10 Nm gear head motor - Page 1
Forum section: electronics / general

author: Jester
author_rank: Frequent Contributor
timestamp: November 25, 2022, 01:54:43 am
content: I have an old round column mill, with a hand crank to lift the head for coarse vertical height adjust.I'm thinking of replacing the hand crank with a gear head motor so I can crank it up or down with a switch from the front. I measured the required torque at 8 NmAny suggestions for a donor motor, I was thinking about possibly using an automotive power window (they look to have a worm style drive), some google searches indicate torque in this rangeIdeas for donor motors: power windows, windshield wiper, power seat?Looking for ideas....

author: Berni
author_rank: Super Contributor
timestamp: November 25, 2022, 06:27:16 am
content: Yep you are already on the right track. Windshield wiper and window winder motors are the most common high torque geared motors.Another source is cheep cordless drills for when you need a bit more RPM (But are not always in the form if a nice one piece motor+gearbox module)For when you want more torque instead, electric wheelchair motors are great.Treadmills also tend to have geared down DC motors inside, but they tend to run from rectified mains voltage (downside in terms of safety when messing with them, but upside in the power supply for it being simple and cheep)

author: Jester
author_rank: Frequent Contributor
timestamp: November 25, 2022, 07:13:11 pm
content: Making progress,I picked up a new surplus 2002-2007 Saturn Vue wiper motor today at princess Auto on sale for $13Looks just like this:https://www.ebay.com/itm/2002-2007-Saturn-Vue-Chevrolet-Equinox-Front-Windshield-Wiper-Motor-New-22665038-/1120882951905 pin connector that is somewhat unclear, see image belowI found the wiring diagram, connections C, D, and E work as expected. A & B are a bit confusingLooks like A would have +12V while the wipers are on, and then I guess +12V gets connected to the normally negative side of the motor via the park contact to stop the motor when it's in the parked position, does that make sense?I find automotive wiring to often be more convoluted than seems necessary

author: Berni
author_rank: Super Contributor
timestamp: November 25, 2022, 08:50:42 pm
content: Yeah looks like you just need to connect to C and D to get direct access to the motor.The other stuff is just there to make sure the wipers return back to the default position if you turn them off mid stroke.

author: Nominal Animal
author_rank: Super Contributor
timestamp: November 28, 2022, 12:02:00 am
content: For just coarse adjust, a geared dc motor – window or wiper motor – sounds the way to go.If you want more precision, take a look at (used) NMRV-030 worm gearboxes and NEMA-23 stepper motors under microcontroller control.I got one off eBay for a satellite tracker antenna elevation (Alaskan Arrow II). (I don't do satellite stuff, but a friend does.)If I were in your position and the crank can be used for finer adjust also, me being in Europe, I'd look at e.g. rattm NMRV-030 on ebay, maybe 20:1, and a dual 8mm shaft (for hand crank on the butt end just in case) NEMA 23 stepper motor (say, 23HS9440B-26), and a TB6600 stepper driver, and just about any microcontroller for generating the pulses. I'd also use a two-step linear regulator from whatever voltage you use on the TB6600 to get the 5V to the microcontroller, to avoid motor noise causing glitches. At 3A or so, a 24VDC supply at 4A or more should work. The only trick on the microcontroller is to use ramping for both start and stop, to reduce wear on the gearbox. If the stepper+gearbox has much more torque than needed, then one can assume no steps will be lost, and count the steps to calculate the distance moved. Or you could add a 5-micron scale, and read it using the microcontroller as well.

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2022, 04:32:33 am
content: https://www.omc-stepperonline.com/nema-23-stepper-motor-bipolar-l-56mm-w-gear-ratio-4-1-planetary-gearbox-23hs22-2804s-pg44:1 gearbox. 20Nm. $60. You would need a driver too. I was looking for a motor with a second output shaft out the other end that you could still have a handwheel on. Just throwing that out there.

author: Jester
author_rank: Frequent Contributor
timestamp: November 28, 2022, 01:26:41 pm
content: Quote from: Nominal Animal on November 28, 2022, 12:02:00 amThanks for that, I already did a CNC conversion of the X,Y, and Z axis quite a while back. Before I added the CNC stuff I installed scales on all three axis, so I can live without precision on the coarse head adjustment. Adding CNC capability turns a useful machine into a fantastic machine capability wise, so happy I converted it. I also made a little custom control board.BTW, I managed to get the windshield wiper motor raising and lowering the head, requires a fair bit of power, 12A@14V is adequate, with 16V it's quite happy. The funny thing is that raising the head under power sounds just like a rainy day in the car. For testing I cobbled together a rough and ready power supply with an old totally overkill toroidal transformer and a bridge rectifier no filter cap. Seems okay without the filter cap. I will need to find/make a more suitably sized power supply.Plate in the vise will be to mount the new motor.

author: Jester
author_rank: Frequent Contributor
timestamp: November 28, 2022, 02:18:09 pm
content: Quote from: Smokey on November 28, 2022, 04:32:33 amThat little NEMA 23 would not have enough oomph for this application, the gearbox is rated for 20Nm, but the motor only produces 1.25Nm, the windshield motor is just adequate at about 175W, peppy with 200WThat being said the 23HP45-4204S with a gearbox would probably work pretty well

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2022, 08:04:23 pm
content: Quote from: Jester on November 28, 2022, 02:18:09 pmMotor torque is multiplied by gear ratio of the gear box. But ya, that particular one is probably undersized. They have bigger motors/gear ratios.

author: Nominal Animal
author_rank: Super Contributor
timestamp: November 28, 2022, 08:55:38 pm
content: With NMRV-030 worm gearboxes, the approximate output torque is 0.8 × ratio × motor torque, up to a limit, according to various NMRV gearbox manufacturers. They're industrial Lego.I like them more than planetary gearboxes for certain applications, because worm gearboxes cannot be back-driven, at least at the higher ratios.

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2022, 09:37:45 pm
content: I would think being back driven would be a feature in this case since you can have a hand wheel and still move the head by hand.

author: Nominal Animal
author_rank: Super Contributor
timestamp: November 28, 2022, 10:25:50 pm
content: Quote from: Smokey on November 28, 2022, 09:37:45 pmNo, that's why I use a stepper with a dual 8mm shafts: you put the hand wheel on the butt shaft of the stepper. If the driven axis is vertical, you can make the axis of the hand wheel horizontal, which is more comfortable too.(If you mean a hand wheel on the output shaft directly, you'll want to be able to uncouple the gearbox and motor, because they add a LOT of friction.)No back-driving means that without input to the gearbox, the output is locked. You cannot rotate the output (other than gearbox backlash, typically about a degree or two in NMRV's), at all: it only rotates by rotating the gearbox input. The holding force is on the same order as the maximum output torque, often over a kiloNewton for well made worm gearboxes (as it is mostly a materials and bearings issue). The -030s usually have an aluminium frame.That applies only to worm gearboxes with sufficiently high ratio, 15:1 or more, perhaps? It is due to the contact geometry and friction between the pinion and the worm, so that with sufficiently high ratios, the pinion physically cannot rotate the worm – but it depends on exactly what kind of worm-pinion geometry is used.In comparison, 15:1 planetary gearboxes can usually be back-driven.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 30, 2022, 02:28:04 pm
content: I also have an (rebranded) RF30 and a long time ago I was also tempted to add a motor to the column. After some brainstorming however, I decided that automating that task was not the mayor issue, but that the bolts to clamp it are on the other side then the cranking handle.My solution was to replace the bolts with a few pieces of longer all thread with brass nuts and add some steel tubes to make the nuts more accessible. Now both the locking nuts and the cranking handle are on the same side and this solves most of the problem.Just in case you (or someone else) is interested, I also added the user manual.

author: Infraviolet
author_rank: Super Contributor
timestamp: November 30, 2022, 08:41:27 pm
content: The other option is always to stick some 3d printed planetary gearboxes infront of an existing lower torque motor, so long as they're big enough (always go far larger than you'd usually expect) and you have space enough for that then they can be reasonably efficient (even with multiple stages for 10 fold, or more, speed reuction) and will cope with this sort of torque level. The most difficult part is usually the strength of the way you join the input gear to the motor shaft, however low the torque at this point the forces occur in a very small area near the flat of a D shaft so are tricky to handle with plastic. A tiny gearbox of this sort I made took 68kg*cm before breaking, so I'd be happy to use it at maybe 10kg*cm long-term. 8Nm is about 80kg*cm, a larger printed gearbox can definitely take this. 37mm 12V dc motors to provide speeds of around 12rpm and torques around 10kg*cm are readily available in a pretty standardised size with 6mm D shafts.

author: Jester
author_rank: Frequent Contributor
timestamp: December 02, 2022, 01:05:47 am
content: Really bad action video of the Saturn Vue wiper motor raising and lowering the head on my round column mill.The wiper motor has two speeds, this is slow speed.https://www.dropbox.com/s/26wb19hzack3i44/VerticalLift%20Movie-short.wmv?dl=0

author: Smokey
author_rank: Super Contributor
timestamp: December 02, 2022, 08:34:03 am
content: nice. anything you want to change, or are you done?

author: Jester
author_rank: Frequent Contributor
timestamp: December 02, 2022, 09:44:19 am
content: Quote from: Smokey on December 02, 2022, 08:34:03 amI’m forever seeking my next project, next up adding linear bearings to maintain location while lifting the head, I have a plan…… to be continued😉