Fitting Inverter Drive to Harrison M300 Lathe

Hi. I am purchasing a Harrison M 300 lathe with 3 phase motor and coolant pump. I want to use a VFD inverter rather than a rotary converter. I also wish to retain all of the original lathe controls. There was an excellent article in MEW September 2009 by Ken Wilson but unfortunately there are a couple of issues that I don’t understand and would very much like to contact Ken if possible. Has anyone else done a similar conversion or able to point me in the right direction for further information? If necessary I am prepared to disconnect the coolant pump. Thank you, Gareth

Welcome to the forum, Ken is a member and I have let him know you were asking so hopefully he will be along in a while to help.

Hi Gareth, you do not mention which type of M300 you have purchased or are purchasing.

I have the same later (2003) white model that Ken Wilson covered in the MEW no.154 -2009. These models have more extended electrical controls than the cream coloured earlier versions. There are more contactors and overload protectors to deal with.

I found Kens version really good but overly complex on the logic controls. I hence did my own circuit diagram on the CAD with a lot of help from a friend who is an electrical wizzard and got him to check it all as i progressed. All the contactors and overload protects are done and supplemented as in Kens circuit but my logic controls differ but still retain all the use of all original controls and safety features.

I do have the coolant pump in the circuit which worked when i tested it but i never use it. I use a none soluble cutting oil from a Wurth oil spray application bottle. I find this far more userfriendly to the machines slideways etc.

I use the Teco inverter which to date has been perfect. I do have an issue with the foot bar brake. It works as normal if not used too heavily but under total emergency hammer down braking it decelerates the inverter too quickly and throws an error that needs a total repower to clear. It does do the dramatic stop that may be needed. This is because it also uses break blocks on the pully alongside the inverters electrical breaking. At the moment i live with this but may be future work in progress as i dont normally use the foot brake as the saddle lever controls work very well on their own. I know the foot brakes is there if i need it in an emergency.

You do need to Joint the yahoo harrison lathe user group as there is masses of info on there on VFD,s and their application and highlighted potential problems that have been overcome. There is a user on there called Rupert Powell who has provided invaluable info and drawings, some of which I have incorporated into the logic part of my controls.

Hi MalcB Yes the M300 I am buying is a 2000 model with the additional sloping panel beneath the headstock gearbox. I am proposing to buy the IMO Jaguar VFD from Transwave. I have joined the Yahoo users group but yet to find my way around using it. I must admit it was the logic side of Ken’s scheme that really had me confused - there is a transformer with a 110 volt ac output which to me suddenly appears to become 24volt dc obviously I am reading it wrong but my electrical knowledge is 50 years old from school physics lessons! It would be brilliant if you can let me have some details of your solution. I am a member of Coventry Model Engineering Society and one of the members has been very helpful but his is an older model without the additional panel and interlocks I want to go a step further and retain the original controls. Thanks Gareth

Gareth, PM sent. As regards rapid shut down of inverter under E foot brake use, I have a minor mini red button that does the reset.

Gareth PM sent

MalcB.

May I reply to your "but overly complex on the logic controls" ?

I merely removed from the original Harrison circuit, those items not necessary for the Inverter approach. I kept otherwise to the Harrison logic approach to controls and safety. I could with a minimum of work, revert to the 3 phase power without the inverter.

Ken Willson

I simply have my coolant pump connected across the spindle motor. So what if it varies in output a bit as I vary the speed of the motor - I just adjust the tap to compensate. It's not a perfect science by any means. Keeps things simple!

Murray

Muzzer, is the VFD happy with sometimes having just 1motor attached and at other times 2 motors?Presumerably the suds pump is controlled by the original switch. I guess that the 2 motors are connected in parallel across the VFD output.

Hi Ken,

How did you get round the chuck guard limit switch when you have to remove the guard?

Gareth,

Not a problem, VFD hardly notices it.

Many thanks for all the advice given which has been most helpful. In light of this I have cancelled my previous order for a rotary converter and will definitely be going down the VFD route.

I have seen some comments on a Yahoo group by Brain Jones and if he is a member of this forum I hope that he may send me a PM. Is anyone able to contact him for me? I hope that this is an appropriate request.

Gareth

MalcB,

The chuck guard limit switch/wiring lies at the base of the left hand pedestal, unused but still wired. I hate chuck guards in general but the M300 one has a use to hold the horribly heavy extra large 4 jaw ind when fitting/removal.

K

Yes, i understand exactly about the 8" heavy Pratt 4 jaw as I got one with my lathe. I did however manage to get a slim bodied 8" Pratt 4 jaw ( almost unused ) at a very good price which also has much narrower jaws. Had to D1-4 backplate mount it but its much lighter and feels a lot more sensitive. In fact its a joy to use against the industrial one which I now only use occasionally. These are well worth looking out for to use on the M300.

Tape it closed, remove and leave tied up, first thing i did 8 1/2 years ago.

I run an invertor and can run the rotary just a simply pull plug out of invertor socket and put in the rotary socket and switch on. Both run through control panel incliding isolator, many contactors and on/off switch.

Did buy a Mitsubishi D720 2.2KW 220V 3PH cheapy and filter last year but cant afford the down time to install and figure out. D720 are not dust proof and need to be enclosed and in reach.
Need another vfd for the coolant pump about £50.

My M300 is an English one and have no use for variable speed they have a brilliant gearbox like all other Harrisons and Colchesters. Only reason want the vfd on is i have supply problems plus limited to 65A input and to compare all three power sources Rotary, Digi Invertor and a decent VFD running 220v.

Thanks Jon, but mines already sorted. I have included for additional switching in my circuitry to engage or disengage the chuck guard switch as needed. I was asking how Ken had dealt with it on his similar machine as dont think it was shown in MEW article.