Switch to change direction

[garage nut]

Perhaps my question got a bit lost in the "Power Hacksaw" Tread.
So here I go.

I have a 220V AC induction motor that allows me to change the direction by switching the a "BRIDGE" and the Capacitor internally. There is a sketch in the other tread.

I need some ideas as how to do this with a switch. What type of switch must I ask for and do I need to fit a second capacitor?or has somebody got a cheap DIY method.

I did go through the Electrical/Switches section.

[garage nut]

Here is an idea using 4 normal household change over switches. the type you use when 2 switches has to switch the same light.



Unfortunately you have to keep your wits about to know to switch all the switches before the POWER switch.

[pfredX1]

If you wire it right you can flip any switch any time you want to. Though when the motor is running the reversing switch does nothing because it is out of circuit then. It got taken out when the centrifugal switch opened. Forget all garage nut's diagrams but the one with the lavender background. We'll use that one. Let's say the top with the capacitor is the start winding, and the bottom labeled bridge is the run winding. Now let's further say that when A & C is hot the motor spins CW. Now if B & C are hot the motor spins CCW. You can do that with one DPST switch. Then just slap a switch on the hot coming in to turn the motor on, and off. That's all there is to it. You never move the capacitor in a motor either. It always stays on the start winding. It is absolutely stunning how much bad information there is on the Internet about this topic.

[ncollar]

Garage Nut
You could also get a rotary switch, like you find an older South Bend lathes. There are switches out there that are a lot cheaper than the $60 plus average. I am kind of puzzled about wanting to have the CW / CCW? I do not see any need for the CCW. You really need to go one direction.

By the way how is your saw doing?

[tonyfoale]

I'm with Nelson about only going one way. If you have a doubt about which way to rotate just do a test. Temporarily hard wire each way and test, decide which way is best and then permanently wire it that way.
Coincidentally today I wired a two way switch on my lathe, 2 hp 1 ph.

[garage nut]

I am also in the process of building a ring roller to roll the 60Dia x 2 walled pipes for my excosceletal car I am building. I do not have an additional motor for this machine so was planning to use the motor of the hacksaw for the roller. The roller will need forward and reverse...so that is my motivation to change the direction easily.

I am following the advice given to me to improve the saw. First thing is a stronger motor. I am going to use a 20mm bright mild steel shaft and 2 very inexpensive flange bearings. First stage to reduce the speed from 1400 RPM to 60is



The cast iron pulley and taper lock was cheaper than and ali blank and then I would still have had to bore it to 20mm. Do not have a boring bar at the moment and do not want to tackle another project whilst the saw is not fully sorted out.

Unfortunately had to start with a bender to bend 12 x 12 solid bar because I need to install some new burglarproofing. Very necessary here where I stay. downloaded the drawings so for now I am only going to have the bare basics and clamp the bender in my vice.



Just for info. The method to change the direction of the motor by swopping the Cap and the Bridge is the instructions received with the motor and it works. I just need it to happen with out the use of a 8mm nut driver.

Please show me how you wired your single phase motor.

[tonyfoale]

I am also in the process of building a ring roller to roll the 60Dia x 2 walled pipes for my excosceletal car I am building. I do not have an additional motor for this machine so was planning to use the motor of the hacksaw for the roller. The roller will need forward and reverse...so that is my motivation to change the direction easily.

OK, that makes sense. I really need to make a roller for exhaust pipes but I'll just fit a large wheel and do it manually. That saves on gym fees.

I am following the advice given to me to improve the saw.

I have done an analysis of the forces and moments of both the sliding type like Olderdan and the rocker type like yours. When I get a moment I'll write it up and post it here. It makes clear the layout that will give down force on the cutting stroke and up force on the return. It is very easy to design a saw which is far from optimum.

Please show me how you wired your single phase motor.

Will do.

[garage nut]

This is what it looks like in the control box of the motor. The bridge is in Yellow