Shrinking (i.e. drying) dowels in a micro-wave oven ?

[pompon44]

Hi,

I'm building a small fence (to protect my daughters from falling in the stairs). The frame of the fence is mortise and tenons, that I'd like to drawbore for re-inforcement.

The only dowels I have in stock are the kind (precut) for dowel assemblies.

They are 8 mm in diameter, but I noticed that drilling at 8 mm, the fit is really snug (on a test piece). I've seen in e.g. "Chairmaking & Design" by Jeff Miller, a method using heated sand in a can to dry dowels, and I was wondering if a micro-wave oven could be used for the same purpose, that is, drying the dowels.

Any ideas on whether this is stupid or not ?

 

[Wanlock Dod]

Doesn't seem like an unreasonable idea, but you need to be careful about not microwaving very much, short bursts on a low power setting with good rests in between.

Why not just stick them in the airing cupboard or similar overnight?

Cheers,

Dod

 

[Paul Chapman]

I was wondering if a micro-wave oven could be used for the same purpose, that is, drying the dowels.

Yes, it works well and is what I do now. I use the method for both dowels and biscuits which I store in my workshop (garage) and which can swell a little when they absorb moisture.

What I have found best is to spread the dowels or biscuits out on the glass tray in the microwave and give them one minute on full power. Then turn them over and give them another minute on full power.

Works every time

Cheers :wink:

Paul

 

[Hokie]

Right, or if you put them in a oven, you should put them directly on the rack unless they are small, then you need to punch holes in some foil. The trick is to get as much moisture out as possible. If you use the microwave, as Paul said, I also use a piece of paper towel to help absorb the moisture. I think I saw some windsor chair makers put their rungs in a box lined with foil and a 100 watt light bulb.

We have a supplier of compressed beech dowels that are sometimes oversize and need the same treatment.

 

[AndyBoyd]

I've done this with sand in an old cooking pan on the kitchen stove, works very well.

 

[bugbear]

Doesn't seem like an unreasonable idea, but you need to be careful about not microwaving very much, short bursts on a low power setting with good rests in between.

Why not just stick them in the airing cupboard or similar overnight?

Yes - seems simpler.

BugBear

 

[pompon44]

Hi all,

Thanks for the answers.

Why not just stick them in the airing cupboard or similar overnight?

My english reached its limits here ;-) What's an "airing cupboard" ?

 

[AndyBoyd]

It's the small cupboard in a house where the hot water tank is ,you traditionally keep your towels in there as it is nice and warm.


I'd say if you have not got one keep them on a radiator will have the same effect , or if you live in a sunny part of France just build a small glass house to warm them up.

 

[Benchwayze]

Hi Pompon,

Strictly speaking, we don't 'draw-bore' for reinforcement. 'Draw-boring' as I am sure you know, is a method of jointing without glue, for working with 'green timber'.

Wouldn't it be far less trouble to glue your joints first and then, after they are dry, peg them with reinforcing dowels? You wouldn't have so much wet glue about and you might find the dowels go into the holes more easily.
Just a thought.

Regards
John

 

[pompon44]

Hi John,

Well, you know, what I know about draw-boring is what I read here and there (and in particular from Chris Schwartz)... So I'm not an expert, but I thought the key in the draw-boring technique was the offset between the holes. That offset makes the joint closing tight when the peg is malletted in place, which would not occur if I peg after the fact, would it ?

Regards,

 

[Benchwayze]

Hi Pompon,

I agree and that's why I said 'reinforce' the glued joint with dowels after the joints are dry. You would cramp the glued joint first to close it. The dowel pegs put in afterwards would prevent the joint from opening again.

Remember, Chris Schwarz closely monitors the timber he uses for its moisture content and this is partly why he draw-bores, rather than glues his M&T's, especially in large section stock.

Maybe I didn't express myself very well in my last post.
My apologies.

Regards
John