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returning to turning

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thescoot:
as requested ... a couple of pics

thescoot:
Sorry guys. that was just to test if i could get the pictures up ok.o how i wish it was one of the £20 invertors off e bay! unfortunatly its a 5kw unit which is fully programable up to 5.5hp and was SLIGHTLY more than £20. Yes its inside a filltered box and is away from most of the dust. If you look at the picture you will notice a small controle above the motor. This is a remote which attatches with magnets and can be simply transfered between the two lathes depending on which i want to use.
I have only produced a couple of small bowls since i got things up and running which are to be fair not brilliant but im re- learning the craft after all.
Pic 1 is a bit of oak i had lying round just to try it out. Its about 700mm and the lathe turns it no bother at all. I have changed the floof bolts to a larger size as it did try to wakl a bit. it wont now!

John D Smith:
Hi Welcome to the Forum thanks for posting the photographs it made the interesting story come to life.

                                                                            Regards John

Bryan Milham:
Hi and welcome to the forum from me (Bryan).

So you're returning to wood turning by building your own 3Hp variable speed lathe that can throw 1200mm dia. Oh boy, this is going to be one to watch.

All I can ask is Post - Post and Post... I think that your out to produce some big pieces.

Woodcrafts:
Hi Scoot,
Welcome to the forum from another ex-engineer. I am most impressed by the conversion but, not wishing to be a 'downer' on the project, can I make some comments about the conversion. I have done several inverter/three phase conversions for other turners but we have always kept the pulley system intact, as that allows you to let the motor run at reasonable speed even though the wood is turning slowly. There are two reasons for this - the full power of the motor is only available at it's rated speed, even for vectored inverters, but more importantly, these motors rely on a shaft impeller to cool the motor. If the motor is run slowly for an extended time, it can overheat. One tip, I set all the lathes I have converted to have a minimum frequency of 5Hz, so that you know if the power is on by the motor moving. If it is left at zero there is still power going into the motor even though it is not turning, and that can burn it out. Even with it set at 5Hz, it should not be left at that speed for any length of time.
Having said that, there are a couple of advantages of these inverters which I am not sure if you/your friend are aware of. First the motor can be switched to run in reverse very easily. (I couldn't tell from the photos if the switch on the remote was for that purpose or not.) Reverse is very handy for sanding but if you do use this option, make sure the chuck/faceplate is locked onto the headstock. Large lumps of wood coming off the lathe are quite spectacular! And if you do have a fwd/rev switch, keep it separate from the run/stop switch. Too many conversions use three position switches, with off at the middle position.  I watched a demonstrator lean on top of the piece which he thought was stopping, when it was actually going to continue at full speed in reverse because he had knocked the switch past the central position.
Having mentioned wood coming off the lathe, another potential accident if the chuck/faceplate is not locked to the headstock, is the momentum of the wood unscrewing itself when you stop the motor. Make sure the braking in the inverter is set to 'free run', not DC braked. That will also prevent overheating if you start/ stop the lathe too often.
Second, but this only applies if you are turning very small spindles (didn't know if you intend to do that as the setup looks to be just for bowl turning), you can increase the frequency past the usual 50Hz, thereby taking the motor speed past its nominal speed. Actually you are probably already aware of this as I notice you say you are "very proud owner of a 3hp direct drive lathe with a fully variable speed range of 0 to 3000rpm" I assume you have used a 4 or 6 pole motor and got the speed up by increasing the maximum frequency.
Sorry about all of this but hope it helps.
Like the other posts, I look forward to seeing the end results of this machine.

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