[Rip VW]

A wood to metal cutting Band saw Project.


I am going to show you my Low buck method I used to convert an old Central Machinery 14 inch Wood Band saw to cut steel and aluminum and even Un-obtanium.

The main difference between the wood band saw and one to cut steel is the blade and blade speed. A wood Band saw blade travels much too fast to cut metal without tearing the blade up and getting things much too hot.

So the main task is to slow the blade speed way down to say 100 SFPM or whatever speed is called out for the material, thickness, and type of blade you are using.

To do this you would need a significant amount of reduction and it would make speed changes difficult. So I decided to try a variable speed DC treadmill Motor and was all set to use it along with some basic pulleys and belts to reduce speed more and increase torque.

I was lucky as a friend of mine stopped by one day and was eying some goodies I had in the shop. I asked him if he had anything to swap for them. He offered up a DC conveyor motor rated at Continuous duty. I dropped my treadmill motor and decided to use this conveyor DC motor instead.

Now that the drive train was figured out I had one more mod to do to the Saw and that was to add some chip brushes to keep chips from imbedding themselves into the rubber wheels. After mounting the brushes it was time to put together the drive train and mount it all up.

The chip brushes were some simple cheep 2 inch wood handled paint brushes I drilled a hole and used a 10/32 screw and nut and mounted the upper and lower as Shown in Figures 2 and 3.





DC Motor



This is the heart of the machine. I traded for this from a good friend. He told me it was off a commercial conveyer. I looked it up and saw it was only rated at 1/5 of an Hp. It also had a top speed of 1750 Rpm.

The motor control voltage was close to my treadmill motor controller so I hooked the motor up and I could not physically hold it from starting it was that powerful. This motor got the nod over my high speed DC treadmill motor.

The drive assembly is real simple. My belt tensioning method is also simple as I could make it.. The motor is bolted to two hinges which are bolted to the bottom of the machine. I used a large spring an attached it to the base of the motor. On the other end of the spring I hooked a short piece of light chain. The other end of the chain is bolted to the frame of the saw. I can add more tension or less tension if needed for a quiet run just by hooking the spring on a different chain link.


Reduction assembly


The heart of the reduction is a jack-shaft between the motor output and saw input. A 1 ½ inch pulley on the motor driving a 6 inch pulley attached to the jack-shaft slows the motor by about a 4 to 1 ratio at the jack-shaft output. The jack-shaft output turns a 1 1/2 pulley running to the lower saw wheel which is an 8 inch pulley. That ratio is 5.3 to 1. Add the variable speed from the DC motor and you are in like a bandit!

The jack-shaft is 5/8 and is supported on 2 pillow block bearings. The bearings mount to the old motor mount and makes adjust-ability easy as can be! I made my own custom keyed jack-shaft by taking a hunk of 3/4 inch round stock chucked it up in the lathe and turned it down to 5/8. I then set it up in the mill and cut a standard 1/4 key slot in the shaft to lock the two pulleys to the shaft.

The Saw came originally with a 6 inch top pulley stock so I swapped it out for an 8 inch pulley. I used the 6 inch pulley on my belt reduction unit and set the motor up with a 1 1/2 in pulley driving a 6 inch pulley and spinning the reduction shaft which has a 1 1/2 inch pulley driving an 8 inch top pulley. Using a larger pulley up top required a bit of dimpling of the belt cover. That dimpling was accomplished with a couple whacks with a large hammer.

I took the motor control box and mounted inside the saw chassis right next to the ON / OFF switch. I drilled a hole and mounted the speed control pot next to the switch. After all was done I took a surface tachometer and then ran the speed control pot through its paces. I then marked on the saw housing some rough speed marks on the dial rotation. I could run as slow as around 50 SFPM and if I remember 500 is near the top.

The saw works excellent and cuts 3/16 plate easy peasy.

Now on to the next project….

[S10xGN]

Nice work! Do you have to weld your own blades or are there some commercially available ones?

Russ

[Irelands child]

It's nice to be able to take a much lower cost wood working band saw and 'convert' it to be able to saw steel.

Good job. Thanks for your post

I do use my little 10" Craftsman to cut aluminum but the only time I tried steel just to see if it would, it cost me a blade

Dave W

[Rip VW]

I was real lucky in the Blade dept. If I remember correctly the blade is the same length as a wood blade at around 92 inches or something like that. It is a standard 14 inch band saw length The local Hardware carries all kinds of steel cutting blades in my length so I just swap blades. I been thinking about getting a welder for blades but I have to justify the cost and so far I haven't used much in the way of blades.

[astroracer]

Look at Enco or MSC for blades. They put them on sale a couple times a year. I use only bi-metal hard backed blades in both my 14" vertical or 4 x 6 horizontal.
Mark