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.
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.
Jig it. You need some way to establish that it IS square - trigonometry or a carpenters square - and some way to clamp it square while the glue sets
Don't bother with screws
For ply - esp. 18mm ply - glue - simple white PVA - is as strong as it gets.
I have used panel pins to stop joints sliding while the glue is wet.
You do not say exactly what the shape is - if its like a square tube you are assembling, well then normally you would use uber long sash clamps on each end ...
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...and a squared up bench, like what you assemble them ON should have a pair of planed battens glued or screwed on making a correct right angle
- use a square to do this - and then you push the clamped up frame into that while the glue sets. What you invest in or make of course depends on how many you are ever going to make.
Id love to know what 'it' is..
I had anticipated using fairly decent
Not much more without knowing what 'it' actually is...
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.
A screwed butt joint will not be so rigid that you can't tweak it later. With cabinets it's usually simplest to rely on the back doing the final squaring.
I would be tempted to assemble the 4 sides of the box, with glue and screws (although with a butt joint, the glue will offer little additional strength over the mechanical fixings). Then measure across the diagonals and check they match. If not, stick a clamp corner to corner on the long diagonal, and tighten until both diagonals match).
Leave it to dry, and then remove the clamp - it may spring back a little, but not enough to worry about.
Now stick a rebate round all four back edges on the inside[1] - say 1/2" deep and wide. Cut you back from 1/2" material, and make sure that is really square - set the dimensions so that it is a snug fit into your rebate. Tap that into place and fix (glue alone will be more than adequate here, but some screws will make it easier to ensure it pulls in tight to the back.
[1] or do it on each piece before you assemble
You can fit the shelf after if you are screwing through the sides. If you are setting it into rebates/dados then it does not need fixing at all, since it will be captive after assembly.
If you want to avoid the routing phase, then you can just cut the back to full width and height, and plant it on the back (although that might be visible from the side)
Yes the corner measure ments and a good right angled square are good, but you do still get some creep afterwards I used to find, even with it held tightly as mentioned. Of course this is often more of an issue if your door is the sort that fits inside the frame, not like Kitchen ones that sit over it. Also the next thing will be the space where it goes will also no doubt be out of true as well.
Thanks very much all for your advice. In response to your questions/ thoughts
- I need to make 2 x base units (900mm x 500mm), 2 x chest of drawers (400 x 500), 2 wall units (450 x probably 1200mm but TBD)
- I am trying to avoid using a router (mainly because I haven't had much luck with one to date) so was planning on using butt joints to connect the pieces of the cabinet together
- what size screws would you suggest I use for the butt joints?
- unfortunately I don't have a sash clamp but do have some G clamps and some quick release clamps like these
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Also have a load of off-cut timber/ boards etc. Was hoping to rig something up to save me buying the sash clamp just for this project - any ideas?
- unfortunately we have decided to have the type of doors which are framed inside the opening rather than the kitchen door type style where it sits on the front of the carcass. I was planning on putting some 18mm timber to frame the door and to hinge the door off so hopefully any slight issue with the cabinets can be hidden with the timber and ensure the opening is square for the door
and some follow up questions :)
- The 900 base units have double doors but was hoping to not have the vertical bar up the front. Will the 18mm ply be ok without the support?
- I have some 12mm MDF and some 12mm ply which I was thinking of using for the middle shelf screwed in through the sides. Will this be sufficient?
Thanks again all - would appreciate any feedback on this.
The vertical is usually there to form a "stop" for where two doors meet in the middle.
That very much depends on the weight of any item you are going to put on the centre of the top.
Just support the 18mm ply on two scraps of wood at 900m centres. Place a representative weight in the middle of the span and use a long spirit level to check deflection. Don't forget if your doors are inside the frame the bend/deflection of the top cannot be hidden by these doors. Furthermore a variable gap between a door and the frame will be very noticeable - you can always spot a gap of 3mm one side and 6mm the other side or in the middle. Leave too little clearance and any deflection of the top will cause the doors to bind and too much clearance just looks naff.
One trick is that you can double up on the thickness of the top by building the 4 sides first and then inserting a 18mm piece of ply inside of the top. This extra ply doesn't need to come right to the front - you can set it back to leave clearance for the doors etc. The chances that you will always view the cabinet from the top and this extra strengthening will not be seen. I had to do this once of a 3ft flatpack unit when I used it to support a 2 foot fish tank , which is f****g heavy when filled with water.
The router was more for making an "inset" back so that its not visible when looking at the sides of the cabinet.
If you have a circular saw and a rip fence, then you can make a pair of
1/2" non through cuts to take the corner out of the back inside edge before you assemble the box.
(when doing the cut on the edge - stack some other boards up beside the one you are cutting to support the saw base and stop it tilting)
40mm to 50mm will be fine. The Reisser "cutter" screws are quite nice - and less likely to split if driven into an edge without a pilot hole.
Yup just take notch out of the timer at each end, on opposite sides to make a clamp extension. Hook one end over the corner you need to pull, then use the clamp to pull the extension toward the other corner.
If you put a (glued on) lipping round the ply of the door, you can then always plane an edge to get nice looking margins all round.
If you use kitchen style hinges, then they provide a positive stop in the closed position without needing any other support.
I would probably want to use 19mm on the 900mm wide unit. If you want to use the thin stuff, then stick a 1" deep lipping on the front (flush with the top of the shelf, and under hanging the underside) - it will stop the front sagging, and also make it look far more substantial.
Let me know if you want me to draw any of the above to make it a bit clearer.
My home-made cabinet supported a fish-tank too - 5' long, 18" front to back and 2' high. The glass itself was 10mm for the sides and 12mm for the base, so it was heavy before filling! I estimated it be about half a tonne once filled (allowing for the weight of glass and the water not being to the top). I did check the floor joists first.
Whoever buys this house in the future will wonder what was going on, as I used to have that tank and a 20 gallon tank, in the living room. To keep the noise down, the air pumps (two, twin diaphragm pumps) were in a kitchen cupboard and there was an air ring-main under the floor, made of
40mm, plastic, waste pipe. Under the floor they will find a D-shaped loop of waste pipe, with eight (hardly visible) holes where feeds and take-offs were connected.
Only the waste pipe remains, as the tanks had to go once we had 3 children and space was at a premium.
Thanks alan_m for your tips. I forgot to mention there will also be an 18mm "worktop" on top of the cupboards which I could screw down into the cabinets is needed. The only real weight is a 450mm cupboard which will sit on top of the left half of the 900mm cupboard but on top of the worktop. The left edge of the upper cupboard is on top of the side of the lower cabinet but the other side is on top of the middle of the lower cupboard.
Thanks John for your tips.
- Yes have a circular saw so could do a groove as you suggest. Might even be able to do it using my track saw :)
- Good idea re: the clamp wonder if making a right angle out of 2 no 4x2 to butt against the sides would work better or maybe it doesn't matter? Was thinking, would I need to clamp top and bottom to ensure both are square? Not sure how I would clamp both at once though as somehow the cabinet would have to sit on the bottom one?
- re: the hinges, I was hoping to use flush hinges to show it was hand made :) and then have a clip/ catch pinned to either the top or the base to clip the door closed.
- re: gluing the 1" to the front of the 12mm shelf, do you mean cutting a 1" strip out of the 12mm MDF and glue it with the top of the 1" edge glued to the front edge of the shelf (tops flush)?
- very kind of you to offer to draw it thanks very much but I think I have it - famous last words :)
A notch in the end of the 4x2 so that you can hook it over one corner of the case, then the same notch on the other end - but on the opposite side, so you can hook the end of your clamp in it, and the other end goes over the other corner of the cabinet.
Another way that works will is a length of ply about 4" wide with a batten screwed to the ends on opposite sides (like an old fashioned "bench hook") - again it just brings one edge close enough to fit your clamp.
Not really - if you cut the timber square - it will be close enough that you can pull it square.
Yup I often do that with roller catches - they work well with the main bit on the top of bottom of the cabinet and the tang on the door. They also allow for a little misalignment (either placement or wood movement):
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I was thinking of a shelf with a (say) 1 x 0.75" cross section stip of softwood planted on the edge:
Viewed from the side:
XXPPPPPPPPPPPPPPPPPPPPP <- ply shelf XX <- softwood lipping
So when you look at the front edge of the shelf, the shelf looks thicker and more substantial than it actually is. The lipping also makes the free edge less likely to sag.
e.g. The "worktop" of this:
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Looks like its over an inch thick. In reality its just 19mm MDF with a thicker trim on the edge.
Similar trick here. 19mm ply top:
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With extra softwood strip glued under it (and in this case setback from the edge a bit), to make it look thicker:
Thought I would post an update in case it helps anyone else. I ended up combining a few ideas :) I made a couple of corners out of 4 x 2 scraps (each cut at 45 deg and screwed together to form a right angle) and then screwed a brace across the ends on top of the 4x2. I then put one on each of the corners of the longer diagonal and a ratchet strap between them to pull them together a notch at a time. This enabled me to measure both diagonals during the process to confirm they were equal.
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