Variable speed

[GeorgiePorgie]

for single belt driven machines.

This is neat..no electronic circuitry.....
http://www.youtube.com/watch?v=pbv7xEckNAc

Can't figure out how its done? I know both pullys are minimising and maximising between pullys but how is the size change taking place?

And how about using a pillar drill as a Lathe for those small jobs.
http://www.youtube.com/watch?v=ZRWz-retwvM&NR=1

 

[hotrodder]

http://en.wikipedia.org/wiki/Continuously_variable_transmission#Variable-diameter_pulley_.28VDP.29_or_Reeves_drive

 

[GeorgiePorgie]

Thanks for that HR,something to ponder over in implementing on my mini-lathe?

 

[hotrodder]

It's used on some proper industrial kit so i don't see why not, not great detail but a Bridgeport mill for example... http://www.lathes.co.uk/bridgeport/page2.html

 

[graffian]

It's used on some proper industrial kit

Like a Daffodil;-)

 

[Shox Dr]

NSU cars used them

 

[knoba]

Like a Daffodil;-)

That was my first thought, too...

 

[vuego100]

Isn't that similar to how the variator/clutch type assembly works on scooters?

I fancy using my meddings pillar drill for a bit of milling but not sure it will take the side loads? even tho it is a bit of a beast.

 

[Wedg1e]

Boxford VSL lathe and VM30 milling machine work in the same way. Forcing the upper pulley halves together causes the belt to have to increase its diameter there, so the other 'end' of the belt forces the lower pulleys apart against spring tension, changing the ratio.

DAF Variomatic cars used it (who remembers them, became the Volvo 66 IIRC).

Bloody great on the lathe, you can fine-tune the cut in real-time.

 

[Pete.]

My lathe has that system. There is a lever on top of the headstock which you push left for faster or right for slower. The driven pulley is adjusted by the lever and the driving pulley is self-compensating via a diaphragm spring. Where it really shines if adjusting the speed on the fly when making facing/parting cuts, and slowing the lathe down when coming to the end of cutting a thread. You can cut at high speed then slow it right down to make it easy to retract.

I have also found a second unit to fit variable speed to my milling machine, but I haven't got around to it yet. Speed ratios range from 1:3 to 3:1.

 

[nodeward]

fiat punto auto has the same arrangement i the gear box(was rubbish!) but the idea is sound and in all honesty i dont know why it is not used more

 

[GeorgiePorgie]

I'll certainly contemplate on applying it to my Mini-Lathe but that would mean figuring out how to throw the Lathe in to reverse? as the electronc speed and reverse is on the controller board.

But the motor I intend to use is a new induction motor and very quiet but 1.5HP.
This came off an Aldi Bench Saw that I found for a fiver in a car booty,saw wasn't worth a blow on a ragmans trumpet but the motor was worth the fiver.

 

[the snooper]

Isn't that similar to how the variator/clutch type assembly works on scooters?

I fancy using my meddings pillar drill for a bit of milling but not sure it will take the side loads? even tho it is a bit of a beast.

thats exaclty what i was going to say
volvo also did an automatic type car and it was lablled varispeed

 

[julianthegypsy]

Check out a raglan mill, or lathe. They both used a variable speed pulley. The top of one pulley was linked to the bottom of the other one, so when you pulled the lever you moved them both. That way the tension was always constant and there was no need for a spring of any kind. Perfectly simple and neat.

 

[Wedg1e]

Isn't that similar to how the variator/clutch type assembly works on scooters?

I fancy using my meddings pillar drill for a bit of milling but not sure it will take the side loads? even tho it is a bit of a beast.

The biggest problem would probably be that the head will try to rotate around the column, bu99ering-up your cut. Guess how I know...

 

[Wedg1e]

I'll certainly contemplate on applying it to my Mini-Lathe but that would mean figuring out how to throw the Lathe in to reverse? as the electronc speed and reverse is on the controller board.

But the motor I intend to use is a new induction motor and very quiet but 1.5HP.

You can usually reverse a single-phase motor if you can access the windings. If it's cap start/run it's usually easier; on some motors it means finding the start and end of the various windings... not impossible but can be a fiddle.
Alternatively, would your electronic speed control not still work in reverse... just wire the motor to run permanently at full speed and use the belt-drive to vary it (or a combination of both!).