# Cold Cut Saw Lessons



## CalgaryPT (Nov 27, 2020)

I recently swapped out my older Makita 14" Abrasive cut saw for a Makita Cold Cut Saw Model LM-1230. I wasn't really intending on doing this right now. I kept thinking if my abrasive saws ever fails, I'll replace with a cold cut. That was years ago...but the abrasive just kept going. Turns out it was really well built and designed, and to be honest I love the smell and the sparks that come off it. That's bad in a shop my size I know. Even though I've removed almost everything flammable I can, sparks still shoot toward some shelves that have cardboard boxes on them (need to fix that).

Anyways, I waited a few weeks until I had used the new one a bit to post some things I've learned.

At first I was worried that the 12" capacity on the saw might limit me compared to the 14" abrasive. That turned out to be a non-issue. Largely I suspect this is because when I first bought the saw I only owned a small horizontal bandsaw. Since then I've upgraded to a larger model, which I use to cut a lot of large tubing. So what I used to use the abrasive saw for I no longer need. However, because the bandsaw is so much larger, I'm more reluctant to pull it out for smaller cuts—hence the cold cut saw.

The next thing I learned is that while there are next to no sparks, they can be noisier. Seems counterintuitive (and maybe it is blade dependent), but sometimes mid way through a cut it screeches horribly for a moment. Not a huge problem, but until you get used to it, you can get thrown off. I know some people recommend a paste lube on the blade, but I haven't tried that yet.

The cuts are very clean on the new saw, although not as square as I expected. However, they are weld-ready immediately—whereas the abrasive always needs some minor cleanup on the sander. In the fabrication world this is a good compromise. Any weld gap from a cold cut is easily bridged through the welding process, and the time saved on each cut on sanding makes it worthwhile. I think this is the main attraction of cold cut saws for those of us who were never bothered by the sparks, dust or noise of abrasives.

Something else to get used to is the shavings. Abrasives make dust. Cold cuts make miniature knife blades that can be weaponized. They throw (relatively cool) little metal shavings that go everywhere. You'll track them into your house. You definitely do not want to let your dog(s) in the shop when using this type of saw. With an abrasive I'd just let the dust fall and sweep it up later. But these shavings need to get picked up immediately or they will find themselves in your boots, carpet, pant cuffs, etc. There is a small collection drawer on the back of the saw for this, but it only collects about 50% I'd say. To combat this problem I built a tray underneath that slides in and out. It was a bit of a head scratcher because it needed to mount on a moveable plasma cutting rack that slides under my welding table. But I managed to design some moveable brackets that don't interfere with the table at all. The saw sits on top of the plasma rack and is bolted there most of the time.

Because it is a small shop with limited space I had to mount it in such a way that my slip roll acts as an in-feed table and the out-feed path goes between some machines already bolted to the welding table. The measurements of the Makita worked best for this. The Dewalt, which is in fact 14" and has a bigger motor, wouldn't have worked because of its measurements. Additionally, there are multiple complaints from some guys that the larger motor consistently trips 15A breakers. Re-wiring for 20A was a no go. I have no complaints with the Mikata's power; I've cut 3x3 angle 1/4" thick with no problem. The Makita is for steel and stainless only; the Dewalt can be used on AL. I suspect this is just a blade issue as the design and rake differs slightly on the two blades. But if you want to cut AL, do some research first.

All in all, I'd say the new saw is a 8 or 9 out of 10 and I am pretty happy. It's so much faster than abrasives, there is no finishing required for fabricators, the cut is cool to the touch, and of course there are almost no sparks.


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## Tom O (Nov 27, 2020)

I have a Evolution saw in the shop and have the same problem with chips a magnetic broom does wonders but a round 2 it that I’ve been thinking about is a funneling hood directing chips to a bucket something like the portable paint booth for modellers. I tried something like that on the shaper using ducting sheet metal with some success.


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## CalgaryPT (Nov 27, 2020)

Tom O said:


> I have a Evolution saw in the shop and have the same problem with chips a magnetic broom does wonders but a round 2 it that I’ve been thinking about is a funneling hood directing chips to a bucket something like the portable paint booth for modellers. I tried something like that on the shaper using ducting sheet metal with some success.


That's a good idea Tom. I've heard there is a non-flammable cloth material that is flexible enough to make a bag arrangement for underneath as well. Apparently even though it's fabric-like, sharp metal edges don't catch on it. I wish I could remember its name.


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## Brent H (Nov 27, 2020)

We have a Milwaukee cold cut saw on the ship and it can cut a lot of surprisingly thick  material with very good results.  The (mostly) non sparking is great for the ship as well.   I threw a cold cut blade on a very old Black and Decker 14" abrasive saw after I re-did the bearings and such and it runs fairly well too.  The RPM is lower and does not exceed the cold cut blades recommendations so I will see how long things last. 

You can get some pretty nice blades for various materials - some are pretty expensive though

The fence looks pretty good on your saw @CalgaryPT


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## kevin.decelles (Nov 27, 2020)

What is the primary difference in the process?  blade?  speed?  what makes cold-cut a cold-cut?  I could google this, yes, but you opened the door!


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## CalgaryPT (Nov 27, 2020)

Brent H said:


> You can get some pretty nice blades for various materials - some are pretty expensive though
> 
> @CalgaryPT


That was another reason why I went with the 12". The blades seem to be a lot cheaper.

BTW - I always meant to ask you Brent....how do you machine properly on a ship? Are there not movement issues that impact quality? Do you have special procedures? I know for example that in the military the machine shops inside Sea-Cans aren't suppose to be used within a certain radius of active combat for fear that artillery can throw off machining operations.


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## CalgaryPT (Nov 27, 2020)

kevin.decelles said:


> What is the primary difference in the process?  blade?  speed?  what makes cold-cut a cold-cut?  I could google this, yes, but you opened the door!


Speed - they turn at fraction of abrasives. The blade is carbide tipped and can be resharpened. It's called cold cut because you can literally touch the metal right after it has been cut.


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## Brent H (Nov 27, 2020)

Hold up a second - I guess I should change up what I said - we have a 'Dry Cut" saw  - so basically has a carbide (or other saw like) material on a saw like blade and it cuts through steel and other metals.  Runs around 3500 RPM.  The Abrasive saw will run about the same or higher RPM  a Cold Cut saw has a similar saw like blade but will use coolant to keep things going and runs about 1500 RPM


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## CalgaryPT (Nov 27, 2020)

Brent H said:


> Hold up a second - I guess I should change up what I said - we have a 'Dry Cut" saw  - so basically has a carbide (or other saw like) material on a saw like blade and it cuts through steel and other metals.  Runs around 3500 RPM.  The Abrasive saw will run about the same or higher RPM  a Cold Cut saw has a similar saw like blade but will use coolant to keep things going and runs about 1500 RPM


That's true. Technically cold cut uses coolant. But people just refer to ones with a carbide blade as cold cuts. You are correct.


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## Brent H (Nov 27, 2020)

@CalgaryPT : we machine stuff on the lathe etc provided the seas are not to bad  - like throwing you about - and the ice breaking is not heavy enough to throw off your finish or tolerance.  If necessary we make stuff happen as its needed  - bombs or no bombs - LOL 

For the most part if it is rough,  no one is working on something with added danger of things flying about.  The ship is always moving and deflecting so the lathe is very big with a short length - it is a 13 x 30 I think  - we used to have a 15 x 72 and it was horrible to work on  - typically 0.005 out of round in the slightest seas.

We can accomplish some pretty neat stuff - surprisingly - and lots of hand work - you get very adept with a grinder and files....


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## CalgaryPT (Nov 27, 2020)

That’s pretty interesting. No one thinks about this stuff unless you’ve been on a ship I guess. I saw a show on TV once about kitchen challenges at sea and it got me thinking I guess. Thanks.


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## Brent H (Nov 27, 2020)

@CalgaryPT : the only reason I guess I corrected myself is that you can buy blades that are "Cold Cut" specific and only rated for less than 1500 RPM and you can hurt yourself if you slip one of them babies on a 3500 RPM saw.   The Cut saw I have is 3500 RPM and the Dry cut blade I put on it is good for 4500 RPM  - during my "test" I lopped a piece of 3/4 thick x 6" long hunk of steel off and it cut great!  I was not expecting the results but it just whipped through it and yep - cool to the touch and I indeed shot so much shrapnel all over that I will be establishing some sort of barrier guards


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## Brent H (Nov 27, 2020)

There are lots of things that mess with you at sea for sure - nothing level, lots of curved surfaces, all the stuff is bolted down and lips and edges on things that really make life difficult.  Clamps are typically- "weld it here to the deck so we can hold it".  You get to see and work with a lot of cool materials and things - coatings, resins metals etc - lots of things to keep water out


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## CalgaryPT (Nov 27, 2020)

Brent H said:


> @CalgaryPT : the only reason I guess I corrected myself is that you can buy blades that are "Cold Cut" specific and only rated for less than 1500 RPM and you can hurt yourself if you slip one of them babies on a 3500 RPM saw.   The Cut saw I have is 3500 RPM and the Dry cut blade I put on it is good for 4500 RPM  - during my "test" I lopped a piece of 3/4 thick x 6" long hunk of steel off and it cut great!  I was not expecting the results but it just whipped through it and yep - cool to the touch and I indeed shot so much shrapnel all over that I will be establishing some sort of barrier guards


I wasn't going to get into it on this thread, but cold cuts can be much more dangerous as well, despite the lower RPM. There are vids on YouTube that explain it better than I can. But in a nutshell, never cut with a cold cut along the longest surface. For example, always cut flat bar vertically; always cut angle iron downward with the apex up, and use a block of wood to push large square tubing backwards so the blade attacks at the corner first (on some saws you can adjust the vice offset).

The rule of thumb is to have the fewest number of teeth on the material as possible. This is because there is much more torque with cold cuts. If too many teeth engage at once you can launch the stock out of the vice. With abrasives you just waste the blade and make a dust storm if you don't do this; but with cold cuts this can be a trip to the ER.


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## Brent H (Nov 27, 2020)

That would probably be another reason why someone putting that blade in a faster saw, cutting long ways could be in for a real crazy time - really good to know - Thanks @CalgaryPT 

Does the saw you have suffer from this - is this best practice with any type saw using the carbide blade?


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## CalgaryPT (Nov 27, 2020)

Brent H said:


> That would probably be another reason why someone putting that blade in a faster saw, cutting long ways could be in for a real crazy time - really good to know - Thanks @CalgaryPT
> 
> Does the saw you have suffer from this - is this best practice with any type saw using the carbide blade?


Yes, it does. The biggest safety section in the manual deals with this danger. Going from an abrasive to a cold cut I have to remember this rule. I'm going to put a warning tag on the saw to remind me until I unlearn that habit. On an abrasive if you do it wrong you realize it because it just doesn't seem to cut—or takes forever. Plus your wheel wears down FAST. But then you have a Homer Simpson moment, reorient your stock and it cuts. 

 You don't get a warning with a cold cut...so I need to retrain my brain.


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## Brent H (Nov 27, 2020)

Thank you very much for the intel - I will alter my practice as well for the thinner items and angle iron - Will also have a chat to the crew


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## kevin.decelles (Nov 27, 2020)

CalgaryPT said:


> On an abrasive if you do it wrong you realize it because it just doesn't seem to cut—or takes forever. Plus your wheel wears down FAST.



i don’t use my abrasive cutoff saw often but sometimes the cut just stalls (doesn’t progress), seems like the blade is toast ,!almost dull which I don’t understand. From your description this is what I experience . What do u believe is the root cause ? 


Sent from my iPhone using Tapatalk


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## CalgaryPT (Nov 27, 2020)

kevin.decelles said:


> i don’t use my abrasive cutoff saw often but sometimes the cut just stalls (doesn’t progress), seems like the blade is toast ,!almost dull which I don’t understand. From your description this is what I experience . What do u believe is the root cause ?
> 
> 
> Sent from my iPhone using Tapatalk


That's a great question. If I had to guess w/o experimenting I'd say it's a heat issue. Microscopically an abrasive wheel is millions of cutting planes. If you cut on the long edge, the amount of surface area causes a heat build up many times greater than cutting on the short edge. The heat doesn't get dissipated fast enough. The evidence for this is the amount of sparks and the glowing surface of the stock if you cut it this way.The heat decreases the efficiently of the abrasive, so instead of cutting you're almost friction welding (like on a lathe). Flip the piece over on its short plane and there's less heat due to the smaller surface area contacting the blade. Like magic it cuts now.

You can see the same principle at work if you use a grinding wheel to try to cut metal instead of a cutting (thin kerf) wheel in an angle grinder. Less surface area = less heat. Too much heat also contributes to disintegration of the abrasive, hence they wear out really fast.

That's my best guess.


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## CalgaryPT (Nov 27, 2020)

Brent H said:


> Thank you very much for the intel - I will alter my practice as well for the thinner items and angle iron - Will also have a chat to the crew


Here's a sample from the manual Brent:


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## cuslog (Nov 28, 2020)

kevin.decelles said:


> i don’t use my abrasive cutoff saw often but sometimes the cut just stalls (doesn’t progress), seems like the blade is toast ,!almost dull which I don’t understand. From your description this is what I experience . What do u believe is the root cause ?
> 
> 
> Sent from my iPhone using Tapatalk


I've always thought of it as "glazing" of the wheel. More than once, (out of frustration), I've raised the wheel and put it back into the cut with a bit of a "bang" and it seemed to break off a layer of the wheel and it started to cut again. Probably not one of the recommended procedures in the owners manual but it does seem to work sometimes.


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## Sailor (Nov 28, 2020)

Very good conversation, thanks. I’ve been looking at replacing my abrasive cutoff and this discussion has been very helpful.


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## CalgaryPT (Nov 28, 2020)

cuslog said:


> I've always thought of it as "glazing" of the wheel. More than once, (out of frustration), I've raised the wheel and put it back into the cut with a bit of a "bang" and it seemed to break off a layer of the wheel and it started to cut again. Probably not one of the recommended procedures in the owners manual but it does seem to work sometimes.


That's a really astute observation. It kind of hints at glazing (dulling of the cutting planes) or loading (where the particles bunch up between the abrasive). Almost like you are "dressing" (or in your case _Power_ dressing  ) your wheel.

In my first house decades ago I had a grinder the neighbour used to come over and use. He use to always give me the gears because I never dressed the wheel and the stock got too hot. He used to look at it and say I was "making glass."

I've since learned.


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## cuslog (Nov 28, 2020)

Abrasive cutoff saws are probably my least favorite method of cutting metal - had one for years and always dis-liked the way I could smell and even taste the dust, sparks etc. that they threw up. Bandsaw is still my favorite.
Grinding wheels certainly do have their place though, I have a shop built tool & cutter grinder of sorts and yes, a freshly dressed wheel is like a freshly sharpened tool - you don't really notice them "going away" but you sure do notice a freshly dressed one.


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## CalgaryPT (Nov 28, 2020)

cuslog said:


> ...always dis-liked the way I could smell and even taste the dust, sparks etc. that they threw up.


Yeah, I get that. 

Funny how personal this stuff can be. For me, I love the smell. It reminds me of when I was a child and we used to have the old Lionel model train engines. The carbon brushes gave off a unique smell and I am reminded of it ever time I use an abrasive.


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## YYCHM (Nov 28, 2020)

Brent H said:


> @CalgaryPT : we machine stuff on the lathe etc provided the seas are not to bad  - like throwing you about - and the ice breaking is not heavy enough to throw off your finish or tolerance.  If necessary we make stuff happen as its needed  - bombs or no bombs - LOL
> 
> For the most part if it is rough,  no one is working on something with added danger of things flying about.  The ship is always moving and deflecting so the lathe is very big with a short length - it is a 13 x 30 I think  - we used to have a 15 x 72 and it was horrible to work on  - typically 0.005 out of round in the slightest seas.
> 
> We can accomplish some pretty neat stuff - surprisingly - and lots of hand work - you get very adept with a grinder and files....



What kind of stuff would you have to make on the fly to keep the ship functional?


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## Brent H (Nov 29, 2020)

Well, probably 60% of the equipment is obsolete or super long lead time so we would make small shafts, bushings, repairs to bearing housings, typically small items that will get something going again.  This, however, has changed a lot over the past 30 years as the talent has died out....so sad.  The ambition in the younger generations is typically not there, unless it involves some sort of sit around computer thing.  

Liability has squashed fun big time.  You always have to be aware of what they will blame you for if something fails and you didn't install parts made by a supposed "professional".   The new stuff that we do get takes a lot of additional maintenance time as it is cheaply made and fails routinely - there are parts available and policies are to only use OEM so we suffer from the logistics side of things. 

The older stuff that seems to last may get the odd part made to keep it in service but in some ways that is shooting ourselves in the foot because the machine doesn't get life cycled properly and becomes more of a liability.

We are always fixing vibration related issues and corrosion issues - making sounding pipe plugs, brackets for stabilizing things, welding up leaky pipes etc 

We have had some neat adventures making custom lifting equipment to retrieve a plane that crashed through the ice, grappling arrangements to fish for lost buoys and moorings and custom tools for repairing the engines and gearboxes.


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## Chicken lights (Nov 29, 2020)

Brent H said:


> Well, probably 60% of the equipment is obsolete or super long lead time so we would make small shafts, bushings, repairs to bearing housings, typically small items that will get something going again.  This, however, has changed a lot over the past 30 years as the talent has died out....so sad.  The ambition in the younger generations is typically not there, unless it involves some sort of sit around computer thing.
> 
> Liability has squashed fun big time.  You always have to be aware of what they will blame you for if something fails and you didn't install parts made by a supposed "professional".   The new stuff that we do get takes a lot of additional maintenance time as it is cheaply made and fails routinely - there are parts available and policies are to only use OEM so we suffer from the logistics side of things.
> 
> ...


Have you had the chance to read Grey Seas Under by Farley Mowat? Fantastic book about a steam powered tug boat used as a salvage tug. 
Anyway the point is those guys often had no choice but to make do and jerry rig stuff to do the job or just to make it home. I think you’d like reading it


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## Janger (Nov 29, 2020)

kevin.decelles said:


> i don’t use my abrasive cutoff saw often but sometimes the cut just stalls (doesn’t progress), seems like the blade is toast ,!almost dull which I don’t understand. From your description this is what I experience . What do u believe is the root cause ?
> 
> 
> Sent from my iPhone using Tapatalk



I've noticed that too and thought it was some sort of work hardening or case hardening happening. @johnnielsen  Have you got an explanation ?


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## Janger (Nov 30, 2020)

Peter I think you have a "Dry cut saw". A cold cut saw is even slower - this one is 52 rpm. https://www.kmstools.com/king-industrial-12-slow-speed-cold-cut-saw-144824
And 4.5 HP! They cut through thick material pretty quick though and the swarf stays contained. Lots of money.


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## johnnielsen (Dec 1, 2020)

Janger said:


> I've noticed that too and thought it was some sort of work hardening or case hardening happening. @johnnielsen  Have you got an explanation ?



I used to experience that alot. It is not the material (mild steel) work hardening but the cutting wheel glazing on the cutting edge and sides. Sometimes you could actually see the wheel had tapered sides. This happens more so when you don't feed the wheel into the workpiece aggressively or you attempt to start your cut in a wide flat profile. The only way to break through the glaze was a series of hard momentary whacks of the spinning wheel into the cut. I switched to the thinnest wheel I could find, preferably with a small wobble so the wheel cut a slightly wider kerf than the thickness of the blade. I had success at the time mostly with Norton abrasive cutoff wheels while flexovit were too well balanced and SAIT wheels were useless on small (14" and under) cut off machines though they worked ok on my 10hp X 20" cutoff machine.


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## AlexJk (Dec 24, 2020)

Manuals can be confusing, so I am more than happy to read all your ideas and warnings. Now I have some insights why my work was taking a lifetime and why I was always stuck...


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## JohnnyTK (Dec 25, 2020)

Brent H said:


> Well, probably 60% of the equipment is obsolete or super long lead time so we would make small shafts, bushings, repairs to bearing housings, typically small items that will get something going again.  This, however, has changed a lot over the past 30 years as the talent has died out....so sad.  The ambition in the younger generations is typically not there, unless it involves some sort of sit around computer thing.
> 
> Liability has squashed fun big time.  You always have to be aware of what they will blame you for if something fails and you didn't install parts made by a supposed "professional".   The new stuff that we do get takes a lot of additional maintenance time as it is cheaply made and fails routinely - there are parts available and policies are to only use OEM so we suffer from the logistics side of things.
> 
> ...



Brent
This was just posted on what I assume is a Canadian Icebreaker & Buoy Tender.


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## Brent H (Dec 26, 2020)

@JohnnyTK : you are correct - that is the “other” (LOL) ice breaker/buoy tender on the Lakes and now quite a bit more in Quebec.  CCGS Griffon.


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