3D Printed Tachometer for Lathe Spindle

STL's and links: fpfdesigns.com/
Hall Effect Sensors: amzn.to/3WG9ogi
Magnets: amzn.to/4bpq2VT
Part 1: • 3D Printed Tachometer ...
Part 2: • 3D Printed Tachometer ...
Part 3: • 3D Printed Tachometer ...
• 3D Printed DRO Mount f...
Outro music is "Quantum" by "Vapora", used with explicit permission from the artist. • Quantum
New videos published every Friday, featuring a new 3D printed functional object, how I use it, and design considerations.
The design depicted in this video is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License or other non-commercial license.
touchdro
tach
rpm
revs
feed rate
pm1440
1440gt
precision matthews
lathe
magnets
hall effect
reluctor
functional
print
fpf
PLA

[@johnsickmann9224]

From the Touch DRO manual the input can cope with 100KHz 2000 RPM with 6 magnets is 2000 * 6 / 10 only 200Hz so you are only just getting started .... if you used a 1024 Line encoder the result would be 34.13KHz ..... As the ring you fit to the spindle will be quit large the more magnets you put around it the better and faster the calculation response should be. Also if you alternate the magnets N S N S .... It could help the response of your sensor as the magnets would counteract any stray and residual magnetic fields. Also if you put 2 sensors side by side so the signals overlap as the magnet passes you will get a quadrature effect which is like you x/y axis and this should show the direction as +/- RPM . I enjoy your content and practical real world use of 3D printing. I'm looking forward to seeing your final design .

[@johnparker2636]

I don't have a lathe and likely never will, but am loving watching this series. Can't wait for the next one. PS those magnets are tiny- you could hot glue one to an ice cream stick when testing the sensor..

[@AlexSwavely]

s-video is a "mini-din" plug which is the same plug as ps/2 mouse/kbd and some serial devices, like receipt printers. What might be a better choice for the rpm sensor is the type of inductive probe used for 3d printers - sealed in a threaded barrel for easy off-contact adjustment.

[@FunctionalPrintFriday]

fair point on the adjustability

[@richardgardiner242]

Thank you for this. I have a Touch DRO on my mill and am in the planning stage at the moment to add an RPM readout. The hall effect sensors I already got seem to match yours. I didn't know about having multiple magnets, so that's good information. I'll be interested to see your solution to mounting the sensor.

[@MatCatSoft]

Hall effect sensors are almost always active low, meaning they swing towards ground when a magnet is detected, and go back up close to supply when not. If your device for some odd reason needed active high signal you could always just use a NOT gate on the signal line.

[@FunctionalPrintFriday]

thx, I didn't realize that

[@michaelgleason4791]

Petition to find out at what RPM those magnets will fly off!

[@FunctionalPrintFriday]

It almost happened by accident. When I was testing the tone ring in the next vid I forgot to remove the magnets from the chuck and only noticed them right before I tested at high speeds :)

[@75keg75]

21:18 3d print a doodad that you put the magnets in a slot that is retained by a screw on cap. then you can unscrew and extract magnets for propper use.

[@tehhamstah]

This is basically what I need to do to complete my self-designed automatic blind opener. Think I'll order some hall effect sensors this week and see what I can pick up on my pi pico.

[@rlschow]

This is awesome! Thanks for doing this topic! I’ve been wanting to figure out the tachometer capability of my TouchDRO for quite some time, but hadn’t got around to it. You’ve just made the chore a whole lot less daunting.

[@unamanic]

All that talk of X slit disks makes me think they’re assuming you’ll have an optical sensor, not a magnetic one.

[@donkultgen4643]

In the automotive world, the cam and crankshaft position hall sensors just use a steel wheel, no magnets needed.

[@aaro_n]

Glad to see you this sounds interesting

[@Godchampion76]

Great video! Looking forward next part of this upgrade.

[@PastThePoint]

Definitely enjoyed this combination! Great job!

[@pintokitkat]

Shouldn't it be R'sPM?

[@somaliskinnypirate]

I really like this channel. Functional prints are all I'm interested in. Now I see you have the same PM lathe and oscilloscope. I was literally thinking about an RPM meter over the winter and never got around to it. I do have one of the PM DRO's that i attached. Wonder if it has some type of input i can use for RPM..maybe ttl... I actually have those same magnets which i used to design a 3d printed led round light strip that clips to my PM mill. So, either i just use touch dro just for rpm or maybe design s cheap interface maybe using an esp32 controller to display the rpm..hmm..anyway, can''t wait to see your next video. Good job.

[@FunctionalPrintFriday]

thx! and good choices :P

[@joell439]

👏🎉👏

[@MatCatSoft]

Something to keep in mind is that RPM will be different depending on diameter, I am guessing that the diameter of the magnet positions on the chuck does not quite match whatever diameter (probably the output shaft) that the stock speed information is based on.

[@tomaspalmquist]

RPM remains constant, I think you are referring to surface speed. A value the Touch DRO most likely can calculate using axis position . That gives the cutting speed an important value for lathe work.