also used them to salvage swollen dowels by sealing one in a ziploc with the dowels overnight.

[Michael Gramm]

Of course it depends on what the atmospheric humidity range is in your shop. However, for an example, assume that the EMC of your dowels ranges from 6% to 9%, and that you have 1/4" diameter maple dowels. The diameter change due to the EMC change will be about three thousandths of an inch. That's pretty imperceptible.




It's enough to make the difference between a snug fit and requiring a mallet to set fully. But the dowel pins are expansible, remember - so they will expand more than regular dowel pins.

The question still remains though - how easily will they absorb moisture, and what measures are necessary for long term storage.

[Michael Gramm]

I keep mine in sealed food storage containers in ziplocs, but that alone usually isn't enough for more than a few months once the package has been opened. I also toss in a couple of these
http://www.leevalley.com/garden/page.aspx?c=2&p=53896&cat=2,2260
They work great - as long as you remember to check / rejuvinate them occassionally. I've also used them to salvage swollen dowels by sealing one in a ziploc with the dowels overnight.




Thank you, that tells me what I need to know. Silica Gel it is!

[Tom Veatch]

...
The question still remains though - how easily will they absorb moisture, and what measures are necessary for long term storage.

The expansion from moisture absorption is reversible, so they aren't necessarily ruined if they do swell somewhat. If you're experiencing difficulty with swollen pins, start with keeping them in a sealed, airtight container - plastic freezer cartons, maybe. That will, at least, limit the amount of moisture they can absorb. If you continue to experience a problem after that, toss some dessicant packages into the container with the pins. Or, if you don't have to buy the dessicant, or want to be more certain about preventing the absorption, toss them in at the beginning.

[Michael Gramm]

The expansion from moisture absorption is reversible, so they aren't necessarily ruined if they do swell somewhat. If you're experiencing difficulty with swollen pins, start with keeping them in a sealed, airtight container - plastic freezer cartons, maybe. That will, at least, limit the amount of moisture they can absorb. If you continue to experience a problem after that, toss some dessicant packages into the container with the pins. Or, if you don't have to buy the dessicant, or want to be more certain about preventing the absorption, toss them in at the beginning.


Will do. Thanks, everyone!

[Mike Hall1]

If you are having trouble with a tight fit (as can often happen with multiple dowels), you can always use a slightly oversize drill bit.
I often use a 9.6mm drill bit instead of a 3/8" (9.52mm) on certain types of wood.

Mike

[Michael Gramm]

If you are having trouble with a tight fit (as can often happen with multiple dowels), you can always use a slightly oversize drill bit.
I often use a 9.6mm drill bit instead of a 3/8" (9.52mm) on certain types of wood.

Mike

The trouble isn't a tight fit, I was simply trying to plan ahead so that I didn't end up ruining a large batch of dowel pins. :)