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Educate me on slitting saws?

catalytic

Cast Iron
Joined
Feb 4, 2010
Location
Boston, Los Angeles, and Cleveland
In my whole time machining I have never used a slitting saw. I have needed them, but always found a way to get the job done with something else. I finally picked up a set of Sierra American arbors yesterday. Is there anything to know about selecting/using them?

-Is it correct to think that I want the thickest saw with the least overhang over the arbor support for each job?
-Does more overhang/larger diameter for the same arbor tend to result in chatter?
-Now that I bought various arbor sizes, I see McMaster sells the vast majority of saws in 1/2" or 1" arbor sizes. Why have other arbor sizes? Just for 'fitting in' places?

-I expect I'll be using HSS saws, as parts are one-offs on manual machines and unless I'm working on the lathe I don't use much carbide.

-Any preferred brands/styles/tooth counts? Most jobs will be slotting aluminum to depths of no more than 3/8" with a slot that can be 3/32" wide.
 
What can go wrong, break the saw, bend the arbor, slot will be lazy (not in a straight line) saw will chater,short life of saw, ect They can be a real pia, I baby them, slow feed, right rpm, sometimes I will cut a very shallow cut so the saw will track in the groove...I am sure there are more tricks...Phil
 
What can go wrong, break the saw, bend the arbor, slot will be lazy (not in a straight line) saw will chater,short life of saw, ect They can be a real pia, I baby them, slow feed, right rpm, sometimes I will cut a very shallow cut so the saw will track in the groove...I am sure there are more tricks...Phil

^^Thanks. Sounds like it's going to be less straight forward than I thought. Do you speed/feed them at the same SFPM as endmills?
 
Sometimes you're better off conventional milling.

When in doubt, take multiple passes rather than try to push through in one cut.

Cut less per tooth than you think you should.

Coolant! Always use coolant, flush the cut and teeth as best you can. Packed chips are death to saws.

Coarse tooth is better for aluminum.

TIR will NEVER be perfect, but try for it (you'll always get a cyclic wirrWIRRwirrWIRR as it cuts eccentrically).

Make sure you have the arbor cap tight, and the saw oriented such that normal cutter rotation further tightens the cap.

Watch for overhangs, allow as much space as needed to ensure you don't rapid the saw into an existing feature if CNCing.

Bite the bullet and get carbide saws when you have an excuse for them. They are better (IMO) for Al work.

If working on a manual machine, wear safety glasses AND a face shield. You'll thank me for this advice if you ever shatter a saw as you're standing there.

Don't die. Saws are stone cold killers just waiting for you to turn your back at them, then they leap off the arbor and go for the spine.

Or so I've heard...
 
I was running about 1500 rpm with a slow F5. a 21 tooth saw in aluminum no problem. Took about .03 each pass. Probably could have been more aggressive. I remembered reading about keeping the depth of cut under the height of the tooth to allow the chips room to clear.
 
Something like this would work great...

Solid Carbide Slitting Saw 1.5 X .50 X .0938 Thick 32 teeth MariTool

typically you dont want to go more than 2x thickness per pass. This is from my website...

Jeweler and slitting saws are designed for slotting and grooving thin material in which minimum tooth engagement is desired. Applications include making slits for collets, cutting wire, tubing, sheeting and extrusions. These saws are excellent for being used as a cutoff tool in lathes with live tooling. Parts will have a much smaller tit if not supported and since these saws are thin you can get more pieces per bar. Large number of teeth will give you great metal removal rates and tool life.
In general it is best not to have a single depth of cut more than 2 times the saw thickness.
If total depth of cut is more than 6 times the saw thickness it is best to use staggered tooth.
If you dont see a size or style that you need email us. We can quote customs and even stock them for you. Typical lead times are 2-3 weeks.

Once set up properly carbide slitting saws can last for thousand of parts even in steels and harder alloys. For deep slitting we can reduce number of teeth and make staggered tooth to allow more room for chips. For above saw in alum I would start out at 600 sfpm, .0004 ipt, and use flood coolant.
 
What Milland said really takes me back. I made my first saw arbor and it drove me crazy trying to eliminate what I thought was a crappy job of turning the arbor. He is correct. The TIR will never be perfect and the sound the saw makes leads you to believe you really screwed something up. It's just one of those things.
 
Swings and roundabouts I always used to take the depth in one cut on manuals would find myself a arbor that was not any good size above bore diameter I wanted.EG:-WANTED 1ins shank arbor,find a old one size above.Take head off m/c stick the arbor in nose on column.Stick a lathe turning tool in vise,C/L turn shank to size should run blob on,no runout.Carbide is different class,save a lot time in longterm
 
All of the above and be sure to measure the saw diameter and use the dang formula for SFPM. Everybody runs them too fast and they don't live long if you do that. Support as much saw as possible if the cut is shallow. Be sure the arbor doesn't introduce any dish in the saw as that will trash the process pretty quickly.
 
Wow -- wasn't expecting it would be this sketchy to run these tools. Now I know why machining training didn't include them.

So, given the choice, do you guys pick a very small (1/8" dia or 3/32" dia) endmill instead of a slitting saw when you have to slot something, assuming you could set up either? I had assumed a saw was the way to go but now I wonder..
 
You stated that what you are going to slot is mostly AL. If it were me I would just mill it out with a two flute mill. It is a lot easier to just stick in an end mill then change out everything. The other issue is that if you use a saw you have to consider how you are going to miss the vise on a long slot. Much easier coming down from the top. You didn't say how long the slot needs to be but on a shaft that is keyed the entire length, it is better to use a saw on a horizontal mill. With a horizontal mill you are again coming down from the top so clamping is a lot less complicated.
 
You stated that what you are going to slot is mostly AL. If it were me I would just mill it out with a two flute mill. It is a lot easier to just stick in an end mill then change out everything.....

Easier huh? This is an 0.080" wide slot an inch deep. In aluminium. But I don't think it would be easier with a 2 flute end mill....:D

2mm slot.jpg
 
If you make a saw arbor finish the shank, face, and fit diameter between centers.

If it is to fit into a tool holder don't make size but fit it into that one holder.

.002 Od run out is a mile for a slitting saw

A few tenths dish at the face is OK but a convex (belly out) face is bad.

The saw bore needs to be near zero to just fit the arbor.

Good to sharpen it mounted on the arbor.
 
Don't die. Saws are stone cold killers just waiting for you to turn your back at them, then they leap off the arbor and go for the spine.

Or so I've heard...

I'm not sure that applies to slitting saws, but just a couple days ago I was standing 10 feet away from a young kid using a cutoff wheel on a 5" hand grinder at a friend's shop. The wheel got misaligned in the midst of cutting and grabbed, exploded. I asked if it got him and he said nope, I'm good. Didn't think much of it as I got back to doing what I was doing and he decided to change the cutoff wheel and go back at it. I heard another wheel let go not two minutes later and glanced over to see quite a bright red puddle forming on his hand and under it on the ground, along with a very ashen young face.

At that point I realized that he hadn't been wearing gloves, which I hadn't paid any attention to earlier. I always wear gloves when using cutoffs. The wheel had cut loose right across the back of his hand, leaving a big old gash across it. I saw him going white so I made him sit down and took care of a quick makeshift bandage and had him hold pressure on it with his arm up to help slow down the blood flow. Pulled it and had a look after a few minutes and then I gave his dad (owner of the shop) a call to get him a ride for some stitches. Ended up with 8.

Anyway, slitting saws aren't that bad, watch the heck out for cutoff wheels. This young fellow got lucky in that he didn't hit any veins or tendons. That isn't always the case and that kind of damage you don't heal 100% from.
 
Anyway, slitting saws aren't that bad, watch the heck out for cutoff wheels. This young fellow got lucky in that he didn't hit any veins or tendons. That isn't always the case and that kind of damage you don't heal 100% from.

Glad he didn't get too F'd up!

Yeah, my statement basically follows for anything machining related. All the tools are just sitting there, waiting for their taste as soon as you give them a chance. What keeps us whole is common sense, training, and sometimes a little luck.
 








 
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