How to cut a narrow slot in thick SS

I am a newbie hobbyist seeking the advice and wisdom of you more experienced than I.

I am going to be cutting a notch in 300 series SS which will be thick stock about 3/8” x 3/4” x 1”. There will actually be two slots in line with each other, with a small gap between them - about 1/16”. The slots will be about 1/8” wide, and one only needs to be about 1/8” deep. The other needs to be at increasingly depth from 1/16” on the end adjacent to the other slot, to 1/2” where it exits the part. The slots are in the 3/8” wide side of the blocks. Precise slot widths are unimportant, and the shape of the ends of the slots are also unimportant - I presume rounded, or square-ish if cut with an abrasive disk.
I have an old Bridgeport clone with a 6” Kurt clone vise. I have no horizontal attachment so if I was going to use thin metal-cutting disks, I will need to make some kind of arbor to hold 4 or 4-1/2” disks and hold the work protruding from the side of the vise, I can adjust the angle of the vise relative to the table if that would be better than using the curve of the disk (assuming use of a cutting disk) or key slot cutter.

I think I have 303, but it might be 304 - yeah, I know that is harder to work with. Pieces are cut to size and squared up.
Thanks for any and all suggestions.

Use a 3/32" end mill then deburr with a countersink. Achieve the angled slot by angling the material in the vise.

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You really need to post at least a sketch, so we can have a better idea of what you're trying to do.

How many do you need to make? If it's "about" 1/8" wide, you could use an end mill, but it may be slowish, or a slitting saw for an R8 arbor. Either could work (without having a super clear mental picture), but may not be the best bet for a run of parts.
You'll know pretty quick if it's 303 or 304. Imagination is the limit on how to get it done. If it's some non-critical part that you only need one of (and it's 304) you could make the cuts with a band saw, fill the cut with a tig weld with slightly more filler than you need, and clean it up with a needle file. Hands down my last choice, but I've done far more redneck things for one-off parts that I needed and didn't have tools for.

Thanks for the helpful replies.

I found a couple surplus keyseat cutters on eBay that are about the right width and diameter, with carbide teeth. They are on the way.

I had initially thought that I could use the Kurt-style vise to hold the workpieces (I have to make 15 in all) and allow me to machine the sloping slot, but I did want to ask about that more carefully in light of car2's comment.

The Kurt clone seems pretty robust, and I thought it could hold the workpiece sticking out of the side of the vise, and that the horizontal cutter held in the vertical mill could cut the slot in the protruding part of the workpiece.

I haven't held a workpiece way off-center in the vise, so I am hoping others here can share their experience. Certainly the keyway cutter would be pushing on the workpiece during cutting passes, and that would be potentially possible of pushing the workpiece toward the center of the vise and away from the cutter.

Do I need to make a different workholding arrangement? I welcome any ideas about how to hold the work and mill the slots.

Thanks in advance for sharing any and all help in this operation!

saw? 4-6 blades have .064 kerf new. 3-4 is 3/32, a 2-3 would be rough, but land you at .109 kerf (1/8" if you unsquint your eyes right). set the part at angle off the blade (if I am seeing this right) and feed saw to depth.

Yup, bandsaw was my first thought too.

strokersix said:

Yup, bandsaw was my first thought too.

Click to expand...

I made a Winchester 1895 Falling block copy by that method. I didn't want to do the broaching or casting or any of the amazing things that the machinists of old could pull off, so I chopped my stock in half with a band saw and machined it in two halves out of 8-1-1 titanium that I tig welded together, then machined/filed the welds to where you couldn't see it was two halves instead of one piece. stubbornness is the mother of invention. Or maybe it was necessity?

I don't have a metal cutting bandsaw, so that isn't an option for me.

I do have a 7-1/4" radial arm saw (meant for wood), but it is a older, high-quality machine; the movement of the saw is precisely controlled; and I have considered trying a abrasive blade on it to cut the slots, possibly using the Kurt vise to hold the workpiece precisely, and then clean up the slots with the keyseat cutter. Or will the abrasive blade just work harden the SS and make it harder for the keyseat cutter to machine the workpiece?

In any case, using the keyslot cutters in the bridgeport, and cutting the slots in the workpiece horizontally in the vise, I need to hold the work rigidly. I know the Kurt will hold the work rigidly in the middle of the vise on parallels for vertical cutting, but holding the workpiece off-center in the vise with the face I need to cut horizontally sticking out of the side of the jaws is something I have no experience with.
Anything you might be able to share about holding a small workpiece off-center in a Kurt (knock-off) with the keyseat cutter trying to push it into the center of the jaws?
Thank you for all the suggestions and, in advance, for any further wisdom and experience you can share.

Put some packing in the vise opposite your work to take up the space. Make it narrow and just a few thousandths taller than your work to encourage the vise to grip your work close to the cutter. Slightly twisting the movable vise jaw.

QT: [and I thought it could hold the workpiece sticking out of the side of the vise,]

You should put a spacer in the vise at the other (open) end so the the jaws are parallel so better holding.
Oh I see strokersix mentioned that.

Abrasinve blades are not so good for SS they like to load up and make the part very hot.

Vises don't hold very well vertical with the movable jaw able to tilt up a tad. I some times set a shim against the part on the moving jaw, make tight to the fixed jaw and then run a C clamp across the vise jaws.

Sticking far out the part may chatter so a parallel, 123 block, angle plate or something might be bolted to the table so bumping the part solid so it can't go that way and chatter.

Cutter likely needs a key to make fast to the arbor.

Thanks very much for the reply!

strokersix said:

Put some packing in the vise opposite your work to take up the space. Make it narrow and just a few thousandths taller than your work to encourage the vise to grip your work close to the cutter. Slightly twisting the movable vise jaw.

Click to expand...

Would you clarify what you mean by "packing"?

Place another workpiece-sized piece slightly smaller and placed higher in the vise on the opposite side of the jaws?

Something softer like a piece of copper or aluminum shim stock along with another workpiece and the workpiece intended to have a slot milled in it?

Thanks, michiganbuck, you posted while I was typing and answered my questions in detail.

A mill arbor is not that good held in a collet. End mill holder with a set screw and a flat on the arbor shank is better, yes with a key.

Held in a collet a light feed and a sharp cutter may work. *Perhaps some/a mill guys can chime in on this.

Im not really the/a mill guy.

QT[ possible of pushing the workpiece toward the center of the vise and away from the cutter.]
Standing part up you might also find a way to bolt on/in some kind of bump-stop to bump the direction it would be pushed/vibrate.
Rock solid holding will also make your cutter last longer.