generating own power

I think if it's one with belt drive & no fancy variable speed stuff, you should be OK. The internal inertia of the drive should smooth out the response to the not very sine waves. If it uses fancy electrickery to make variable speed with controllers, then I would be much more cautious as I think they assume a constant frequency input, which a genny would not be good at supplying.

My only concern for a basic motor system would be the startup current may possibly be so high it would stall a small genny.

Regards,

Richard.

A cheap auto-throttle gennie might be a problem.

You know another option might be a good general purpose inverter running off a leisure battery. You would get several hours running and recharge offline from the genny. They used to hate speed controllers but they are better now.

If the lathe is a conquest then it should be rectifying the AC so the frequency won't be important, but poor voltage regulation may be an issue.

Does it have a 12V output? You might get a more stable output sticking that through a hefty inverter.

Neil

Sounds like you have an Inverter type generator.
Some of these do not produce a good Sine wave so some things won't play well with them, mainly Digital Electronics, TV's and Computers. They are designed for Lighting and other resistive applications.
Your Lathe has a DC Motor, so the first thing it does with the Mains to drive the motor is rectify it. At that point it's DC and the generator makes no odds.
There will be a transformer and other bits to run the Speed electronics. As it's all analogue electronics you should have no issue there.
You may find that the Power Factor of your lathe is rather poor (getting technical) but your 800W Genny should easily drive your lathe without issue.

Don't forget to make sure the genny is earthed !

Alex.

What I have found through the years, is that whatever generator you use you have to allow at least 150% over the requirement. For instance you say the requirement is 800 Watts then then you need at least a 2.5 Kva generator to allow cool running and constant power. My 1500 Watt genny will barely run a 1000 Watt grass cutter but will run an 800 Watt strimmer. having in service had to couple up 27.5 Kva gennies to accomadate the loads that were required. When heavy loads were applied they really used to grunt and strain.

Clive

I have a very limited knowledge of electrical matters, but I do power my workshop with a petrol generator. I started off with a 3.2 KVA job, which powered a mini-lathe with speed controller, and lighting, without problems. However, an older 350-watt motor on a small mill stalled it, the starting current was so high. I now have a generator pretty well twice as powerful, which allows a small fan heater to be run in addition to the lathe. A more modern motor on the mill doesn't stall the bigger generator, either Do be aware, however, that "brewing your own" is an expensive alternative - you can easily get through five litres of petrol in a busy day.,

You could buy a Drummond flat bed lathe complete with treadle - the Royal Navy used them on submarines for many years!

Mars bars are more expensive than petrol calorie for calorie!

I can recommend watching the National Grid Status website , especially on the next cold winters day, when the wind isn't blowing. Add up what's available on the dials, takeaway 4GW ( Ferrybridge) , now start your generator !

Yes, we will all be following your route soon.

Generating your own costs about 4 X more than the mains, on a low loading a 27.5 Kva used about 9-10 Ltr per hour but under load that doubled. On a 6 week exercise the overall consumption was 9000 Ltrs.

Clive

Alex, I am a bit surprised by your comment regarding Inverter Generators and the quality of thier output. They are not designed for 'lighting and other resistive loads' - a standard generator will do that quite adequately. The Inverter generator rectifies the output from the alternator and then electronically produces a good quality sine wave suitable for powering digital equipment, computers, televisions etc. These days its fairly difficult to get a decent generator (depending on power level) that hasnt got an inverter output. cheers, Brian

I use a couple of generators- a little 2 stroke 800w (very nominal) and a 2.4 kw 4 stroke. The little one is really only good for battery charging or a hand drill. The 2.4 will run most things I use including my Chester 8" lathe- but with belt drive. I do not know how it will react with more sophisticated motors. It easily runs and starts the 1hp water pump. The 2.4 uses about 1 litre of petrol an hour on no load, I guess it's cheaper to run than the 2 stroke but never measured it.

If it IS an inverter type generator, it's worth bearing in mind that there are 2 types of inverter output - "true sinewave" and "quasi sinewave". The latter has amplitude +/-340Vdc nominal and a 70% duty cycle (so it has the same RMS value as a 240Vac sinewave). These aren't always happy driving capacitive / rectified loads. In this instance, the risk is that the inverter may keep dropping out or more seriously, may subject the input of the motor drive to overvoltages which might let the smoke out. I don't know what devices they have specified but it's not customary to build in a massive voltage margin as this costs money.

Having developed a variety of mains powered power electronics products including chargers and inverters, I can tell you that portable generators are often a cruel test of robustness in a way that many of the standard regulatory tests are not. The voltage waveforms are often poorly regulated, sometimes unstable and often far from sinusoidal - you might be horrified if you had a look. Bottom line is whether you think it's worth the risk finding out how your lathe gets on with what sounds like a cheap and nasty generator. Let us know how you get on!

Murray

Apologies if this is going too far off-topic:

Our son has bought a small plot of land, with a old static caravan, and is about to start building a cabin to replace the 'van. The site is completely 'off-Grid' so I am very interested in this discussion.

He recently acquired a [very] secondhand 400W wind turbine, which we had a look at last week

... The result of our investigation being that the alternator will probably get used elsewhere. ... One possibility being to build a Pedal-Power trainer/generator. It was sobering to realise that 400W is pretty serious cycling effort, and that the 'pay rate' for generating electricity this way would be about 15p per hour [when compared to Mains supply].

Comments and advice would be appreciated.

MichaelG.

Going seriously OT, Michael, can I suggest this (rather poorly scanned) pdf: **LINK** I have the original book, and really suggest it is worth getting a paper copy. Very good for 12V generation for not a lot. BTW, the site the PDF is on is Hugh Piggott's (the author) so I don't think he's breaking his own copyright by putting the scanned version of the web - did feel the need to check.

Regards,

Richard.

Many thanks for the link, Richard

MichaelG.