LUCCA M58 by Quick Mill, reviews and owners thread - Page 46

#451: Post by **marlodmb** » February 20th, 2018, 9:11 pm

So basically a 16oz milk drink is the biggest I can go before the steaming is too low to do anything (with the 4 hole tip). Got my 100pk of disposable and 5 reusable 16oz to go cups today (to make for going to work if I get up early enough

) I usually get 20oz as a normal drinks at cafes. I used the 4 hole for the 16oz drinks and temp set at 263 because I'm at 638ft elevation for 1.4bar.

**I'll try the 2 hole tomorrow**

*#*# tired the 2 hole today.. and ordered the izzo 3 pack steam tips. Should hopefully be here Saturday.

#452: Post by **Jetfuel** » February 23rd, 2018, 11:16 pm

Mine arrived today! Custom maccasar ebony by cannon fodder!

February 26th, 2018, 10:12 am

Hey all,

I am wondering what you guys see on the PID on the brew boiler. I have it set to 201, and i see it hover anywhere between 200 and 205. This doesn't seem right to me, should it vary that much? I have it running at 15A.

~Matt

#454: Post by **al3xx** » February 26th, 2018, 2:36 pm

liquidmetal wrote:Hey all,

I am wondering what you guys see on the PID on the brew boiler. I have it set to 201, and i see it hover anywhere between 200 and 205. This doesn't seem right to me, should it vary that much? I have it running at 15A.

~Matt

Mine oscillates similarly, so it's not that your machine is functioning improperly, it's probably that the PID is not tuned optimally. I found this from Stack Exchange. While the poster said it's for motors responding to disturbance, the response of a heating element to cold water input is very similar. The manual has info on how to get into the settings for tuning the PID control. You may also want to read about PID theory, if you are interested or want to understand it better.

For small, low torque motors with little or no gearing, one procedure you can use to get a good baseline tune is to probe it's response to a disturbance.

To tune a PID use the following steps:

Set all gains to zero.
Increase the P gain until the response to a disturbance is steady oscillation.
Increase the D gain until the the oscillations go away (i.e. it's critically damped).
Repeat steps 2 and 3 until increasing the D gain does not stop the oscillations.
Set P and D to the last stable values.
Increase the I gain until it brings you to the setpoint with the number of oscillations desired (normally zero but a quicker response can be had if you don't mind a couple oscillations of overshoot)
What disturbance you use depends on the mechanism the controller is attached to. Normally moving the mechanism by hand away from the setpoint and letting go is enough. If the oscillations grow bigger and bigger then you need to reduce the P gain.

If you set the D gain too high the system will begin to chatter (vibrate at a higher frequency than the P gain oscillations). If this happens, reduce the D gain until it stops.

I believe this technique has a name. I'll put it here when I find it

February 26th, 2018, 8:16 pm

Thanks Alex! Glad that my machine is functioning properly. Time to do some reading, I knew that computer engineering degree would be useful at some point in my life...