Lathe advice needed

[Burdekin]

Are you saying if I buy a new motor I need a VFD as well?? or is the VFD for speed control? I have a large gearbox and clutch so all I need is spinning motor....lol

A new single phase motor is 334. I was happy with the finish of my Raglan 5 inch lathe I was using till 5 years ago but this colchester is fitted with DRO and has better tooling etc.

The motor on the colchester is 240/415 3phase.

Whats most confusing is everyone seems to have different solutions to the same problem at varying prices.

What I really need is the person running a 5hp motor the CHEAPEST way and thats proving harder to identify.

I looked at that option and didn't go for it as I'm no electrician and didn't want to mess with the lathe electrics as you'll need to to convert it all to be powered off 240v. My head spun with the options so good luck.

 

[printcom]

what power is your lathe motor?/ Does it have a clutch??

The motor is rated at 3HP output, no clutch.
The motor is plated 415v 4.6/4.9amp so if my maths is right that equals
415*4.9*1.73 = 3518 watts. Approx 750 watts to an HP =4.69.
Not very efficient these ching chong motors.
I had a chat with the chap at Boost energy systems before I fell across the used one and he advised a 4KW converter.
Looking at a previous post yours is rated at 7.8amps = 5568watts
The way I see it is you need a 7.5Hp converter to be sure of running that thing or a 20HP + inverter. (Drives Direct recommended multiplying the output by 3 to cater for startup draw)
If you keep your eyes open you should be able to pick up a used 7.5hp converter for around £600 ish (just be prepared to change the run capacitors – not difficult or expensive) and that’s a lot cheaper than even a 7.5HP inverter.
I stand ready to be corrected by those who know a lot more than I do.

 

[Burdekin]

One thing with the Boost Energy converters is that you just round up one level, so my 3hp I just needed the 3kw (4hp) one. It has a 600% 10 second overload which does the trick for my stuff anyway as I've never had any issues with my lathe, you wouldn't know it's not normal 3ph power. I've read the info on the net about having to oversize rotary converters and asked the engineer at Boost Energy and he told me you could do that if you want, but from an engineering perspective there is no reason to do that with their product. Also my converter is not loud at all, it's just a hum next to the lathe, you can't hear it with the lathe going, you can talk right next to it without raising your voice and with the radio going I don't even notice it at all.

This is some info I wrote on another forum about my set-up:

Took some noise readings, 44db in my workshop with nothing running, 65/66db with converter only going and 80db at 800rpm with the lathe going. All readings taken in front of my lathe with the converter sitting at the end of the lathe. I am just pleased it works. 2500rpm with the 3 jaw chuck in takes 5 sec for full speed, probably 2 to 3 sec more than without the chuck on. It came down to 63db when the converter was placed at the side of the lathe on the timber plinth.

Apologies for sounding like a salesman but I just think this was the best result for me and I also think there is a lot of BS out there and you want to make the correct decision otherwise it could end up being a real pita.

 

[hareng]

Interesting but would like to see proof of spindle not slowing or convertor not moaning whilst a mediocre cut is put on using traverse.
If these are a quarter as good as you say, I would have thought the producers would have made a big song and dance over it.

Further to that its pretty damn too close a price I paid for my 1ph 240V to 400V+ 3ph 7.5kw inverter £900. Add postage on yours as well, were there same price.
Incidentally it takes minimum of 10secs more like 15 secs to startup on 2500rpm. Inverter don't trip on 7.5kw.

From memory last two inverters have had 150% for 10 secs. What that means is my older caput 4.5kw could have the effect of being 6.75kw up to 10 secs starting a 3hp motor No where near enough, well in excess of 9hp needed, hence the blown output £236 repair bill and three months.
Could well be the efficiency of the motor and have thought about changing.http://i1140.photobucket.com/albums/n563/Jonhareng/Harrison M300/Motorterminals.jpg

Theres only 5 options available:-
3ph installation, costly.
Static convertor
Rotary convertor
Digital inverter At this point all three deliver 3ph 400v+ and direct plug in jobby.
1ph 240v input inverter to 3ph 220V output often ran as a VFD

 

[graffian]

I made my own rotary and it runs everything I wire it to.
The two worst loads were probably a plasma and a 5hp
type 30 compressor, I had a 5hp single phase motor on the compressor
and it pulsed the lights of everyone on the same phase as us, it's fine on a
3phase motor run off the converter. Noise isn't a problem.

 

[Wedg1e]

Not sure if I already posted this, but I run my Boxford VSL lathe and one of my mills from the same VFD using a pair of contactors to switch between them.
The control circuits of both machines are configured to be mutually-exclusive, i.e. you can run one or the other but not both at the same time.
The Boxford has a suds pump that runs as long as the main motor is running, the load of the pump is so low that stopping and starting it at will seems to have no effect on the VFD.

 

[Burdekin]

Interesting but would like to see proof of spindle not slowing or convertor not moaning whilst a mediocre cut is put on using traverse.
If these are a quarter as good as you say, I would have thought the producers would have made a big song and dance over it.

Further to that its pretty damn too close a price I paid for my 1ph 240V to 400V+ 3ph 7.5kw inverter £900. Add postage on yours as well, were there same price.
Incidentally it takes minimum of 10secs more like 15 secs to startup on 2500rpm. Inverter don't trip on 7.5kw.

From memory last two inverters have had 150% for 10 secs. What that means is my older caput 4.5kw could have the effect of being 6.75kw up to 10 secs starting a 3hp motor No where near enough, well in excess of 9hp needed, hence the blown output £236 repair bill and three months.
Could well be the efficiency of the motor and have thought about changing.http://i1140.photobucket.com/albums/n563/Jonhareng/Harrison M300/Motorterminals.jpg

Theres only 5 options available:-
3ph installation, costly.
Static convertor
Rotary convertor
Digital inverter At this point all three deliver 3ph 400v+ and direct plug in jobby.
1ph 240v input inverter to 3ph 220V output often ran as a VFD

Is this proof enough for you???

http://www.youtube.com/watch?v=kg_Vz4PIgBo&feature=youtu.be

http://www.youtube.com/watch?v=qj8evGFNkhk&feature=youtu.be

http://www.youtube.com/watch?v=l0AjxnasjTk&feature=youtu.be

Some noise comparison charts, the converter isn't loud:

http://www.chem.purdue.edu/chemsafety/Training/PPETrain/dblevels.htm

http://www.gcaudio.com/resources/howtos/loudness.html

http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm

 

[hareng]

No you still haven't done what I have enquired about, put a cut on.

 

[Burdekin]

No you still haven't done what I have enquired about, put a cut on.

You asked for a "mediocre cut is put on using traverse."

What do you think this is?

http://www.youtube.com/watch?v=l0AjxnasjTk

If you want something more, you post something from your set-up, post a vid and the details and I'll copy it the best I can...

 

[printcom]

No you still haven't done what I have enquired about, put a cut on.

Maybe my memory if not as clear as it could be but i am sure I remember one the machinists on board telling me if the cut you are making slows the machine down - its too big.

But for the sake of clarity how big a cut are you referring to.

 

[graffian]

Not a cut but a bit of swarf.
Only 1/16", it was off a bit of 1/2" bar I was turning down to 3/8", deep.
Cut was at 2,500rpm and 7-1/2 thou feed[maximum my lathe can do], the cut was 10" long.
The swarf came off pretty hot, and pretty rapid. I get the same with
a cut 1/4 deep, problem is dealing with the hot swarf, I can't squirt enough coolant as it goes everywhere.

 

[Pete.]

You asked for a "mediocre cut is put on using traverse."

What do you think this is?

http://www.youtube.com/watch?v=l0AjxnasjTk

If you want something more, you post something from your set-up, post a vid and the details and I'll copy it the best I can...

It says a 3mm cut but the dial reads 3mm off the diameter which means the cut is actually only 1.5mm

 

[Hopefuldave]

Not a cut but a bit of swarf.
Only 1/16", it was off a bit of 1/2" bar I was turning down to 3/8", deep.
Cut was at 2,500rpm and 7-1/2 thou feed[maximum my lathe can do], the cut was 10" long.
The swarf came off pretty hot, and pretty rapid. I get the same with
a cut 1/4 deep, problem is dealing with the hot swarf, I can't squirt enough coolant as it goes everywhere.

Nice piece of swarf, but I think you should grind a chip breaker on the tool... If you do, you won't have the whole long string to cool, just the tool and workpiece?

 

[Shox Dr]

Nice piece of swarf, but I think you should grind a chip breaker on the tool... If you do, you won't have the whole long string to cool, just the tool and workpiece?

Not so easy when it's an insert type

 

[mike 109444]

And that sort of swarf was why they banned the brogue type safety shoes (the ones with little pattern holes just behind the toe area) Collage (union rep!) machining away and length of swarf like that screwed it's self into one of the holes and found his toe, ouch. If used correctly the tool should chip, with guard in place will sound like machine gun fire. You could try raising the tool height a tiny bit or clamp a strip of steel near the tip to force chipping.

 

[Wedg1e]

Cut was at 2,500rpm

2500rpm! I don't even get near that cutting plastics!

 

[graffian]

Nice piece of swarf, but I think you should grind a chip breaker on the tool... If you do, you won't have the whole long string to cool, just the tool and workpiece?

Not so easy when it's an insert type

Chips are not as spectacular as the hot wriggley snake;-)

 

[MrFluffy]

There is something magical about 3m long wriggling snakes. And its a damn sight easier to stuff six wriggles in the swarf bin than have to take the brush to the machine for 10 mins

 

[Pete.]

I once got a wriggly snake out the shed door and 30ft up to the house. Would have got in through the dining room but I bottled it thinking I might crash the chuck. turns out I was only half way down the cut

 

[graffian]

I once got a wriggly snake out the shed door and 30ft up to the house. Would have got in through the dining room but I bottled it thinking I might crash the chuck. turns out I was only half way down the cut

I am keep that wriggley snake to replace my mig liner with;-)