It's Alive! (El Cheapo Dyna 2400 Mach III conversion)

[Jeff_Birt]

Well, it is alive but not tuned.

We had an old Dyna 2400 table top CNC mill in the lab with its wonderful 900 line Conversational control.  A few years ago I wrote a drip feed program and modified a MasterCAM post processor enough that it would work (most of the time) feeding the program line by line from the PC.    Enter Mach III, I whipped up a homebrew 4 axis opto-isolation board with a charge-pump safety circuit (still have to add spindle control).  It is fully opto-isolated and will run on 3.3 or 5V LPT and it steals 5V from a USB port (for PC side of circuit), the existing machines +5 and +24V power supplies were retained.  As the machine was already stepper based and the OEM drivers were a standard Step/DIR control not much else was needed.

So, now I have to do is motor tuning and get homing set up and we should be good to cut some parts!

[Brian Barker]

Jeff,
The last one that I did i had to use Sherline mode to make it run right

Just wanted you to know that before you started!
BTW Nice mill 

Later
Brian

[Jeff_Birt]

Thanks Brian, that's good to know.  I know the optos on my isolation board are fast enough, but I have no idea about the drivers themselves.  I guess maybe that is where the problem might lie.

Thanks again, I'll get her tuned up tomorrow.

[Raca]

 Hi everybody ,I have found one Dyna 2400 two years ago on the e-buy and I did full retrofit by renewing  old Dyna control, power supply and driver. Dyna has made originally at the power limit not for stabile long-term run and low quality components. Made not to last, at least my show that marks. We have made new driver and now run in the half step mode. Motors are tuned up and now we have 30% power more in full step and some 15-20 %  more. This is the largest problem of Dyna. 27 oz power for this cast iron machine is to small but it can run. I have made 5 axis control but it was run only in 4 axis simultaneously. Still work on construction to make precise ficsation of one sherline rotary table positioned normally to another. First of all I needed to change rolling bearings on the spindle and my advice is to use p4 standard of bearings and SKF LGLT2 grease for lubrification (permanent) .Spindle will run smoothly and with less noise. We did make new control for the spindle and now we have achieved 180 rpm minimal and regular 10000 rpm for the top speed, but we have made that we can reverse direction and have vector control . That means we can cut the screw (sorry for my English) I don't know proper word for all technical process but I hope you will understood. this means that we can control speed from the Mach 3 but Dyna's head is the weaker part of the macine, beacouse is made from Dural and vibration that pass thru make small problems. I have found Precise SC52 spindle with 60000 rpm and it is now on service but after I believe that we will doo much bather job. Precision of old head is to make around 0.01 mm in production and much precise in positioning. I wanted to have control of positioning corrected from linear scale but Mach3 can't  support that and I hope that new version will do that .So all yellow cabinet was put in the waste  and new electronic has made. My advice is don't try to make old electronics to work, I have spend 6-7 months try to figure out what is wrong. If you have question send me a message. Best regards Raca Sasa

[Jeff_Birt]

Well, tuning went so-so today.  I can't get eth velocity above 7.5 Inch/min without missing steps.  I suspect that even though my laptop appears to pass the driver test, that it may be the source of the trouble.  And yes, Brian Sherline mode did help a bunch.

[Jeff_Birt]

I hooked up the new PC today, did a fresh and lean XP build on it yesterday, installed Mach III, ran driver test,  copied over the profile from my laptop and finidhed tuning.  Got the velocity up to 20 IPM for jogging, 25 IPM seemed OK 30 IPM was too much.  I did find that the infamous qt.exe was running on my laptop which could have been causing the problem.

I got the homing mostly figure out BUT...the home switches on this machine are at the far positive end of each axis, I got homing set up so it homes and sets the machine coords with the proper offsets.  But the local coords are not affected, I would like it to reset the local coords to the machine coords on a home.

[Brian Barker]

it should set the Machine coordinates to zero when you home (Unless you changed the settings under the homing and limits)

Check you settings under Config/Homing and Limits

Thanks
Brian

[Jeff_Birt]

Brain, since the limits are at the positive extremes of all three axis I have added in offsets to that the machine coords are correct.  For simplicty I just want it to also set the local coords to the same values so the machine is forced into working in machine coords unless/until you reference to a workpiece/fixture.  This machine is used for a few classes I teach where I only have one semester to give an introduction to CNC, PLC's, robotics, MMI's, etc; so I'm thinking that having the local-machine after a home (in a known state after a 'reset') will take some of the guess work out of it for the students. I think I found a post about this yesterday referring to adding some addtional code to the 'Ref All' button.

[Jeff_Birt]

After squashing a self induced hardware bug today (cold solder joint), I moved my computer cart around to the front of the machine and thought I would try running the first part program.  I was greatly confused at first as all the X and Y axis were moving backwords (but homing OK).  It was then that I realized that when I had the computer cart on the backside of the machine (so I could run Mach and probe stuff withteh Oscope) that I set up the X&Y backwords!  So, after removing my head from my butt, I changes things around in 'Ports and Pins' and 'Homing' and now all is well.  All the home switches are infact at '0', so I had to remove my offsets in homing.  I now have the machine moving the table to about mid position after homing.  I tried to force the soft limits and machine coords on (and LED's) but my script will only toggle them (below).  Any idea what I may be foing wrong?

Thanks

Code:

DoButton( 24 )
DoButton( 23 )
DoButton( 22 )
DoButton( 25 )

'' Wait until the axis are done moving and then
'  Set to machine coords and move table to front
While IsMoving()
Wend

Code "G53"
Code "G0 X3 Y2"

'' Wait until the axis are done moving and then
'  set the proper modes
While IsMoving()
Wend

'' Make DRO and Screen reflect Machine coord mode
If GetUserLed(16) = 0 Then
DoOEMButton(107)
End If

'' <ake sure that we enter into soft limit mode
If GetUserLed(23) = 0 Then
DoOEMButton(119)
End If     

[Brian Barker]

Try GetOEMLED(23) = false it is not a user led

That should do it

Nice job!
Brian