Differences between a metal and a wood band saw?
I looked at an older smallish Walker Turner vertical band saw today. Nice piece of cast-iron that has been nicely rebuilt. I wondered whether this saw would be suitable for light metalwork use, mainly on smaller aluminum parts, perhaps with a maximum of cutting aluminum bar for mill vise jaws.
I know that the speeds will need to be fixed (and, of course, the blades) but I have a pretty good selection of AC and DC motors with VFD controllers so I can solve this problem without difficulty.
Are there any major physical construction differences between metal and wood bandsaws?
Do metal bandsaws have the rubber tires on the drive wheels that are used in this bandsaw?
Any other factors?
If you can slow the saw down, I can't see any problem cutting light metals. The rubber tires on the wheels will get impregnated with chips, but that can be scraped of when needed. For light shop use it should work out fine. I have used a Delta band saw with a DC drive at home for years.
Metal bandsaws will often be rigged for coolant and might have blade brushes. The metal bandsaws I've seen all have the rubber tires on the wheels. Other than that at least to my eye they sure look like it comes down to blade speed. I've wondered if metal bandsaws would have better guides but I have no evidence of that. I also speculated that metal saws would be stouter so they could handler same HP on a slower blade, but I've looked at a some saws and couldn't really tell a stoutness difference. Who made it and when seems to matter a lot more than if it's metal or wood saw. A friend of mine has an old woodworking vert that is built like a tank.
I have a saw set up for both. It has a gearbox of about 30:1 reduction, step pulleys vary from there, Then shift out gearbox drive and the saw runs at wood speed (3000 SFM). Occaisionally I cut wood with the saw in metal speeds, its just slow.
This saw has 1hp motor, when cutting metal it never sounds like the motor loads up at all. The wheel speeds are only 20-40 RPM in metal mode. You will need some reduction gearing if slowing a motor down with a VFD to those rpms, as you will have little torque to cut with a normal fractional HP motor.
+1 for Tom's suggestion - seems like the large reduction and a different blade is the key elements
OP says he will be cutting aluminum. Some modest adjustment in speed (pulley size changes?) will make the wood saw a very respectable non-ferrous saw. Walker-Turners are heavy old dogs and cutting aluminum won't faze one even a little bit, assuming it is in even modestly good shape. But if you plan on cutting steel or iron, all bets are off!
As previously mentioned, you will be going from something like 3000 FPM (the speed you mentioned) or about 2000 FPM (good for general non-ferrous cutting) down to something in the range of 50 - 200 FPM. A VFD won't have the range to allow such speeds, at least not as a practical matter. If the VFD happens to let the motor run at a speed you like it will be running so slowly it will overheat. Adapting that saw to steel cutting will involve tinkering and adding speed-reducing drive components. In my opinion, if you are planning to cut steel with your saw, keep looking for a wood/metal version with the transmission as described above. The cost won't be significantly different and you will have something proven and ready to go. I have the 14" Delta wood/metal bandsaw and the little thing is a known steel gobbler. It's not too fast and you can't push it too hard but it will cut 1" plate all day long and not break a sweat. Walker-Turner, Parks, Powermatic and Wilton, among others, make (or, more precisely, made) similar small light duty metal cutters. Any of them should make you happy.
I have one of the Walker Turner 16's with gearbox.
I use mostly for wood and have the saw set up with a carbide blade and leave it at the higher speeds.
For for the odd aluminum cut I don't change a thing and it zips right through the 1/2" aluminum plate I have been using for building fixtures.
Mine is a great saw and sees use daily.
I also have one of the old Deltas 14's with the gearbox as mentioned above- another great saw.
I've had two dual-mode bandsaws, and both suggested the same or similar speeds for wood and aluminum.
My doall vertical cuts both. In spite of it's fancy VFD, it also has a gearbox, so as to have torque at both slow speeds (steel) and high speeds (aluminum, wood, etc.)
(Which I think agrees with what most others wrote.)
About 30 years ago, I designed a double reduction belt drive for a Craftsman 12" wood bandsaw with a cast aluminum frame. I could switch from wood/brass/aluminum speed to steel speed in half a minute. It would cut 1/2" steel quite well, using flex-back carbon steel blades. But after a few years I bought a used Powermatic wood/metal saw and sold the Craftsman. The main features I appreciate on the Powermatic are the cast iron table, more rigid frame and easy blade changing. The Craftsman saw had an aluminum table, which was not ideal for sawing steel.
The Craftsman saw would cut aluminum with no modifications beyond selecting a good blade. The common blades Sears sold were soft enough to sharpen with a file, and no good for anything but wood.
My all cast iron 14" Delta worked out well, (not to be confused with fast!) after I replaced the belt/pulley sytem that I started with on the 30:1 gearmotor change-out, with 40R chain and sprockets. No way to load the belt enough to to keep it from slipping under heavy cuts. Chain just hunkers down and cuts, with light loadings of side thrust on the shafts bearings, saw and motor.
Still cogitating on chain lube. I think I've rejected a Rube Goldberg system of a well around the lower sprocket and sheet metal shields to channel oil back to the well, for motorcycle sticky-lube.
Chain would not be my choice for wood cutting speeds.
My target was cutting steel, I'm sure that just pulley changes if needed, will work for non ferrous that's not too thick.
You still will not have a "real" metal cutting bandsaw, thumb feed becomes numb feed.
While I spend time pushing on a piece of steel, with nothing better to do with my mind, I scheme on weighted draw of part into blade, like real saws.
I have cut aluminum & brass on my wood bandsaw lots of times.
I use same blade and speed as I do for wood.
The first item I purchased after I bought the bandsaw was a Heinrich Bandsaw Vise, Prevents Numb thumb, and save's fingers.
Thank's Tom, those light Heinrich bandsaw vices are nice, even at $200+ and I have a similar drill press vice, (used at $20) that I have pressed into service but the entire reason for modifying the Delta was to saw intricate parts to quickly bring the metal to clean-up tolerance for machine finishing or just finishing on my Porter Cable belt grinder.
The dual weighted chain and serrated 90° fixed jaw devise that provides adjustable cutting pressure, very "steerable" control, and quick part resetting to complete a 360° workover, will be my next project for that saw. Vertical wooden handles will keep my hands safe and prevent numb-thumb. I'll start with just the jaws and handles, then if indicated, I'll probably add weighted, 1/16 aircraft cables for cutting pressure....an idle mind is the devils workshop....
I've become very "artistic" with my old Kysor-Johnson 10" by 18" model J horizontal over the years, quickly cutting a series of flats and Vee's to remove most of the waste and my Heinrich look-a-like (but larger and clumsier) vise on the vertical bandsaw, doesn't improve on that a lot, mainly because the K-J is so much faster than the Delta.
A downside to shaping with the K-J with Vee cuts, is holding the part on edge where anything less than about 1/2" material, with fine blade teeth, demands very gentle entry, followed by light down-feed to keep the beast from pulling it's own teeth. Pulling out just one, gives a running start at quickly snicking out a big gap. Those big blades could soon add up to a used, real metal vertical bandsaw's cost.