Machinists' comb and backscratcher

I just finished making a chip rake (doll's pitchfork?) for cleaning swarf out of the chip pan of my 5914 lathe.
I got the idea from a food tool called a "cake breaker" (US Patent
1,858,790) that I picked up in the reusables section of the town dump. The patent number was stamped into the tool, and I looked the number up to figure out just what the tool was intended for. Cake breakers are for dividing cakes without squishing them.
The cake breaker tines are perpendicular to the handle, which is awkward for swarf removal duty, where one wants the tines more or less parallel to the handle. And cutting oil does not improve cakes. So I kept the cake breaker for cakes, and made a dedicated tool for swarf.
The handle is a piece of half-inch stressproof (1144) steel rod, and the crossbar is a piece of 3/8 by 3/4 mild (1018) steel rectangle 4" long; these were used because I had them. The times are made of 0.080" diameter music wire, bought for the purpose.
The cross bar is attached to the end of the handle rod with a 1/4-28 flat head screw with hex socket. At first I was just going to machine the rod end off flat, and depend on the screw to keep bar tight to the handle. But my experience is that this usually loosens. What to do? I recalled lots of Starrett tools where a locking thumb screw prevents rotation. The general design is a male cone is forced into a female conical seat by the thumbscrew, everything being made of greasy hardened steel. It's the wedging action of the cones that makes the difference, and provides the mechanical advantage so a thumbscrew can generate sufficient clamping force. So, I decided to implement a conical seat in the bar, with handle rod tip machined to fit.
First the conical seat in the bar. This is easy to do on a lathe faceplate. The bar was firmly clamped to the faceplate, with center of rotation somewhat offset from the bar centerline, to accommodate the row of holes that will accept the tines. Drill through with 1/4", rough out the seat with a 3/8" drill, and then make the conical sides. This was done with a boring bar held on the tool post slide, with the compound set to 60 degrees. Crank slide in and out, back compound out a bit, crank slide in and out, until done. Lubricated with lots of black sulfur oil. This yields a more or less flat-bottomed hole with conical walls. The depth of the recess is about 3/16, the outer diameter is almost exactly 0.500".
Then the handle rod. Change to a 5C collet chuck, center drill and tap for 1/4-28, using lots of black sulfur oil.
Now the trick. We want the cone angle of rod end to exactly match the angle of the conical recess, but angle settings on a lathe compound are not all that precise. So, without unclamping the compound, run the lathe in reverse and machine the cone on the back side of the rod, running the slide in and out as before. One can use the same boring tool for this, or (what I did) a regular tool. I used a insert tool with triangular insert to make the rough cut by moving a long edge against rod tip, and then did a finish pass with the tip moving in and out.
The machining was a bit rough (from impatience - no power feed on the toolpost slide), so I ground things together with the rod in the mill, the bar on the table, and some valve grinding compound between. After all this, the bar centers and palpably nests on the rod. This will not wiggle when clamped by the 1/4-28 screw.
The other side of the bar then got a countersink, and a row of about 20 blind holes to accept the tines. The spacing between tines is 0.200", and the holes are drilled ~0.250" deep with a #44 (0.086") stub drill. A pass with a spotting drill was made so the #44 would not be tempted to wander. The 0.086" drill was used to ensure enough clearance that solder could easily wick into the space between tine and hole.
[If one has a taper attachment, one can machine a tapered female thread in the bar and the matching male thread in the rod, again by running in reverse for the bar. An alternate non-late approach would be to use a pipe thread tap and die to make tapered threads. In both cases, the 1/4-28 screw is not required.]
Also made was an aluminum fixture, a 1/4 by 1/2" by 4.5" with a row of #45 (0.082") holes on 0.200" centers.
Then made the tines. The tines are 6" long when cut, ignoring the curve of the wire as removed from the 12" diameter spool. Each tine is mechanically deburred and one end sharpened on a vertical belt sander, and the blunt end abraded clean for at least 1/2" using a wet 3M polishing pad. When pointing the tines, it's useful to use the aluminum fixture to hold the tine while the other hand rotates it as grinding proceeds. There are about 20 tines.
The cross-bar was also cleaned and polished where there will be solder, and the screw liberally coated with anti-sieze compound.
The tines are then soft-soldered to the cross bar, using the aluminum fixture and some black iron wire to keep the tines aligned during soldering. Soft-soldering does not seem to soften the music wire. The solder I used appears to be 60/40 radio solder, but this isn't all that critical.
For soldering, the bar was assembled to the rod and the rod was clamped vertically in a vise, arranged so the top of the bar is horizontal and the tines are vertical. The tine-bar joint area was liberally doused with acid flux (tinners' flux), and the bar was heated from below using a mapp torch, with care not to heat the tines directly (which would anneal them).
Flowed the solder till everything had nice fillets, turned the torch off, and went off to read newsgroups without touching anything. This step is critical, as the assembly will cool far slower than impatience demands, and the joints will be ruined if anything is moved too soon.
Wash it all off with hot water and a brush, replace the now softish 1/4-28 screw with a new one, and we are done. The anti-seize compound prevented the screw from being soldered to the bar. And will prevent the screw rusting to the handle.
Initial tests show that the rake works quite well for its intended purpose.
Joe Gwinn
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[snip]
I have those on the mill as well, for T slots, but they are not successful for shoveling piles of swarf into the trashcan. I made a little copper scoop for cleaning out the end bells on the mill, and while the scoop works on the lathe, it really isn't large enough. So I made the machinist's comb.
Joe Gwinn
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I inherited a gardening tool that I use on the SB, my dad found it in some bucket of junk he had, probably from one of the multi-greats. Stamped out of heavy tin with 4 claws about an inch apart. Handle is rolled into a taper for a good grip. All one piece, nothing to split, chip or absorb oil. Works well enough for getting the big bundles out of the pan, then I can use a brush and pan for getting the small stuff out. Don't know what the original purpose is, they still have similar ones in the hardware stores. Probably for busting clods before planting flower seeds, I suppose.
Stan
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On Sun, 22 Jan 2012 19:21:35 -0800 (PST), Stanley Schaefer

Cultivator, used to open up the soil so weeds can come out more easily. http://tinyurl.com/7kh7mxb They're great for getting handfuls of nails out of a bucket, too.
Newfangled version is called the Garden Weasel, a tool which sounds like the Old West. The tines ring like spurs. ;) http://tinyurl.com/7ohl384
-- I have the consolation of having added nothing to my private fortune during my public service, and of retiring with hands clean as they are empty. -- Thomas Jefferson, letter to Count Diodati, 1807
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wrote:

The first item is more like it, only that one is pink and plastic. This one is black iron and has one more tine. I think it's got a bit longer handle and maybe longer tines, too. Garden Weasel may be used for the same purpose in the garden, I guarantee it's not going to be much use for pulling swarf out from under a lathe bed!
I've seen and used the gadgets for getting bulk nails out, some of the Real Hardware stores had them in the bins. Were a lot like that cultivator gadget but I think the tines were closer together. Newer joints make do with sugar scoops if they carry bulk hardware at all, just not the same. One of the really deluxe old-timey stores had a squared-off sheet metal scoop/pan to go with the rake, made getting the nails out really easy and easy to dump in the scale pan, too.
Stan
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On Mon, 23 Jan 2012 12:32:07 -0800 (PST), Stanley Schaefer

I did that on porpoise. <titter>

http://tinyurl.com/83hy3xk Ideal for swarf?

I can just imagine the tangles it would cause...

The small rakes were just great. Real hardware stores were great, weren't they? The ACE/Fields around here is pretty much still intact as it heads toward a Lowes in size and content.
-- I have the consolation of having added nothing to my private fortune during my public service, and of retiring with hands clean as they are empty. -- Thomas Jefferson, letter to Count Diodati, 1807
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I did take some pictures. I think I'll put pictures and posting text up on the dropbox in the next week or two.
The agricultural implement that this backscratcher most resembles is a 9-prong potato fork.
Joe Gwinn
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