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Emco compact 5 cnc lathe with Welturn

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mike T02/01/2016 15:17:10
173 forum posts
1 photos

Muzzer, What you say is correct for a correctly wired installation. But it does not explain Wills unusual voltage measurements.It could be that the machines earthing has been disturbed during all the modifications leaving some boards floating.

Connector X21 pin 6 on the speed control card is the wire that ties the motor and the speed controller to ground, therefore a good place to check


Fatgadgi02/01/2016 16:02:52
163 forum posts
21 photos

I agree, my assumption was that I have disturbed something and ended up without proper grounding on the board (the motor and case etc are all well earthed).

But the scary thing is that there is no wire to X21 pin 6, and I don't think that I would have pulled a wire out there as I kept everything as it was where I didn't fully understand - the electrics had obviously been hacked a bit when I got it, but actually there is no evidence that there ever was a wire going into that pin on the connector. Gulp.

Anyway, I will pull the board out and trace what grounding pin 6 would do .......... but it may be academic now, idiot that I am, as I've just shorted out one of the potentiometer legs to the earthed cabinet trying to re-measure in the dim light (too lazy to get the inspection light). Now it's only working at minimum speed.

Guess how stupid I'm feeling !!!

Could be following JS's example and getting a third party board in there after all.

Cheers Will

mike T02/01/2016 16:47:40
173 forum posts
1 photos

Bad luck Will.

However it more or less confirms that motor card was not properly grounded. The board ground and the chassis ground should be the same potential and would have had no permanent effect. But as you say, that's now history.

There may still be a way of sorting it out. The motor control occupies the lower half of the board, the display is the upper half of the board. There are only two chips of the lower motor control half. Both are UA324 or LM324, quad low power operational amplifiers, ( an equvilent chip is theNTE987 ). If you can get these two chips replaced, you may get lucky.

For your information X21 pin 6 is the end pin on the right nearest the centre of the board. There are several unused positions in the connector which don't count.


Trev6702/01/2016 17:49:30
37 forum posts
1 photos


I know very little about electronics, so be gentle with me.

I'm converting an old Denford Starturn 8 lathe to run from a PC, haven't yet tackled the speed control, it currently has a manual pot to control it. Whilst trawling the net for information I have come across warnings that the control side of old speed control boards is not grounded and floats at up to 100 volts, so it may be that there should be a floating voltage at the pot terminals. As I say I don't much about electronics, but thought this could be helpful.

I've not investigated mine yet, but obviously interested in the solution to controlling these old boards.

My speed control board is a JAY JE 124/1, and controls a DC motor, if anyone has any useful info

Good luck with your projects, and happy new year to you all


mike T02/01/2016 18:20:42
173 forum posts
1 photos

Will, Trevor

You can clearly see the problems with these old motor controllers. The Emco controller and now perhaps the Denford controller are stand alone boards which do not connect to the rest of the control gear, therefore their zero volt may be allowed to float (bad electronic practice). The problem happens when you attempt to connect them to an external system such as the Mach controller or make voltage measurements. THEN you must connect up all the various zero volt (earth) connections so they all refer to the same zero volts.

Ask yourself if you really MUST control the speed by software. Consider the risk, if you are not that experienced in electronics and settle for manual control and turn the speed pot by hand. In practice you don't change the spindle speed very often. I still use manual control of the spindle speed of My Emco F1 mill and my Emco Compact 5 lathe; never found the need for the software to control the speed.

For Will, I could have a go at replacing the LM324 chips for you. No guarantees just best effort.


Fatgadgi02/01/2016 19:54:31
163 forum posts
21 photos

That's a very kind offer Mike, but I'm going to give up on the board and replace it with a modern equivalent. Probably one of the KB boards.

The wire from pin 6 (ie the end one as you explained) is one of the wires that go to the motor connector and one of the other 3 is a proper earth, so on my version, I don't ever think it was truly grounded.

So I think with what I'm hearing (and thanks Trevor) and previously measured, the board voltage floats, which is not what I expected, and seems a bad idea. Certainly controlling with an external voltage rather than the pot is not going to work with the bob I have now.

You are right, speed control by the program is far from necessary, but I fancy having Mach control the speed for screwcutting, if only for the feedback option. So far as I can see, it will try to keep the speed constant by varying the requested speed which should be more accurate than manually setting, although it doesn't attempt to compensate for speed variation with the x-axis.

Having played today with screwcutting, I don't think Mach is as clever or accurate as I had hoped for, and it cannot screw cut with the nice multi slot encoder disc I made for it. It seems it can only thread with a single index slot on the disc and play the average game. Oh well, for normal threads I'm sure this will be reasonable enough.

Cheers - Will

Stefan Kovačević03/05/2016 21:35:12
10 forum posts

Hi to all of you

I have recently purchased both Compact 5 cnc lathe and F1 cnc mill, and they are on route to me. They are untested (they should come in with Welmil and Welturn software) so I dont know are they gonna work when they arrive with what they have mounted (most likely not).

Since I have to work fast in order to have them up and running as soon as possible, and I want to use Mach3 to control them, can you folks tell me where can I source out proper Nema23 motors (from what I have read, they will fit perfectly on existing mount holes) and proper controllers (and the rest of the bits) to go along with them in Europe (with decent prices of course), and if there is something else I would need, besides computer? Compact 5 should be able to do threading operations as well.

I ve read a lot on the net on this, but I am still confused about where to look and buy these parts - and I want to make this easy swap as it can be.

Thank you all in advance,


Martin Connelly04/05/2016 14:48:40
1422 forum posts
165 photos

Zapp Automation sell a lot of the parts you will need. Don't know if they are the cheapest, just that they sell these items.

Leadshine 3 phase Easy Servo steppers and drives have a good power to size ratio. They also have the option to give an error signal if there is a position error which is not a feature of standard open loop stepper systems. If it is important to have a system where missed steps are not acceptable then they should be considered.


Stefan Kovačević04/05/2016 20:51:05
10 forum posts

Thank you Martin, that is something to be considered, but it is not that important for what I do (the expense doesnt justify the cost)

I am thinking about Gecko drivers, but I am not sure which one to consider with these machines? And reading the previous posts, from what I understand, there are boards that are compatible with spindle motors, that can control the speed through Mach3 (with a help from optical decoder for actual spindle speed)?

Edited By Stefan Kovačević on 04/05/2016 21:02:10

Martin Connelly05/05/2016 11:03:04
1422 forum posts
165 photos

Stefan, have a look at the Pokeys range from Polabs, I think that is a good starting point for the motion controller. The steppers and drives need to be compatible with the motion controller so should be chosen after that.


They will probably advise you regarding what motion controller is good for your needs and what drives and motors to use with their boards.


Stefan Kovačević08/05/2016 16:36:27
10 forum posts

Thanks for that Martin. Polabs gave me quick reply, and that is something to be considered, although its 30% more from the budget I prepared.

From Longs motor china i got an offer for

5 pcs Nema 23 stepper motor 425

5 pcs Stepper motor driver DM542A (cant find it on their website)

2 pcs Power supply 350W-36V

1 pc parallal cable + 1 pc breakout board ( 6-axis)

that falls into the budget, but then again I am not sure what to expect for that, and from them?

Muzzer08/05/2016 17:16:43
2904 forum posts
448 photos

Check the dimensions very carefully if you are hoping these will just bolt right on. The NEMA "standard" seems to be interpreted very loosely, so you may find some of the key dimensions aren't the same. In particular, check things like shaft diameter and length, key width and height, register diameter (the cylindrical feature on the mounting face), fixing hole diameters and positions and possibly the overall length. And make sure the motor has the correct number of phases for the driver etc - good to buy the motors and drivers from the same manufacturer.

Driver DM542A seems to be here?

The specs for steppers quote stall torques, yet the torque drops off rapidly with speed. To check if you have the correct ratings, the simplest thing may be to refer to previous (successful) conversions and go off the back of them. Have you found anyone who has done this conversion before?

Stefan Kovačević08/05/2016 17:23:40
10 forum posts

yes, that seems to be the DM542A. I couldnt open the drivers page on my browser before.

Thanks for the tip for the motor mounts and dimensions, I will check on that for sure.

I am looking to get everything at one place (same manufacturer I suppose).

I havent found any conversion with these same elements, but these stall torques are OK from what I remember reading all over the net.

Someone with more experience might chip in

Stefan Kovačević21/05/2016 13:39:00
10 forum posts

Well they finally arrived. Lathe and mill i mean. They were at some UK school. They seem OK, but got stains from age etc. from what I see, all of the equipment was electrically tested last year, so I hope they are in working order. And I got two pc with wellmill/wellturn software - they were retrofited with them. There are almost no thtorials how to work with these. And now I am wondering do I even have to do the conversion I wanted to do - due to need for threading operations etc.

Emgee21/05/2016 14:00:25
1655 forum posts
224 photos

Stefan, if the Welmill and Welturn are working fully there is very little to be gained by retrofitting. If you search the Yahoo Emco forums you may find operating manuals for the software.

If you are a member there just ask for some info on running the software and I'm sure someone will help.


Stefan Kovačević21/05/2016 16:55:13
10 forum posts

Thanks! I ve checked the lathe right now, it is working. I ll check the mill in a few days. Lathe has the optical encoder for the spindle, I am not sure is this the standard option. Motors seems a bit slow for my liking, but maybe they wouldnt be much faster with stronger ones fitted? Anyway, I ll look at yahoo group

Emgee21/05/2016 17:36:16
1655 forum posts
224 photos


New steppers and control will mean faster rates of travel, but the standard motors will traverse faster than needed when cutting so the only time faster travel is useful, and saves time, is on non cutting moves.

New steppers with 200 steps per rev would be theoretically more accurate than the existing, although the std set up may prove to give consistently accurate results within your allowable tolerances.


Stefan Kovačević27/05/2016 18:44:26
10 forum posts

OK, in these few days I have managed to understand more, and to see in what way I want to go on.

Both of the machines are working properly, and I have found a way to get gcode generated elsewhere to work.

This will do for now, but I really want and need more out of these two little machines.

I ve made 10 tool holders for the lathe (base is there, but no holders) so I can finally mount the cutters and get some chips flying.

The main spindle optical encoder isnt working. Signal is there on the back of the panel, but no reading what so ever. I ve also realized that I cant control speed with it lol. I cant get the reading too :D

If and when I get it to read speed, I am not sure how will Welturn work with it (the readout) regarding threading operation. I believe that cant be achieved, so that is why I will move on with getting new electrical stuff to use in the future.

I have ordered M542 drivers, 2Nm motors and a simple 5 axis BOB.

I wanted to get a suggested Digispeed controller, but they are out of stock. Can you suggest some (cheaper) alternative?

And an spindle encoder that will work with Mach3(I ve read that the one mounted is too fine to get a proper reading for it)?

I will use the existing power supply, and other bits needed from the old housing. And do I need anything else at this moment to get Compact 5 to make threads also?


Stefan Kovačević07/06/2016 10:39:35
10 forum posts

Done some hardware tinkering with help from Sam and derstrap on cnczone, removed the welturn "card" placed the 4th dip switch in lower position, and used Sam's config files for EMC2 and it works like a charm!

MICHAEL Moore 124/02/2017 12:05:22
10 forum posts

Hi all,

Michael Moore from Ireland here.

I have an x school Emco Compact 5 that I am looking to upgrade to a cnc jobby.

I just started following an American site who have done this

Has anyone attempted this sucessfully and can you give me any advice please.

Thanks in advance


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