IanW
18th January 2010, 11:41 AM
This project was a bit more ambitious. I have long wanted a really large trysquare – one that can span a 12” board with room to spare. I picked up an old Rosewood stock type 10” many years back, but it’s too big for everyday cabinet work & too short for the jobs that need a long blade. The really annoying thing about the old square is that it was out of whack when I got it. I managed to get it close to square, but it just isn't reliable when close tolerances are called for.
It occurred to me that a chunk of the 0.8mm Bunnies scraper I've been making some saws from would make an ideal trysquare blade, so I thought I would try my hand at an adjustable large square using the pushrod & screws principle Colen Clenton has made famous. I’ve had one of his 6” trysquares for about 12 years, and I love it. It's my everyday setting-out square – just the right size for most jobs, and easily recalibrated when necessary. So I sez to meself, it must be pretty straightforward to make something like that.
I assembled the required bits & pieces (pic 1). Attaching the wear plates to the stock was simple enough. I took great care to get the stock square & parallel, then attached the wear plates with epoxy & brass screws driven into shallow countersinks. The heads were peined down hard & filed off, the idea being that they would disappear, but the Philips head screws I used had very deep driver slots, which went deeper than the head of the screw, so my wear-plates have little stars on them.
Mistake # 1 was NOT drilling for the pushrods & threaded rods before wasting all that time & material. The Sheoak I used has huge medullary rays, & I think they threw the drill off. One hole managed to contact the edge of the blade slot – the other was so far off it missed entirely. So back to the start. This time I selected a piece of Bull Oak (Casuarina leuhmanii) which has small, very regular rays. I set up very carefully (as I did the first time!) and also backed out & cleared the drill more often. Whether it was that or the better choice of wood, or both, this time everything met up nicely, so I went ahead & applied the brass. I cut the brasses off the original stock & found the epoxy had made a really good bond, which is reasuring. I have had mixed success gluing brass to wood with epoxy – sometimes it works well, other times it just doesn’t seem to want to hang onto the brass.
Because of the stuffup with the original stock, I got carried away & didn’t do any WIP pics until the trial fitup. There really isn’t much to show, anyway – it’s all pretty simple, but requires care – particularly getting the wood right, & the blade square, straight & parallel. I did the final trueing of that with 180 paper on the sawbench – it’s as close to parallel as my dial calipers can measure, & accurate enough for me. For the trial fit, I used steel push-screws, which you can see sticking out the bottom in pic 2, then switched to brass once all was working smoothly. The screws go about 10mm past the threaded inserts, and the rest of the way is taken up by 3/16” brass rod. I had to reduce the rod diameter a bit to make it slide smoothly in the drilled holes, which I did by chucking it in the lathe & sanding it down a fraction. Using threaded rod for the whole thing would probably work, but might bind when the threads catch and would also require a lot of srewing to get them in & out.
When all was right, it was just a matter of nipping off some brass screws so they would take up just as they enter thr deep countersink in the stock (oic 3), then a cleanup & polish of the brass & woodwork, & a pretty spiffy tool is ready for use (pic 4). Adjusting this behemoth to perfect squareness is a bit fiddly – the meerest fraction of a turn of the adjustment screws moves the outer end of the blade a mm. so it takes a fine touch & a few well-chosen words to get it spot-on.
I like the blued blade, but it’s not very robust blueing, & it got a few minor scratches during the cutting-out, trueing & fitting stages. I’ll see how it goes, & if it starts looking too manky I will either get used to it (most likely) or get some blueing compound & re-blue it (some day, perhaps...)
It was a fun project, with a few challenges. But I’m certainly no danger to the established toolmakers – making this square has made me realise why they ain’t cheap!
I'm making a small bevel square with one of the last bits of scrap - have taken a few more pictures of it in progress, so will post it when finished.
Cheers,
It occurred to me that a chunk of the 0.8mm Bunnies scraper I've been making some saws from would make an ideal trysquare blade, so I thought I would try my hand at an adjustable large square using the pushrod & screws principle Colen Clenton has made famous. I’ve had one of his 6” trysquares for about 12 years, and I love it. It's my everyday setting-out square – just the right size for most jobs, and easily recalibrated when necessary. So I sez to meself, it must be pretty straightforward to make something like that.
I assembled the required bits & pieces (pic 1). Attaching the wear plates to the stock was simple enough. I took great care to get the stock square & parallel, then attached the wear plates with epoxy & brass screws driven into shallow countersinks. The heads were peined down hard & filed off, the idea being that they would disappear, but the Philips head screws I used had very deep driver slots, which went deeper than the head of the screw, so my wear-plates have little stars on them.
Mistake # 1 was NOT drilling for the pushrods & threaded rods before wasting all that time & material. The Sheoak I used has huge medullary rays, & I think they threw the drill off. One hole managed to contact the edge of the blade slot – the other was so far off it missed entirely. So back to the start. This time I selected a piece of Bull Oak (Casuarina leuhmanii) which has small, very regular rays. I set up very carefully (as I did the first time!) and also backed out & cleared the drill more often. Whether it was that or the better choice of wood, or both, this time everything met up nicely, so I went ahead & applied the brass. I cut the brasses off the original stock & found the epoxy had made a really good bond, which is reasuring. I have had mixed success gluing brass to wood with epoxy – sometimes it works well, other times it just doesn’t seem to want to hang onto the brass.
Because of the stuffup with the original stock, I got carried away & didn’t do any WIP pics until the trial fitup. There really isn’t much to show, anyway – it’s all pretty simple, but requires care – particularly getting the wood right, & the blade square, straight & parallel. I did the final trueing of that with 180 paper on the sawbench – it’s as close to parallel as my dial calipers can measure, & accurate enough for me. For the trial fit, I used steel push-screws, which you can see sticking out the bottom in pic 2, then switched to brass once all was working smoothly. The screws go about 10mm past the threaded inserts, and the rest of the way is taken up by 3/16” brass rod. I had to reduce the rod diameter a bit to make it slide smoothly in the drilled holes, which I did by chucking it in the lathe & sanding it down a fraction. Using threaded rod for the whole thing would probably work, but might bind when the threads catch and would also require a lot of srewing to get them in & out.
When all was right, it was just a matter of nipping off some brass screws so they would take up just as they enter thr deep countersink in the stock (oic 3), then a cleanup & polish of the brass & woodwork, & a pretty spiffy tool is ready for use (pic 4). Adjusting this behemoth to perfect squareness is a bit fiddly – the meerest fraction of a turn of the adjustment screws moves the outer end of the blade a mm. so it takes a fine touch & a few well-chosen words to get it spot-on.
I like the blued blade, but it’s not very robust blueing, & it got a few minor scratches during the cutting-out, trueing & fitting stages. I’ll see how it goes, & if it starts looking too manky I will either get used to it (most likely) or get some blueing compound & re-blue it (some day, perhaps...)
It was a fun project, with a few challenges. But I’m certainly no danger to the established toolmakers – making this square has made me realise why they ain’t cheap!
I'm making a small bevel square with one of the last bits of scrap - have taken a few more pictures of it in progress, so will post it when finished.
Cheers,