How do I get a slitter saw to work?

[JoeEM]

All I want to do is put a 12x4x1/2 piece of CRS on the mill and run a slitter saw down its length so I can have a 12x2x1/2 piece and a leftover a bit narrower than that.
I was using a brand new sawblade from Grizzly. First I tried a slow rpm and all the saw said was "whap whap whap I don't feel like cutting whap whap whap" so I dialed the VFD up a notch and it went "wheee" and although I didn't see any swarf come off it did seem to make a slight impression in the metal (not like it was cutting, but more like it was trynig to rub its way through the bar). But at the same time it turned into a glowing spinning disc of blues and yellows and when I added more coolant it erupted in a giant mushroom cloud of steam and smoke and when it all cleared I got this:



I did make sure that I had the blade oriented correctly, not trying to cut backwards. I had everything tight as could be. For now I just turned the piece 90 degrees and I'm plowing the cut out with an end mill but it sure would be nice to be able to use a slitter saw like the grownups do. Any advice would be appreciated.

thanks in advance
Joe

[Kevin45]

A fast speed is not good. You have gotten the cutter way too hot from the looks of it. It sounds like you may have a piece of material other than Cold Rolled Steel. It's hard to make a judgement call though over the internet. What you have should have worked. I know that slitting saws aren't as precision on the diameter as they should be hence the whap, whap, whap, sound you got, but instead of cranking the rpm's up, you should have put up with the noise.

[JoeEM]

Well that really sucks. I am sure it is CRS though - it still had the sticker on it and the end mill is cutting it fine.
thanks

[Highpower]

What was your depth of cut?

[Bob Fisher]

Splitter saws never seem to run true, that has always bothered me, but I guess each time you mount the saw different teeth are cutting. On the average, they all get some exercise. Only the really thin ones scare me, they can bind and shatter almost instantly. Generally, I have had good results with saws though. Bob.

[mars-red]

I use cutting fluid, low RPM, and pretty small depth of cut. Most of the time I'm using really thin saws (0.015" is about the thickest I tend to use, and my thinnest is 0.006"). I rarely cut deeper than 1/8" or so with them, and I had always thought that slitting saws were made for fairly shallow cuts. I assume they make saws with relief for making deep cuts without binding, but I haven't needed them yet.

[JoeEM]

Highpower I started at the far end and first I tried to cut about 1/8" deep. That wasn't doing anything so after about 1/8" of trying that I backed off to about 1/16th deep.
Bob - if you're getting good results can you tell me what RPM speed, depth, feed rate etc you're using?
thanks
Joe

EDIT: Max - what's a low RPM? This saw is a fatty - 1/8". I thought it should work just like a 1/8" end mill but sideways, but I guess I thought wrong.

[Arthur.Marks]

Oh no, no, no. Calculate speed by the OD not the width!
Also, depth of cut is really regulated by the relative number of teeth to the OD size. Too many teeth, their gullet is too small and load up before exiting the work. For thick, deep cuts, use a coarse pitch (fewer teeth). To some extent, though, adjustment of feed can mitigate a saw with too fine a pitch (too many teeth - too small of an area for swarf to collect). Using a slower feed presents less of a cut to each tooth on the saw. Lastly, conventional cut. Avoid climb-milling.

[JoeEM]

I understood about 1/4th of that...
Calculate speed by the OD I get, but what's the formula? I'm not even sure that my "slow" is in the ballpark of your "slow" without some numbers.
What is too many teeth, and is that on the cutter itself, or in the kerf?
When is it a conventional cut, when the chips get pushed out the front, or thrown out the back? I had the blade in front, moving the piece from my left to right, so the blade was moving into the piece - just like a woodworking tablesaw but with the blade sideways so that's my "normal."

Joe

[jkilroy]

Tell me what the OD is, and number of teeth and I will do the calcs right here on the board for all to see, that will help you do it again in the future.

Lets say its a 3" OD, looks like about 28 teeth and lets target 60 sfm to start, with a feed per tooth of .001.

.001 x 28 teeth = .0280 Inches of feed per revolution

60 sfm x 12 / (3" x Pi) = 76.394 rpm

.0280 x 76 rpm = 2.139 Inches per minute feed rate

Generally your depth of cut should not exceed the width of the cutter. So, 1/4 cutter, 1/4 DOC.

So the feed rate here is very important, and almost impossible to maintain a decent feed rate manually though a cut of that length.

[bob_s]

Conventional cut also termed "lifting cut" has the chips coming out from the blade in the same direction as the blade is being fed into the stock.

[Arthur.Marks]

RPM = SFM *4 / diameter. SFM = Surface Feet per Minute. This you need a table to know based on cutter material and work material. Let's just use a round 100SFM in this example for a HSS cutter on cold rolled steel. I don't know what size saw you're using. I'll take 3" OD as a guess. So...

133 RPM = 100SFM * 4 / 3"

For a 3" OD HSS cutter, try to use a speed near 133rpm if you can. Judging from the pictures on the Grizzly site, the tooth pitch looks about medium to me. For a 3" OD cutter, 50 or so teeth on the saw is basically medium pitch. 30 would be coarse. 70+ would be fine. I am sure some may have slightly different opinions on the numbers there. I still think it is a pretty good rough guide for 2-3/4" to 3" OD saws. Hmmm... & you might search for an image of conventional vs. climb-milling cut. It is far easier to relate in a picture than in words. (Sorry, I'm pecking on a tablet right now, so no image links)

[Black_Moons]

60 sfm x 12 / (3" x Pi) = 76.394 rpm
.0280 x 76 rpm = 2.139 Inches per minute feed rate

Exactly. Great numbers. What people don't understand is just how *SLOW* slow really is.
we mean *SLOW*, mind numbingly slow. So slow you can watch the cutter turn around.
at 2" a minute, that means with 0.1" table feed per revolution that you only rotate the handle around once every 3 seconds.

Also note that by going too fast can ruin a cutter near instantly. If your frist cut was at 300rpm its likey you ruined the cutter within the first second.

[toolznthings]

Hi,
Don't know your complete situation, but you are going to have two warped pieces of stock if you are able to cut the larger piece in half. You may also run into binding on the saw cutter if the stock moves inward during the cut. I thing you would be way ahead by buying
1/2 x 2 crs bar. A standard size. Mcmaster has it.

Brian

[dp]

Exactly. Great numbers. What people don't understand is just how *SLOW* slow really is.
we mean *SLOW*, mind numbingly slow. So slow you can watch the cutter turn around.
at 2" a minute, that means with 0.1" table feed per revolution that you only rotate the handle around once every 3 seconds.

Also note that by going too fast can ruin a cutter near instantly. If your frist cut was at 300rpm its likey you ruined the cutter within the first second.

It is also worth keeping in mind that 80% of the work is being done by 20% of the teeth owing to imperfections in the arbor, chuck, and saw.