Saturday, July 25, 2009

Tool repair: Hacksaws, Bench Grinders and ACE Hardware

As a known estate and garage sale habitué, it shouldn't surprise anyone that more than half of my tools are less than new & are sometimes purchased in need of love.
Today (out of a box of tools labelled "50 sents each") I got a reciprocating saw-blade holder. Really, just a handle that would let you use Sawzall blades as a small handsaw. This one was made by Craftsman, and except for the missing thumbscrew to secure the blade is in great shape. Of course I tried to track it down, but it either came as an included accessory of a reciprocating saw, or wasn't deemed worthy of maintaining parts for (the plate that grips the blade is trapped / non-removable, so the only replacement part *IS* the thumbscrew.) No matter, my local ACE hardware has a ton of bolts and thumbscrews, so an easy fix.
Took the handle to the store and using the bins of bolts determined that it was 1/4", 20 tpi (threads per inch.) Second step was to decide what sort of head I wanted - wing nut, thumbscrew, slotted, hex drive with round knurled side - lots of options. Having no idea what the original looked like (although I'm guessing low-profile knurled edge, coin-slot to tighten so as not to get in the way) I decided on a thumbscrew. I may have gone with something with a lower-profile head, but this handle can be used to grip the blade either way - straight up, or flipped 180 degrees, so if a thumbscrew would get in the way one way, I could simply remove and flip the blade and retighten and be back in business.
ACE "only" had 2 lengths in the thread size that I needed - too long, and even longer. I really only need 3/8" of threaded length and leaving it long would have gotten in the way even worse. So, in addition to the thumbscrew, I also bought a stainless steel nut of the right size, and a couple washers. Sure, I probably have those, but rather than finding them in the garage, it was easy to spend the extra 20 cents to save time. After I got home, I slipped the washers onto the thumbscrew and tightened down the nut - the threads under the washers and nut were about the length that I wanted. If I wanted to leave any longer length of threads, I would have bought 2 nuts and not bothered with the washers and simply tightened the nuts against each other. I then used a hacksaw (although using my reciprocating saw would have had a certain poetry to it) to cut off the extra threads. The next part could be accomplished with a hand file, but I wanted this tool to cost less than buying one new (time is money) so I used a bench grinder to smooth the end of the threads up to the stainless steel nut. Depending on how good your hacksaw job is, this can be pretty painless & accomplished quickly without the need for quenching.
I then removed the nut and washers, and did a trial fit. Note - one of the main reasons for putting the nut(s) on is so that you can keep the threads clean / relatively burr free. Simply removing the nut slowly can clean up / chase the threads a bit for you. That is why I spent the extra couple of cents on the stainless steel nut - as it was a bit harder than the thumbscrew, it was adjusting it, rather than the thumbscrew adjusting the nut. If there was room for 2 nuts, I wouldn't have bothered with stainless steel. Trial fit - a bit long. Replaced the nut without the washers and got a cube of ice from the kitchen. Too short to make an adjustment cut with a hacksaw, I would have to grind off about the thickness of a washer. Tightly trapping the "thumb" part of the screw between my thumb and cradled ice cube, I ground off what I needed, rounding a bit this time to allow easier insertion. I got the idea for using ice for grinding from Frank Ford's Frets.Com website. Thanks Frank! It works great! The whole site is interesting / useful, but his shop tips are wonderful.
To conclude - even if a part isn't available, there isn't any reason you can't find (and adjust) something into a suitable replacement. A minimum number of metalworking tools you should already have (hacksaw, bench grinder, files) will get you there most of the time. Ice is wonderful for grinding & will prevent you from removing temper and/or keep you from burning yourself. A well stocked local hardware store is worth its weight in... ...broken tools that would otherwise be binned or recycled. If it is a complex part, try the manufacturer first, generally through their website.

Sunday, July 19, 2009

Ed makes a computer desk for his Mom's birthday

This is a computer desk that my son Edward made for his Mother's 50th birthday. A simple trestle design, and sized to fit a particular space, this was something that she had been wanting.
You can see that it is glued up from strips of wood (hardwood, mostly Oak) and fairly thick. The wood was purchased from a guy advertising "12 inch wide Oak boards." Of course I got excited and made the 45 minute drive without asking enough critical questions. Even though the product wasn't exactly what was mentally pictured when I read the Craigslist ad, I still left with the little pickup loaded with boards. These boards are tongue and groove and look like oversized pieces of flooring. They were made to be installed as flooring and rub rails for the trailers of tractor/trailer long-haul trucks (strong enough for forklifts to drive on.) They are finger-jointed, but the finger-joints are on the sides of the planks instead of the face, so not very noticeable.
The design is pretty simple. The top is glued up of 3 pieces (after the tongue and groves were cut off as they weren't precise enough to use.) The legs and the stretcher are cut from single boards, and the feet and battens are cut from smaller pieces of the same material. All of the exposed edges were softened / mildly rounded using a random-orbit hand-sander, except for the exposed end-grain of the legs and stretchers which have a much larger radius round-over. We wanted a design that would be easy to build, move / transport and if needed, easy to store. Also, although we would have liked to use a through-tenon on each end of the stretcher, it wasn't something we wanted Ed to tackle on his first large project.
Instead, we used cross-dowel nuts to attach the modesty panel/trestle/stretcher. We got the idea from a pair of work benches brother Greg made (using regular nuts and bolts as the larger cross-dowel nut sizes are uncommon.) A little industrial but look OK & is very solid. The battens are secured to the desktop with screws and glue, with glue just on the middle of each piece: although we don't expect much cross-grain wood movement, it didn't cost us anything to allow for it.
The battens and the feet are cut to the same width, and the battens are through-bolted to the legs. We used nylon-bushing locknuts to make the connection. A good change would have been to use thicker battens to make using socket wrenches easier as the nuts and bolt heads are very close to the bottom surface of the desk. The legs are secured to the feet with long square drive screws.
The feet and the feet pads are worth commenting on. Rounding over the end-grain could have been accomplished with a router table and sled, but we took a simpler approach. We already had the monster 4" wide "hand held" Porter-Cable belt-sander out for sanding both sides of the glued up top, so we inverted it and secured it in the jaws of a Workmate, cut small 45 degree angles across the ends of all 8 pieces (two battens, 2 feet, and both ends 4 feet pads) and Ed rounded the ends over on the belt-sander. The results were fantastic! If you are just rounding the ends of a workpiece, this is a pretty good method and gives good repeatable / consistent results with no edge tear out. As observed in the illustration, it is best not to linger on the flat of the cut 45 angle, and just make the roundover in one smooth pass, repeating as necessary to complete. It took 5 slow passes to make each roundover.
Ed finished it by brushing on coats of clear semi-gloss Minwax Poly: 3 coats for the top, 2 coats for the rest of the desk. Fine grit hand-sanding and triple-aught "000" degreased steel wool to knock down nibs, bubbles, etc. between coats. Another thing that we would change if we were doing it over again would be to pre-finish (at least 1 coat) the pieces before assembly.
The desk was a success (his Mom loved it) and it was a lot of fun helping Edward get his first large project completed.
As this will primarily be used as a laptop desk, Ed's next project / present for his Mom will be to make a back-of-desk-organizer, with pigeon holes for paper and other supplies.