On 13/04/2021 10:06, Tricky Dicky wrote:
On Tuesday, 13 April 2021 at 09:52:12 UTC+1, wrote:
Hi all,

Firstly thanks very much for all the info on the other thread. Study now designed so now in build phase

I have cut the pieces for the first cabinet out of 18mm ply so now looking to put it together. It is 900mm wide (500mm deep) so wondering what the best way to glue/ screw it all together to make sure it is square. I have done some searching but they seem to make it up first them adjust it. I had anticipated using fairly decent screw lengths (say 60mm) so thinking that it would be very rigid (and heavy) so ability to adjust this way would be somewhat limited. Also, I was planning on having a fixed shelf in the middle to add further strength (and in reality we never change the height anyway) so this would further impede this approach.

Any ideas how best to go about it?

Thanks

Lee.

The normal way to square up cabinet whilst glueing it together is to clamp it with Sash cramps and measure the diagonals if equal the cabinet is square if not a slight adjustment in the cramp positions can usually bring it square.

Are you fitting a back to the cabinet because with a good fit and the back cut square that often does the trick. A lot of self assembly cabinets, IKEA et al, rely on the back fixing to square them up.

Exactly. Forget about trying to use long screws, the reactions to the
bending moments will just deform the wood if you put the four pieces in
shear. For decent strength, I'd have an inset back of the same thickness
cut to exact size. Easy to do if you use a sawboard. "Shed" type units
typically have a 6mm hardboard back sometimes set into a rebate and then
pinned. For lighter duty you can get away with 6, 9, or 12mm ply. But
using 18mm you can set the back in with biscuits, using the same biscuit
size and cutter setting that you do for the "90 degree" joints.