Oh great, thanks. I was looking for the option in the upper bar. I'm adding some pictures.

SO here's what I 've been thinking of. First of all a 6 bolt part attached to the motor with a collar on the outer part. Don't worry about the bolts not being the same size as the threads, it's just that it was a pre-built motor. The size of the parts is calculated for the Gobilda motor. But the length of the motor is the real Gobilda one.
then an shaft adaptor to convert it to a procon pump end. Of course it would require a standard clamp to link the pump and motor.

Bottom line: for a small home machine, the vibe pump is as good a solution as possible. It's small, it's inexpensive, it works very well, and you can utilize a simple AC dimmer to control the flow.

The tradeoff is that it's noisy.

connected to a procon pump in order to have an idea of the scale. 215mm long in total.



and compared to the size of my RPM assembly

Either the motor you've chosen will turn the pump or it won't. Try it and see, I'd get a blind basket and put a very small hole in it and then see if you can both control the pressure by controlling the speed and if you can get to 9 bar? I would guess maybe that motor does not have enough power to get to 9 bar or maybe not enough power to sustain 9 bar at very low flow rates. Steppers will stall at low speeds if the load is to high.

That motor is actually a brushed 12VDC motor with a 5V encoder on the back and a 5.2:1 reducer gearbox on the front. Not a stepper at all.

https://www.gobilda.com/modern-robotics ... vdc-motor/

I never said it was a stepper motor. I just made an adpator. I even said this motor may not fit due to its low torque. Fin me a motor and I'll make an adaptor

Sorry, my bad. I've no idea where you might find the torque vs pressure curve for a pump like that. But remember that at the recommended 1500 RPM, the pump puts out many time the required volume and a few hundred RPM or less might be all that's needed for your application.

I can't find any torque mesure about the RPM motors. I any body has any idea?
As for the pumps itself, I made a test ith a maximum pressure and it reaches 16 bars with a 120 watts motor. I don't know if it's the case for all the machines with a rotary pumps but on the one I'm bulding I put an OPV for safety reasons between the pump and the boiler.
You're right about the speed. A slower motor should work but it requires a high torque nevertheless.

I knew that, I just pointed out because it means you can use more gears.

Torque is relatively easy.

120W is 120N•m/s
Since torque units are N•m, you divide the power by the rotational speed in radians per second to cancel out the seconds. Assuming a 4 pole motor, the speed is most likely 1760rpm or so, under load.

Torque = 120W / (2π•1760)•60 ≈ 0.651N•m

The motor you listed has a stall torque of 1.47kg•cm, which is roughly 1.44N•m. Run that through the 5.2:1 speed reduction and you've got just about 7.5N•m of torque on the gobilda motor.

Should be just fine!

ToM4 wrote:I don't know if it's the case for all the machines with a rotary pumps but on the one I'm bulding I put an OPV for safety reasons between the pump and the boiler.
image

Your boiler will need an expansion valve either way to protect from bursting if you heat it when saturated, for this reason, there is generally an expansion valve attached to the boiler with rotary pumps.

Cheers!

- Jake