Fastening baseboard frames together \ bolt options?

[centenary]

Im building the garage layout in modular form and require all the baseboard frames to be fixed together one way or another. I dont want to simply screw them to one another as I want a section in front of the garage door to be removable for maintenance of the door wires and mechanism if and when needed. Other than that, the fixing has to securely hold the modular board frames together. No power will be passed through the fixings, they will be mechanical only.

I was intending to use "carriage bolts" but, while I can find them in the required size, they all seem to have a square section about 10mm or so directly under the head before the thread starts and, square section doesnt tend to fit snugly into an M6 hole!

Also, using a slightly larger drill size so the square section seats in the hole would result in the bolt shank having a bit of wiggle room in the holes so might not make for perfect alignment? Im not certain hammering the bolt in to the wood to bury the square section is a good idea. Or maybe Im wrong and that's the way to use them?

Im looking for suggestions what people generally use to fasten boards together other than screws. Does anyone have specific fixings in mind or do they just use an ordinary bolt, couple of washers and a wing nut?

[Mountain]

I use the old method of using hinges that have had their pins removed and I use a suitable thickness of stiff wire instead with the tops bent to act as handles if I needto remove them.
Allows for good alignment and ease of assembly/dissasembly with the only downside is finding budget hinges which are easy to remove their pins.

[b308]

I was intending to use "carriage bolts" but, while I can find them in the required size, they all seem to have a square section about 10mm or so directly under the head before the thread starts and, square section doesnt tend to fit snugly into an M6 hole!

Also, using a slightly larger drill size so the square section seats in the hole would result in the bolt shank having a bit of wiggle room in the holes so might not make for perfect alignment? Im not certain hammering the bolt in to the wood to bury the square section is a good idea. Or maybe Im wrong and that's the way to use them?

I normally use some special ones made by a friend, but my current ones use nuts and bolts. There seems to be several schools of thought concerning joining baseboards, one is the ridged one where you use dowels for alignment and with bolts to hold them together and the other with just bolts (the loigic there is that it gives you wiggle room. Frankly I feel it's down to personal preference but if you do use dowels you need to ensure everything is lined up before fitting them!!

Re the bolts, if you go to a decent old style ironmonger you'll find proper bolts rather than carriage bolts, using proper bolts also helps with tightening up as you can hold both the nut and bolt. BTW use wing nuts, not ordinary bolts, it makes life so much easier if you have to dismantle it, again a decent ironmonger will stock them. I also use washers both sides to stop the nuts and bolts biting into the wood.

[GeraldH]

I use bolts with the square section at the head with wingnuts at the other end with large'ish washers. The bolts go through the softwood frame and the first time the wingnuts are tightened it pulls the square section into the frame making a square indent which stops the bolt from rotating. It doesn't damage the wood. I think I used 8mm bolts. Getting the bolt holes perpendicular was a problem until I bought a "Big Gator Tools drill guide" - an excellent piece of kit, though not cheap.

My major mistake was using MDF as baseboard top. It has very little strength, is hard to get track pins in, has toxic dust and the ends swelled slightly from the moisture when ballasting creating a slight hump at the baseboard joint. My more recent boards use ply.

[Flashbang]

On my first couple of layouts I used M6 Coach Bolts and large M6 Penny Washer and a M6 Wing Nut - Two bolts etc per baseboard joint. But crawling under the layout to fit and tighten around 20 or so bolts then undo them at the end of an exhibition or after home use became too much of a chore!

I now use two Cabinet Makers Dowels and two strong Toggle Latches which are fitted onto the outer side frames per board pair and pull the two boards tightly together. The dowels maintaining the two boards in correct alinement every time.

[FatController]

I use two sets of the pattern makers dowels from Station Road Baseboards - not cheap but very accurate - and follow the instructions. I take what is going to be the end of one module (so the 12 mm thick pieces) and the corresponding connecting end from the other module and clamp them together so they are perfectly aligned at what is going to be the top edge. I then drill two 3 mm holes where the pattern makers dowels are going to go, use a 25 mm spade bit to cut an inset for the dowels and then bore out the centre to 9 mm. I make the holes and insets a little bigger than needed so the dowels can move about a bit.
This is where I maybe deviate from usual practice - if I was to just fit the dowels at this stage I'd be a fraction of a millimetre out. What I do instead is to coat the mating surface of dowels with Vaseline such that they stick together (and keep out epoxy glue). I then put epoxy glue in the insets in both pieces of wood, put the dowels in one inset and then put the other wood onto it and clamp them in place making sure the top edges are perfectly aligned again. Leave glue to dry and then un-clamp and finally use the (supplied) screws to fit the dowels. If all goes to plan, then each dowel is now connected to its respective bit of wood and they mate in a completely aligned and repeatable fashion. That's alignment sorted - I then re-clamp in position and drill three 6 mm holes that I will use for bolts to give strength.

[centenary]

Thanks all for the tips!