My wife is into calligraphy and other arty stuff, so I decided to make her this light table. At the time we were in a rented unit, so I wanted to make it a bit portable, but anticipated making it a freestanding table later. This is my first instructable, and unfortunately it's already built, so I can't show you the steps quite as well as I should.
WARNING. This project uses mains electricity. Be responsible, because I won't be.
I have provided measurements, quantities etc. for my particular project, but when you do your planning your requirements could vary quite a bit.
As this has been prepared post-project, I suggest you take this as a guide only - work out all your own measurements etc. as I may have missed out or messed up somewhere.
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Step 1: Material and Tools
Timber for framing - I went kinda heavy-duty, so I could later add legs and still have a solid table , but if you will only ever sit this on a regular table, you can save a lot of weight. (I kinda inherited a preference for super-strong from my Dad - trying to learn that sometimes lighter is better :-) )
I used 239x30 (dressed size) oregon fascia board, that already had a nice rebate just near each edge (where the eave lining would normally slot in) to save some work. We had about 4m left over from a job on the house. I needed 2 x 790mm, 3 x 730mm (well, 2 x 730 and 1 x 690, but the third one was trimmed to provide the retaining bar and hand rest)
A base panel - I used 6mm plywood, 710mm x 770mm
Frosted glass topsheet - choose your thickness according to the area you want - bigger area means you need thicker glass. Mine was 6mm laminated (for safety)
A fluorescent tube to fit comfortably inside - I used a twin tube (2 x 20W) 600mm unit
Mains cable with plug
Mains switch (including fixing screws)
To be sure it remained cool in use, I also added a cooling fan, but this is optional. Mine came with a protective wire screen and fixing screws.
Mesh/filter for air intake if using a fan - you can improvise with a 6" square of flyscreen and similar piece of non-woven material - it's not critical.
Reflective material/white paint
20 woodscrews ~50mm
optional 4 small corner brackets with fixing screws
2 bolts ~50mm
2 nuts to suit
4 flat washers
2 wingnuts to suit
Screws to mount fluoro tube
strain relief and mounting screws for cabling
Mounting screws for mains switch (and cooling fan if being used) usually come with it
Router (or alternate - maybe a circular saw and extra effort)
Glasscutter (if not cut to size previously)
Longish clamps (800mm opening)
Step 2: Planning
Work out the size you want. As big as you need, but no bigger. Planning around the size of a sheet of glass you have might be a good idea.
Consider height - both working height, and the internal height. The latter is important as a greater internal height allows more even lighting and cooler operating temperature.
Will you want to use it as a regular drawing board as well? - If so, the left edge must be flush for the T-square, and the glass must be wide enough as well. If not, no worries.
Will you be doing 'smudgy' work on it (like calligraphy)? If so, raised edges and a movable hand-support bar will be very handy.
I wanted both of these, so made the left edge flush, and the other three raised.
Do you want a rest area at the bottom, or a storage area for pens etc.? I incorporated these, but you could easily omit for a simpler, lighter unit.
Step 3: Cutting the Timber
The main frame has mitred corners - I cut 2 x 790 and 2 x 730 with mitres
The cross-member is also 730mm, but straight-cut. I first ripped off a strip 80mm wide, then trimmed it to 690 long.
I then cut two strips 10mm wide from the full-length remainder. (see hand rest in third photo, and leftside retainer in first photo that is held on with wingnuts)
I next ripped 19mm off the top of the back and side members leaving it 220mm high - it already had a rebate, so I was just trimming down to give a smaller lip at the back. If you have unrebated timber, no need to trim - just adjust your other measurements and do your own rebate.
Next, mark the 790mm pieces for the angle. I measured in 172mm from one end, and 68mm in from the (trimmed) side. From this point I used a straightedge to the top corner, and cut the angle and then the straight cut from the lower end.
Use a large holesaw to cut the holes for the fan inlet and exhaust. It's the fluoro that generates the neat, so having the holes in line with each other just in front of the fluoro draws the air past it and stops the heat spreading toward the user.
Use a smaller holesaw to cut the hole for the mains switch.
Cut the ply to size (770x710)
I smoothed everything, and rounded most edges slightly (the fascia had a slight rounding anyway) EXCEPT for the left side slope.
Step 4: Rebate to Reduce Weight
Clearly if I'd used a frame and lighter cladding this wouldn't be necessary, but the fascia was what I had. I rebated the sides and front to reduce weight. Nothing fancy. I used a guide, and went 20mm into the 30mm timber.
Step 5: Rebate for Glass and Crossmember
The rebate for the glass was 10mm wide and 15mm deep. I placed it 6mm from the top edges.
This needs to be in the right sloping side, the tall back piece, and the 80mm wide crossmember.
The left sloping side needs to be trimmed off 16mm along the slope. This allows the glass to be slid in after assembly of the frame (and removed for cleaning or replacement after ward)
You also need a rebate 10mm deep x 80mm long in each side member for the crossmember to sit in.
Finally, if you didn't start with a piece of fascia, you'll also need to rebate a slot 7mm wide x 15mm deep for the ply base, 25mm up from the bottom of the frame members.
Step 6: Assemble Frame
I assembled the frame by placing the rear and right side in it's 'in-use' position with the corner hanging in space. I used a small bracket with two screws per leg to fasten it below the bottom rebate where the ply would sit. It would have been neater to put them internally.
Next, attach the front in similar fashion.
Now you can insert the ply base, and place the left side and cross-member in position and check for square, and clamp.
I then screwed the right side to the front, back and cross members. (pre-drill and countersink for neater result)
After screwing the left side, I turned the work over and added the little corner brackets.
Step 7: Finishing the Frame
Drill two holes in retaining bar. These must be placed so bar protrudes 6mm above left slope.
Drill two matching holes (i.e. 6mm offset) in left side member to take the 50mm bolts. Rebate the outer side and fasten with washer and nut in outside so bolt is captive to frame and protrudes.
Slide in glass, and fit retaining bar with two washers and two wingnuts. If all is well, remove glass again while we do the inside stuff.
Step 8: Painting and Electrical
Paint the inside white for better light distribution. Get fancy with aluminium foil reflectors if you like, but I didn't think it necessary.
Mount the fluoro on the back member.
Mount the fan in the left-side hole, and it's shield cage on the outside (I rebated the cage mounting). Mount the filter over the right-side hole.
Bring the mains cable in through the left side frame and fasten with a strain relief clamp.
Run the active mains wire out through the mounting hole for the mains switch and wire to the switch. From the other side of the switch, run a wire back through the switch mounting hole to one side of the mains fan, and from there to one side of the fluoro light.
Wire the neutral wire of the mains cable to the other side of the fan and the other side of the fluoro.
This puts the fan and fluoro in parallel, so both will come on together with the switch, and if one fails, it won't stop the other.
Mount the mains switch. (If you do this first, the thickness of the frame makes wiring impossible.
My diagrams are kinda clunky, but may help. The first shows approximate physical layout, the second shows more a logical view of the connections.
Step 9: Done!
Check your wiring, slide the glass in, and fix the retaining bar.