Pulley sizes

I have to decide what pulley size to get for the motor.

You want your bandsaw blade to go past the wood at a reasonable speed. This will depend on the speed of the motor,  the size of the pulleys and the size of the bandsaw wheels.

I made a spreadsheet to juggle the pulley sizes, blade speed and v-belt length:

Pulley size, blade speed and v-belt length calculator

The motor

I got a cheap 2hp motor from eBay. 

Shiny and motory.

2 HP Seems like it might do the job. Is that 50% duty cycle? Probably ok.

Actually, S3 50% means 

S3 = Intermittent periodic duty
Sequential, identical run and rest cycles with constant load. Temperature equilibrium is never reached. Starting current has little effect on temperature rise.

Hmm, not a continuous duty motor. Is it a problem, no idea. I guess, worst case, it might melt if I do any serious re-sawing.

I immediately stuck a plug on it and turned it on. Looking at the business end, it ran anti-clockwise. This would make the bandsaw blade go round the wrong way. Rather than mount it backwards, I looked into reversing it.

I had watched this video from Matthias:

http://woodgears.ca/motors/reversing.html

Which gave me hope. When I took the plastic box apart that housed the capacitor etc,  I could see that there were only 3 cables going into the body of the motor. This is thus a 'non reversible' motor.

The Red and black wires are thick and obviously the main winding, the white one is one end of the starter winding. The other end is inside the motor somewhere, connected to the other end of the black wire. (Deduced from a circuit diagram in Matthias's video). I need to bring that end of the starter winding out to be able to swap it with the white wire.


I took the front off the motor to investigate :

Front Off

It looked hopeful - I just had to find the end of the black wire. Trimming off some of the insulation and so on revealed:

Success

Slightly perturbed by there being 3 wires attached to the black wire, all the same gauge. I was expecting two. I guess that probably the main winding has two wires and the starter winding only one and they've doubled up on the main winding rather than use a thicker gauge, or something like that. To check, i unearthed the end of the red cable (the other end of the main winding) and that indeed had two wires attached.

Anyway I detached all the wires and used the multimeter to find the starter winding, soldered a new cable to it and routed that back to the box. Now I could swap the ends of the starter winding over and put everything back together.

A bit of kapton tape and a wire-tie to stop my solder joint vibrating loose

The original joints were brazed.  Hopefully my solder joints will be ok. I tied everything down; vibration would be the danger. We'll see how it goes. If anything goes wrong, at least I know how to fix it now. Worse-case scenario; one of the wires comes loose and the motor stops. Or doesn't start. The case is earthed, however there's not enough movement in anything for a cable to get as far as touching it anyway. Conclusion: fixed.

It works!

I felt good about myself. I was the king of induction motor reversing.

Startup

I decided that a bandsaw would be a good addition to my workshop. By wading through Matthias Wandel's youtube channel and realising that it was something I could actually make myself I decided to go ahead. Buying one is an option, but bang-for-buck, making one is the best option.

Before the bandsaw though, I need to sort my workshop out a bit. Stuff has been thrown in there for expediency's sake. It looks a bit like this at the moment:

Argghhh

Not a lot of efficient storage space and I have no work surface except my table saw. My current project to the right there is a mobile power-tool island thing on wheels for housing my welder and various power tools (belt sander, drills, etc) with a vice. I then need to put up some sort of work bench and I can start.

The table saw is also on wheels so I can swivel it round if I have something really long to cut on the cross-feed or whatever. In fact wheels will feature large in the new workshop.

So this is the bandsaw I'm looking at:

http://woodgears.ca/bandsaw/homemade.html

It's a 16" - plans at that address. (I later switched to his 20" bandsaw:  Me from 2 years in the future)