Paint dispenser with DC motor and encoder I want to design a peristaltic pump to dispense laquer. I picked a geared DC motor with encoder to do the job. [attachment 109222 gearedmotorw_Encoder.jpg] [attachment 109221 motor-specs.png] I think, my Duet-boards can drive it without H-bridge, but how do I config the two encoder lines in RRF for speed control? Even add another (analog or encoder ) input for fine tuning... Thanks for reading https://reprap.org/forum/read.php?4,843531,843531#msg-843531 Wed, 14 Oct 2026 03:13:13 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,843531,844080#msg-844080 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,844080#msg-844080 the_digital_dentist Reprappers Wed, 09 Jan 2019 12:59:59 -0500 https://reprap.org/forum/read.php?4,843531,844037#msg-844037 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,844037#msg-844037
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o_lampe
The reason for not spraying the paint is: selective coating. I want to ooze the paint while the toolhead meanders across the selected area.
I think, that requires an encoder to sync with acceleration/deceleration moves

I fail to see why a stepper wouldn't do it ?]]> MKSA Reprappers Wed, 09 Jan 2019 04:55:07 -0500 https://reprap.org/forum/read.php?4,843531,844022#msg-844022 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,844022#msg-844022 I think, that requires an encoder to sync with acceleration/deceleration moves]]> o_lampe Reprappers Wed, 09 Jan 2019 03:34:26 -0500 https://reprap.org/forum/read.php?4,843531,843801#msg-843801 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843801#msg-843801
You can buy cheapo peristaltic pumps from China for $10 or so. Some use silicone tubing, others use something called BPT. The BPT tubing lasts much longer than silicone (see pg 23)]]> the_digital_dentist Reprappers Mon, 07 Jan 2019 11:43:02 -0500 https://reprap.org/forum/read.php?4,843531,843800#msg-843800 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843800#msg-843800
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the most significant problem may be that the output is somewhat pulsitile.

It would be cool to sync the pulsing with the XY speed to compensate that. In my case it would only be one axis I had to compensate.]]> o_lampe Reprappers Mon, 07 Jan 2019 11:27:59 -0500 https://reprap.org/forum/read.php?4,843531,843799#msg-843799 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843799#msg-843799 It's the same with fan motors running on PWM. You have to start them with 50-100% to make them spin, than you can go down to even 10%. But they wouldn't start at 10% at all.]]> o_lampe Reprappers Mon, 07 Jan 2019 11:24:30 -0500 https://reprap.org/forum/read.php?4,843531,843542#msg-843542 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843542#msg-843542
I tried a number of the motors that you show for a toggle mechanism on a 3D printer but found that the minimum speed was a substantial fraction of the full speed: a 12V motor became very eratic to start even at 5V and speed control even when started was not good at less than rated voltage. I did try several motors of various reduction ratios but the motor part aways had the same problem. Lacking the funds to get a Maxon ironless motor to do this I built my own stepper motor to fit the same mountings - I will try to put the STL files on Thingiverse in the next few day if this option helps.

[attachment 109232 GearedStepper.jpg]

Mike]]> leadinglights Reprappers Sat, 05 Jan 2019 05:50:38 -0500 https://reprap.org/forum/read.php?4,843531,843534#msg-843534 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843534#msg-843534
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Even add another (analog or encoder ) input for fine tuning...

Got it! The dispenser has to act like a extruder and by adjusting extruder ratio, I can tune it while it runs. The encoder-wheel of a simple 12864LCD will work too, I hope?]]> o_lampe Reprappers Sat, 05 Jan 2019 03:44:41 -0500 https://reprap.org/forum/read.php?4,843531,843532#msg-843532 Re: Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843532#msg-843532 Are they able to build up any pressure?
I don't want to spray the paint, but have a oozeless tip in mind, where the opening is held close by a springloaded delrin ball.
The pressure has to lift up the ball.]]> o_lampe Reprappers Sat, 05 Jan 2019 03:29:56 -0500 https://reprap.org/forum/read.php?4,843531,843531#msg-843531 Paint dispenser with DC motor and encoder https://reprap.org/forum/read.php?4,843531,843531#msg-843531
[attachment 109222 gearedmotorw_Encoder.jpg]
[attachment 109221 motor-specs.png]

I think, my Duet-boards can drive it without H-bridge, but how do I config the two encoder lines in RRF for speed control? Even add another (analog or encoder ) input for fine tuning...

Thanks for reading]]> o_lampe Reprappers Sat, 05 Jan 2019 03:24:58 -0500