Build Thread Dyna Myte 2800

[MonsterMatt]

I've aquired a Dyna Myte 2800 that has been modernized to run mach 3. It has a geckodrive G540 stepper driver and an Advanced Motion Control B25A20 spindle driver. It's main purpose will be engraving so the 10k spindle was a key selling point.

Google Album:

Documentation:
https://drive.google.com/drive/folders/ ... sp=sharing

[MonsterMatt]

I have a question about the Acorn and acorn six analog out. The acornsix says 0-10v and + - 10 V. In all the documentation i've looked at the acorn only references 0-10V. Is the +- 10V used for forward and reverse and is the acorn capable of it? On the AMC B25A20 it says +-10V input but i cant find anything in the documentation explaining that that is used for reversing. Is the +- just to show that is is an isolated input/output?

AMC B25A20 Data sheet:

AMC B25A20 Photo:

[cncsnw]

Since that is designed to be a servo drive (not a spindle drive), it would use positive and negative analog to control both speed and direction (-10V = full scale reverse, 0V = stopped, +10V = full scale forward).

Unless it has an additional digital input specifically for reversing direction, then providing a negative voltage would be the only way to run in reverse.

If you need the +/- 10V for speed and direction, then you cannot use Acorn, but you can use AcornSix.

[MonsterMatt]

If you need the +/- 10V for speed and direction, then you cannot use Acorn, but you can use AcornSix.

Would it work to invert the polarity with a relay? As long as as the signal is isolated from ground on at least 1 end of the circuit it should work.

[cncsnw]

Probably.

It is not isolated from ground at the Acorn, so it would have to be isolated in the AMC drive.

It appears that it is isolated in the AMC drive ("differential").

[suntravel]

Why do you want CCW for engraving?

Uwe

[MonsterMatt]

@suntravel, It's main purpose will be engraving (RIP Pantograph) I can also see it being used for anything a mini mill can be used for. CCW rotation would open up tapping with a Tension/Compression tapping head and using a slitting saw either direction. I guess in the grand scheme of things i can live with cw rotation only and if i really need to do tapping just throw a reversing tapping head on it. If it becomes a problem i'll just do a spindle motor upgrade.

Looking at the block diagram for the AMC B25A20 the - Ref in is referenced to ground through a 20k resistor. I know at 10v that would create 0.0005A of current to ground. What i don't know is if that would be bad or even noticeable.

[centroid467]

Looking at the block diagram for the AMC B25A20 the - Ref in is referenced to ground through a 20k resistor. I know at 10v that would create 0.0005A of current to ground. What i don't know is if that would be bad or even noticeable.

The main purpose of that resistor is to provide an equivalent load on the -REF IN input. Its counterpart is the 20kOhm feedback resistor going to the inverting input of the op amp. I wouldn't worry about it too much.

I think you'll be able to get away with using relays to switch the polarity of the 0-10V signal. I don't know whether you'd need an isolator or RC filter.

I was looking at these machines not too long ago. I hear they are very solid little mills!

[MonsterMatt]

I spent a little time and made an Input/Output list. Some things which i left blank i can't find a canned input or output for, such as the e-stop signal shown on S14979.DWG and Coolant Low. I hate fan noise so I'd like to shut off any fans that aren't actively cooling something. I found a spindle fan output I'd like to use for the spindle and steppers. I doubt I'd run the steppers hard enough to need fans without the spindle active. I'm considering a pneumatic tail-stock for the 4th axis which is why i have tail-stock I/O. I'm also considering Feeding the mist coolant with the coolant pump and use solenoids to direct the flow. I'm not sure how well this will work. I'm hesitant to just put a siphon line in the sump because I'm worried about contaminates clogging the siphon line.

Current I/O list:

S14979.DWG:
https://www.centroidcnc.com/dealersuppo ... 979.r3.pdf

I was able to get the machine back up on it's stand and fire it up. The pc shuts the screen off right after the no password login unless you boot in safe mode. it's a core I3 (I'll get exact specs this weekend) running Windows 7 pro. I'm hoping it will hack it for CNC12 use but if not it should make a good router for the shop. It's configured for mach3 and after my initial experience all i can say is that the overwhelming GUI made my decision to go Centroid that much easier.

[centroid467]

If you look at the bottom of the schematic, there is a little chart that says the E-Stop input assignment is EStopOK in the Wizard.

I think you could probably get away with using SpindleTempAlarmMessage or SpindleTempAlarmStop for the coolant level sensor and modify the message to read as such. In my plcmsg.txt from 5.22 Acorn Mill, it would be the line reading "46 9046 Spindle Temperature Alarm!"

Do you have separate pumps for Flood and Mist? I'm not familiar with how coolant systems are typically set up but looking at Acorn Wizard PLC seems to imply separate pumps or a way to divert coolant to one or both. Depending on your setup, it might make sense to use additional external relays to engage the pumps or do additional switching when the canned Flood and Mist outputs are active.