new Harrison L6 mk3

Andy,

Yeah, If you're pockets are deep enough, then a rotary phase converter that can output true 3 phase 415/440VAC from a single phase 220/240VAC input is the best solution all round.

Graham

This is sud wiring, the red green blue and white are the input, on the left..

So where do i look up these rotary converters?

Thanks

James

I take it doing it the rotary way, you dont need to do anything, cause it just tricks the lathe into being fed 3 phase?

I suppose the 2 speed is still just controlled from the fron panel?

Thanks

James

So is it a case of just calling drives direct tomoz?

James

James, it depends on your budget. I was shocked at the current price of one of these Digital Convertors. I remember thinking very hard when I bought mine a few years ago, it was about three or four times the cost of the cheaper inverters at the time and in the end I plumped for the expensive route. I think the cost is in the same ball park today.

Have a look at the website and their ebay shop.

You pays yer money...........................................................................!

OK, I'm not sure what the heck that wiring is inside the suds pump. Is there a wiring diagram stuck to the back of the lid that shows you how to rewire it to 220 Delta?

Transwave or Drives direct are two places that can provide you the inverters/converters.

Give drives direct a call and see what they recommend.

You could get a 5hp (ish) rotary phase converter that takes a single phase 240V input and generates 3 phase 415VAC. These are noisy (they have an idler motor that runs continuously inside the converter to generate the power) and expensive (somewhere between 500 and 1000 notes). These will power any number of 3 phase devices you have simultaneously and you wouldnt need to modify any of your motors or lathe wiring. Just leave them as 415VAC star. This is the closest equivalent of having a three phase supply installed from your electricity supplier.

You could also get digital inverters that generate 415VAC three phase which would mean that you dont need to alter your motors, but these are equally as expensive, a 3hp version costing well over 500 notes and still require direct connection to the lathe motor and bypassing the lathe controls.

I am in no way an expert in this area, best to call drives direct me thinks. They will know all of the options.

Graham

Ive found a transwave static converter 3hp, would that do tje job?

Yes, by the looks of it the transwave static converters would do what you need to do (as would the rotary converters). They even support operating multiple motors at the same time, providing you start the largest motor first, then start the smaller motor second.

Static converters also require you to "tune" the output depending on load. The transwave units have a multi position switch on the unit that you can switch in and out additional capacitance to balance out the 3 phases. I have no experience on how much of a pain it is to do.

Both static and rotary phase converters would allow you to just stick a standard three phase plug on the end of the lathe power lead and plug into the transwave box without modifying anything inside the lathe. Both types output 415VAC three phase from a 240VAC single phase input. Motors should be configured for 415VAC i.e no need to convert any to delta 240VAC.

The downside of a static converter is that your lathe will probably be a bit down on power. The static converters will only run your motor at somewhere between 60 and 80% power, whereas a rotary phase converter will generate full power in your motor.

Do some googling on static vs rotary phase converters for a million different opinions of which tyope is best and where.

Graham

Also note that both the 3hp static and rotary converters from transwave have a maximum single motor rating of 2hp.

You would need to buy the 4hp one, which supports individual motors up to 3hp with a max total draw of 4hp.

Another thing to be aware of is you would need a 16A supply with a type C MCB fitted to avoid nuisance trips. Neither the 3hp or 4hp converter will run from a 13A socket. The 4hp rotary converter requires a 25A supply.

Graham

Worth mentioning that you can easily build your own Rotary Phase Converter, plenty of info on the web including circuit diagrams.

I built one to run a Harrison L5a, worked a treat and cost less than £50 in parts, infact its still in use 20 years on, powering my pedestal drill which has a two speed motor.

At one point i had a workshop with 3 phase and ran the Harrison from it thinking it would run better than on the RPC.....it didn't, there was no discernible difference.

Only bugbear with RPC's is the noise of the idler motor gets on your nerves, i keep meaning to relocate mine to the shed. On the Harrison i had the idler motor mounted inside the lathe cabinet, so you didn't notice it so much.

Alan,

Did you include a transformer to step the voltage up to 415, if so do you know of a cheap source. I have a half built rotary phase converter in my workshop and need a transformer for it.

Graham

As an observation I run my 3HP lathe from a Transwave static inverter. The motor on the lathe is not set up for delta/star so would require finding the star point in the motor or a motor change. If this had been done I could have used a VFD. The electrician who wired my static inverter could not get the lathe to run and I had to get the guy from Transwave to sort it for me. Once done it has been reliable for nearly 4 years of use but on some days sounds a bit odd, turning off and on again usually smooths things out. I run a Chinese VFD on a 2HP Bridgeport mill and it is very smooth.

Ok well, i had a coversation with dave at drives direct and we seemed to of solved the problem with a dual stage digital inverter, which will handle both the suds and the main motor at the same time

Nice work James, I'm sure that will get you up and running quickly. Those dual stage units look quite capable.

Graham

GandM Tools stock some spares for Harrison lathes. **LINK**

They have a couple of tailstock nuts listed on ebay but they are for the L15 not the L6. It might be worth giving them a call to see if they can get hold of one for you.

The alternative is that the nut and screw are both perfect items for you to make on your new lathe

Cheers

Graham

Yeah, you can screwcut the internal thread on your lathe, but you will need to grind up a suitable cutting bit to get inside the bore (or commercial internal cutting tools are available).

You can also get taps.

You can calculate the thread pitch. Look at the handwheel and read off the scale how many thou are in one full rotation. On my later L6 it is 100 thou per revolution, which equates to 10TPI. The thread will be a left hand thread. You will have to measure the outside diameter of the screw to get the OD of the thread. Thread form will most likely be ACME.

You can get 3/8", 1/2", 7/16", 5/8" 10TPI Left Hand ACME taps on ebay for around the £20 mark, although it will be pretty hard going cutting a 5/8" x 10TPI thread in brass in one pass so people would normally rough it out on the lathe using whatever tooling they had first, and then push the tap through as a final pass to finish to size and thread form.

Graham