Thread: A new drive shaft

Can you actually see wear on the shaft?
Some photos of any said wear might be helpful.
If not its unlikely to be the cause of the problem.

Have you tried disconnecting things etc
Eg running motor with out the belt
Running the motor without the band?

Hi Bob. Thanks, you have got me thinking. The pulley wobbles and the wear might be there and not shaft. I noticed the issue when I was putting everything back together but I was a bit to keen to get it all up and running

Do you know if the the motor pulley is the correct diameter? If it is too big it could be that the machine is spinning too fast which will cause vibration.

Hi Treecycle. Good question but no idea? How would I find out?

You can buy a $10 photo tachometer on fleabay and measure the speed of one of the wheels. Find a comparable sized one, new, on the web, and look at the m/min spec.

Eg. A BP 360 (wheel diameter is 360mm and a circumference of 1.13112 metres) had two wheel speeds; 370 and 800m/min

800/1.13112 = 707.36 RPM

OR

Use this link

PFERD rotational speed calculator

From memory, a typical woodworking bandsaw blade runs somewhere between 700 - 1200 metres per minute. This is the speed the blade itself cuts at, not to be confused with feed rates.

(Although I'll admit to having imbibed a bit this arvo... it's friday after all. so my figures may be off. Just sayin'... )

The thicker/denser the timber, the slower the blade should run, to prevent charring and general blade overheating. Many people assume that the lower speed on 2-speed BS's is for metal but they're wrong... it's generally still way too fast for most metals, even non-ferrous.

Anyways, let's say you're normally cutting in the 1"-4" thickness range, medium or light density timbers. So, you'd want the top blade speed to be around 1000 m/min.

Measure the driven BS wheel (the one blade sits on, not the pulley) and determine its' circumference. Either measure it directly or measure the diameter and multiply the result by 3.14 Near enough is good enough, these are "rule of thumb" measurements, not precision engineering.

The target RPM you want that wheel to be running at is the blade cutting speed you desire (1000 m/min) divided by the circumference.

OK, now let's look at the motor and see what RPM it runs at. Usually printed on a plate, somewhere.

Let's say (for convenience of example) that you want the BS wheel to run at 100rpm, while the motor is running at 2400rpm. You need to size your pulleys to give you a 2400:100 (24:1) reduction.

ie. You want the blade-side pulley to have a circumference that is 24 times larger than the circumference of the motor pulley.

Or, in your case, you want your motor pulley's circumference to be 1/24th of the blade-side pulley.


Mind you, a cheap remote tacho is a very handy thing to have. But I've found it's often best to crunch the numbers to get ball-park figures first, before spending pennies.

Here's an online calculator that you can use once you measure everything. Looking at your bandsaw it looks like about a 14" but the photos could be decptive. A basic 14" bandsaw is quoted as running at 800m/min so once you get your answer in feet/min you can put it in this calculator to work out your m/min. Keep adjusting your motor pulley diameter until you get the desired blade speed then compare that to what you currently have.

Thanks again all. 12" wheels. I will do some measuring asap.