Drilling a hole for doweling in 2x2

[CAMRAMan]

I'm making a camp bed for the rear of my car. It's two parallel 2x2 pine bars joined with plywood. For transport, I need to have it in two pieces about 90cm long. That means I have to have a strong joint. My thought is to use 12mm dowel. That means I'll need to have a precisely aligned holes in the 2x2. I don't have access to a lathe, but have a drill and bit, but how do I ensure the holes are aligned and what depth of hole would be needed?


Are there any other ways of joining the two sections?

[Asterix, the former Gaul.]

I would try to fit a metal sleeve like a tent pole. I think it would be stronger.

[Kim]

The trick to precisely aligned holes when using dowel to join wood is to drill the hole in the first piece, insert a dowel-alignment stabby hat thing, align and squeeze the two pieces of wood together, then drill the second hole at the dimple where the dowel-alignment stabby hat thing has done its stabbing.  This seems to work well enough, at least to within dead vegetable tolerances.

But I agree, this sounds like a job for a proper material, like metal.

[CAMRAMan]

Thanks. I don't think the metal sleeve option would work. The two halves need to butt up beside each other and there will be plywood slats right up to the joints.

[PaulF]

Can you build a jig/template to act as a drill guide?

So a piece of ply 2x2 with a hole in it. Use that as a guide to drill a hole in the first piece and then flip over to drill in the second

[Canardly]

Hinges?

[Diver300]

Anything supported at the ends has the biggest bending moment in the middle. I know that 2x2 is generously sized for a bed, but the joint has to be quite strong and I don't think that 12 mm dowel would be enough.

[Kim]

How about a mortise joint with a bolt through it or something?

[iddu]

Take two 200 x 50 x 50 lengths, cut a channel on each (for your slats), halve  into four 100 lengths, make a 10 lap joint at one end of each 100, butt together and drill thru butt section as wanted, bolt/dowel to taste for security/disassembly

(All values as centimetres, convert as you wish…)

[aidan.f]

It reads to me as If the OP wants to join the two side rails with dowel inserted into the end grains to make a pin and socket joint.
It's not going to be possible to drill co-axially aligned holes by hand and the joint will be weak.

If the bed will be fully supported on a flat surface I would use fish plates about 250 mm long.  Through bolts will make a very strong joint.  50mm (2x2") is IMO a bit weedy. 50x75 carcassing timber better.

A drill stand will be essential to get holes vertically aligned through the side rails. Once you have one suddenly other jobs become much easier ..

If the camp bed sections are to be stored stacked careful jiggling of relative hole position would allow it to hinge.

Best type of bolts would be only part threaded. M8 x 75mm

Refinement:  drill rail holes oversize and glue sleeves inside, plastic pipe would do.

Just to make it clear what I mean by fish plate.

[fruitcake]

how do I ensure the holes are aligned...?

The tool for this is a dowelling jig. It creates a fixed channel to guide your drill bit in order to create a hole at 90 degrees to the surface of the wood. I have a metal one made by Stanley and a modern plastic one with metal bushings. The Stanley one is the nicer tool.
https://duckduckgo.com/?q=dowelling+jig+stanley&t=ffab&iar=images&iax=images&ia=images

I agree with Kim that a mortice joint would be stronger.

[fruitcake]

To make a demountable camp bed, I might try a pair of 'pallets' fixed together with a removable jointing plate each side. The jointing plate can be a strip of timber with allen head bolts.

[CAMRAMan]

A few points of clarification: The bed will be fully supported on the car seats, so the joint won't be bearing too much of my load. The width is 80cm and has to be so to fit the car. I'll be putting a thick, self-inflating mattress on top.

[Polar Bear]

I would imagine that car seats will have some give in them due to their very nature.  Will this flexibility be a risk to joint integrity?

[aidan.f]

A few points of clarification: The bed will be fully supported on the car seats, so the joint won't be bearing too much of my load. The width is 80cm and has to be so to fit the car. I'll be putting a thick, self-inflating mattress on top.

If that's across a row of seats you may need packing to level. Don't under esimate the strain on top of seat cushions - you will sit up on the joint

To make a demountable camp bed, I might try a pair of 'pallets' fixed together with a removable jointing plate each side. The jointing plate can be a strip of timber with allen head bolts.

You mean fish plates? - timber would need to be similar in thickness to the rails - Metals4U could supply 4x250mm lengths of 31.7mm x 3.2mm (1 1/4" x 1/8" ) Aluminium Flat Bar for £4.31 collected from Wetherby.

[mrcharly-YHT]

How are these rails going to fasten to the ply?

I assume you are adding them to give the ply some rigidity; I think that will be a very uncomfortable bed, like sleeping on concrete.

Is this setup resting part on one row of seats and part in the air, and that is why you need a flat sheet?

[robgul]

I've sent you a PM - but in the meantime . .

What you describe in the OP sounds like it's a "stretcher" 1.8m long with two side rails and the bed part being a solid plywood sheet - and you want it to separate into 2 halves?

Joining the two bits end to end could be achieved by having a rod that fits into a deep hole in the end of each rail . . . I don't wooden towels would work as the flex, even if supported from underneath would be too great.  It should be possible to drill a hole about 150/170 deep in the end of each rail and then use two lengths of steel rod, probably 12mm 300mm+ long(threaded rod is readily available from B&Q) - the steel rods would be stored separately when the thing is demounted.   You would also need to have a mechanism to lock the two sections together when they are in use - the other possible issue is the strength of the 50 x 50 timber (whoich would be 47 x 47 in reality) not splitting with the weight on the contraption and the steel rods.

Have you considered just curling up on the back seat?

[Kim]

One of the ALC regulars fettled an Ikea children's bedframe (with proper spingy slats) to fit in her Skoda Yeti.  I think she used the fish-plate approach to make the long edges separable.

[grams]

You could make the connecting pieces out of 2x2 and put dowels (or bolts) sideways into the fixed beams. Clamp them together and drill both at once and the holes will have perfect alignment.

[Ham]

This dowel jig can be very useful https://www.amazon.co.uk/Wolfcraft-4640000-Dowel-Master-dowel/dp/B0001P19PY - mine also has metal dowel with centre pins you drop in a hole and use to mark the centre on the other piece, it isn't clear if this one has or not, and I've had mine for 20-ish years
ETA here you go https://www.amazon.co.uk/Dowel-Pins/b?ie=UTF8&node=1938571031

[CrazyEnglishTriathlete]

I'm not a DIY person so take this with a pinch of salt, but when it came to making CET juniors' sandpit deeper, I added another large pine post horizontally on top of them and secured them using four pieces of 12mm dowel.  This stood no end of jumping up and down and weathering - 10 years later when I reclaimed the sandpit for patio and a seating area the two posts were inseparable, even though the bottom one, being on the ground, had rotted halfway through.

[CAMRAMan]

I've sent you a PM - but in the meantime . .

What you describe in the OP sounds like it's a "stretcher" 1.8m long with two side rails and the bed part being a solid plywood sheet - and you want it to separate into 2 halves?

Exactly, except I'll be using numerous plywood slats, not sheet. Mainly because I've managed to get hold of some.

[robgul]

This dowel jig can be very useful https://www.amazon.co.uk/Wolfcraft-4640000-Dowel-Master-dowel/dp/B0001P19PY - mine also has metal dowel with centre pins you drop in a hole and use to mark the centre on the other piece, it isn't clear if this one has or not, and I've had mine for 20-ish years
ETA here you go https://www.amazon.co.uk/Dowel-Pins/b?ie=UTF8&node=1938571031

The Wolf thing is OK for short dowels but I think the proposed task is going to need a much longer and stronger linking mechanism - the jig isn't stable enough for very long drill . . . I've just fitted 12mm studding (threaded rod) in 150mm lengths into some laminated plywood legs I'm making for a table using a drill press gadget.
Clamping the timber to drill in the vice and then with some supporting blocks of wood clamped around it and the press clamped on - the press takes a corded (Bosch in my case) electric drill.   I also have a pillar drill but getting the timber loaded was problematic.

This is the press:

[hubner]

A dowel joint is usually glued but it seems the OP wants a joint that can be taken apart.

A picture is worth a thousands and all that, but if the aim is to join two lengths of wood end to end and that it needs to be able to be taken apart, then the simplest way is to use bolts and nuts and plate brackets.

[Ham]

The Wolf thing is brilliant for drilling centres, but it was the metal dowel pins that would serve to accurately locate the start of the dowel hole in the other work piece, and to that measure answered the OP question.

Drilling it straight is an exercise I was leaving to the reader's technical skills although the wolf thing does help, as does drilling through a CD using the reflection to ensure verticality in multiple axes. I've always fancied one of those portable drill presses, but I've never really had the use for it.