Introduction: Black & Decker Workmate Repair
These are old original b&d workmates, salvaged from a skip 30+ years ago used and abused since then frequently left outside in all weather for years at a time and still the frames aren't rusty. New ones of similar pattern but different make with only mdf for the worktops /jaws were only £10, the off cuts of 18mm ply £7. So for the sake of a little time new tops was the order of the day
Step 1: Work Top Material
I acquired an 2.44m (8') offcut of 18mm (3/4") ply from a local woodworking trader. I'd already cut it in half and halved one of the sections again before I realised the width of the front fixed jaw was critical any wider and to keep the same holding capacity you can't turn the handles to move the jaws . I set a circular saw to the width of the existing top and cut the remaining full half of the offcut down to size and cut it in half to form the work top jaw blanks before I thought to document it
Step 2: Strip Down
The worktop halves/ jaws are held to the base with 2 bolts per jaw with a 14mm hex head in a recess just wide enough to accept a socket. Over the years these reccess have become filled with sawdust, glue,mud,and epoxy a little work with a probe cleaned this out enough to undo the bolts
Step 3: Duplication
This step is technically reverse engineering and if they were still in patients would be illegal. They're not. So I'm happy to give dimensions obtained. Even if they were so long as you are just repairing your own stuff not planning on selling knock off spares I doubt anyone is going to bother you.
Place your old jaw over the new blank and clamp together. Select a Brad point drill that is a good fit in the hole (8mm for the bolts 12.5mm for the pins) and use them to mark the centers of your holes. Use a carpenters square or a straight edge to connect the marks to the edge and take measurements the jaws are actually identical the 45mm to the back edge is only critical if like I did, you make the rear moving jaw wider the front one has to be the same width the 65mm from the ends is also not critical the 480mm between the center lines is as is the 50mm between the pairs of holes the18mm can be a few mm more before fouling the handles but dont make it less and it has to be the same for both pairs of holes on the same jaw. The 5 large holes are only of interest if you are using holding dogs they do not need duplicating and can be drilled if or when you need them where you need them.
The jaws are not hand one is just 180° rotated to the other. However the width of the rear moving jaw is not critical being wider is OK and in my view a bonus. the position of the bolt and counter bore center is 45mm from the edge
Step 4: Drill It Out
I've recently acquired a drill press. This is not essential a brace and bit will do if used with care. And even on its slowest setting the bits still got hot.
I started with the 12.5mm peg holes. Checked the fit of the first one found it to be tight so went up to 13mm for the rest this still need loosening up with sand paper wrapped around a dowl. Next I did the counter bore for the bolt heads with a 20mm fortsner bit cutting and checking a little at a time until the bolt head would go under flush. Then with the drill off marked the edge of the bit with a marker pen meaning the rest could be drilled to the right depth in one go. The marker will wipe off with some meths or luckily the light oil I spray bits with after use to prevent rust whilst stored. Finally I drilled the 8mm through hole for the bolts.
It is then simply a case of locating the new jaws on the pegs and replacing the bolts, a coat of varnish wouldn't hurt, but that can wait until I'm varnishing something else.
Step 5: Clean Up
The mechanism worked but they have been out side a lot and the lead screws are rusted so I took the opportunity to remove them and clean them up with a good wire brushing. This requires driving the handle securing pin out with a punch and hammer then refitting it the pins tapper slightly so if they don't want to move from one side try from the other