Peristaltic Fine Spray: no mist: no fog coolant pump

[Vixen]

Hello Hugh and Jason,

I have been looking at the A4988 stepper drive module. They look to be a quick and easy to add and would give me back the big 4.7Amp stepper driver to use with the 4th axis. The only reason I have not done it yet, is the hassle of cutting a hole in the enclosure back panel to fit an additional bulkhead connector,

Looks like there are now three different options to generate the step pulses, 1) N555 pulse generator module  2) modify the HAL software in LinuxCNC  2) Hugh's Arduino.

If you are already using LinuxCNC then the easiest route is to edit the HAL file by adding the six lines of code I showed earlier. No need to understand the intricacies of the HAL programming language. I have done that for you, so just copy and paste into the HAL file.

Thinking again about the mist fluid. I will only get a small amount of lubrication from the 4% imulsion delivered a 15 drops per minute, it will mostly cool. For better lubrication, it will be necessary to increase the strength of synthetic cutting oil imulsion or go for straight 'mist' fluid.  Jason and I are both having difficulties in sourcing smallish quantities in the UK, it only appears to be available in industrial quantities of 25 litres or more.       So I have a plan....... I am going to take one of my model engines along to one (or more) of the local machine shops and ask them what cutting fluids or mist fluids they use and where do they obtain them from.  Hopefully they may offer to give me a small quauntity to try. And, by good fortune, I happen to have an empty 1 litre container in the car.

Mike

[Jasonb]

Sounds like a cunning plan

[Vixen]

Sounds like a cunning plan

Blackadder : "Baldrick, I have a very, very, very cunning plan."
Baldric : "Is it a cunning and subtle one?”
Blackadder :  “Yes Baldrick. A really cunning and subtle one?”
Baldrick : "Is it as cunning as a fox what used to be Professor of Cunning at Oxford University but has moved on and is now working for the U.N. at the High Commission of International Cunning Planning?"
Blackadder : "Yes it is."
Baldrick : "Hmm... that's cunning."

[Hugh Currin]

Mike:

Do you then have to modify LinuxCNC to change the pump rate? That would necessitate restarting the controller. Using an axis for this would only require an MDI command to change pump speed. But then you can't change flow rate during a program run. I do like the external pot for flow adjustment, but a lot more parts to accomplish it. I do like the pump you found and I may have to try the mods to LinuxCNC.

Thanks.

If you are already using LinuxCNC then the easiest route is to edit the HAL file by adding the six lines of code I showed earlier. No need to understand the intricacies of the HAL programming language. I have done that for you, so just copy and paste into the HAL file.

[Vixen]

Hugh,

The modifications to the linuxCNC HAL file only give a fixed flow rate. It can be adjusted, up or down but requires a restart. I am not convinced for the need for variable flow


You cannot use of the 4th (rotary) axis to drive the peri-pump, other than for test purposes. An MDI command or a programmed command is a 'move to' command, and all 'move' commands are sequential, you must finish one move before the next can commence.  The pump would just stop at the end of the 4th axis move and would be off while the subsequent command lines were executed. We therefore need an independant means of continuously providing the stepper motor with step pulses at the required rate. Hence the  N555, HAL file changes, or the Arduino options.

I had a look at the A4988 stepper driver data sheet. The A4988 needs two power supplies, 5 volt for the logic and 12+ volts for the motor. Not very convenient. There are other inexpensive, single supply, stepper driver bricks available.

Mike