I made these for Joe earlier today/evening. Tried several things, and they aren't perfect, but will make fine saws. It's hard to get the profile perfect with 4 chamfers on them, but when the saw it put together you won't be able to notice for the most part. You can see in the pics. I used a 45 degree double angle cutter on them, so each side is 22.5 degrees. I figure that the steeper angle would be better on these 3/16" pieces of brass. In the pic with the cutters, the 90 degree is on the left, the 45 degree on the right. I always clean up the flats of the chamfers with a file, and I am very meticulous about those type of details. Hopefully I can figure out how to get the chamfers smoother in the future. I'll be picking some metal heads this week about that. Got one of my bronze backs cleaned up but didn't chamfer or slot it yet, but did get the piece cleaned up after I munged the cut in a vise...
Drive-By with one of Joe's backs... Joe, One of your backs in a mock-up to give you an idea. You can cut them down to anything you like. These are 12". To cut the back use a regular hack saw. To cut the plate use tin snips, and clean it up with a file. This looks fine on 2" plate also. I have a saw I built like that. Great saw, cuts great.
yes please Alan, This is so very cool and they look great. I can't wait to give them a go!!!! I have ordered some stock from Dominic Greco and also gotten my latest foley in good shape and ready to get cutting. Joe
Slotting description... Hi Alan! Could You please say something more about the slotting. When You use a 0.025" blade how deep do You go and in how many passes? What RPM do You use and what "feed speed"? When You use different blades, ie. 0.018" or 0.020" would You change something? I also have a few questions about your milling machine...what is the power and could You link me a to a site with the description of your model...or maybe some equivalent of JET, please? Kindest regards, Lukasz.
Depends on the blade, and how many teeth they have, some of it is trial/error. Of course this type of work requires various size Jeweler's saws, in the proper bore for one's arbor. Vertical mills are more popular these days, but horizontal mills are well suited for slotting. I just ordered some blades, as I broke my last 2 of .020" blades over the weekend experimenting. I cut the slots at about 200-400 RPM. But this depends on the blade also. I previously had some screw slotting saws in .025", they only have about 70 teeth on them, where a Jeweler's saw of similar size will have about 200. Depends on the size, I have 2-3/4" saws, and a lot of 3". I prefer 3" saws with a 1" arbor, but 4" will work also...any bigger starts to get flimsy for a thin cut like that. 4" is pretty big, 3" is much better, IMO. I like to go about 1/3rd the height of the back. When it starts to get to 1/2 or greater, it's a deep cut for that particular sized stock and can weaken it overall I would imagine, but even 1/2 the distance is ok. I have seen people say that it would be better to slot deeper, but I don't agree, 1/3rd is about right. I was testing this last weekend, I have one back with about 1/4, another with about 1/3rd, and another with 1/2 (all of height). There is no comparison in a Jet machine, but there are inexpensive machines that will do this work. My mill was designed to be used in a production environment, and has a rack/pinion gear on the table. I have a screw for it, but haven't hooked it up. I feed pretty fast, but probably need to slow down as I've been having some problems keeping the slot together. The more passes and the less material taken is always best. Brass is best cut dry. Personally I would look for a used machine, I like old machines. This Nichols mill was made in the 40s and weighs about 1200 lbs., so it's pretty light for a milling machine. A bridgeport will weigh in about 2-3 times that weight. I have a small mini-mill also, and it can do the work but is just not near the machine that the Nichols is. Grizzly now sells a small horizontal that the table will go about 11-3/4", so that would work pretty well for *most* backs, but a 20" table movement is better. I also have one of these Grizzly mini-mills. I bought it used for $250 on craigslist...but metalworking requires an entire different set of tools, and requires much more accuracy...it opens up another can of worms. FWIW, Mike Wenzloff used to slot on 2 mini-mills, the Harbor Freight version with the R8 adapter. Mine has the Morse 3T. They both work if you have the proper tooling. Mike uses some type of wooden fixture to slot, or at least used to...not sure what he's doing these days. I attached a pic of my mini-mill. I probably have about $700 in the mill and accessories to get going, plus a lot of time to learn how to make the fixtures. I also have a small South Bend 9 lathe, which I'm trying to convert to a turret lathe to make split-nuts.
Some mo' millin' around this weekend... Didn't get my .020" blades I ordered, so cut some .025" in 1/4" x 3/4" x 14" backs (a pair), and a 1/4" x 3/4" x 12", and a 1/4" x 5/8 x 12" which was slotted at .018". Last pic is a family shot of the backs I've slotted over the past couple weeks. The 2 backs in the rear are 1/4x3/4x14, slotted for .025". The one in front of those is a 1/4x3/4x12 slotted for .025". In front of that is a 3/16x3/4x12 with chamfers, slotted at .020" In front of that is a 3/16x3/4x10, slotted for .020" in front of that is a 3/16x3/4x9.5, slotted for .020" Lastly in the front, 1/4x5/8x12, slotted for .018".
I found one of these used which a guy had but was not using. I need to get a cutter for it, which aren't cheap, but this should assist me in getting backs chamfered. The one I'm getting is an older Simco model...these little machines are PRICEY new! (linky pic)
Did some more experimenting today...I used 2 cutters stacked together, but as I had suspected I might run into clearance issues. I think this picture shows pretty well that there is limited space and that the ends of the cutters will hit the top of the slotting fixture. I think the way around this could be to add a few screws up higher, so that a bigger spacer can be put under the back. As you can see, there is a 1/8" spacer there now, but that's about as far as I can lift it before the screws to not catch the back. So, if some screw holes were higher, I could put a 1/2" spacer under and get the back up higher. Still, this will most likely always be limited to backs in which it can chamfer, and the Bur-Beaver machine, or similar, is most likely the best solution.
Nice looking backs Alan! I've got one of those little Grizzly mills in my basement, along with a small lathe, but my time problems remain my greatest obstacle! Over the next couple of weeks, I'm planning on experimenting (at my plant, and probably having one of my guys do it!) with bending brass for backs. I would like to think I've figured out the Foley re-toother and have done a couple of saws with it. I've decided not to play around with the remaining machinery. Anyhow, again, nice backs! T.Z.
Don't be fooled by pictures on Al Gore's Internet! lol There seem to be people looking for folded backs. You must have a brake that is big enough to do that stuff. Usually .093" thick 260 is what people fold. Can you reliably change the rake? Don't you think there's a better method ??? I heard that water cutting was the next big thing, but it seems the expense prohibit it being used for small runs. Can a CNC mill a tooth pattern. Thanks but they still have a ways to go. I did some more experimenting today. I had a piece of 1-1/2" wide brass, about 4" section. That was able to clear the fixture. When I ran at slow speeds I got an uneven finish (200 rpm), and when I ran at my middle speed (780 rpm) I got a much better finish but not quite acceptable for off the mill, IMO. I have 2 more speeds, but on a different pulley. The problem might be setting up a decent fixture so that I can get down low enough.