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Newcomer to inverters, please advise.

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choochoo_baloo13/12/2017 18:58:57
183 forum posts
25 photos

I am soon to receive a Senior M1 milling machine with the self powered S type vertical head. It's coming from a 3 phase workshop.

I've been advised by an electrical engineer I know that variable inverters for single phase domestic supplies offer the best of both worlds (compared to either just single or just 3 phase). He also said Transwave is as good a brand as any. However he is not a hobby machinist, so couldn't advise any further.

Before I contact Transwave, can any other inverter users outline what components I actually need? The machine has only the bare wire ends, no other electrical wizardry! I know very little about this subject.

Thanks in advance.

John Haine13/12/2017 19:45:11
2577 forum posts
133 photos

Apart from the inverter itself, ideally you need a mains filter and suitable screened 3-phase cable to connect the inverter to the motor. A nice-to-have is also a remote pendant to give stop/fwd/rev and variable speed. Easy to make yourself needing typically a single pole double throw switch and a 10k potentiometer - about a couple of quid from Maplin. In my case I fitted these into a box also containing a no-volt release switch that is the mains master switch for the inverter and also an e-stop button. If I understand correctly you will have 2 3 phase motors, only one used at a time. Therefore you may want a 3-phase plug and socket arrangement so you can connect the motor you are using to the inverter output.

I'm not sure what "compared to either just single or just 3 phase" means. Obviously you have to have a 3 phase output, but the input could be either single phase or 3 phase - the latter only really needed if you have a rather high power motor. A 13 amp single phase mains supply should be OK up to 3 hp I would think.

Tim Stevens13/12/2017 20:13:47
1052 forum posts

I found Transwave both helpful, and knowledgeable about the kit I was likely to have, and the problems I was hoping to solve. I would take photos of what you have, bare wires and all, and put yourself in their hands.

I have no connection with them except as a satisfied customer.

Cheers, Tim

Gray13/12/2017 20:37:17
994 forum posts
8 photos

+1 for Tims recommendation. Transwave are an excellent company to deal with and always helpful. Another satisfied customer.

Chris Evans 614/12/2017 16:42:28
1442 forum posts

I run my 3HP lathe from a Transwave static inverter, around 5 years now and no problems. I tried running my Bridgeport mill from the same inverter with no success, the machine would run for a few minutes and then cut out. Pressing a reset in the machine electrics box restored use for another few minutes. Transwave where very helpful even coming out to the house to try and sort the issue but could not resolve it. A cheap ebay Chinese VFD all wired and set up by a friend cured the problem and it now just runs from a 13amp plug.

David Hughes 314/12/2017 18:06:30
7 forum posts

Have you had a look at the Newton Tesla site, They cover the Tom Senior milling machine with a variable speed control unit,

not done it yet14/12/2017 18:18:53
3166 forum posts
11 photos

It's coming from a 3 phase workshop.

240V three phase or 415V three phase? Start there.

Hevanscc14/12/2017 19:51:41
88 forum posts
33 photos

I did a refurb om my Tom Senior M1 (though without the S-type head), converted the 3 phase motor from Star to Delta and added an inverter. The thread is at this link


John Haine15/12/2017 17:12:03
2577 forum posts
133 photos

Hi-ho. A standard 3-phase supply voltage is measured line to line, as a neutral may not be run to a load. The line-to-line voltage is 415V rms nominal. If you measure voltage from neutral to any one line it is 240V. 240 x square root of 3 is 415. So there is no difference.

carl carley24/04/2019 16:19:08
5 forum posts

worm gears - im looking for a largish worm gear and gear wheel its not important about the ratios, its more for an industrial look on this project, when i say largish im thinking the worm would be 3" long with an OD of about 1" and a 1/4" bore or large.

anyone think what gets scrapped with something like this in it?

Brian H24/04/2019 16:26:50
1175 forum posts
86 photos

I found this company very helpful.


Chris Oakley 124/04/2019 17:01:48
1 forum posts


+1 for Newton Tesla.

My Myford went a tad smokey and Newton's plug & play replacement included a 3phase upgrade with variable speed.

Jon24/04/2019 18:29:06
988 forum posts
46 photos

Brian yes when he can be bothered to return your call, weeks later----.
4 inverters later still using it, shame about the others cost me £1600.

Chris nearly went that way Oct 2017 then looked at their exorbitant prices, so much so bought motor from Scotland, Mitsubishi from Gloucester region and pod with the extravagant £20 odd delivery and still saved £80 after paying £25 for a filter.
They do not and will not set the invertor up for use.

Plasma25/04/2019 17:18:14
326 forum posts
41 photos

Is buying an inverter and wiring it to a dual voltage motor a fairly straightforward thing or is it something best left to a professional?

Looking at transwave the packages look expensive compared to buying an inverter only.

I did email Steve Lilman at premier machine tools but he is I'll after suffering a stroke so unable to help.

Best wishes to him for a speedy recovery.


john fletcher 125/04/2019 17:46:45
516 forum posts

Hello Mick, in general term the answer to your question it is easy. You can buy an inverter which will do almost every thing you will aspire to do via ebay for around £100. Four of my ME friends bought Huangyang inverters and have been very happy with their purchases.

I'm no expert here, but helped them to modify their lathes motor wise and to fit inverters. As for locating replacement motors, all four picked up second hand motors very cheaply, which only needed the brass links moving to convert from Star to Delta a 5 minute job. All four bought Huangyang inverters and have been very happy with their purchase.

iI you go down the HuangYang VFD route I'll send you a copy of the program which I used. By the way, there is thingy on youtube which explain the programing Huangyang inverters very well. I'm sure members will be only to glad to help you in any way as required.

As the control voltages are very low, a home brew control box can be made. Unfortunately Maplin has now gone which was a good source for variable resistors and switches. However, ESR at Cullercoats up the North East coast, have almost the same range of components needed. John

John Paton 125/04/2019 20:58:28
169 forum posts
6 photos

I bought a variable frequency drive (inverter) from Honeywell Controls about 25 years ago for £80 including the programmer pad. It has been brilliant and never missed a beat. Best £80 I have invested in the workshop. The power , torque and quietness of the 3 phase motor combined with speed control and soft start is simply superb.

Go for it!


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