Generator for a mill?

[AlexBrown_1]

Hi all,
I posted a thread a while back about the electrical in my current (rented) house not playing well with my milling machine.

Some good suggestions including replacing the capacitors, which I duly did, and immediately the same problem.

I'm pretty annoyed about it now and I don't really want to waste another 50 odd quid and a bunch of time trying any more solutions because it really seems like the be all and end all is that the garage wiring isn't up to snuff to run the mill motor, and I'm not upgrading any wiring or fuses because that makes me liable for all sorts of business that I don't want to be liable for.

So - as an almost last resort, can a small, reasonably priced generator help here? The mill has two motors I believe around 2-3hp for one and 1/2 to 3/4 for the other (z axis drive). The mill is also single phase FYI)

Are quiet generators actually quiet? I don't have any experience really so what would they compare to? An idling car? Lawnmower? I'm not going for something that'll annoy the neighbours but I'm also gutted to not be able to use my pride and joy.

Thanks for any help!

 

[finyuk2005]

Hi all,
I posted a thread a while back about the electrical in my current (rented) house not playing well with my milling machine.

Some good suggestions including replacing the capacitors, which I duly did, and immediately the same problem.

I'm pretty annoyed about it now and I don't really want to waste another 50 odd quid and a bunch of time trying any more solutions because it really seems like the be all and end all is that the garage wiring isn't up to snuff to run the mill motor, and I'm not upgrading any wiring or fuses because that makes me liable for all sorts of business that I don't want to be liable for.

So - as an almost last resort, can a small, reasonably priced generator help here? The mill has two motors I believe around 2-3hp for one and 1/2 to 3/4 for the other (z axis drive). The mill is also single phase FYI)

Are quiet generators actually quiet? I don't have any experience really so what would they compare to? An idling car? Lawnmower? I'm not going for something that'll annoy the neighbours but I'm also gutted to not be able to use my pride and joy.

Thanks for any help!

that wee yanmar single cylinder diesel gennerators are great, (pramac 6000, stephill or similar) but even the "silent" ones are far from quiet!!! really bloody loud!
you would need to look for a 1500rpm one, but then you might end up with a generator that is too big for your needs, which actually isnt a good thing, a diesel generator needs to be worked pretty hard to keep them happy,
a smaller petrol one might be the best bet

 

[James1979]

that wee yanmar single cylinder diesel gennerators are great, (pramac 6000, stephill or similar) but even the "silent" ones are far from quiet!!! really bloody loud!
you would need to look for a 1500rpm one, but then you might end up with a generator that is too big for your needs, which actually isnt a good thing, a diesel generator needs to be worked pretty hard to keep them happy,
a smaller petrol one might be the best bet

You have a good sound proof enclosure

I’ve never met a generator that’s quiet in that sort of small/mid size I think he needs.

Small suitcase whisper ones are not too bad, or the big ole container ones aren’t bad either but anything in between is a dead loss.

I look after a Teksan backup unit. It’s nice and quiet but about the size of a small car. Overspecced for its need because of the sound proofing requirements. The more appropriate unit didn’t have sound proofing built in and it was cheaper to buy the bigger one with all the db certs than bugger about building sheds.

 

[GRW]

A 1ph motormight take 6x its running current to start (maybe 3-4x if its got a soft-start).
Plus the Mill connected means it starts under some load (even if its just the belts and drive kit).
So (without being able to measure the kit) as a guesstimate the start-up current might be (if 2hp) between say 6 to 12kva (mitigated by whatever the starting power factor is).
The above assumes you can start the biggest motor alone first, and then start the smaller feed motor 2nd. If they start together the transient will be rather higher again.

Bottom line... you'd have to be very lucky if something like any 1-cyl portable generator would start your mill

 

[finyuk2005]

You have a good sound proof enclosure

I’ve never met a generator that’s quiet in that sort of small/mid size I think he needs.

Small suitcase whisper ones are not too bad, or the big ole container ones aren’t bad either but anything in between is a dead loss.

I look after a Teksan backup unit. It’s nice and quiet but about the size of a small car. Overspecced for its need because of the sound proofing requirements. The more appropriate unit didn’t have sound proofing built in and it was cheaper to buy the bigger one with all the db certs than bugger about building sheds.

Ha ha thats true, all he needs is an old scrap car as a generator "shed", could pack it full of rockwool or something to absorb some noise

 

[8ob]

Is there no way of getting a decent feed to the shed from the consumer unit even if its temporary?

bob

 

[finyuk2005]

My uncles boat has a 3 cylinder beta marine genny, kubota engine, 1500rpm, i bet one of those in a proper enclosure would be fairly quiet as far as gennys go,
and as GRW says something 10kw+ would have the motor starting capabilities

 

[hotponyshoes]

I don't remember seeing the previous thread so not sure what problems you were having?

Usually the problem with shed power supplies is they are not man enough for the equipment but, in my experience, tend to trip out at the supply end.
I've seen a couple of volt drop issues but that's normally using extension leads from a normal 13a socket when the ring main is on a 32a breaker.

Basically, I'm saying you'd want to be sure a generator would sort the problem before buying one!
I've had a couple of bits of kit that trip out the mains but will run fine on a generator, most of those have had small earth faults and the generator does not seem to be as sensitive (safe??) as the mains breakers.

My 10kva 'silent running' diesel is probably equivalent to a ride-on lawn mower, ie not so high pitched as a push-along mower. But it's a long long way from silent.
At events I put it at the far end of a 10m lead with the exhaust facing away..
It's got a remote/electric start which is handy...

It uses diesel at about a litre an hour. Regardless of load.
It needs a service every 100hrs.
It was fairly expensive so I'd also be wary of plugging a known problematic machine into it.

A length of heavy duty cable might be a better investment. Certainly easier/nicer to use and a lot less mantainance.
If you find a length of used cable it's also a long term investment as the price of copper does not seem to be going down..

 

[AlexBrown_1]

Is there no way of getting a decent feed to the shed from the consumer unit even if its temporary?

bob

I can't think of how I would to be honest, everything seems to be on the lightest fuses possible. I'll look into it more though

 

[GRW]

The opening post suggests that the issue might be that the outbuilding housing the Milling Machine is fed by a poor feed (maybe only a 2.5mm cable or similar) ..... & the voltage drop over this supply when it has the start load of the mill - is the root cause.
It's something that could be measured at either end easily enough.
Being a rental and therefore I can see that upgrading might not be possible or agreeable.

 

[AlexBrown_1]

Seems like a generator isn't the right option then, thanks everyone. Glad I can ask here rather than wasting a few hundred quid on the wrong thing!

The right answer is to change the switch the fuse out at the mcb for a slower breaking fuse, but I just really don't want to touch anything I can be liable for in a rented property, even if I could switch it back without anyone knowing.

The garage wiring is fairly shoddy at best (as is the whole house) and I'm sure was only designed to run the door opener, not any heavy equipment so is probably the thinnest wire possible, but the mill wiring has been redone and tested and that's about all I can do.


It'll be a shame not to run it but these are the pitfalls of not owning your own place.

I have seen soft start boxes as an idea? But 60 odd quid for the cheapest with no guarantee it will work with the motor, and then I would need to build an enclosure for it

 

[brightspark]

The opening post suggests that the issue might be that the outbuilding housing the Milling Machine is fed by a poor feed (maybe only a 2.5mm cable or similar) ..... & the voltage drop over this supply when it has the start load of the mill - is the root cause.
It's something that could be measured at either end easily enough.
Being a rental and therefore I can see that upgrading might not be possible or agreeable.

a 16 amp c type would more than likely cure it for the inrush current . a new breaker probably only under 6 quid and an easy swap

 

[hotponyshoes]

It's not a lot of money to hire a generator to see how you get on with it..

 

[AlexBrown_1]

a 16 amp c type would more than likely cure it for the inrush current . a new breaker probably only under 6 quid and an easy swap

Absolutely, it's definitely what I would do in my own house, but without knowing the quality of the wiring there's just a bit of risk I can't justify.
While I disagree with a lot about the landlord and tenancy agreement, I can see how having tenants changing fuses in an mcb would be a no-no if and I think it's fairly justified. I guess it's easy to say that you know you would do it safely but I have to imagine if the shoe was on the other foot how I would feel.

 

[AlexBrown_1]

It's not a lot of money to hire a generator to see how you get on with it..

Didn't think of this before! An excellent idea

 

[GRW]

a 16 amp c type would more than likely cure it for the inrush current . a new breaker probably only under 6 quid and an easy swap

I can't recall the original post and the actual issue with the Mill.... I.e. does the supply just trip the MCB, or does the Mill also struggle to start/run?
The less sensitive MCB might do the trick.... but if the volts drop at the Mill on start demand is too much - an MCB alone won't be enough

 

[AlexBrown_1]

I can't recall the original post and the actual issue with the Mill.... I.e. does the supply just trip the MCB, or does the Mill also struggle to start/run?
The less sensitive MCB might do the trick.... but if the volts drop at the Mill on start demand is too much - an MCB alone won't be enough

Mill trips the mcb almost immediately, you can just see the spindle start to turn then click and the lights go out. Entire garage is on one 16a fuse.

Occasionally if lucky mill will run on the slowest setting but it's a 1/3 times sort of thing and would lead to very frustrating machining

 

[HughF]

We ran our workshop for ETERNITY on a Lister 6/1 start-o-matic - provided the generator is anyway half decent, it'll start an induction motor. Most recently we've run @sasquar 's new lathe (with a 2,2kW VFD doing the work) off a SILENT DIESEL GENERATOR (Hyundai Yanmar clone) and it didn't even notice.

I've also started 2kW compressors off the same generic 5.5kVa yanmar clones without issue.

Although you'd be much better off just doing your own electrics and getting the garage supply upgraded.

EDIT: I see you're in a rental... Worst case, you don't get your deposit back. Still cheaper than a generator.

 

[GRW]

Mill trips the mcb almost immediately, you can just see the spindle start to turn then click and the lights go out. Entire garage is on one 16a fuse.

Occasionally if lucky mill will run on the slowest setting but it's a 1/3 times sort of thing and would lead to very frustrating machining

Sounds encouraging then that a better breaker would cure it for a few quid and maybe 30-mins faffing

I'd be in the group saying "stuff it, change the MCB & keep schtum" tbh.

 

[Richiew]

It's unlikely any future tenant will be ragging the shed electrics like you are. Get it working and stop worrying. It's an upgrade.

They're welcome.