Quasi-Coldsaws (1500 rpm 12in carbide cutoff saws)

So while I have no delusions they would be a replacement for a proper cold-saw or band saw what is the deal with these saws such as the Bosch GCD 12 JL which are running carbide at a surface speed drastically more than is normal. 1500 rpm and a 12 inch/305mm blade works out to 4700 fpm (1400 mpm). I am sure they are ok with aluminum but they are advertised for cutting steel which just seems crazy. Is this some sort of magic carbide with very high temperature attachment to the steel blade or are they just a good way to sell a bunch of very expensive replacement blades?

thanks

Luke

I think the very short contact each teeth has with the workpiece and high number of teeth help keeping the blade enough sharp for needed time. Single teeth doesn't spend much time doing actual cutting and doesn't remove much material.

If "cold" saw like that seems crazy you should check the handheld circular saws. 12mm steel plate seems to be reasonably fast to cut and even a 38x38 solid steel bar is possible.
YouTube

Yup, easy to do and the cut is indeed cold. I have a Makita cold chopper and a small battery saw with the same type of blade. I often take a piece of 1.5" pipe and slice off about 1/8", pick it up and toss it to an onlooker. It is cold.
Also have the Milwaukee hand held unit that I slice I beams to length with 2 passes. Often slice up half inch plate too. Little heat and almost never a spark.

There aint no free lunch. These are light, cheap, and go thru blades. But they are also light and cheap- neither of which a real cold saw is.
A real cold saw, running at 40 rpm, with a resharpenable blade is much better- but they cost 10 to 20 times as much.
You get what you pay for- these saws will work for light duty stuff, hobby use. If you try to run one all day long every day, it will disappoint. The blades can last a reasonable time, or, if you dont clamp tightly enough, lose teeth in a random way.

they do work. for how long depends on how you treat em, and how hard you need them to work.

This blade may what is referenced: https://www.amazon.com/gp/product/B...45F69&linkId=4b624a9f4c650ae693d044e84a426662

In this video by a chirpy young lady there is a demo of a chopsaw using these blades at ~8min mark cutting some stout iron.
YouTube
Cutting speed seems reasonably fast.

Looking into this I think the money and shop space is better spent towards a real cold saw. I am really mostly curious about the cutting speed physics.

These things are probably ok for cutting tubing for fabrication but not really for anything I am going to do. I have tried to get away with a small horizontal band-saw and it was, to put it politely, unacceptable. I am currently building a new workshop and once it is done I will get a proper (manual) cold saw with a coolant etc. I don't need huge capacity but I do need nice straight cuts and would rather spend the money up front on a proper tool than a bunch of expensive blades and mediocre cutting. Reading the more respectable company's copy (Makita and Bosch) they say these are for 3mm mild steel which is really not very helpful for anything other than tubing, angle etc. I am going to guess the heat gets too high in thicker cuts.

Ries said:

There aint no free lunch. These are light, cheap, and go thru blades. But they are also light and cheap- neither of which a real cold saw is.
A real cold saw, running at 40 rpm, with a resharpenable blade is much better- but they cost 10 to 20 times as much.
You get what you pay for- these saws will work for light duty stuff, hobby use. If you try to run one all day long every day, it will disappoint. The blades can last a reasonable time, or, if you dont clamp tightly enough, lose teeth in a random way.

they do work. for how long depends on how you treat em, and how hard you need them to work.

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I agree, but on the other hand if you happen to have one why not use it. I do a fair amount of prototyping and late last year was asked to make a number of units from small diameter aluminum square and round stock. At first I was using the bandsaw, but got tired of changing blades every day. To that end I started looking around for another way to cut aluminum stock. I've had an old Black & Decker chop saw sitting in the corner for years. About a month ago I dug it out. I put a 14" aluminum cutting blade and a speed control on it. I use it several times a day to cut small blanks for turning and milling.

It does an acceptable job and is inexpensive. If the prototypes lead to anything I will certainly replace the saw with something more durable. For now it works well enough to get the job done. If it dies tomorrow no loss.

Concerning durability comments on YouTube for other makes, Makita & DeWalt, suggest that at least some folks are using them for full time jobs on both tube and solid sections. Couple or three years and still going being typical comments. Obviously full time and actual material size are very moveable feasts but it does suggest that professional use isn't unreasonable. Realistically in the shop a £400 - £500 tool in very regular use is a consumable to be destroyed for the value of the work it does.

Blade life is certainly down to working with appropriate care and not forcing the cut.

For my money its the tool you get when you don't really know how much work you will need it to do. The real thing will last far better and, probably, be a little quicker but you need to have the work to justify the cost. If it took you 5 years to kill off one of those I'd seriously consider whether the real thing would be worth it. I'd rather have a proper cold saw than my £40 used'n scruffy abrasive saw but it gets used half a dozen times a year so it does well enough. Even if I do have to cart it outside.

For me work holding would be the big issue. Those vices are very sketchy.

Clive

I have a saw like that, a Makita LC1230. I have also been wondering about the cutting speed - 20 m/s to me sounds more like a grinder than a saw. Then again I don't do much metalworking.

I haven't used the saw much, so I can't give any reliable advice on blade longevity. It does cut solid bar, albeit noisily and with much vibration. (The universal motor does not help the noise.) The cuts are generally smooth and straight yet with visible saw marks. On most cuts the blade will push the last part of the cut downwards to form a burr. The saw lacks a stop to set cut length. Here are some materials I've tried:

Square tubing, 5 mm thick, 70x70 mm section, mild steel
With the standard blade. (Makita A-86723, 305x2.4x25.4 mm, 60 teeth.) 20 seconds a cut. Works fine.

Square 3/4 " mild steel bar
With a replacement steel cutting blade. (Makita B-09765, 305x2.1x25.4 mm, 60 teeth, 0° rake.) 10 seconds a cut. Works fine.

Ø 50 mm EN 1.4418, S165M, X4CrNiMo16-5-1 stainless
With a cermet tipped blade. (CMT 226.580.12, 305x?x25.4, 80 teeth.) CMT offers better pricing than Makita. 20 seconds per cut. I'm not sure the blade would last long cutting these.

Ø 100 mm aluminium 6082-T6
With the standard blade. Maybe 120 seconds per cut. Cut fine halfway through, then started gumming up. Would be better with some sort of coolant, or cut from multiple sides. I'd say the saw is too flimsy for this size stock.

Ø 52 mm SS2244-05 / 42CRMO4
With the standard blade. 20 seconds per cut. Chips come off glowing and turn black after cooling. New blade dull after 3 cuts. Fourth cut behaved like i was using an abrasive saw. Terrible idea on my part. I'm not sure about the temper on the stock I cut - a fresh HSS drill dulled after about 100 mm total in this material.

I also have a blade intended for aluminium (Makita B-09684, 305x2.4x30 mm, 100 teeth, -5° rake.), but I haven't used it yet. Do tell if you'd like to know how it performs.

I'd say the saw is good for tubing, okay for smaller diameter soft material (say up to Ø 50 mm aluminium and mild steel) and pretty bad for larger stock and harder materials. For larger size stock, I recon a saw blade like this mounted on a motor on an XZ slide (so as only to cut a portion of the stock per pass) would work well. 1400 rpm is just right for an induction motor.

As Clive mentions, the vices on these saws will make your Schaublin cry.

I think I am going to sell my coldsaw and buy one of these. I have the smaller hand held version circular saw that milwaukee makes (model 6370-21 I think). It has been amazing. I have cut all kinds of stuff 8" beams (had to cut the web with a torch), large channel, lots of plate, a 3/4" thick by 6' wide road plate, etc. All still on the same blade. The cut is way better than anything else I could use to cut the same stuff with. The hand held saw is amazing- I'd have never believed it. I think the chop saw would be much more handy than my cold saw. Partly because my cold saw will only cut up to 2" material, but it is also much more portable.

I have a couple of the makita version. They're fantastic for what they are. That said...

Do NOT cut aluminum with one. One cut and the $100 blade is trashed. Plus they do a bad job on that one cut. Had to break an employee of this very expensive habit. The blades have basically no chip clearance by design and an AlTiN type coating that sticks to aluminum.

They're great on profiles like square tubing, mediocre on solid sections, bad on thin stainless.

It's a handy tool.

nitromarsjipan said:

As Clive mentions, the vices on these saws will make your Schaublin cry.

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I was concerned with the vise quality and that is an excellent way put things nitromarsjipan (do I know you by the way, Norway isn't such a big place?)


Also needing to have a stock of different expensive blades for various materials is also a bit of a down side (both cost and needing to change them). These saws seem to be a replacement for abrasive cutoff saws in the fab shop for metal pipe, uni-strut, and thin steel bars rather than a cutoff proper machine shop tool. If I needed portablilty that might justify one of these are they are for sure better than other portable options.

I do have to wonder about those "cermet" blades. I don't think ceramic cutting materials would like that type of use and I really have to wonder if they are just another flavor of tungsten carbide with a fancy name. If they could handle the impact etc the heat wouldn't be an issue at least.
L

Comatose said:

I have a couple of the makita version. They're fantastic for what they are. That said...

Do NOT cut aluminum with one. One cut and the $100 blade is trashed. Plus they do a bad job on that one cut. Had to break an employee of this very expensive habit. The blades have basically no chip clearance by design and an AlTiN type coating that sticks to aluminum.

They're great on profiles like square tubing, mediocre on solid sections, bad on thin stainless.

It's a handy tool.

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I have the same saw and cut aluminum all the time with it, I just keep some WD40 handy to keep it from galling.
OP, I cut 2" 8620 rod with this saw with no problems and at a surprisingly fast rate.
The Makita has a good clamping vise with the quick release. Seemed better than the DeWalt which was the reason I choose it. Works good for plastics too.

I have a DeWalt all purpose chop saw I have had for at least 15 years. Have cut everything imaginable with that thing and just keeps working. The only thing I have found that really eats blades is SS. Other than that blades will last a long time if used with care. The blade that is in it now is about four years old.

whidbey said:

[..](do I know you by the way, Norway isn't such a big place?)

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It is tiny indeed, yet I'm not aware we've met. Where in Norway are you? I'm in Oslo. Perhaps we'll meet at a machine sale some time.

whidbey said:

Also needing to have a stock of different expensive blades for various materials is also a bit of a down side (both cost and needing to change them). [..]

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From what the others say it seems one can get a lot done with just the standard blade. I wonder whether it would be economical to have them reground when dull.

Before I bought the LC1230 I considered a used cold saw of about the same footprint (but weighing 100 kg instead of 20 kg). Prices were about the same. At that time I skipped it for want of space and transportation. I think it would be better suited for what I use the 1230 for. Even so it works okay.

I think you all are right in that the low speed cold saws are better for work at fixed locations, whereas the high speed ones are better for mobility.

whidbey said:

I do have to wonder about those "cermet" blades. I don't think ceramic cutting materials would like that type of use and I really have to wonder if they are just another flavor of tungsten carbide with a fancy name. [..]
L

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I recon you might be right, here's an excerpt of their product page:



industrial-circular-saw-blades-for-stainless-steel

They specify "ISO grade K30". Is that a tungsten carbide?

I noticed the blade in the picture is described as a "Low Speed Blade" on the other hand it has a speed rating of 5,900 rpm. I would think that 5,900 rpm is hardly low speed. Most of the newer chop/cold saws now run between 1,500 and 1,800 rpm. My ancient B&D runs at 3,800 rpm. I just installed a speed control to bring the rpm's down to 1,800.