Running lathe off an Inverter

[chrism]

Hi Guys

Unfortunatly im limited my single phase at home and am looking for a lathe at the moment.

Im after a colchester student ideally, that sort of size anyway. I cant find anything single phase like that or anything big enough so im looking down the route of an inverter/converter.

Anyone had much luck with these? I have heard a lot of bad reports about them but have also heard newer rotary converters are pretty good? A colchester student has a 5hp motor so would i want an inverter that is much bigger than this or would a 5/5.5hp converter be ok?

That sort of size converter seems to be about £800-£1000 which i could spend a lot of times before im at the cost of getting 3 phase at home!

Any help appreciated, also if anyone knows of any colchester lathes...i want one!

Chris

[Mark]

Chris, I know of both a master and a student that are for sale if you are interested?

Also I am running my Milling machine using an inverter on my domestic supply, and it works very well. There is a chap who often advertises on www.homeworkshop.co.uk who often has second hand inverters for sale - that is where mine came from. He dosn't often have larger stuff (usually in the 2 or 3 HP range) but he might be worth a call.

The other option is someone like Newton-Tesla who may be able to spec up a suitable motor and inverter package to convert an existing machine? My lathe has one of their systems on it (came with it when I bought the lathe) and it is very good.

Cheers

Mark

[chrism]

Chris, I know of both a master and a student that are for sale if you are interested?

Also I am running my Milling machine using an inverter on my domestic supply, and it works very well. There is a chap who often advertises on www.homeworkshop.co.uk who often has second hand inverters for sale - that is where mine came from. He dosn't often have larger stuff (usually in the 2 or 3 HP range) but he might be worth a call.

The other option is someone like Newton-Tesla who may be able to spec up a suitable motor and inverter package to convert an existing machine? My lathe has one of their systems on it (came with it when I bought the lathe) and it is very good.

Cheers

Mark

Good to hear someone is having some luck with an inverter! Im unsure if i would want to go bigger so i could add more 3 phase tools to my collection in the future, for a couple of hundred quid extra it may be worth it.

Yes i would be interested in the lathes, im looking for something ideally with as many tools as possible and in good condidtion with little or no play. Where abouts are they located?

Thanks

[simonr]

I'm running my mill (9.5Hp) from a 4.5Hp inverter (Variable Frequency Drive).

The mill is a Bridgeport Interact CNC. The inverter is just a Siemens 'Simotion' drive - very similar to Mitsubishi and the like and not terribly expensive.

I figured that I would never have to use the full 9.5Hp in what I wanted to do. I never put much strain on my old 2.2Hp Bridgeport.

As it's turned out, that's not quite true. When you execute an 'M6' instruction which stops and retracts the tool - it uses the full power of the motor plus its brake to stop it dead - which then trips the cut-out on the inverter.

If I slow the spindle down to 100rpm (which it does more slowly) then issue the stop command - it stays happy.

Running a colchester or similar, I doubt you will need anything like 5hp. 2Hp would be plenty. When you consider that a Myford is 0.3Hp, on a machine that is 50% bigger - does it really need 15x the power?

The long and the short of it is that the inverter does not have to be higher power than the motor - just powerful enough to do what you need it to do.

Si

[Mark]

Similar to Si, I run my Mill with a 4HP motor on a 2HP inverter, which works OK so long as I ramp the speed up and down. It is a flat belt drive and dosn't have anything fancy like CNC involved, and works well for me.

The lathes are in West Sussex, near Horsham. I have some pictures, if you drop me a pm with an email address I will forward them on.

Cheers

Mark

[LandyManLuke]

The inverter is just a Siemens 'Simotion' drive

A Simotion motion controller is pretty expensive, usually used on servo position control/motion systems, a Sinamics G or Micromaster 4 inverter would be more suited to running a lathe.

Si, which drive do you have? it should be possible to set it up to bring the motor to a standstill at current limit, without tripping it out. most brakes are holding brakes and as such should come on at the end of a ramp-down. Is an 'M6' instruction comparable to an 'e-stop' situation, or a normal machine instruction?

Luke

[simonr]

Si, which drive do you have? it should be possible to set it up to bring the motor to a standstill at current limit, without tripping it out. most brakes are holding brakes and as such should come on at the end of a ramp-down. Is an 'M6' instruction comparable to an 'e-stop' situation, or a normal machine instruction?

You are right, but inside the machine, there is another Spindle inverter which rectifies the 3 phase then re-cobbles it back in to 3ph AC variable frequency to drive the spindle motor.

If you tell the inverter to do anything more than cut-out - the spindle inverter throws a wobbly then tells the computer which then reports a 'critical spindle fault' and needs to be re-started to clear it. Much easier just to re-set the trip and carry on.

M6 is different to an e-stop, but stops the spindle equally quickly. I guess because it's a production machine you don't want to be wasting time waiting for the spindle to stop for a tool change.

I can use M05 just to stop the spindle - but then you need to lock it manually to change the tool and more importantly remember to unlock it before you resume - otherwise you get a spindle fault. M06 seems to handle the lock/unlock itself.

Si

[TOR4x4]

An M6 command is an instruction for tool change. I wouldn't have thought it decellerates any quicker than an M5 command (spindle stop), but i'm not that familiar with Interacts.

If it has a spindle brake it is probably just for holding, not decellerating. Electricity is used to stop the motor (similar to DC injection).

Very often the power from decellerating is just sent off to some large resistors on top of the electrical panel and converted to heat.

[integerspin]

A converter can be put together for very little, completly free very possibly. It all depends what you want it to do.

I haven't yet used an inverter, I did wonder about motor stopping and starting. I can power tap with mill and lathe,

the lathe has to stop and reverse a considerable mass of gears and spindles.

What sort of Interact is that, before I bought my Matsuura I was looking at Interacts, The larger one I looked at had DC

motors? I am refitting my matssura with modern lectronics, the original inverter is the size of a fridge, it also has an

acre of heatsink which had a bank of cooling fans!!! At a wild guess it wasn't very efficient.

Few questions about inverters.

Is voltage an adjustable parameter, my spindle is 200V.

Is it possible to use the feedback from the spindle with them.

Can position be controled.