Emco compact 5 cnc lathe with Welturn

[EmgeeParticipant @emgee]

Hi sam

I can only guess the inputs to the Compact 5 steppers will be as used on the 5PC model, I'm sure they were the same steppers.

You mention buffer/bob, electronics is not my forte so that means nothing to me although I can recognise some components and make up simple ccts from schematics.

Emgee

[mike TParticipant @miket56243]

Emgee

Correct, the L297D interface board (three chips) sits between the 25 Pin parallel port and the 2 (3) input connectors on the Emco stepper drive card. The connectors are disconnected from the on-board computer, which I no longer use. The interface board is simple enough to be hard wired, does not need a PCB.

As I said in an earlier post, I use DeskNC control software or LinuxCNC. The 25 pin parallel port will also be compatible with Mach.

Do you have contact details for Henk Versuren? I cannot find him with Google

Mike T

[EmgeeParticipant @emgee]

Mike T,

check your PM inbox for a message.

Emgee

[FatgadgiParticipant @fatgadgi]

Hi Mike

First an erratum ….. should have been Homann not Hofmann and the boards are called "Digispeed"

http://www.homanndesigns.com/store/index.php?main_page=index&cPath=1&zenid=sm3s1t10peg5d5cj57itvukvh3

Secondly about where the 0 to 10v comes from, the jist from my simple Mechanical Engineer's brain is as follows:

This breakout board takes signals from Mach3 and outputs them again (and inputs as well of course), but in a protected way. So if anything happens to the lathe electrics, ie it lets out smoke and I get a nasty damaging electric spike from it, it's not passed down to the PC. So it provides (opto) isolation for inputs and outputs.

It also modifies and isolates the spindle speed control signal from Mach3.

Mach3 can provide output to control a spindle, but (I believe) it uses a digital signal (PWM). The breakout board modifies this output from the parallel port to provide an old school analogue voltage that varies between 0 to 10v, which probably came about to emulate the potentiometer control in the first place ??

Anyway, this can be used to control VFDs (or all the ones I have come across at least) in a simple manner – not as accurate as PWM, perhaps, but for my needs perfectly practical.

And somehow I'm sure I can use it to replace the manual potentiometer, perhaps by changing the voltage to suit. I'll know shortly when the Emco runs again and I can do some measurements.

Feedback from the spindle speed can be fed back into Mach3 as well from the shaft encoder. The resolution of the original Emco disc was too fine for Mach3 and so I have made and fitted a coarser one (ie less holes per revolution). Don't know how good this will turn out to be and whether fluctuations in spindle speed can be handled quickly enough, but we'll see.

[EmgeeParticipant @emgee]

Hi Will Bells

Sorry about the earlier typo, Which model Digispeed have you decided on ?

Emgee

[FatgadgiParticipant @fatgadgi]

Hi Emgee – I'm guessing my breakout board does exactly the same thing as the Homann ones do. I'll try what I have first …. if it goes pop, I've only wasted £14 (cheap compared to one of the ballscrews I had to replace !!!!!)

[FatgadgiParticipant @fatgadgi]

Had the old girl jogging under her own steam today using Mach3- the Emco that is.

So still want to finish adding homing and limit switches, but just mulling over whether to integrate the tailstock or not. I can see how to add one on the X axis (cross slide) and two on the Z axis, with the one near the chuck adjustable.

But what happens if I leave the tailstock clamped and the limit or homing switch is behind it ? I want to keep it on the lathe, so I'm thinking that I should add a forth sensor and have the limit on the tailstock itself

Anyone done this ?

(And, the spindle speed control pot was measured at 8.5v. Result)

[John Stevenson 1Participant @johnstevenson1]

Disconnected mine.

Found out they were more trouble than they were worth.

Every time it went into machine co-ordinates it shot off to the home switches at the far end of the bed, spent more time travelling to home than it did cutting.

Eventually set machine co-ordinates same as work co-ordinates as they are always on the end of the bar you are turning and spent the time writing decent tool change macros so it went just far enough away in both the plus axis to swap tools safely and then get back to turning which is what it's paid to do.

[FatgadgiParticipant @fatgadgi]

Mmmm ….. never thought of that, but I guess the saddle legs it to the pre-defined tool change position at the far end of the bed every time a change is called up.

Guess for me there is a high chance of causing damage by hitting the limits by mistake and a low chance of worrying about cycle time.

[EmgeeParticipant @emgee]

Hi Will

Could you please send detail of the method and settings in Mach that enabled the use of the Emco spindle controller.

How did the new speed indicator disc work with Mach and do you still have ability to thread ?

As for the Z limit why not have the home switch behind the carriage fitted to the bed but adjustable by sliding to suit the length of the workpiece. Like John says put a line of code in to move the saddle away in Z before the toolchange line then after the toolchange move back by the same amount, tool offsets will be used in the toolchange line to ensure the tool is at the correct place.

Sending the carriage to a home switch positioned at the tailstock end of the bed creates far more use/wear on all components than necessary.

Emgee

[FatgadgiParticipant @fatgadgi]

Hi Emgee

Sorry to fall short, but the spindle speed is not connected to Mach3 yet – I will attempt to do that in a few weeks time I think, probably over Christmas. I have a relay connected to the breakout board to start the spindle though, which was straight forward enough to set up.

It cut metal on Sunday in manual mode, which was a nice milestone. Just aluminium and a fine cut, but the finish, even with a lot of overhang, was pretty good. Next weekend I will try to run a short g-code program.

I haven't connected the encoder sensor either yet, but I'm going to bypass the breakout board for that and temporarily hack straight into the parallel connector. If that works, I'll set up a second parallel port.

I will not get a chance to do much before the weekend though, so I'll see how far I get on that.

[FatgadgiParticipant @fatgadgi]

Just a quick update on the compact 5 update to Mach3 – basically everything I wanted to change has been done with the exception of the speed control being directly controlled from the program (sorry Emgee, but the voltages on the pot are not what I wanted after all – 10v across the pot, but 50v to ground, which I need to think about before going further).

So it all seems to work nicely, just the external motor wires to tidy up a bit.

I've added limit/homing sensors and modified the photo interrupter and encoder disc on the spindle to feed Mach3, which I want for screw cutting which I'm going to try tomorrow (just bought the license to unlock this feature in Mach3) and run some longer programs.

My original intention was to add the computer into the box at the back, but after a bit of deliberation, I've chopped 6 inches off the top of the cabinet and turned it into a 5 PC. So the computer is stand alone and the rest of the control stuff is in the box.

Also used Fusion 360 to write the gcode after a bit of messing around with the standard Fanuc turning post processing settings.

Cheers Will

[EmgeeParticipant @emgee]

Hi Will

Thanks for the update, seems you will need the Homann DC06, just then need to wire from the speed pot connections on the Emco control board to the Homann board, this part of the board will then be at mains voltage but is isolated from the electronic side and earth, just be aware.

The other connections on the board are all to provide Mach control of spindle on/off/speed/direction and will be similar to your b/o board connections.

Keep us posted.

Emgee

[mike TParticipant @miket56243]

Hello Will

You are making good progress with your machine update program. Well done.

I am not clear about what you discovered about the voltages on the Emco motor speed board pot. Can you give a bit more detail?

I made some triangular pieces to fit under the lathe base to tilt it forward until box at the back was vertical. This gives a semi slant bed, which improves visibility and helps clear the swarf . You also gain a flat surface on top of the box to put stuff.

Keep up the good work

Mike

[mike TParticipant @miket56243]

Hello Will

According to my Emco circuit diagram for the motor spindle speed board. The speed control pot (50K) is connected between +12 volt and ground via a 27K dropper resistor. Therefore the voltage across the pot should be about 8 volts and the voltage on the pot wiper should vary between + 8 volt and 0 volt.

I cannot understand where the 50 volt to ground comes from. Make sure you are measuring using the chassis earth ( connector X21 pin 6) and not mains neutral.

Hope this helps

Mike

[MuzzerParticipant @muzzer]

Mains neutral and mains chassis earth / ground should all be the same potential, within a volt or so. Neutral is grounded at the substation.

Have you connected the control system "ground" to anything earthed? If it's floating, the voltage to earth could measure 10s of volts AC and/or DC.

[mike TParticipant @miket56243]

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

Mike

[FatgadgiParticipant @fatgadgi]

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 TParticipant @miket56243]

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.

Mike

[Trev67Participant @trev67]

Hi

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

Trevor

[mike TParticipant @miket56243]

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.

Mike

[FatgadgiParticipant @fatgadgi]

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 KovačevićParticipant @stefankovaevi19988]

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,

Stefan

[Martin ConnellyParticipant @martinconnelly55370]

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.

Martin

[Stefan KovačevićParticipant @stefankovaevi19988]

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

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