Turning Cone Shaped

[GeorgiePorgie]

Rather than dig up the old thread for just a link to Variable-diameter pulley (VDP) or Reeves drive.

http://www.youtube.com/watch?v=pbv7xEckNAc

How do I turn disc pullys like this on the Lathe? I suppose if me Lathe was CNC orientated there wouldn't be a problem but is this shape hard to accomplish on a manual Lathe?

I've done all the tweaking on the Mini-Lathe now and its time to put some better variable motor speed ie a better motor than the standard 500w jobby.

Thank yer very much.

 

[shenion]

If your compound has enough travel, then turning the tapers is not difficult.

No need for CNC, set the angle on the compound. I advance the cross slide, do a pass with the compound, then advance the cross slide and repeat.

 

[gordon stephenson]

My Boxford has a variable speed pulley arrangement ,but the belt is around 40mm wide.for the lighter duty as shown in the video you can maybe just modify a couple of standard V belt pulleys by splitting them in the centre into your design.

 

[FranV8]

Hmm, if you're upgrading the motor anyway, why not just go for a 3ph ac motor and a small vfd (variable frequency drive) - that takes a single phase input.

Common mod to small machines these days. Try homeworkshop.org

 

[shenion]

I have a 3P motor and VFD on my Atlas 12". Made a big difference in operation.

My Sherline came with a similar motor. It had a crappy speed control. At lower speeds it had no torque.

I replaced the controller with a real DC motor controller. It then had much better torque and the speed did not change with load.

Another option is to use a treadmill motor and controller. You might be able to use the controller with the existing motor.

 

[GeorgiePorgie]

Thanks for the input guys.

I've had this motor from new and its never been used,its an induction 1.3HP and its extremely quite hence me wanting to adapt it to the Mini-Lathe.

I worked it out that the conical speed disc would have to be about 4" to 5" in diameter,alas It was not possible to do a mod this way on the Lathe because of not enough clearence on the drive shaft and spindle.

 

[shenion]

1.3HP is way overkill for that size lathe.

My 12x36 has a 1/2HP and has no problems with power. The existing motor looks to be 1/2HP and should be more than adequate with a proper controller.

 

[brightspark]

1.3HP is way overkill for that size lathe.

My 12x36 has a 1/2HP and has no problems with power. The existing motor looks to be 1/2HP and should be more than adequate with a proper controller.

he probably means 1 third hp not 1.3hp

 

[GeorgiePorgie]

nope I mean 1.3HP,BS sure its an overkill but at least its got the oomph and quietness about it.

No sense in going out and buying another motor surely.

 

[brightspark]

nope I mean 1.3HP,BS sure its an overkill but at least its got the oomph and quietness about it.

No sense in going out and buying another motor surely.

i stand corrected theres nowt wrong with having a larger motor fitted if u allready have it id do the same

 

[Wedg1e]

My Boxford has a variable speed pulley arrangement ,but the belt is around 40mm wide.

Aha, another VSL owner Mine's a '78 5" in that two-tone cowpat colour-scheme, with the tacho in the centre of the speed control dial. Came out of a school in Retford.

I'd agree that 1.3HP is a bit... generous... for a mini-lathe: the Boxie runs a 1.5HP that looks like it could be used to spin the Earth on its axis!

 

[gordon stephenson]

Just to go up a notch, My Boxford came out of a school too in Guisborough, came fitted with a 3 phase motor,Only spare motor I had was a 2hp,so on it went.I had to turn the shaft down to size,which I did with only the fan cowling removed and put the complete motor between ctrs with the shaft spinning and motor body remaining stationary,worked a treat!!

 

[GeorgiePorgie]

Can anyone with a mini-lathe on the forum do this test for us.

Through the vid you will see the run out on the old bearings and on the new bearings.
I've done the mod of changing the bearings to the tapered type but I think I've found out what is causing the runout and I suspect that its a condition tomost if not all these lathes.

The test
http://www.youtube.com/watch?v=kKsC_KKU_8E

And step b step of the mod
http://www.youtube.com/watch?v=Vwkc68doF6U&feature=related

 

[Wedg1e]

Just to go up a notch, My Boxford came out of a school too in Guisborough, came fitted with a 3 phase motor,Only spare motor I had was a 2hp,so on it went.I had to turn the shaft down to size,which I did with only the fan cowling removed and put the complete motor between ctrs with the shaft spinning and motor body remaining stationary,worked a treat!!

Mine has the original humungous 3-phase still in it, I run it from a single-to-3-phase inverter, one that outputs 415v rather than the usual 220v.

I doubt you'd get the Boxford motor between centres on a Mini-lathe...

 

[gordon stephenson]

Wedg1e,
I still have the original 3phase motor if you ever need a spare, From memory I think it was about 3phase X 3/4hp,Not very long but quite a fat little casing.The 2hp I fitted in It's place was longer but a lump smaller diameter so I had to take off the louvred end plate and make another,letting the motor stick out about 4"
The machining was done using my older Boxford, V belt drive with the motor mounted behind the headstock.

 

[Wedg1e]

Wedg1e,
I still have the original 3phase motor if you ever need a spare, From memory I think it was about 3phase X 3/4hp,Not very long but quite a fat little casing.The 2hp I fitted in It's place was longer but a lump smaller diameter so I had to take off the louvred end plate and make another,letting the motor stick out about 4"
The machining was done using my older Boxford, V belt drive with the motor mounted behind the headstock.

My VSL has an extension piece to the cabinet at the headstock end to accommodate the double-ended spindle of the motor, I understand that earlier VSLs had the option of an electromagnetic brake that acted on the outboard end of the motor spindle, would be nice to have and I've occasionally wondered how I might go about creating such a setup from scratch.
If this pic works you'll get an idea how big this motor is...! I'll bear your spare in mind, thanks for that

 

[KemppiFrog]

Off to one side, most scooters have VSDs. I saw a bin of the bits at the local scrappy last week, belts included. If bigger power needed, get an old DAF transmission. Cheep as chips and can absorbe 50hp, so prob OK for a lathe...
KF

 

[ronan]

Hmm, if you're upgrading the motor anyway, why not just go for a 3ph ac motor and a small vfd (variable frequency drive) - that takes a single phase input.

Common mod to small machines these days. Try homeworkshop.org

+1 , i fitted a vfd to my colchester (5hp motor 3ph) and its great , working a large machine off a single phase supply.

 

[GeorgiePorgie]

Another option is to use a treadmill motor and controller

Thought about that but...I noticed the existing motor is 6000rpm and the treadmills are 4600rpm,thats a bit unusual for a 1hp(750w thereabout) considering the lathe motor is only 350w

 

[Rudi McAnichal]

Variable pulley drive with a large speed ratio needs a wide belt, and the wide belt has to be deep section to avoid collapse. Moving this stiff belt needs a lot of torque, especially at min/max ratios (ie minimum pulley diameter), and that is probably why such lathes tend to have large motors.

How do I know this? I was once posted to a remote workshop with a nice variable speed lathe of about 6” centre height, but no power other than a 1.25kVA Honda generator. (Overseas aid project, donor provided machine tools on time, but funds assigned for the main power supply went astray). The belt was so stiff that the little genny could not turn the lathe at all. After changing to a small fixed pulley on the motor shaft, with a LandRover fan belt, I had a single-speed lathe that was easily able to turn 3” shafts and face 10” discs, still using the Honda generator.