Slitting Saw technique.
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  1. #1
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    Default Slitting Saw technique.

    Every time I use a slitting saw I always seem to have trouble. So I'm looking for any advice you have that I don't. Obviously I've missed some rules along the way.

    My current job is 1018 2" wide bar with a 1.500 x .062 slot.

    My first attempt was with a solid carbide 100 tooth 5" x 062 saw, straight tooth I would suppose it would be classified. I had actually ordered a carbide tipped saw, but due to a miscommunication, I ended up with solid carbide. It was not cheap. Anyway, I took it in 3 passes, climb, at I believe 400sfm at an embarrassing .0003 per tooth, I ended up there because my saw was running out like a motherfucker, and this machine is only 10hp. The arbor is new, and was made in America. We ran about 20 parts before failure. Which I suppose I expected, but couldn't get a better cut.

    I came in today and reprogrammed for my only other saw, a HSS 6" x .062 x 42 tooth. Also straight tooth. I've switched to trying it in one pass, at 200sfm, and an even worse, .0001 per tooth. Any more an I stall the motor. The saw is also running out like crazy, which I can't seem to remedy, I see my spindle load bounce from 0-60 percent on each rev, and obviously it sounds like shit. Finally my slot is coming out angled, as in the saw is bending, approximately .030 higher near the arbor.

    Aside from all the problems above, how does one prevent run-out with a saw?

    Thanks,
    Brian

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    Starts with a properly ground, high quality saw, and I do prefer carbide if it's a rational size (after 3"OD it gets expensive).

    Then, I sometimes will make my own arbors with as large a clamping face diameter as I can get away with, and an oversize pilot. Set up the machine, clamp a lathe bit in the vise, and face/turn the pilot and clamp surface dead true (and "0" clearance).

    Install the blade, and if it runs out you know it's the manufacturer's fault.

    And yes, FPT is frequently very low, but stiffness and really flooding the cut with coolant help when trying to up it.

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    I always conventional mill at full depth with a slitting saw.

    Sent from my XT1710-02 using Tapatalk

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    [QUOTE=mTeryk;3427873]I always conventional mill at full depth with a slitting saw.

    Sent from my XT1710-02 using Tapatalk[/QUOTE

    I also conventional mill. Tried climb initially but after breaking one... well, Haven't broken one conventional milling yet. Been years now.

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    Millands got it. Get yourself a quality saw(I personally like RobbJack). But it sounds like the arbor is your issue if the carbide saw was running way out. Have you put an indicator on the arbor shank and flange?

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    As others have said I usually conventional mill at full depth. Throw an indicator on the arbor with no saw on it. If that's bad then work barckwards….tool holder, spindle taper so on. As Milland said turning your own arbor in the machine will make for theatrically zero runout.

    If you have runout your actually chipload is zero to little on most teeth and then a few of them are making up all the lost cutting. Which is why your chipload calc is so low and why cutters self destruct.

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    I ended up there because my saw was running out like a mother.....
    Twooooooo that arbor away or fix it...should run perhaps .002 or better for diameters and sides.

    .0001 per tooth. Any more an I stall the motor.

    Finally my slot is coming out angled, as in the saw is bending, approximately .030 higher near the arbor.

    Seems an full description of the operation might be due..

    RE: [As Milland said turning your own arbor in the machine will make for theatrically zero runout.]

    But that can be off with removing the arbor and replacing at a different radial location..good to tell your plan of how you intend to hold it and let the PM guys think it over and give advice..proper use of slitting saws makes them do very well and last a good long time.

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    +1 on conventional cutting. Also, you've got to solve your runout problem, otherwise there's no point in getting started.
    200sfm is way too fast for hss.
    What kind of machine are you running this on? If you've got a direct drive spindle, your torque drops to zero at low rpms, and trying to run a 5" cutter in steel just aint ever going to happen.

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    Runout is key. Saw must run dead true. Wost case try to find a way to "face" the arbor surface while still in the spindle. Put some tool holder or stick tool in a vise and manualy travers the arbor.

    Going that deep is a little tricky. Solid carbide and staggerred tooth will certainly help. I have a standard 4" X .062 solid carbide in stock. But even better I have a 4" Staggerred tooth with Tialn coating in stock !! but it is .058 thick. Not sure if you can use that.
    Solid Carbide Slitting Saw 4.0 X 1.0 X .058 Thick 64 teeth Staggered TiAlN Coate MariTool

    If interested let me know and I can have some .062 thick made up. But will need 3-4 weeks. Above saw is in stock. $185/each.

    Also we have this on our page. Helpful guide....
    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.

    Ok nevermind, I read too quickly. I guess you need 5". I dont have anything off the shelf. If you have time let me know. 3-4 weeks still apply. Cost would be around $280ea.

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    Quote Originally Posted by Milland View Post
    Starts with a properly ground, high quality saw, and I do prefer carbide if it's a rational size (after 3"OD it gets expensive).

    Then, I sometimes will make my own arbors with as large a clamping face diameter as I can get away with, and an oversize pilot. Set up the machine, clamp a lathe bit in the vise, and face/turn the pilot and clamp surface dead true (and "0" clearance).

    Install the blade, and if it runs out you know it's the manufacturer's fault.

    And yes, FPT is frequently very low, but stiffness and really flooding the cut with coolant help when trying to up it.
    That's a very good idea, I've never considered turning an arbor in my mill before. As for conventional mill, it's seems like everyone is on the same page with that, which is great news for me. What's the theory behind conventional milling with a saw I wonder?

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    Quote Originally Posted by Larry Dickman View Post
    +1 on conventional cutting. Also, you've got to solve your runout problem, otherwise there's no point in getting started.
    200sfm is way too fast for hss.
    What kind of machine are you running this on? If you've got a direct drive spindle, your torque drops to zero at low rpms, and trying to run a 5" cutter in steel just aint ever going to happen.
    Yeah I agree, with you on the sfm issue, however I also agree with you on the torque issue, which is why I sped it up. 200sfm is something like 150 rpm. I probably should have been closer to 75 rpm, I try to stay away from the upper and lower end of the room spectrum when taking heavier cuts.

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    Quote Originally Posted by fmari --MariTool- View Post
    Runout is key. Saw must run dead true. Wost case try to find a way to "face" the arbor surface while still in the spindle. Put some tool holder or stick tool in a vise and manualy travers the arbor.

    Going that deep is a little tricky. Solid carbide and staggerred tooth will certainly help. I have a standard 4" X .062 solid carbide in stock. But even better I have a 4" Staggerred tooth with Tialn coating in stock !! but it is .058 thick. Not sure if you can use that.
    Solid Carbide Slitting Saw 4.0 X 1.0 X .058 Thick 64 teeth Staggered TiAlN Coate MariTool

    If interested let me know and I can have some .062 thick made up. But will need 3-4 weeks. Above saw is in stock. $185/each.

    Also we have this on our page. Helpful guide....
    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.

    Ok nevermind, I read too quickly. I guess you need 5". I dont have anything off the shelf. If you have time let me know. 3-4 weeks still apply. Cost would be around $280ea.
    That's super helpful, and I always appreciate hearing from you, unfortunately a 4" saw won't make that depth. At least not with my arbor. You don't have any 5" is stock?

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    I have a job I run every so often, sound very similar to what you're doing. 1018, 1//8 wide x 1-1/2 deep. I tried everything I could think of. With a direct drive spindle there's no way to do it. (Down load a torque graph for your machine and you'll see why) The first lot I ended up doing on a Bridgeport. what a nightmare. Then I ended up sending them out, but that was expensive. If the job comes around again, I plan on setting up an old horizontal for it.

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    QT:[That's a very good idea, I've never considered turning an arbor in my mill before.]
    With the arbor made/turned in an end mill holder , mark the spindle nose, the holder and the arbor so everything goes back all lines matching and it will run true when replaced. Keyed arbor is best for saws.

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    BRIAN.T
    Sorry. The only thing in 5" we have in stock is .125 thick. Next time I order I will bring in some .062 thick saws.

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    Quote Originally Posted by BRIAN.T View Post
    What's the theory behind conventional milling with a saw I wonder?
    With a circular saw the blade on climb cut is in extreme tension at and just beyond entering the material and into compression by the time it gets to the bottom of the cut, having this variance in less than 1/4 of circle causes warp/twist. In conventional cut the blade is in compression, increasing from bottom up which helps prevent warpage of blade. Blades will walk instantly if a shadow of a twist gets near it. Saws have no strength outside tension OR compression.

    slowing rpm will help blades stay in compression with some run out, just keep the feed pressure solid.. I know it is set by feed rate- which makes for the conundrum of needing zero run out blade.

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    Harvey Tool has pretty reasonable prices on their saws - I was surprised that their solid carbides are usually cheaper than the brazed saws we got from other suppliers.

    I'm glad I saw this thread - I had a hell of a time with a project at the old shop that used three different slitting saws or keyseat cutters. I was climb milling them all! You live, you learn.

    I have had good luck making my own arbors. I will turn them so that the pilot boss is longer than the blade is thick, and then I make a counterbored clamping cap with a tight slip fit onto the pilot. It seems to keep everything square.

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    I seem to be quite conservative in my slitting compared to you guys running it in one pass

    I regularly run 4" x (0.040"-0.080") x 96t carbide saws in mild steel. ~400 sfm, 0.0005" ipt, climb cut, and only enough step over to cover 4 teeth of engagement (~0.050"-0.060")

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    Quote Originally Posted by BRIAN.T View Post
    That's a very good idea, I've never considered turning an arbor in my mill before. As for conventional mill, it's seems like everyone is on the same page with that, which is great news for me. What's the theory behind conventional milling with a saw I wonder?
    Have you ever tried climb cutting with a Skill Saw...

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    Back in the old days before "Trochoidal" became a household hot word, I'd create the linear path, then back out of the cut, on both X and Y, very briefly (.025") or something, then re-engage it another half Inch or so.

    R


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