Posted By Kenneth Milner on 11/14/2008 4:09 PM
Hi Les . . . . Just a curiosity question for you since you have machining experience. If I had some 0.080 square brass rod, how difficult a process would it be to cut little slices off the rod that are 0.030 thick. I could then hold them with some pliers, then drill and tape them as needed to get my square nuts. Mind you, I just scheming.
I have found some 00-90 thread round-head "bolts" that will work for one-half my application.
Chuck . . . . Phi's Narrow Gaugel only has simulate "square" nuts.
Ken,
Weeellll... doing it with hand tools is possible and may be your best option. I assume you don't have a lathe or know anyone who does.What you can do is make yourself some sort of clamp-on guide for hacksawing. You have to clamp the brass anyway, so killing two birds with one stone ought to be doable. I assume you do have a bench-mount vise. If not, you can use a clamp on type, or even a big clamp from the edge the workbench to the far side of the wooden clamp-guide to hold the brass inside the guide to do the sawing.
The guide can be any block of wood that will fit in your vise/clamp setup. Drill an undersized hole and file out or haggle out to just take your squarestock. Note: if you make the hole too big, or it gets sloppy, you can cut a slot in one side or both for 'compressability' to squeeze the stock tighter. All you care is that your stock doesn't move around after you've clamped it.
Next, lay off (mark) one line farther away than .030". That's so if you wobble or miscue with the hacksaw, there will be enough material to file (dress) the nut blank to the thickness you want, and incidentally, get rid of the saw marks. You'll have to do this on each side after the first nut blank, all the subsequent ones will have saw marks and will therefore have to be thicker than your finished dimension. And the amount you mark off must take into account the kerf, the width of your hacksaw blade. Be sure to use the finest-tooth blade you can find, or a jeweler's saw blade. Make sure the blade is darn near as tight as a fiddle string in the saw frame, you don't want flexing of the blade. Make slow, steady cuts.
Don't put a fine finish on your blanks, after you get them sized and reasonably parallel to each other. Because now you need to mark for the center by drawing a line from each opposite corner, so you end up with an "X" in the middle. If you're off a tiny bit, it won't really matter, so long as you don't get too far out. Now, take a sharp-pointed metal punch (grind it down to a pencil point if you have to) and mark your center with a light tap of the ballpeen hammer. Use a light hammer, in any case--a claw hammer isn't exactly what you need. Now, look and see how far off the X you are. A tad, you say? Well, not to worry: just take the punch, angle it in the direction you want to 'move' your mark, and tap it again. You can 'walk' your mark to where you want it. Within reason. Satisfied now? Okay, put the punch in the mark and tap it harder to make a good crater. Doesn't have to be deep, just enough so your drill bit won't want to climb out of it.
Is your drill sloppy? Does it have sideplay? If so, you'll just have to live with it. Now, brass is 'sticky' or 'buttery'--it wants to cling and move rather than cut. A common machine-shop practice is to lightly dull the drill bit, works wonders, but on the sizes you'll be drilling, don't. Just use some light oil (3-in-1 is okay) and drill as carefully and perpendicular as you can. Take your time, those tiny bits flex. A feather-touch is what you're after. This is why a $50 Asian benchtop drill press is a good deal. They rarely have the slop in the chuck a hand drill has.
Well, I see I didn't explain how to hold the tiny nut blanks for drilling. (Old guy syndrome). Two ways leap to mind: drill a blind hole (one with a bottom) in a different side of your first blank. No need to waste wood. Now, take your piece of square stock--or you could even use one of your tiny nut blanks, and whap it hard enough to put an impression as deep as the nut is thick into the board. Now you have a nice nut-blank holder, except it will want to crawl up the drill bit. I'd use a thumbnail to keep the little rascal in place, drive and bend a small finish nail so it swings over and puts some pressure on the nut. In any case, before you drill you want to make sure that nut is not cocked off level. If it is, drive it down in the high place. It is important that hole goes in as straight up and down as you can get it. Go right on into the wood at your first nut that you drill. (the sacrificial one. The one you make all your mistakes on). Go perhaps 1/4" or so.
Now, take the nut out of the square hole. Might have to use an ice pick (ground down flat 'n thin) and gently pry it out. Remember, you want that hole to last before you have to drive another. You'll see that hole in the wood you just drilled. Now put a bigger drill in there, bigger than the tap, and there you have clearance underneath so your tap doesn't get fouled with wood chips 'n whatnot.
There you are, off and running. Don't get frustrated if you fail on a few. Especially if you make half a dozen great ones and then a bad one shows up. Change the drill bit. Rest. Get untense. check all your clamping and saw blade and everything. Then go at it again.
To tap USE OIL. Best if you use tapping fluid, but not necessary. Kroil is my choice. WD-40, etc will do. Do NOT put your tap in the hand drill. USE a TAP WRENCH. Start your tap carefully, making sure it isn't leaning. This is as much a matter of feel as anything. Good eyes help too. Twist it perhaps 45 degrees, and back it out. DON'T take the tap out of the hole. Now, advance the tap 45 degrees past where you were, or less, depending on how much 'pull' you're getting. Breaking taps is the only way I know of to learn how much is too much. I can say, if you advance only 45 deg or less at a time,before backing up, you'll have more luck in the long run. This backing up is calle 'chip breaking' or 'chip clearing'. Your tap will dent to crowd up with material. YOur threads will be nicer if you do it this way, too.
Don't buy cheap taps or drills. The good ones are only slightly more expensive.
Now, you're all done, and you have a handful of beautiful square nuts. If you want true historical accuracy, you need a shallower square hole and a very fine file followed with crocus cloth or aluminum cloth to put a very slight 'curve' to the outside face of the nut. And polish it. Lastly, drag each edge of the nut over the fine cloth enough to but a tiny bevel on it. Just the side that will show should be okay. Now you've got about as good as can be bought, anywhere.
Hope this helps.
Oh, the only thing a lathe would do for you is to make the 'parting off' cuts faster and cleaner, and you could center drill the stock for a good ways to eliminate hand drilling. Accuracy would probably be only slightly better for the purposes.
Les