Cold saw vs. Dry saw vs. Abrasive saw.

[oughtsix]

I have a HF 14" abrasive chop saw and it does eventually get the job done. It has a heck of a wable no matter what blade it has on it. When I get sick of the HF or want to cut an accurate angle I put an abrasive blade in my 16" RedStar 7 1/2 hp radial arm saw which is a pleasure to cut with in comparison. I would use the Redstar (Circa 1947) all the time if it weren't for the mess. (I do a lot of woodworking).

Well today I finally bought a 3hp Walker Turner Radial arm saw (circa 1950's) to dedicate to metal cutting. The beast is about 700lbs and plenty beefy for cutting metal. Cragis list - $70. I'm going to have to pull wire from my phase converter to the saw to use it as is with an abrasive blade. The way the motor mounts on the Walker Turner is kind of unique for a RAS in that there is a plate that looks like it would be easy enough to mount any base mount motor on. I am kind of thinking of mounting a gear reduction motor in the 40rpm - 80rpm range and make a cold saw out of it. Another option would be to put a 1750 rpm motor on it and make it a Dry Saw. One thing I haven't worked out in my mind yet is how to mount a blade on a motor or gear box shaft?

Can anyone give me a comparison between a cold saw (40rpm - 100rpm) vs. a Dry saw (1000 rpm - 1700rpm)? I know the cold saw would be more work because I would have to come up with the coolant system... table, pump, tank, etc.

I am thinking of making an auto feed for the carriage on the WT RAS so I can start it and forget it like a bandsaw.

I am also debating what to use to clamp the work down with. I haven't found any suitable clamp on HF that I can adapt. I am considering making my own clamp out of a pair of pipe clamps. Or possibly just make my own material vise. Or I am really kind of considering using a magnetic chuck. I have an electrical magnetic chuck stowed in the attic the weighs a couple hundred pounds itself. One of my considerations is the WT RAS has 24" of carriage travel. I would like to make use of this and be able to clamp a fair sized piece of box steel.

Anyone care to offer any thoughts?

[eyeball engineer]

I dislike the dewalt dry saw, it throws out some knarly a$$ chips that like to stick in your clothes and skin, I like to use my porta band, some day I'll get a big band saw, if you have the know how I'd shoot for the cold saw, those are bitchin, but I don't know how you plan to make your own, I think there's more to it than slowing down the blade, I don't know for sure though

[oughtsix]

I have been researching cold saws and dry saws. From everything I have found a cold saw is low speed with High torque and coolant. Add a really beefy chassis and you have a cold saw. Auto feed seems like a good idea from everything I have read. It sounds like most dry saw problems come from feeding too fast... but I haven't every used one so I really don't know.

I am looking at a 2hp inline 12:1 gear reducer on E-bay for a very reasonable price. But 146rpm seems a little high for a cold saw from everything I have read.

For some reason most of the Cold saw blades I have come across have been high speed steel teeth instead of carbide... which seems a little funny to me.

[DSW]

I've never run a true cold saw so I can't help there.

I get this real cold feeling reading this however. I've seen enough incidents with general radial arm saws thru the years and seen a few guy attempts at cutting metal with improper tools like table saws, circular saws and a few other, where they really didn't quite get all the basics down before giving this a go. This just looks like a good chance to see high speed objects getting tossed around or large moving blades suddenly lurching forward to give me a warm fuzzy feeling about this. That saws old enough to be lacking many of the modern safety devises like anti-kickback pawls and some other things like safety shut downs that you might just want to slow down and start thinking about failure options.


Since keeping the stock clamped firmly down will be one of the big safety things with this I'll make a suggestion even though this screams "run away, run away" to me very loudly. I'd skip the bar clamp idea. If you don't get both equally tight, you are only using one and I've seen standard clamps loosen from vibration in the chops saws often enough. My 1st thought was a heavy machinists vise from a mill. Used machinery shops, and rebuild places sometimes have these that are not accurate enough to use in a mill any more. They are designed to rigidly hold steel for machining, which is what you really are doing. You've got a BIG rotary horizontal mill with a slotting cutter. The only question is if you want to spend the $100 or so to get one or if you can find one big enough. (I'm not sure what you define "fair sized piece of box steel" as.)

Lacking this, or if your a cheap F'k, I'd look at a wood workers vise. These are often rail guided with a single large turn screw and a large clamping surface. The rails usually will keep it straight so it will clamp evenly over the large area, and if you install a hex and crank like a machinist vice you can probably get some good leverage on an acme screw.

Remember 16" dia even at low RPMs will have quite a high surface speed and with a gear reduction tons of torque. This thing will want to climb and plow thru material in the blink of an eye. If you've ever seen someone mishandle even a small radial arm saw you'll understand.

Be careful. A cheap saw's not cheap, if it literally cost you an arm or a leg. At that point it's way too late to wish you'd spent thousands on this, instead of on medical costs that won't bring the parts back.

[joedirt1966]

Originally Posted by oughtsix

I am thinking of making an auto feed for the carriage on the WT RAS so I can start it and forget it like a bandsaw.

Anyone care to offer any thoughts?

Why not get a 4x6 bandsaw? They can be had for about $175.00 new (Harbor Freight with 20% off coupon). I sold my 14" Milwaukee abrassive saw, purchased the 4x6 bandsaw (below) and never looked back (no regrets). The bandsaw is quiet, has auto feed, and has a greater capacity than the 14" abrasive saws.

A first project could be a better stand. Add a coolant system later if you like. It's a very cheap but very effective cutting system.

[slodat]

I bought a used Grizzly 6.5 x 9.5 band saw with built in coolant system off of craigslist for $400 because the guy said he couldn't get a blade to track. I know Grizzly has parts available and a tech support line you can call so I bought it. It had made a handful of cuts when I got it. I bought a new bi-metal blade and went at aligning the blade using the instructions from the 4x6 bandsaw list. In an hour, I had a great working bandsaw. It cuts like a dream..

[ed mac]

i went with a grizzly saw too works great

[Jim Stabe]

I have a Porter Cable dry saw and I haven't used my Milwaukee abrasive saw since except for one piece of hardened stock and some rebar. As Eyeball stated it does throw nice blue chips around but I just slip on an old jacket and face shield and start cutting. If you let the saw do the cutting and not force it the cuts are beautiful, straight and fast. The only cold saw I ever used must have had a dull blade because it was painfully slow and you had to hand on the arm to get it to cut.

My $0.02

[Quick]

Save your money and don't buy the Dewalt cold saw. Just got one 3 weeks ago and returned it after 25 cuts. (2x2x1/8 tube steel) The vise is too light, the blades don't hold up well and if the vice slips and loses its grip (it will) it will jam and kiss the blade good by. The blades are $150 to $210 ea. A lot of band saws will do the job. If you have a lot of cutting, the wet cold saw is the way to go. I had one for years. Just not light enough to pack to the onsite jobs. (easily)

[oughtsix]

Originally Posted by DSW

I've never run a true cold saw so I can't help there.

I get this real cold feeling reading this however. I've seen enough incidents with general radial arm saws thru the years and seen a few guy attempts at cutting metal with improper tools like table saws, circular saws and a few other, where they really didn't quite get all the basics down before giving this a go. This just looks like a good chance to see high speed objects getting tossed around or large moving blades suddenly lurching forward to give me a warm fuzzy feeling about this. That saws old enough to be lacking many of the modern safety devises like anti-kickback pawls and some other things like safety shut downs that you might just want to slow down and start thinking about failure options.

Duly noted, appreciated and very much understood. I have been using radial arm saws since I was 6 (for 36 years now). My father has had a Delta turret arm RAS since before I was born. My first personal saw was a Craftsman RAS and I did a lot of woodworking with it. The Walker Turner is NOT a Craftsman RAS. It isn't even close. The motor on the Walker turner weighs more than the entire Craftsman RAS I owned way back when. The 3ph Walker was a great buy... it is not a cheap saw. The WT actually has the original kickback pawls for ripping which is a rare find in itself. I have a Powermatic cabinet saw that I use for ripping wood and never rip on my RAS anymore. As far as the saw being outdated it isn't. These old saws have something that you just can't get for under $10K today... huge mass! It is not a hobby saw it is an industrial saw. The motor on the Walker Turner easily weighs as much as 3 entire ~$400 dry saws, probably more. In my opinion and experience small radial arm saws are MUCH more dangerous than big industrial saws! Due to the mass of the carriage and power of the motor it is almost impossible to get a climb cut with a large saw. I have seen and even once had a climb cut on a Craftsman RAS. There just isn't the same rigidity in a light Craftsman RAS that there is in big old iron saws.

The WT RAS does have a toggle switch which I will be replacing with a starter (I have several 220v 3ph starters stashed that will be plenty overkill as far as current rating).

The motor on the Walker Turner spins at 3600rpm and the arbor is geared down to 3000rpm. I am really thinking of trying a 3hp rated VFD and running the motor at 30hz. = 1500rpm blade speed. I am a little concerned about loosing too much power running the motor at 1750 on the VFD? Looking at the shear mass of the motor my gut feeling is I should have plenty of power. (It isn't a Craftsman 3hp it is a 1950's 3ph 3hp!)

I don't understand why cold saws (~40rpm ~ 100rpm) use high speed steel instead of carbide blades? I know you can get a sharper edge on HSS but it doesn't seem like it would last nearly as long. I am wondering if the the gullet on the tooth has to be too big for brazed on carbide teeth so they use HSS instead allowing many more teeth?

Why don't they make "Dry" saws (~1500rpm) with coolant capabilities? Wouldn't adding coolant to a carbide blade greatly extend the blade live?

I considered the wood vise and kind of like the idea. I like the size of the jaws, the opening width and the quick release for quickly setting the jaw widths. I actually have a 10" wood vise on my wood bench. I will have to take a good look at it and see if I can come up with a good mounting option for the RAS.

One of the things I want to be able to do is cut an accurate angle. This is where I really love the RAS. But the Walker Turner RAS is a column pivot (opposed to the turret pivot on my Redstar which eventually became the Delta turret arm design). The problem this causes is the blade cut entry point changes a fair distance when the arm is set for at an angle. Not to much of a problem with wood and a wooden fence but I want any metal clamped as close to the cut entry point as possible. I am thinking of mounting the vise on a lateral track that can be locked down so I can quickly adjust the vise left or right depending on the miter angle. One of the things I HATE on all of the cheap chop saws I have used it the cheap vises. I agree... they seem very dangerous to me. This is part of the reason I decided to go with a RAS and put my own over sized vise on it.

I would love to find a reasonable price on an old milling vise. But most of the milling vises I have any familiarity with have a very limited opening width.

[oughtsix]

P,S, I very very very much considered going the band saw route. I am looking for accurate angles. I really like the pivoting head band saws so I can put a long piece of stock in and cut an angle without having to rotate the entire saw base to accommodate the stock in my shop. They aren't cheap though!

I will see how the radial arm saw works out... I very well might end up with a horizontal band saw... some day.

[RoadHammer]

Originally Posted by oughtsix

Why don't they make "Dry" saws (~1500rpm) with coolant capabilities? Wouldn't adding coolant to a carbide blade greatly extend the blade live?

Carbides like to be run bone-dry. Adding a little coolant to carbide will cause the carbide to crack and shatter. The exception to this is in CNC machining, where a flood of coolant is used due to high speeds and feeds that CNC machining centre is capable of generating.

How carbides were explained to me is that when a carbide tool makes contact with the workpiece being cut, the carbide "rubs off" the material being cut. This action is different to that of a high-speed steel tool that actually "shears" the material that the tool makes contact with.

[MoonRise]

A kick-back or climb in wood is scary and dangerous enough. A big (BIG!) no-thank-you to having that happen in metal!

Yes the big ol' industrial beast RAS is big and massive and all. But it was made to cut wood and similar, not steel!

How in the heck are you going to control the blade/motor/carriage when cutting some steel? Free-hand and try to hold on for the ride if (more like WHEN) a blade grabs and the motor/blade/carriage launches itself at you with multiple horsepower behind it?

And most anti-kickback pawls are made to dig into the wood surface when a kickback occurs (although there are some anti-kickback feed rollers that have the pawls internal to the rollers so that the 'grab' is in the roller and not from a pawl digging into the workpiece). And most anti-kickback (external tooth style) pawls won't do squat on a piece of steel except skid and skip over the surface.

Yeah, an abrasive chop saw is not a precision instrument. Sometimes it is Good-Enough. It is loud and kind of messy and not super precise, but it is pretty fast and can go through LOTS of things.


Metal-cutting band saw, or a cold cut saw, or a mill.

And some carbides on some materials may be made to cut dry, but other situations (carbide and the material being cut and the process/machines being used) may call for coolant/lubricant. So, It Depends.

[greenbuggy]

For the headache and safety issues being brought up I think that you'd be much better off just buying one used. I picked up a Haberle H300 at auction for $270, had to sink about $100 into new coolant, some misc parts and some cleanup but it works great now. I'm told its about a $6000 saw new.

I'm fairly certain that they use HSS blades so they can be resharpened easily. I know the Haberle dist in the US resharpens blades.

[Wicked_Welder]

Originally Posted by joedirt1966

Why not get a 4x6 bandsaw? They can be had for about $175.00 new (Harbor Freight with 20% off coupon). I sold my 14" Milwaukee abrassive saw, purchased the 4x6 bandsaw (below) and never looked back (no regrets). The bandsaw is quiet, has auto feed, and has a greater capacity than the 14" abrasive saws.

A first project could be a better stand. Add a coolant system later if you like. It's a very cheap but very effective cutting system.

Can you post some close up pictures of your cooling system, I have the same saw and have been trying to figure out the best was to go about installing a coolant system.

And for what its worth I love my bandsaw too; I have a 14 inch abrasive it is not acurate the blade walks so you never get that perfect up and down or angles cut, the band saw is the way to go.

[joedirt1966]

Wicked Welder,
I purchased all the parts for the coolant system and then never assembled it. I use the little 4x6 dry and mostly for small stock (angle, tubing, etc.). If you go to the 4x6 bandsaw forum at the following link you can look at different modifications to this saw (coolant systems, vises, stands, etc.). http://groups.yahoo.com/group/4x6ban...s/album/0/list

You can also google search 4x6 bandsaw modifications. There are some plans online for homemade coolant systems for these saws. (I don't have the link right now)

Grizzly has a complete coolant system for 149.00 at:
http://grizzly.com/products/7-Gallon...k-System/H8140

[oughtsix]

Originally Posted by MoonRise

A kick-back or climb in wood is scary and dangerous enough. A big (BIG!) no-thank-you to having that happen in metal!

How in the heck are you going to control the blade/motor/carriage when cutting some steel? Free-hand and try to hold on for the ride if (more like WHEN) a blade grabs and the motor/blade/carriage launches itself at you with multiple horsepower behind it?

Radial arm saws CAN'T kickback when used for cross cuts.

With the work piece clamped in a vise I can set the blade to intersect the work piece at pretty much any point on the blade I want. Anyone that has used an industrial radial arm saw for any length of time knows they don't climb cut unless they are just being very outrageously abused by an idiot. Small flimsy underpowered misaligned misused radial arm saws are where the dangers of climb cutting exist.

Like I said in my original post I am thinking of putting a power carriage feed on the saw. Not because I am worried about climb cuts but more because I am worried about burning out a dry blade by trying to cut too fast. From what I have read this is the leading cause of death for dry saw blades. I have a Parker Compumotor stepped controller and a screw drive stepper linear actuator I am thinking of using. I used this setup when I helped my father build his router table as a power router lift. It is a very sweet setup! And very versatile! It will be great for the saw carriage. I also like the option of clamping the work piece in securely and pressing go and then coming back when the cut is finished. My biggest weakness in cutting metal is getting too anxious and forcing a cut making too much heat. My cheap little Harbor Freight chopsaw HAS done a great job of teaching me patients though!

Originally Posted by MoonRise

And most anti-kickback pawls are made to dig into the wood surface when a kickback occurs (although there are some anti-kickback feed rollers that have the pawls internal to the rollers so that the 'grab' is in the roller and not from a pawl digging into the workpiece). And most anti-kickback (external tooth style) pawls won't do squat on a piece of steel except skid and skip over the surface.

I don't think you quite understand the function of a radial arm saw. The kick back pawls are only used when ripping a board. It is not even POSSIBLE to use use them when cross cutting. This is why they are usually missing on old saws. Most people remove them and loose them because they only use a radial arm saw for crosscutting. I hadn't imagined trying to rip a piece of 20' tubing in half lengthwise.

Originally Posted by MoonRise

Yes the big ol' industrial beast RAS is big and massive and all. But it was made to cut wood and similar, not steel!

Actually here is the manual for the saw I just purchased. If you look down at the bottom of the document you will see the ones they sold specifically for metal cutting. Virtually identical to their "wood saws".

http://www.owwm.com/pubs/808/2242.pdf

I have used an abrasive blade on my 16" Redstar radial arm saw quite a bit. I just hate doing that because it makes a big mess that I have to clean up before I can use it for woodworking. It is MUCH nicer than my harbor freight chop saw and quite a bit safer. And I actually get quite accurate cuts with it. Much better than my friend does on his 4x6.

Originally Posted by MoonRise

How in the heck are you going to control the blade/motor/carriage when cutting some steel? Free-hand and try to hold on for the ride if (more like WHEN) a blade grabs and the motor/blade/carriage launches itself at you with multiple horsepower behind it?

Controlling the carriage has never been a problem with an abrasive blade. But I don't have any experience with a dry saw blade in any kind of saw. Not enough horse power is dangerous. Radial arm saws only catch on a piece and try to climb cut when there isn't enough power to cut through the piece. A big ridged radial arm saw will stall the motor before it will climb cut. Even 7 1/2 hp power isn't enough to cause any kind of flexing in my Redstar which is what HAS to happen for a run away climb cut.

[oughtsix]

Scored a new 3hp rated Hitachi VFD with single phase input capability on ebay last night for $100 + $15 shipping. It will pay for itself in not having to run wire from my phase convertor to the saw.

It looks like I am going to be able to try out a dry saw blade on my Walker turner RAS sooner rather than later. I am thinking of buying a Morse Metal Devil 12" blade off ebay. I think I came across some favorable remarks about this blade on this site but I need to do a little more searching before plunking down my cash.

There are some Dewalt 12" dry saw blades on ebay also for around the same price. Anyone want to give me a push towards one blade over the other (Morse Metal Devil vs Dewalt)?

[CharleyL]

Double check the speed of that radial saw and make sure that the blade you buy is designed to run at that speed. The dry saws that I have experience with run at lower speeds than woodworking saws. You need to match the saw speed with the blade speed rating much closer when cutting metal. It won't cut well, if at all if it's turning too fast.

Charley

[Jack Olsen]

You need 1500 rpm or less for most metal cutting blades.

Morse is not the brand of the Metal Devil. It's Freud, which is an Italian outfit. I've really liked the Freud blades, but I know some guys have hated them.

[oughtsix]

[oughtsix]

The VFD (Variable frequency Drive) will allow me to slow the blade speed down to 1500rpm.

[viper522]

Originally Posted by slodat

In an hour, I had a great working bandsaw. It cuts like a dream..

Since it's fluid-cooled, would that be a wet dream?

[Jack Olsen]

Originally Posted by oughtsix

The VFD (Variable frequency Drive) will allow me to slow the blade speed down to 1500rpm.

Will that reduce the torque? I ask not because I know much of what I'm talking about, but because I tried using a router speed controller to slow down a miter saw to a speed appropriate for steel, and... it didn't work. The blade just stopped.

[oughtsix]

Originally Posted by Jack Olsen

Will that reduce the torque? I ask not because I know much of what I'm talking about, but because I tried using a router speed controller to slow down a miter saw to a speed appropriate for steel, and... it didn't work. The blade just stopped.

My father is an engineer and my understanding of what he told me is the torque from the motor should be the same even when it is running at half speed due to the VFD. BUT since the rpm is halved the horse power of the motor will be halved. Where as if I used a pulley or gear speed reduction system when the speed is halved the torque is doubled.

So my interpretation is trying to run this RAS as a Dry saw at 1500rpm via a VFD would be comparable to a 1.5hp dry saw. Which sounds a little iffy to me.

On a "split phase" motor i.e. 1740rpm the speed is halved and the torque is doubled electromagnetically(?) maintaining a comparable HP per amp of electricity used.