How Are "slots And Slits" Cut For Bushings?

EmilioG said:
I would like to learn to correctly cut slits and slots, down to 1/32", (width of slots (.794") in steel to make bushings, sleeves,
etc... Like the slits that you see on R8 collets, grinder collets, reducing sleeves, etc...?

What type of tooling is used to make this fine straight cuts?
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Emilio, you need a slitting saw holder and some slitting saws. Slitting saws come in many sizes and thicknesses but for the thin slits you are looking at, jeweler's saws work well. Most of these smaller saws come with a 1/2" arbor so your holder has to match that diameter. You can either buy the holder or make one - lots of info on this on the net.

Look at this pdf for more info. Pay particular attention to the tips and tricks section on how to use these saws. They are intended to take full-depth cuts; pecking away at the work wears the blade prematurely. Hope this helps.

http://www.martindaleco.com/pdfs/Metal_Working_Mica_Saws/Saws.pdf
 
Thanks to all for the helpful ideas and thanks Mikey, you are a constant source of great advice and as usual, very helpful
and informed. Making these sleeves and bushings , I think, is a good skill to learn. So many times, I've need to fit two parts
together, even temporarily, and finding a pre-made part for the ID/OD is not easy to find.
Thanks so much to you all. The combined experience and talent here is awesome. I hope to one day have some of the skills
that most of you have. Have a Merry Christmas and a Joyous Holiday season everyone. Good luck, Good health and good fortune.
 
mikey said:
I usually drill and ream the stock, then turn the OD profile I want. I put some layout dye on the end of the sleeve and use my center gauge (the V-shaped head on a combination blade) to mark a center line. Then I put the sleeve in a vise so the marked line is even with the top of the jaw and the bore is sticking past the end of the jaw about half way. A spacer is used on the other end of the jaws to balance the clamping forces, then I use a slitting saw to cut a through slot. I almost always cut an expansion slot 180 degrees from the through slot so I just turn the work piece over, line up the layout line to the top of the jaw and cut the partial slot about 1/2 way through the wall.

This has worked well for me and I've made a number of sleeves this way.
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I thought of that idea but guessed it would not work very well because of the unsupported tube, which could spring open or closed on the saw, and possibly raise other problems, not the least of them being chatter. I have the saws and arbor, just don't want to try anything dumb and break a saw while also destroying the work. I will have to try it and see, though I like Jim Dawson's ideas even though they take more effort to get set up.
 
The spring of the tube is sort of unpredictable, but usually it opens up rather than clamps down on the blade. As long as you are using a non-keyed arbor and haven't overtightened the nut, worst case it just slips. But if you are power feeding, of course this is a problem. This is one time I prefer to have everything backwards. As in the threaded part of the arbor. I would much rather have it loosen the nut and harmlessly spin if it gets hung than tighten up more and break. And I rarely power feed a really small slit/jewelers blade. I don't do a lot of slitting, but I have done my share. There are times when I have pushed tapered shims in behind the cutter if I think there is a chance of it closing up, but I don't recall it ever being needed.

If you have a close fitting mandrel, cut a wider clearance slot in it where the slit saw will run and you won't have to saw it at the same time as the sleeve or whatever you are slitting. Or if you are using a vise with it held end-ways, leave only enough hanging out of the vise to allow the cut. The vise will minimize any springing either open or closed. One last tip I can think of right now, is to make an exception and climb cut. The saw will have a much better chance of staying straight and this will make it less likely to get in a bind and break. Climbing won't allow it to wander and poses less break risk. I have broken a few fragile saws because of this wandering off milling conventionally.
 
Bob Korves said:
I thought of that idea but guessed it would not work very well because of the unsupported tube, which could spring open or closed on the saw, and possibly raise other problems, not the least of them being chatter. I have the saws and arbor, just don't want to try anything dumb and break a saw while also destroying the work. I will have to try it and see, though I like Jim Dawson's ideas even though they take more effort to get set up.
Click to expand...

Never had a saw pinch or have any problems with this process. As the cut completes, it opens up so the saw has never gotten bound up, ever. Moreover, with the right feeds and speeds the saw cuts cleanly - no chatter. With that said, I'm sure there are many ways to do this job - good luck, Bob, and let us know what worked for you.
 
Tony Wells said:
The spring of the tube is sort of unpredictable, but usually it opens up rather than clamps down on the blade. As long as you are using a non-keyed arbor and haven't overtightened the nut, worst case it just slips. But if you are power feeding, of course this is a problem. This is one time I prefer to have everything backwards. As in the threaded part of the arbor. I would much rather have it loosen the nut and harmlessly spin if it gets hung than tighten up more and break. And I rarely power feed a really small slit/jewelers blade. I don't do a lot of slitting, but I have done my share. There are times when I have pushed tapered shims in behind the cutter if I think there is a chance of it closing up, but I don't recall it ever being needed.

If you have a close fitting mandrel, cut a wider clearance slot in it where the slit saw will run and you won't have to saw it at the same time as the sleeve or whatever you are slitting. Or if you are using a vise with it held end-ways, leave only enough hanging out of the vise to allow the cut. The vise will minimize any springing either open or closed. One last tip I can think of right now, is to make an exception and climb cut. The saw will have a much better chance of staying straight and this will make it less likely to get in a bind and break. Climbing won't allow it to wander and poses less break risk. I have broken a few fragile saws because of this wandering off milling conventionally.
Click to expand...
Yes, I am thinking climb cutting without much cutter protrusion through the I.D. of the bushing. That would keep more teeth in the cut and the cut forces more in line with the bushing center line. Does that sound correct?
 
Correct, but as usual, if you have any slack in the lead screw, you have to drag the lock a little. Slit saws don't have much strength in pulling themselves into the material like a larger cutter or end mill, so climbing isn't so bad with them. And they do cut straight when climbing.
 
Tony Wells said:
Correct, but as usual, if you have any slack in the lead screw, you have to drag the lock a little. Slit saws don't have much strength in pulling themselves into the material like a larger cutter or end mill, so climbing isn't so bad with them. And they do cut straight when climbing.
Click to expand...
Thanks, Tony. Yes, way lock snugged a bit and cutting in the correct direction so the cutter keeps pulling the work away from the backlash. With a bit of thought climb cutting gets a whole lot less scary...
 
It's usually not as big a deal as some people think, as long as you aren't crowding it, and have a little drag on your side. And of course, that's not for roughing. Lights cuts, and low loads like this slit saw we're talking about.
 
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