CNC Plasma build

[MattH]

Tbf I have an authorised HT dealer just around the corner.
I bought the unit from @Tom Orrow L so if I need to I’ll get spares for him.

 

[ukracer]

Tbf I have an authorised HT dealer just around the corner.
I bought the unit from @Tom Orrow L so if I need to I’ll get spares for him.

Sorry mate just trying to be helpful.

 

[MattH]

I know mate

 

[MattH]

Measured the OEM O-ring today and ordered a few replacements as it seems it will take a while to get a cosher HT part.

I thought that having the machine out of action today wasn't a bad thing as I needed to change a couple of bits.

Firstly I was using the relay on-board the awful Chinese break out board to fire the plasma. Being cheap it's a very low quality part and needed tapping with a screwdriver handle a few times to get it to behave.
I have some good quality DIN rail mount relays so I installed one of these to a spare output which will be much more reliable plus they are quick change incase the relay contacts weld etc.

Great, job done. But then I thought I really don't like the Estop logic.

At the moment dual redundant EStop switch chains are wired into two of the safety relay inputs, the safety relay switches off power to the drives and also initiates an Estop in the software by activating an EStop input pin on one of the breakout boards.

The trouble with this is that the software couldn't cause the safety relay to trip as this would cause a logic loop and never allow the software to reset.

So I decided to split the dual EStop chains and take one into the safety relay and one into the breakout board, I could then use the charge pump relay on the breakout board to feed into the second safety relay input.
This has the benefit that if an EStop is pressed both the safety relay (i.e. drive power) is stopped and the software is stopped. But also if the software EStops then the driver power is also cut.

All great, but I wired the input and outputs around the wrong way i.e. the the EStop switch went to the charge pump relay and the safety relay input went to the EStop input on the breakout board.
No bother, just switch them around. Oh, it's not working. Why are all my limit switch inputs lite even though their not active????

Turns out the safety relay is pumping out 30v on it's inputs which I feed directly into a TTL level board. Poof!

Worst than that, this is the board that I had to settle on to feed the servo drives properly and I had to special order it from Canada.

Bugger.

2 new boards ordered. One as a spare (DOH). Plasma is now out of action until they show up.

 

[eSCHEn]

I've given you a like for sympathy Matt. That's an easy mistake to make and sucks the big one waiting on the replacement ones

Any chance of tracing the blown components and replacing or is it SMD hell in there?

 

[MattH]

I've given you a like for sympathy Matt. That's an easy mistake to make and sucks the big one waiting on the replacement ones

Any chance of tracing the blown components and replacing or is it SMD hell in there?

It's not an overly complex board but there is a bit of tiny SMD on there. I will probably fault find it one I have a working board next to it.
If it gets fixed it's then another spare.

Thankfully the company usually gets stuff out next day and uses FEDEX international express so I should have it Monday barring any virus delays.

 

[MattH]

Well new boards turned up with exactly the same fault.
I gave up on this DMM kit once before on a router build, so I decided to switch to Leadshine again.

Thankfully I have a couple of full sets of the Leadshine servos and the motors have the same mountings as the DMM’s.

First thing I did was unwire the control cab and pull it off the machine.
I then pulled the controller, breakout boards, servo drivers, DC power supply etc so I could start mounting the new kit.


All new power wiring with solid state relays to control motor power on the drives.


I’m using a UB1 breakout board with a UC300 controller, this means the UCCNC software installed on the PC will still be used.


Now all the internal wiring is done I’ve mounted the cab back on the machine.


I’ve already replaced the A and Y axis motors so I need to swap out the X and Z motors and pull through new encoder cables. Thankfully the motor power cables don’t need changing. Then it’s just a case of attaching all the external cables into the control cab and servo tuning. Probably another 10-12 hours work.

Hopefully after all that’s done I can prove that the Oring was the issue on the torch.