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    Default Handheld Cold Saw SFM

    Hi this is my first post here but I have been looking into buying a handheld Cold Saw for cutting structural steel onsite. I have some experience setting up CNC machines but not much experience with actually making parts on them but I'm learning.

    I'm a little confused by the specs for some of the hand held metal cutting saws. The 8" blades on these are spinning at 4400RPM (I think this is the no load speed) with 50 teeth on the blade. It looks like ~20ipm through 1/4" DOC is reasonable to expect from a saw like this so I'm cutting 1/11000 " per tooth with the tooth travelling at 9000 SFM. Does this greatly reduce the life of the blade or is this acceptable because each tooth is only cutting a hot chip for a short length of time and can cool off before the next cut? I mostly would use it on cheese grade structural steel.

    I never see recommended speeds for carbide near 9000SFM. Did I calculate something wrong or are these cutters just totally different for speeds?

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    Yeah, the speeds on these are something what you would not expect for steel cutting with carbide.
    WAG its a combination of very short time in cut and lots of time to cool off.
    Short time in cut has a side effect that even 1 minute actual cutting time for insert life is acceptable. One teeth cuts maybe 1/2" and swooshes air for 24" so it spends only about 2% of time actually cutting something. 1 minute insert life would suck on lathe but on these it would be nearly one hour of cutting.

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    I would think a port-a-band would be more useful for structural steel- columns, beams, etc. have pretty large cross sections.

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    I have used the 7 1/4 steel blades on a worm drive skilsaw and it works great. I think I have 4 dead ones now. I beam with 3/4" flange 12" wide, no problem. 15" 2nd weight channel iron, no problem. 12x12x3/8 wall tube, no problem. The cuts look great. I have a friend with the milwaukee 8" and he likes it. Just have to pay attention and not push too hard and know when to back off the pressure.

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    I don't think there's a portaband big enough to cut all the material I'm going through. I'm looking into ways to save time compared to plasma cutting it and grinding. Plasma is plenty fast but it requires a good deal of grinding afterwards. Another nice feature of the handheld saw is you can cut pretty well anything with it as long as it's not too thick but even then you can break it down into multiple passes. It does require a little more thinking as you can trap the blade easily in big stuff.

    SFM seems to be not that big of a deal compared to heat from what I understand. At my previous job there were routers running 1/4" single flute cutters at 18000 - 24000 rpm through aluminum with 0.003 chipload no problem but they needed a chip big enough to pull the heat away from the cutter so it doesn't start welding the material. When people slowed the feedrate the spoilboard would start smouldering.

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    If i had to guess I would say about 20-30' of cutting thick (3/8"+) stock per blade. Ay about $30/ blade that is aprox $1 per foot of cutting. 8" may last longer but also cost more to buy.

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    We use one of those evolution hand saws and they cut through steel like it's butter.

    For cutting plate and other items, it works great. Most commonly we use it for cutting 3/4"thick x 6" 4140 flat bar into blanks for the mill. Smokes a bandsaw in time and we usually get 380+ pieces per saw blade.

    Sent from my Pixel 3 using Tapatalk

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    Quote Originally Posted by as9100d View Post
    We use one of those evolution hand saws and they cut through steel like it's butter.

    For cutting plate and other items, it works great. Most commonly we use it for cutting 3/4"thick x 6" 4140 flat bar into blanks for the mill. Smokes a bandsaw in time and we usually get 380+ pieces per saw blade.

    Sent from my Pixel 3 using Tapatalk
    Are you cutting the whole 3/4" in one go or do you have to do it in multiple passes? I like the idea of a single pass but the chips would start getting pretty long especially with the blade only sticking out ~3/4" from the base

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    Quote Originally Posted by cscott92 View Post
    Are you cutting the whole 3/4" in one go or do you have to do it in multiple passes? I like the idea of a single pass but the chips would start getting pretty long especially with the blade only sticking out ~3/4" from the base
    All in one pass chips aren't long, it makes a million "9 & 6's" hot as hell and beautiful blue color.



    Sent from my Pixel 3 using Tapatalk

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    Quote Originally Posted by as9100d View Post
    We use one of those evolution hand saws and they cut through steel like it's butter.

    For cutting plate and other items, it works great. Most commonly we use it for cutting 3/4"thick x 6" 4140 flat bar into blanks for the mill. Smokes a bandsaw in time and we usually get 380+ pieces per saw blade.

    Sent from my Pixel 3 using Tapatalk
    Is that not absolutely deafening?

    Sent from my SM-G973U using Tapatalk

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    Quote Originally Posted by cscott92 View Post
    Hi this is my first post here but I have been looking into buying a handheld Cold Saw for cutting structural steel onsite. I have some experience setting up CNC machines but not much experience with actually making parts on them but I'm learning.

    I'm a little confused by the specs for some of the hand held metal cutting saws. The 8" blades on these are spinning at 4400RPM (I think this is the no load speed) with 50 teeth on the blade. It looks like ~20ipm through 1/4" DOC is reasonable to expect from a saw like this so I'm cutting 1/11000 " per tooth with the tooth travelling at 9000 SFM. Does this greatly reduce the life of the blade or is this acceptable because each tooth is only cutting a hot chip for a short length of time and can cool off before the next cut? I mostly would use it on cheese grade structural steel.

    I never see recommended speeds for carbide near 9000SFM. Did I calculate something wrong or are these cutters just totally different for speeds?
    .
    1) i have a 5" and a 7" hand held metal cutting circular saws
    2) they do run slower than wood saw but still high sfpm
    3) they have stronger guarding and better at keeping metal dust
    from being inhaled by the motor
    4) 7" has high hp and need 2 hands to hold on to it
    5) they made for 3/8" or thinner metal. if you cut over 1/2" performance goes way way down, overheating and loosing saw teeth. if cutting flat plate works very good. just got to watch dropping
    a heavy plate on your feet.
    .
    the 5" saw i tried cheap wood saw blade made for occasional nails and it lasts less but still pretty good for a $5. blade. if cutting aluminum watch overheating and aluminum sticking to teeth
    .
    you really cannot cut thick material with them. no way cut solid 3/4" or thicker steel normally wont do it. but cutting 3/8 or thinner about 10x faster than regular saw, almost like cutting plywood

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    Quote Originally Posted by Cole2534 View Post
    Is that not absolutely deafening?

    Sent from my SM-G973U using Tapatalk
    Not sure. We wear PPE and it's fine.

    Sent from my Pixel 3 using Tapatalk

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    Quote Originally Posted by DMF_TomB View Post
    .
    1) i have a 5" and a 7" hand held metal cutting circular saws
    2) they do run slower than wood saw but still high sfpm
    3) they have stronger guarding and better at keeping metal dust
    from being inhaled by the motor
    4) 7" has high hp and need 2 hands to hold on to it
    5) they made for 3/8" or thinner metal. if you cut over 1/2" performance goes way way down, overheating and loosing saw teeth. if cutting flat plate works very good. just got to watch dropping
    a heavy plate on your feet.
    .
    the 5" saw i tried cheap wood saw blade made for occasional nails and it lasts less but still pretty good for a $5. blade. if cutting aluminum watch overheating and aluminum sticking to teeth
    .
    you really cannot cut thick material with them. no way cut solid 3/4" or thicker steel normally wont do it. but cutting 3/8 or thinner about 10x faster than regular saw, almost like cutting plywood
    I disagree, we cut 3/4" often

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    Quote Originally Posted by as9100d View Post
    I disagree, we cut 3/4" often

    Sent from my Pixel 3 using Tapatalk
    ,
    both my saws in the operator manuals both mention limits to cutting thickness. mine says 1/4" thick max steel recommended cutting thickness but i have cut 1/2" thick before over that and it has problems or a lot slower and harder on blade life if cutting thicker
    .
    if you cut steel in a miter chop saw with router speed control to slow down i find its a lot easier to cut 1/4 by 3" with the 1/4 up so blade cutting thinner metal, if flat and blade tries to cut 3" solid it tends to slow to 2% cutting rate and overheat blade and carbide comes off, brazing tends to not hold if it gets red hot. probably blade contact cutting % per revolution cannot be too high or teeth overheat. cutting 3/4" or thicker, teeth cutting longer per rev and teeth start to overheat cutting steel. blade life gets a lot shorter, not 10% shorter more like 95% shorter tool life

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    Quote Originally Posted by DMF_TomB View Post
    ,
    both my saws in the operator manuals both mention limits to cutting thickness. mine says 1/4" thick max steel recommended cutting thickness but i have cut 1/2" thick before over that and it has problems or a lot slower and harder on blade life if cutting thicker
    .
    if you cut steel in a miter chop saw with router speed control to slow down i find its a lot easier to cut 1/4 by 3" with the 1/4 up so blade cutting thinner metal, if flat and blade tries to cut 3" solid it tends to slow to 2% cutting rate and overheat blade and carbide comes off, brazing tends to not hold if it gets red hot
    Which blades and saw are you using? We use the 7" evolution with their hand saw.



    Sent from my Pixel 3 using Tapatalk

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    Quote Originally Posted by as9100d View Post
    Which blades and saw are you using? We use the 7" evolution with their hand saw.



    Sent from my Pixel 3 using Tapatalk
    .
    if carbide brazed on when carbide gets red hot the brazing wont hold and you loose teeth. when cutting thick material at like 5000 to 10,000 sfpm its to be expected if teeth get red hot.
    .
    it says right in the operator manuals a cutting thickness limit. i tried expensive and cheaper blades. not much difference. sure some better tool life but not a lot more tool life
    .
    actually construction wood blade for occasional cutting nails in wood works fairly well cutting 1/4" thick steel considering its a lot cheaper in price. cuts 1/4" to 3/8" thick steel plate like cutting thick plywood

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    Quote Originally Posted by DMF_TomB View Post
    .
    if carbide brazed on when carbide gets red hot the brazing wont hold and you loose teeth. when cutting thick material at like 5000 to 10,000 sfpm its to be expected if teeth get red hot.
    .
    it says right in the operator manuals a cutting thickness limit. i tried expensive and cheaper blades. not much difference. sure some better tool life but not a lot more tool life
    .
    actually construction wood blade for occasional cutting nails in wood works fairly well cutting 1/4" thick steel considering its a lot cheaper in price. cuts 1/4" to 3/8" thick steel plate like cutting thick plywood
    EVOSAW230 - 9 In. TCT Steel Fabrication Circular Saw

    Mine says 1/2" max but I assure you it cuts 3/4" just fine. I also misspoke, it's a 9" blade.




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    Quote Originally Posted by as9100d View Post
    EVOSAW230 - 9 In. TCT Steel Fabrication Circular Saw

    Mine says 1/2" max but I assure you it cuts 3/4" just fine. I also misspoke, it's a 9" blade.




    Sent from my Pixel 3 using Tapatalk
    sure mine says 1/4" max but i have cut 1/2" but its a lot harder to cut and blade life is shorter.
    .
    just saying cutting thick material especially if you got enough hp to maintain the sfpm or rpm the blade teeth will get hot. i notice missing teeth more if cutting thicker material. obviously if teeth brazed on and brazing melts at a red or orange heat if carbide gets that hot the teeth will come off

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    Quote Originally Posted by DMF_TomB View Post
    sure mine says 1/4" max but i have cut 1/2" but its a lot harder to cut and blade life is shorter.
    .
    just saying cutting thick material especially if you got enough hp to maintain the sfpm or rpm the blade teeth will get hot. i notice missing teeth more if cutting thicker material. obviously if teeth brazed on and brazing melts at a red or orange heat if carbide gets that hot the teeth will come off
    Maybe you should buy these evolution blades. 1/2" cuts no different than 3/16" with this saw. Just let the saw do the work.

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    Quote Originally Posted by as9100d View Post
    Maybe you should buy these evolution blades. 1/2" cuts no different than 3/16" with this saw. Just let the saw do the work.

    Sent from my Pixel 3 using Tapatalk
    .
    my 7" saw got enough hp i have to hold on with 2 hands.
    .
    my 5" saw has less hp and i can use 1 handed. if i got a small piece of 1/4 or 3/8" thick steel i prefer the smaller 5" saw and if i use wood blades made for occasional nails they are only $5. a blade and i can cut usually over 10 feet of steel 10x faster so its worth it to me. small saw often can hold metal with left hand and hold saw with right hand. bigger saw cannot do that, way too much hp


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