Ok, I bought a smaller stand mounted vertical wood bandsaw because it was cheap and because I thought I could make it better. Its not bad in most respects, and is quite robust and has a capacity of the throat that is usefull. The blade guides need some work but I can do that myself. Its a joy to use on aluminium because you can see and steer the blade for cutting out odd shapes.
Now I did some calculations and the current blade speed and its 1100fps, which is far far too high to cut steel, as you would expect.
From :-
http://www.sawing.com/html/CuttingChart.htm
I picked a typical speed I would like to use as my max top speed for metal of 350fpm. Now, Im not too worried about slowing down the speeds for the tougher stuff as the bandsaw motor I have picked up for it is a 1/2hp 3 phase unit, and I have a suitably sized vector-n 3phase->3phase variable frequency inverter, but would like to get the top speed needed in the region of the higher efficiency bit of the converter, so would someone be so good as to confirm I havent made a bobo in my calcuations?
They are as follows :-
350fpm max cutting surface speed.
350fpm is 5.833333333 fps
5.833333 is 1.77799 m/s
Diameter of bandsaw blade wheel is 252mm which in metres is 0.252m.
Circumfrence is Pi x D = 0.252m * 3.142857143 = 0.792m per revolution
To achieve wheel speed of 1.77799m/s , with a rolling diameter of 0.792M we need to spin the wheel at :-
1.77799/0.792 = 2.2449 revolutions per second.
2.2449rps = 135rpm
Motor spins at max speed of 1350rpm, 1300/135=10:1 reduction ratio.
Driven pulley is currently 51mm or 0.051m, which /10 = 5.1 mm shaft pulley size. Not good...
Running number again with a driven wheel diameter of 220mm.
0.220 /10 = 22mm driver, with a 220mm driven which looks more sensible.
Ill take some pics as the conversion takes place...
Now I did some calculations and the current blade speed and its 1100fps, which is far far too high to cut steel, as you would expect.
From :-
http://www.sawing.com/html/CuttingChart.htm
I picked a typical speed I would like to use as my max top speed for metal of 350fpm. Now, Im not too worried about slowing down the speeds for the tougher stuff as the bandsaw motor I have picked up for it is a 1/2hp 3 phase unit, and I have a suitably sized vector-n 3phase->3phase variable frequency inverter, but would like to get the top speed needed in the region of the higher efficiency bit of the converter, so would someone be so good as to confirm I havent made a bobo in my calcuations?
They are as follows :-
350fpm max cutting surface speed.
350fpm is 5.833333333 fps
5.833333 is 1.77799 m/s
Diameter of bandsaw blade wheel is 252mm which in metres is 0.252m.
Circumfrence is Pi x D = 0.252m * 3.142857143 = 0.792m per revolution
To achieve wheel speed of 1.77799m/s , with a rolling diameter of 0.792M we need to spin the wheel at :-
1.77799/0.792 = 2.2449 revolutions per second.
2.2449rps = 135rpm
Motor spins at max speed of 1350rpm, 1300/135=10:1 reduction ratio.
Driven pulley is currently 51mm or 0.051m, which /10 = 5.1 mm shaft pulley size. Not good...
Running number again with a driven wheel diameter of 220mm.
0.220 /10 = 22mm driver, with a 220mm driven which looks more sensible.
Ill take some pics as the conversion takes place...