Author Topic: Variable speed conversion progress. (Read 13703 times)

Pete. · « **on:** January 08, 2012, 10:28:12 AM »

Been working on this all day yesterday. I had the pulleys and belt with this in mind but never got round to it. After my motor blew I decided to get it under way. Hopefully, I'll have it working today.
Photo is with the belt covers removed, I have to modify those to allow for the extra pulleys. What I've done is removed the step-pulleys and mounted them onto the bottom of the variable-speed pulley which itself is on a bearing shaft I have mounted on an extension plate bolted to the motor mount. The variable pulley distance is fixed but the whole assembly movs in and out on the original belt tensioning system to allow for the step-pulley belt to be adjusted.

All that's left to do is fit up a control system for the cone pulleys.

BillTodd · « **Reply #1 on:** January 08, 2012, 11:28:21 AM »

Neat

Is one of them sprung or are you going to couple the pair with a lever?

On the scooter one I fitted to my drill/mill, I had to swap the spring onto the driven pulley so the control was easier. I used a hollow intermediate shaft with a simple threaded wheel to squeeze the non-sprung pulley.

Pete. · « **Reply #2 on:** January 08, 2012, 11:53:21 AM »

One is sprung - I can fit them either way round as the hubs interchange.

What is it that makes changing the speed easier with the sprung cone on the motor Bill?

BillTodd · « **Reply #3 on:** January 08, 2012, 01:04:56 PM »

Quote from: Pete. on January 08, 2012, 11:53:21 AM

One is sprung - I can fit them either way round as the hubs interchange.

What is it that makes changing the speed easier with the sprung cone on the motor Bill?

My pulleys would only really fit well if the drive pulley (originally the one with the centrifugal weights) was fitted to the motor, and the originally sprung pulley on the intermediate shaft.

I couldn't see a way to control the spacings of the motor pulley - I looked at various lever mechanisms. So instead, I swapped the spring onto the motor pulley and used a pull rod, down inside the centre of the intermediate shaft, to control the spacing of the driven sheaves.

BTW Since the website pictures were taken, I have increased the tension of the spring and fixed the motor adjusting plate rigidly, to reduce vibration (you may find those rubber motor mount will also cause vibration/ resonance). The six screws that hold the extended motor shaft allow me to dial it in, to run as true as possible on my worn motor shaft. The nut on the extended shaft is a LHT to stop it undoing under load.

Bill

Pete. · « **Reply #4 on:** January 08, 2012, 01:12:35 PM »

Aah I see now, a matter of covenient fit rather than a problem it the operation. I just tried to swap mine and they are ever so slightly different - one slides nicely but the other binds, so I'll carry on as I am fror now and see how it goes.

My mounts are plastic - just spacers really, and I'm fitting a bar across the pulley tops to stop things bending under load.

BillTodd · « **Reply #5 on:** January 08, 2012, 01:35:25 PM »

Quote

My mounts are plastic - just spacers really, and I'm fitting a bar across the pulley tops to stop things bending under load.

Ah.

The bar's a good idea; I was going to fit one to mine... - it would also help to reduce vibration

The force required to close the sheaves isn't great (I'm using a standard deep groove bearing on the top of my pull rod) , so as long as your motor can stand a reasonable thrust, all you need to do is arrange something to push on the top sheave via a thrust bearing ...

and belt-swapping will be rare event

Pete. · « **Reply #6 on:** January 16, 2012, 07:51:58 PM »

Got it working now. I used an old cast iron flywheel I had kicking around for a speed adjuster. I can now get infinately variable speeds from 220-2550rpm.

Got to cut the guard about to accomodate the new variable drive then get it fitted up so I don't get caught up in the doings:

BillTodd · « **Reply #7 on:** January 17, 2012, 08:16:02 AM »

Terrific job Pete

What sort of variable range do you get ?

raynerd · « **Reply #8 on:** January 17, 2012, 08:38:43 AM »

Nice job pete but me being a thicky

, I don`t know how that speed adjuster works!! Can you explain?

Rob.Wilson · « **Reply #9 on:** January 17, 2012, 01:18:05 PM »

Nicely done Pete

Can i ask what the cone pulleys are off or were the can be bought ? as i may go down that route on my CNC build

Rob

Pete. · « **Reply #10 on:** January 17, 2012, 03:53:05 PM »

Quote from: BillTodd on January 17, 2012, 08:16:02 AM

Terrific job Pete

What sort of variable range do you get ?

Thanks Bill. On the top step pulley I get 220-1300rpm at the spindle, on the bottom (fastest) pulley I get 400-2550 spindle RPM. Middle is somewhere in between. It'd probably go a bit faster when it's warmed up fully. Swapping the belt is a very quick job on this mill because it has a nifty tensioner that jacks the motor back. I deliberately suspended all of the variable speed drive off the motor mount plate so I could still use that. Takes just a minute to adjust the belt.

Quote from: craynerd on January 17, 2012, 08:38:43 AM

Nice job pete but me being a thicky , I don`t know how that speed adjuster works!! Can you explain?

Chris it works by using cone shaped pulleys and a wide belt. The pulley on the right is adjusted by turning the handwheel on top, which pulls the lever at the bottom upwards closing the pulley and making the belt move to the outside. The pulley on the left is sprung-loaded and adjusts itself according to how you set the right one. You can see the diaphragm spring in both positions in the pics. The adjuster screw is actually a chopped up G-clamp from Wickes

Quote from: Rob.Wilson on January 17, 2012, 01:18:05 PM

Nicely done Pete

Can i ask what the cone pulleys are off or were the can be bought ? as i may go down that route on my CNC build

Rob

Rob the cone pulleys are simplabelt pulleys, these ones came off a Denford viceroy lather, Either a 280VS or 280 Synchro. They are also fitted to some wadkin stuff. Easier to find would be the pulleys Bill uses on his mill which is the cariable speed drive off a scooter. There are millions of those on the road right now.

Rob.Wilson · « **Reply #11 on:** January 17, 2012, 05:24:42 PM »

Thanks Pete

Now you come to mention it , i thought it looked the same as the set up on a spindle moulding machine i use to run as a lad

I will have a look into the scooter ones

Rob

BillTodd · « **Reply #12 on:** January 17, 2012, 05:51:41 PM »

The disadvantage of the scooter one is they will probably only give, like mine, a range of about 3:1 to 4:1 at best (it's all that is required for a small scooter transmission)

Pete's lathe set gives nearly 6:1 range, which is much more useful.

Bill

Rob.Wilson · « **Reply #13 on:** January 18, 2012, 12:52:51 PM »

Thanks Bill

Saves me wasting time looking for a scooter unit

,,,,,probably just have to make one

Rob

Noitoen · « **Reply #14 on:** January 18, 2012, 02:21:49 PM »

If you replace the adjusting handle with a wiper motor, you have push-button speed control

Pete. · « **Reply #15 on:** January 18, 2012, 04:42:16 PM »

I had thought about that, but decided to stick with the manual adjuster. On my lathe the speed is controlled with a lever which is really handy for facing and parting as you can bump up the speed in a moment, but I see no reason to have that feature on the mill.

One thing I do intend to do is mount a RPM readout. I have a tachometer but I don't want to keep getting it out of the box each time to check the speed.

NeoTech · « **Reply #16 on:** January 19, 2012, 03:15:03 AM »

After seeing these i had to google a bit.. Variable speed - pulleys.. that was a knew one for me. =)
Wouldnt that belt wear down faster due to the fact that the pulleys change size?!

Fergus OMore · « **Reply #17 on:** January 19, 2012, 03:36:23 AM »

Think 'Daf'cars

Tony Wells · « **Reply #18 on:** January 19, 2012, 03:52:45 AM »

It's one version of a CVT known as a Reeves drive, I believe:

http://en.wikipedia.org/wiki/Continuously_variable_transmission

It's available commercially on some machinery. I've had trouble with one on a Startrite bandsaw, and on Enco knee mills they tend to eat belts. I always assumed that the tension was too high on the Enco's, but it was just hours of use on the saw. It ended up being a single speed saw.

John Rudd · « **Reply #19 on:** January 19, 2012, 03:59:29 AM »

Quote from: Fergus OMore on January 19, 2012, 03:36:23 AM

Think 'Daf'cars

I remember them...The DAF 44 with variomatic speed.....

Fergus OMore · « **Reply #20 on:** January 19, 2012, 04:34:08 AM »

Actually, many of the earliest motor cycles had variable speed pulleys as opposed to gear boxes.
That was in the days when there was no kick start and they had running boards and one held the valve lifter up until the whole lot eventually fired up-----------and by then you were too tired to jump on.

crankshafter · « **Reply #21 on:** January 19, 2012, 05:11:00 AM »

hello all.
How about this: http://www.gokartsupply.com/comet.htm

Have a nice day

CS

BillTodd · « **Reply #22 on:** February 10, 2012, 03:18:55 PM »

I finally got around to making a better video of my scooter one:

Bill

Rob.Wilson · « **Reply #23 on:** February 10, 2012, 03:39:34 PM »

Hi Bill

I am really impressed with you M/D mods

i think i may do like wise to mine

Rob

BillTodd · « **Reply #24 on:** February 10, 2012, 04:11:54 PM »

Quote from: Rob.Wilson on February 10, 2012, 03:39:34 PM

Hi Bill

I am really impressed with you M/D mods i think i may do like wise to mine

Rob

Thanks Rob

Do the spindle brake mod first - you will not regret it

Bill

Rob.Wilson · « **Reply #25 on:** February 10, 2012, 04:44:49 PM »

Hi Bill

What are you using as a brake lining ?

Rob

BillTodd · « **Reply #26 on:** February 10, 2012, 05:47:48 PM »

A short length of the old V-belt:

Bill

Pete. · « **Reply #27 on:** February 10, 2012, 06:55:18 PM »

Nice Bill.

Your sounds a lot smoother than mine.

News:

Author Topic: Variable speed conversion progress. (Read 13703 times)

Rob.Wilson

Rob.Wilson

Rob.Wilson

Rob.Wilson

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