Band saws....? Cutting theory

[FlyFishn]

Ive done a lot of cutting on mild steel over the past couple years with projects and have thought about getting a band saw. Truth be told, all my power tools, aside from a cheap table saw for wood and a floor drill press, are hand tools at the moment. In time I hope to change that. That having been said - using hand power tools to cut a bunch(!!!) of steel is not pleasant. I ripped several hundred inches of 3/16" A36 with a reciprocating saw and Diablo carbide blade last summer. I hope I never have to do that again. Though, it is an example of a potential use for a band saw.

However, there seems to be a fairly large cut between "wood band saws" and "metal band saws" in that "wood band saws" are upright with a table where you feed the work through the cut and "metal band saws" are a fixed frame with clamped work and the whole band saw assembly gravity (or pneumatic) feeds through the clamped work.

In thinking of how I want to work with my projects - an upright saw with a table where I move the work through the saw is what I want. But that fits the category of a wood working band saw.

I don't like the idea of clamping the work piece and using a gravity fed saw. I suppose if I was cutting routine dimensional parts with square cuts that is one thing, but that is too limiting. I want to be able to cut angles, and possibly curves. Most tables have a keyway track for a miter gage. Why not make a vice mount that can lock in to that track to keep the piece passing straight through the blade?

Are there any drawbacks for setting up a wood band saw for metal duty?

I suppose one advantage to a properly set up "metal band saw" is the coolant/lube system. For repetitive dimensional cutting I could see that being about the only way to go, but I think the limits of the ability to work with the work piece during the cut might be a better advantage than needing to manually lube the cut.

 

[matthewsx]

Wood bandsaws operate at a much higher speed than metal ones.

 

[DavidR8]

I have a combination wood and metal cutting 14” bandsaw.
It has a series of pulleys and jackshafts to reduce the blade speed when cutting metal.
Works excellent.


Sent from my iPhone using Tapatalk

 

[C-Bag]

I have both horizontal and vertical bandsaws. Both inexpensive Harbor Freight. I got the horizontal first almost 40yrs ago. And the vertical 14” HF I got 7-8yrs ago. The horizontal can be stood up vertical and I used it like that until I got tired of wrestling with it. Like has been mentioned most often you find vertical bandsaws and they run at 3,000ft a min while I run mine 120ft min. Quit a difference. I don’t need coolant because I run slow. If you run like 300ft min then you will get into needing coolant. My vertical was a home made double reduction and can only run that speed and for me is perfect. It does what the horizontal can’t do like small odd parts because I made an air powered sled for it to feed parts.

 

[682bear]

You are describing the difference between horizontal and vertical bandsaws... there are vertical (upright) bandsaws for metal also... they are generally more expensive than wood cutting bandsaws.

Metal cutting bandsaws run much slower blade speeds and are generally more rigid. Wood cutting saws can be slowed down with some modifications, but many of them are not really rigid enough for anything but light cuts in metal.

If you attempt cutting metals at the blade speeds that wood cutting saws run, you will find that the blades don't last long at all.

-Bear

 

[jwmelvin]

So, you’re distinguishing vertical band saws from horizontal band saws.

The vertical band saw is like you have experienced with wood saws; the blade runs over the wheels and is straight between them. So the longest piece that one can cut is equal to the throat of the saw (about the wheel diameter). They are flexible in that one guides the work piece (using a fence or miter gauge if desired) and can cut curves to a degree. Vertical band saws may cut wood or metal; the blades differ and, more significantly, blade speed differs. Some saws are designed for both and use a gearbox to change speed ranges.

Horizontal band saws are different in that the blade twists between the wheels; by twisting the axis of the wheels, the cutting side of the blade can sit forward of the return side. Now there is no limit to the length of the work piece, as it passes in front of the returning blade. The limit is to the cross section of the work piece, which will depend on the wheel diameter, separation, and amount of twist. Horizontal band saws seem generally configured for metal but I don’t know enough about wood saws to say (maybe a slab mill uses a similar configuration?). Horizontal saws are super useful for cutting bar and tube down from its stock lengths (generally around 12-24 feet). It’s nice that they can run unattended.

I have had a small horizontal saw for some time and it’s been great. The little ones like mine (4x6 cross-section capacity) generally will allow one to use them like a vertical saw, with the head flipped up and resting on a stop. They come with small tables to facilitate such use but I’ve never installed mine, despite using my saw in the vertical position frequently. The vertical position is a little awkward, as the base of the saw is in your way, etc.

I recently got a 14” vertical combo saw, which has a gear box and belts to set a few speeds in the wood range and a few in the metal range. I’m very happy about it but I will continue to use my horizontal for cutting bar stock. The horizontal saws are very inexpensive (like $150 ish). Mine is from HF and has done well. Vertical saws are a lot more expensive and heavy. It is possible to convert a wood saw to metal, by reducing the speed. Usually that is done with a gearbox reducer.

 

[Dabbler]

@FlyFishn The only real difference between the wood bandsaw and wood/metal saws is the blade speed. You want between 100 and 200 SFPM... I use 80SFPM when cutting semi hardened tool steels like O1 or 40 Rc 4140.

That can be achieved by adding pulleys and/or gears - a lot of work, but it works well. Another approach is to replace the motor with a hefty 3Phase motor and a VFD. Nowadays the prices have come down enough to make it viable. My 18" metal bandsaw has a 1.5HP 3ph motor. vfd, and it has plenty of power for all the work I do.

 

[Shootymacshootface]

As mentioned, there are many routes to go on this. If you do decide to go double duty (wood and metal with the same saw) be sure to clean it out good after cutting wood. You might end up with a nice fire inside your machine.

 

[sycle1]

I bought a second hand 18' inch Rexon Taiwanese made vertical band saw, it says that it is a metal band saw, I thought this would be a good thing, but everytime I put a metal blade on it run the blade in nice and easy doing a slow run in.
Then when I do use it on mild steel it just dulls the 14 tpi bi steel blades real quick, so figure it must be running too fast for steel (maybe the motor has been upgraded from stock) so I tend to use it for wood and everything else but steel.
I use the little sabre band saw for steel I think you guys call em the Harbour Freight saw it seems to cut steel much better.

 

[Alcap]

Maybe this would be an option for you. I don have the floor space for a full size band saw so mounted a HF saw on a wooden stand . It can be removed quickly and throat plate switched back . The switch it locked ON and plugged into a remote ON OFF switch , it also has a thumb wheel speed control which comes in handy . Pictures are from the building it’s now in the garage