Varying motor speed

[Oakbear]

Hey folks,

After a days jigging my lathe around, i seem to finally have it set so it'll run speeds other than just 'really very fast' or 'really b****y fast!'. Woo!
However it is a single speed motor, and i've noticed some belt positions still cause a bit of vibration.
It would make sense if i could keep the belt in position and vary the motor speed.
So any way to do this? Some kind of restister, dimmer or reostat?
The cheaper the better....

 

[DaveL]

It would make sense if i could keep the belt in position and vary the motor speed.
So any way to do this? Some kind of restister, dimmer or reostat?
The cheaper the better....

Unfortunately the way to do this is not cheap.
I guess that you have a single phase induction motor on the lathe, most are. These motors synchronise to the frequency of the supply, the number of poles in the motor are a factor, the more poles the slower it goes, but you cannot change the number of poles.
The way most variable speed lathes are powered is with a 3 phase motor, driven with a variable frequency inverter, for some lathes there are upgrade kits but all of then could never be described as cheap. :x

 

[Oakbear]

Ah thankyou that explains it!

I thought there probably wasn't a cheap and easy solution, but thought it might be worth a bash.

Cheers!

 

[NickWelford]

The way most variable speed lathes are powered is with a 3 phase motor,

Mine has a DC motor with associated ellectronic gubbins on normal household supply.

 

[DaveL]

The way most variable speed lathes are powered is with a 3 phase motor,

Mine has a DC motor with associated ellectronic gubbins on normal household supply.

I did say most, I know DC motors are used on some, like yours, I don't think they are as common, so you have a high class drive. :wink:

 

[thomvic]

I converted my ancient Coronet Major with a £70 motor from Machine Mart and an inverter that I got for a tenner at a farm sale!

You can get all you require from www.drivesdirect.co.uk but as has been said before - it's not cheap!

Richard

 

[Boothie14]

i'm not sure if these would work,but there cheap and they look like they would do the job.
http://www.quasarelectronics.com/motor- ... ontrollers

 

[DaveL]

i'm not sure if these would work,but there cheap and they look like they would do the job.
http://www.quasarelectronics.com/motor- ... ontrollers

Well I don't think so, I looked at one of their units and here from their web site

This module can be used to control control 230Vac single-phase induction motors, lights, machinery pedals, digital control in panel lighting, etc… It is NOT suitable for use with synchronous AC motors or inductive loads like halogen or PL lamps, neon, etc..

I think this is misleading, induction motors are synchronous in their design.
The units they are selling will work with what I know as universal motors, basically brushed DC motors that run on AC or DC, like routers and electric drills, they are no use for a single phase induction motor as used on lots of small lathes.