Now you have all your plywood cut out as below ?
Cutting out the top curve
You will notice little wedge shaped pieces of ply on the base and top "dovetails" .... these you need to cut very carefully at 45 degrees .... later you will make and cut slots in the sides for these to fit into like a jigsaw puzzle - these are important as they will really hold your trolley together well - so take your time to get these right.
You should mark them out with a 35 degree try square and cut with your jigsaw as below.
If you cut them with a knife as below the jig saw will sort of follow the line - don't try to cut out the corresponding holes in the sides till later.
Here are all the basic pieces cut out of the one sheet
To mark out where to "doves" should cut on the sides for the "tails" ... fix (ie screw) the base to the side of your bench and then lay the corresponding side on it lined up so that front of the base is a 110 mm back from the very front of the side.
Now you can carefully mark where each "tail" intersects with the side ready to cut out ... note you have to be careful here as the base (and later the top) has a curve in it so you have to kind of "rotate" the side around this curve marking as you go ..... need more than 2 hands here! If you just mark it "straight" then the back cutout will not be in the right place as you bend the sides into place.
Once you have the side cutouts marked for the base .... repeat for the top ... starting it at the same point 110 mm back from the front. This one is easier as there are just 2 cutouts and they are on the straight section so easier to mark.
Once both sides top and bottom are marked out you need to cut them the correct depth and width ... you can do with your jigsaw or you can do them with a table saw with a smallish blade by winding the blade up into the ply (only do this method if you have good table saw skills!).... set the guide so that the saw cut is the right width for 12 mm ply and test on a scrap of ply as to where the blade has to cut up to to reach each side of the long side of the doves ... underside of the plywood shown below which is the outside of the trolley.
Once you have established how far the saw has to be raised up and where the center point of the dove has to be in relation to a mark on you guide you can set up and cut all the doves out.
Now you can cut the 45 degrees of the doves with a back saw and cut out any remaining bits not cut on the table saw or with the jig saw.
Now that all your doves are cut you can "marry" them to the corresponding side of the base and fit in place ... dry fit to start as you may have to recut the doves a bit to fit into the corresponding tails ...
Once happy with it you can glue and screw it together (I use
Gorilla Glue as it tends to fill any gaps you may have but you can
use white glue if you want)
Use #6 1-14 Pozi screws or similar (as #8 tend to be a bit big and split the ply ).... you can screw in from the sides and also up from the underside in each tail to pull it all together nicely.
Once both sides are screwed to the base you need to install the back rest which will make sure it is all square. This is laid out as per the dimensions on the sides layout detail - 385 mm from the back at the base and 100 mm at the top.
The back gets glued and screwed behind this line.
Now you can dry fit the top in place but DO NOT screw in place permanently. You now have the basics of your trolley.
Now screw and glue together your axle pivot blocks.
Once all three are together you need to nail and glue some ABS plastic or similar on top (I used offcuts from the Vent Shop here in Nelson who make ABS plumbing pieces but you could use the lid of a 10 lt plastic paint can). Glue with Gorilla glue and hold in place with for 30 mm brads. This plastic provides a smooth slippery surface for the axle to pivot on.
The axle pivot block is then screwed and glued in the front of the base ... it is centered (the 150 mm dimension goes across the base) and over hangs the front of the base by 10 mm - screw from underneath through the base .
Now you need to make up the axle and cutout the sides for it.
Below is a made up one
470 mm long x 100 mm wide - 12 mm ply
The block in the middle is where the tiller will mount.
The black blocks are foam and ABS plastic that run in the slots in the sides and form a bit of a shock absorber for the axle.
You will need some 12 mm high density foam rubber (from Para Rubber). Cut this into 40 mm wide strips and the same length as the width of the axle ply. Also cut 2 strips of ABS plastic the same size.
Mark in 45 mm from the end of the axle, glue and nail the rubber with ABS on top .... hold in place with 30 mm pins making sure that you don't drive the nails home (you will remove them when glue has cured).
Tack the nails into the plastic before you drive them through the rubber and into the ply.
Once the blocks glue has cured then you can remove the pins by twisting and pulling with a pair of pliers ... (don't pull out with a claw hammer as the plastic will come off). Then you can place the axle on pivot block in the front of the trolley and you can mark where the heights of the side slot that the axle will pass through. Transcribe these marks to the outside and then mark it out 25 mm infront of the "110 mm line" and 140 mm long.
Cut out the square with your jigsaw ... you can then slide the axle through from side to side.
More next week when we cut up the 4x2s install the wheels and put the final trolley together ready for Resene's Paint day
Happy Building - Tim Bayley - email@example.com