56 replies to this topic

[Spider]

I know that different drives and AC or DC both have advantages and disadvantages. Certainly finding a disused Tread Mill as 68-86 has suggested is appealing if on a tight budged. It might needs a few mechanical speeds, eg, stepped pulleys or a gearbox to adequately cover the range of speeds needed (mine goes to 5000 RPM, but I'd suggest you'd want a minimum of 4000). While most of the 'action' happens below 2000 (Distributor) RPM with the advance mech, it's good to be able to check for bounce, sucking from higher speeds, dwell variation at high speeds and even that the rotor button has enough swipe angle at these higher speeds.

 

I know mine is DC, I can't recall if it's 12 or 24V, it used a PWM Controller. It tales back EMF from the motor if it over speeds and uses that to brake and tightly regulate it's speed.

 

I think the type of Slip Ring you've described is referred to as a Flat Face Slip Ring. You can find Slip Rings of Flat Face and Cylindrical design. in just about any Automotive Alternator and most are 2 pole

[68+86auto]

Treadmill motors go to about 6000rpm. I'm not sure of the minimum speed but it's quite low. I have one on a drill press but it has a reduction.

I say an AC motor simply because that generally means mains voltage. AC or DC it doesn't matter but you'll find that when dealing with motors in the 100s of watts, it's cheaper to use a higher voltage than 12v. Both the motors and controllers are cheaper. A 12v motor around 500w is going to need a controller capable of around 50a which is quite high and becomes expensive.

Just have a look around and see what you can find new/used for the right price.

Edited by 68+86auto, 23 November 2024 - 07:15 AM.

[Steam]

AC or DC (High voltage rock and roll ) doesnt make much differemce. If you are using a standard coil then you will need a battery anyway and PWM controllers are cheap enough on ebay.
Ac motors are more flexible but the speed controllers are more expensive, as are the motors.

[gaspen]

I started to sketch-up the machine in Sketch-up 

 

On TEMU I can find flanged disc in many sizes. One attaches to the motor's shaft, the upper I will slot to accept the dizzy's drive. Beetween the two flange I can install the degree wheel.

 

The motor I can find is a 24V/150W, but is also have 12V versions. These are small, cheap and reliable, as they said.

 

My Makita cordless drill  can easily rotate the dizzy so I think 150-200W will be enough.

 

Beetween the motor housing and the degree wheel I will have ~25mm room for the slip ring. A flat facedslip ring would be easier to setup.

 

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[gaspen]

AC or DC (High voltage rock and roll ) doesnt make much differemce. If you are using a standard coil then you will need a battery anyway and PWM controllers are cheap enough on ebay.
Ac motors are more flexible but the speed controllers are more expensive, as are the motors.

 

I have a small 12V power supply but it can be loaded with 2 Amps only. Last week I've put together a basic ignition system on the bench just to see if it works or not.

 

Of course I will need an other power supply for drive the motor but to blink a LED it could be enough

 

And as I wrote this I say to myself : why don't I use one 12V power supply for both task ?!

Edited by gaspen, 23 November 2024 - 04:39 PM.

[gaspen]

Use a mains (AC) powered motor and a speed controller.

Alternatively a common motor to find is a treadmill motor which can usually be found for free. They are 180V DC. If you don't mind messing with all the settings you can use the treadmill control panel. It will even regulate the speed. Some cheap basic treadmills have a simple controller with a potentiometer but they are much harder to find. A treadmill motor is way more than enough power but the price is perfect.

 

For the slip ring assembly, simply have a google search. I get a lot of results from Aliexpress which look like they would work. Example https://www.aliexpre...2xoCPfwQAvD_BwE

 

I have found the specs of this slip ring. It's rated for max. 1000 RPM

 

 

 

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Edited by gaspen, 23 November 2024 - 08:45 PM.

[Spider]

I have found the specs of this slip ring. It's rated for max. 1000 RPM

 

If you were to use a slip ring from an Automotive Alternator, there are generally rated to 12000 RPM +.

[gaspen]

 

I have found the specs of this slip ring. It's rated for max. 1000 RPM

 

If you were to use a slip ring from an Automotive Alternator, there are generally rated to 12000 RPM +.

 

 

Yes, I just have to find one which fits to my design.

 

Maybe this ? 

 

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[Spider]

Yes, I just have to find one which fits to my design.

 

Maybe this ? 

 

2a1ec19b30aad4809e3c5bb0d35278e0c74af1f5_original.jpeg

 

 

Yes, looks good to me, though I was thinking you could get it from a used alternator for next to no cost.
 

[gaspen]

 

Yes, I just have to find one which fits to my design.

 

Maybe this ? 

 

2a1ec19b30aad4809e3c5bb0d35278e0c74af1f5_original.jpeg

 

 

Yes, looks good to me, though I was thinking you could get it from a used alternator for next to no cost.
 

 

 

I don't have any used alternator, but I am working in a truck workshop where I can order parts from a local supplier. I found some cheap rings and brush boxes also, tomorrow I will order these.

 

Other idea that I'm thinking of to drive the degree wheel on half speed instead. I will measure the engine RPM from the coil so it would be easier to draw the curve. 

 

This complicates the design but I need some brainstorming 

 

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Edited by gaspen, 24 November 2024 - 06:06 PM.

[Spider]

There's nothing really wrong with your proposal, but it does unnecessarily add to the complexity of it.

 

I'm a great believer in KISS when designing and making stuff - Keep It Simple, Stupid.

 

And it'll keep you sharp when reading it. I would suggest doing it all in distributor angles and speeds.

[gaspen]

Okay, okay

 

This is what I've purchased for ~10USD

 

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