Stainless Steel Project Help

My goal is to create a circular trough(which will have an outer diameter of 3 inches) in a flat 4" x 4" piece of stainless steel. This stainless steel plate will need to be 3/8" thick. And in the trough, which will be 1/4" deep and 3/8" wide, I will be putting 3/8" stainless steel ball bearings.(This will allow the top 1/8" of the bearings to protrude up out of the trough where they will be in contact with another flat stainless steel plate).
I'm assuming that this can only be done on a lathe. But before I begin my search for all necessary tools and materials, I was wondering if the trough walls can/should be rounded or square, and hoping to get feedback here on what kind of tooling would be needed to accomplish this.(Stainless steel recommendations would also be appreciated).
I'll probably will have to get someone who knows what he doing to make these. :-)
Thanks a lot.
Darren Harris Staten Island, New York

If you don't need something really accurate, I would suggest you mount the plate in a 4 jaw and use a tool post grinder with a 3/8" spherical carbide cutter.
And unless you have some special requirements, any hunk of stainless will do.
DOC
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snipped-for-privacy@mail.con.com wrote:
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On a manual lathe you would typically drill and bore the hole first. Then you would groove with a full nose radius grooving tool. The problem is the length cut of the grooving tool is likely to produce serious chatter especailly on stainless. Using 303 stainless will cut much easier and adding a positive rake to the tool will reduce the cutting force. A more precise method would be to profile the form with a CNC lathe.

If I understanad what you want....
This would be a piece of cake on a CNC mill. Use a 3/8 ball nose endmill and machine a circulat slot 1/4" deep. First preference is for 303 stainless. This won't work if you need to weld it later, 303 doesn't weld.
Karl

It wouldn't be too hard on a normal mill with a rotary table. Will a ball endmill will produce a groove suitable for ball bearings ?
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Depends on the accuracy that you need, but I'd say yes.

snipped-for-privacy@mail.con.com wrote:
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Rather that getting a bunch of tooling and then hiring somebody to run it, you'd do better to find the person who is going to run it and then ask him what he needs. Unless this is going to be ongoing production of a very large number of pieces, you'd do better to have a couple or three machine shops give you an estimate.
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snipped-for-privacy@mail.con.com says...
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Umm, you just described a stainless thrust bearing.
My suggestion is you check out what's available commercially before making it yourself. You could save your client some money if he changed the design to take advantage of an inexpensive bearing.
Jim

    --Getcher self a copy of the plans for building the Quorn Tool and Cutter Grinder; there's a treatise in there about making a Tee slot in the o.d. of a round bit of cast steel. It's much the same kind of thing you're trying to do and the tooling would be the same. Description of tooling is also in the article.

snipped-for-privacy@mail.con.com wrote:
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The fastest and cheapest way to do it is in a cnc lathe. It would be easy to add a face cut if you needed that done. If you can't find anyone to make them give me a call. Im about an hour away from you. In quantities they would run less than 15 a piece plus material.
John

On 28 Nov 2005 20:06:03 -0800, snipped-for-privacy@mail.con.com wrote:
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I'd do this with a 3/8" ball end mill and a rotary table in a vertical mill e.g. Bridgeport. That may not be the best way to do it, but it's how I'd do it with what I have.
I think this would be tricky to do on a lathe other than a CNC lathe. I shudder to think about using a form tool that big on SS.

Don Foreman wrote:
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Good answer, Don, but I'm afraid that Darren doesn't have a rotary table - much less a mill or a lathe. He might consider buying one, but has to also decide whether to make his part out of SS or Delrin.
Pretty hard to advise on something when you don't know the end use, isn't it? After all, this could be a thrust bearing carrying several tons at 2500 RPM, for which you'd probably want to grind the slot, no? On the other hand, it could be for a carousel for his hamster cage. Or a piece of artwork. Darren probably won't tell us, though, because he is an inventor and this is his secret invention.
Maybe someday Darren will come here saying that he has actually bought a machine or even a tool and is having a specific problem using it. I won't hold my breath waiting.
We've been had, again.
Feeling especially curmudgeonly this morning,
John Martin

John Martin wrote:
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For the second time I'll ignore the moron and bring this back to what's important.
Doc. As far as accuracy, it's not really important beyond the ball bearings spinning freely at their positions. The flat plate will only move about an inch in any direction over them, and under no more than 3 or 4 lbs of pressure.
Tomcas. I've been in the market for a mini-lathe and a mini-mill-drill in an attempt to cover a lot of needs for small projects.(Space is at a premium). But I may just have to start with getting good, versatile bench-top drill, which probably means I'll have to find a used older one.(So if anyone has recommendations on what to keep my eyes open for I would appreciated it). :-)
And like you mentioned, I was thinking about drilling holes around the diameter and then using a lathe to finish. Thanks for the info on 303. Does 303 have good corrosion resistance?
Karl Townsend. Too bad a CNC mill is not an option for me. :-(
J. Clarke. If I get a bunch of tooling, it definitely wouldn't be with the intent of hiring someone to run it. :-)
Jim Rozen. I've never seen any thrust bearings like what I'm trying to make. And also this is a personal project. No business or clients involved. I would like to crank out two or three protypes before I decide how far to go with production(as far as duplicating this project for friends).
Steamer. The "Quorn Tool and Cutter Grinder" is a project that is way off my course and abilities at the moment.
John. Thanks. For a first prototype run you pose a good option. In fact another related part of this project involves a one piece "joystick" also made from stainless steel. I know there would be a lot of waste involved, but I'm wondering about the plausibility of taking a 1-1/2" diameter, 4-1/2" long stainless steel rod and turning it into a 3/8" diameter rod with a 1-1/2" diameter ball at one end.(All other parts of this project will be made out of other materials).
As for the bearings I mentioned, I'm actually an thinking of using chrome steel bearings because corrosion resistance is always important to me.
Don Foreman. I've spent hours here studying up on mini-lathes/mills, and drills and I'm starting to get a good idea there limitations and coming up with project changes that will make things easier to get done.
***So I am now considering starting with a bench-top drill to make 8 holes in the 4" x 4" stainless steel plate in that 3" diameter configuration, so I can just drop in the ball bearings.(Perhaps mill a small circular trough to connect the holes anyway to help when I may have to use some 3-in-1 oil). I don't know if 303 would still be the recommendation for this, and if there is a good drill bit for making these bowl-shaped holes for the bearings, but the machien and tooling needed would be a lot simpler for me.
Thanks everyone. I'm learning a lot.
Darren Harris Staten Island, New York

On 1 Dec 2005 19:31:36 -0800, snipped-for-privacy@mail.con.com wrote:
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Make the ball separately and silverbraze it onto the rod -- or drill it, tap it, thread the rod and screw it in with some Loctite.
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Drill 1/8" dia pilot holes a bit deeper than 3/8". Then use a ball end mill in your drillpress to make the little bowls. You could get by without the pilot holes, but the ball-end mill will work better if you have them.
You'll want something considerably more substantial than 3-in-1 oil. Consider way oil, chain saw bar oil which stays put like way oil, or a molebdynum disulfide or teflon grease. It'll still have considerably more friction than if the balls could roll in a trough, but lube can make a big difference. White lead would work great but I suppose it's verboten unobtanium now.
With your light loading, another thought might be to make some little graphite rods that would go in the pilot holes and project just a couple of thou above the bottom of the bowls. This might result in much lower friction. Maybe drill the pilot holes clear thru and tap the bottom part, put the graphite rods in the holes, make your bowls with the ball end mil (that will result in a similar cavity in the graphite rod), then raise the rods a coupla thou with setscrews from the other side.
You might also drill 1/2" holes, make or buy oilite or teflon bushings with 1/4" holes thru them, press them into the holes and "ball" them with the ball-end mill in a drillpress. Chrome steel balls might run real nice on oilite bushings like this.
Another possibility might be to forget the cavities or trough, let the balls roll between two flat plates, keeping the balls captive with a disc carrier with holes in it. It might be made of delryn.
Happy inventing.

Don Foreman wrote:
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That's not within my capabilities. I don't even know how I'd make the ball shaped end.
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"Deeper than 3/8"" is all the way through the plate since that will be it's thickness.
Also, I think I'll go with smaller 1/4" bearings situated in 3/16" deep holes instead.
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I know that there will be less friction for each individual bearing with the original trough idea because there is less contact between each bearing and where it sits, but there will be less overall friction with the "8 bowls" idea in regard to the plate that will have to slide over them because the total number of bearings will be lower, so there will be even less contact there.
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Since travel will be in all directions, ball bearings by themselves are definitely the way to go for me.
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Complexity, work and cost go up. Reliability goes down. I think my simple "8 bowls" idea is the best way for me.
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I'm not sure I'm visualizing that the way you are thinking about it, but I'll keep things simple and look for the best bench-top drill press(with rotating table) I can get along with the necessary bits so I can get started. Any recommendations here would be appreciated.
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Thanks.
Darren Harris Staten Island, New York.

snipped-for-privacy@mail.con.com wrote:
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Also, is it possible/plausible to attach a 3/8" statinless tell rod to a 1-1/2" Diameter Chrome Steel Bearing, or would the chrome bearing be too hard for this?
Thanks.
Darren Harris Staten Island, New York.

snipped-for-privacy@mail.con.com wrote:
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Also, is it possible/plausible to attach the end of a 3/8" stainless steel rod to a 1-1/2" Diameter Chrome Steel Bearing, or would the chrome bearing be too hard for this?
Thanks.
Darren Harris Staten Island, New York.

snipped-for-privacy@mail.con.com says... .
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For about $8 you can buy a 1-3/8" stainless steel ball knob with your choice of threaded hole from McMaster. A steel ball knob is about $4. BTW, chrome bearing steel (AISI 52100) is not rust resistant.
Ned Simmons

Ned Simmons wrote:
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I thought that adding chrome to steel made it more corrosion resistant than "ordinary" (martensite)S.S. I'd still need a ball that is at least 1-1/2" in diameter.
Also, as far as the 4" x 4" stainless steel plate, 304 is suppposed to have better corrosion resistance than 303, while still retaining good machinability. And 316 is even more corrosion resistant and just as easy to machine as 304. So perhaps I'll go with one of these instead of 303.
Thanks.
Darren Harris Staten Island, New York.

snipped-for-privacy@mail.con.com says...
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McMaster has 1-7/8 ball knobs as well. Check with Reid Tool, Carr-Lane, and Misumi and you may find something closer to 1-1/2".
52100 is probably a bit more corrosion resistant than mild steel, but not much. If you handle a nice clean bearing then set it aside for a few days, chances are it'll have rusty fingerprints on it when you return.
I'd be more inclined to call austenitic SS "ordinary" than martensitic. I'll bet you come in daily contact with more austenitic than martensitic SS.
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I doubt many folks who've worked with 304/316 SS would rate its machinability as good. I used to be in the marine hardware business so have worked a lot with 304/316 and had large rigid machines to do the work. It's nothing to be frightened of, and there's stuff that's much worse, but easy to machine? Uh-uh. 303 is much easier.
Ned Simmons