Re: Question on how to make this extractor.
Posted: Mon Feb 29, 2016 7:00 pm
Years ago I made the wax's and took them to a foundry which cast my parts
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Are you implying that the three radii shown in the last picture, the three in the center, are all ½" radius? If so, I don't think so, as that doesn't make sense unless the cut isn't intended to mate with another surface. If it is intended to do so, it wouldn't make contact in the center, and the sides would conflict with contact unless you machined the piece too deeply, then the center wouldn't make contact. I expect that the cuts each have the appropriate radius for that reason, so the deep portion could not be cut successfully with a 1" radius, to say nothing of the shank interfering with the cut if you tried.TheGreenMan wrote:Doing some measurements and some math (not my strong suit) it looks like the three deeper radii of the 'spoon' were cut with a 1'' diameter. It looks like a 1'' diameter side cutter or slot cutter would work. As long as the shank or arbor of the cutter was 0.5'' or less it should be able to cut even the deepest section as long as the curve in the tip of the extractor is already cut.
Figured you hadn't.hanermo wrote:Lots of people melt steel in a coffee can, with charcoal and a hair dryer.
Its not hard, for small parts.
Never done it.
I was saying that in the last picture the center one is 0.5'' radius and the two on the outside have a 0.6'' radius.Harold_V wrote: Are you implying that the three radii shown in the last picture, the three in the center, are all ½" radius? If so, I don't think so, as that doesn't make sense unless the cut isn't intended to mate with another surface. If it is intended to do so, it wouldn't make contact in the center, and the sides would conflict with contact unless you machined the piece too deeply, then the center wouldn't make contact. I expect that the cuts each have the appropriate radius for that reason, so the deep portion could not be cut successfully with a 1" radius, to say nothing of the shank interfering with the cut if you tried.
I am some what new to all this.It is my opinion that you don't understand the problem with running this part in a lathe. If I'm wrong, forgive me, as I may not understand your intentions. However, from my perspective, here's how I see it. A boring bar will work ONLY if you don't swing the part, as you don't have any room to get the bar in a hole that is, for all practical purposes, the same diameter as the bar. If you could get the bar in the hole, you couldn't feed it to make the cuts. In order to do that, you must have enough clearance for the bar to move away from center the amount you must bore, and that precludes any chance that a boring bar will work with the work turning. That's why I said the bar needed would be too slender.
Yep. This looks to be the best route if I never get a mill or want to do this before then.With the part stationary, plunging in to a rotating cutter, yeah, it can be done, as all that is required is for your tool to be set at the proper radius, and the bar no larger in diameter than the diameter of the radius cut in the extractor, plus a few thou for clearance. In this case, the bar must rotate on center, otherwise you face the same problem as you would if the part rotated.
Making a milling cutter may sound like a good lesson, though trying one with multiple cutting radii is most likely beyond me at the moment. Even making a single radius one will be 'interesting'. Two cutters is probably the way to go for me. And since the diameters of the cutters will need to be a strange diameter making my own may be the only way to go.For the reasons I mentioned, above, you would be best served to make a milling cutter. It's not all that difficult, and would be a good and valuable lesson in making functional tools. This tool would resemble a stack of cutters, but machined to the precise radii required to make the part, with proper lengths held. To perform well, you'd want a small amount of side releif on the teeth, which wouldn't be a problem. If you found that generating the teeth for the cutter was a problem, you could make two cutters, one for each radius. That would simplify making the tool, but necessitate changing of cutters when running a part. You could get around making two cutters by properly staggering the teeth on a single cutter, which would provide the necessary clearance to machine and grind the teeth. The cutter need not have a lot of teeth, although the more teeth, the longer it will last, assuming you don't allow them to tarry in the cut.
This cutter could be made on a lathe, with the teeth generated using a milling attachment, but you'd be well served to have a cutter grinder sharpen the teeth after heat treat.
Harold