Reversing 24v 8000rpm motor - Page 1
Forum section: electronics / beginners

author: Verge
author_rank: Contributor
timestamp: February 21, 2025, 04:47:13 pm
content: So I have this mini lathe I would like to have a reverse speed option with. It has a transformer with 5 step switch.I am looking at this DPDT:https://fr.aliexpress.com/item/1005008339005874.html?spm=a2g0o.productlist.main.7.59393fa55NpQpu&aem_p4p_detail=20250221074918510573136363200004481085&algo_pvid=87a8cb12-6796-4704-8ad2-59dd1e4a0f8e&algo_exp_id=87a8cb12-6796-4704-8ad2-59dd1e4a0f8e-3&pdp_ext_f=%7B"order"%3A"23"%2C"eval"%3A"1"%7D&pdp_npi=4%40dis%21EUR%210.48%210.48%21%21%210.49%210.49%21%40211b61ae17401529580341384ea5a1%2112000045322184525%21sea%21FR%214841011536%21X&curPageLogUid=EJTEbqEv9iAN&utparam-url=scene%3Asearch%7Cquery_from%3A&search_p4p_id=20250221074918510573136363200004481085_1should I put a delay circuit, or what would be the way to protect the motor during the polarity change?I would also like to have a speed ramp... any ideeas?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 21, 2025, 06:58:39 pm
content: You didn't post any information about your lathe. First can you make the lathe to run in reverse simply by swapping the 2 wires from the motor (assuming again the motor has 2 wires only)? If so the switch would work. I think the switch would work but you would need a switch to turn it on and off. You just have to make sure the motor stops before you reverse it. Sure you can have a delay circuit but it would be a lot more complicated and the switch actually won't work. You would need a DPDT relay and timing circuit etc..

author: Verge
author_rank: Contributor
timestamp: February 21, 2025, 08:02:59 pm
content: Yes. this is it... I need to make sure that the motor stops... no big deal. That is OFF ON OFF switch. Lathe is 24v they say 96W. 8200rpm max.I would like to know how to induce an acceleration ramp to the motor. I've avoided the rotary knob model because of the making sure thing.... anyway... this is it I suppose...Thanks!

author: benseno
author_rank: Regular Contributor
timestamp: February 21, 2025, 08:58:27 pm
content: What are the current/voltage/wattage ratings on lathe's motor plate?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 21, 2025, 10:46:01 pm
content: To have an acceleration ramp (or deceleration ramp) you need a drive. It would be relatively expensive but many of the drive has facility for reversing and of course the drive can make the motor run at variable speed.

author: amyk
author_rank: Super Contributor
timestamp: February 22, 2025, 05:48:25 am
content: Make sure the chuck won't unscrew itself if you try to run it in reverse.

author: Verge
author_rank: Contributor
timestamp: February 22, 2025, 10:47:45 am
content: Quote from: amyk on February 22, 2025, 05:48:25 amWell pointed out. I bought some dremel bits for carving and they are in reverse so I have to have it like that but it's not a big deal if it doesn't work.... and chucks are notoriously hard to unscrew... I'l have to get a connector to tie the flexshaft directly.Quote from: BeBuLamar on February 21, 2025, 10:46:01 pm...combined with a dpdt switch. I know with an arduino a 10%s ramp can be made. I would have liked to learn how to do that. A ramp for on off and protection for polarity change.Otherwise I'll just put in the switch and take care not to change too fast. I won't put an Arduino on a lathe but I'll definetly learn that in the future. Sci Fi shines proper with acceleration ramps.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 22, 2025, 10:50:18 am
content: I don't know what size of motor you have but I doubt that an Andruino can output enough current/voltage to run a lathe.

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2025, 01:29:10 pm
content: Of course an Arduino cant directly output enough current to run a lathe, nor can any other MCU. That's the job of the H-bridge its controlling and depending on the parts used, it could be controlling anywhere between a few amps and a few thousand amps!You probably *DON'T* want a simple DPDT center off switch - especially not an illuminated rocker switch such as in the O.P's link, which I suspect to have seriously underrated contacts. It is far too easy to over-shoot the 'Off' position, resulting in 'plug' reversing*, which can be as destructive as crashing the lathe. The minimum switching to do this job properly would be a three pole three way rotary switch, with the motor wired to two of the pole commons, and their end ways wired to reverse the motor supply. The third pole should be wired to trip a ZVR contactor as the switch goes through the center off position so that the motor cannot restart until the operator selects forward or reverse *AND* goes through the normal starting sequence. You may also want to consider a contactor, latched on via an auxiliary contact, that disconnects the motor and switches in a breaking resistor if you cut power or hit E-stop.Even with all the safety and protection circuits, normal operating procedure should be to slow down and stop the lathe preferably by reducing the speed control to zero, and wait for it to stop before operating the reversing switch. Just treat the reversing switch as you would a spindle or leadscrew gearbox - not to be shifted while running. It reduces stress on the switchgear and motor drive, which are typically expensive to replace or repair.* Reversing a DC or three phase motor by instantaneously reversing the polarity or phase sequence respectively. 'Plug' reversing is generally regarded as a bad idea as it transiently pulls up to double the stall current, so is very hard on switchgear, and the high deceleration/acceleration is also very hard on drivetrain mechanical parts.

author: MrAl
author_rank: Super Contributor
timestamp: February 22, 2025, 02:43:03 pm
content: Quote from: Verge on February 21, 2025, 08:02:59 pmHi,One thing that might help is you could look into how to brake a DC motor. A lot of tools do this these days like portable drills, and even battery-operated circular saws which makes them safer to run.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 22, 2025, 03:04:19 pm
content: If the motor is a permanent magnet DC motor then you simply disconnect the power to the motor and connect the motor to a resistor.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 22, 2025, 07:51:28 pm
content: Not all motors run as well in reverse as the run in the normal direction. The position of the carbon brushes can be so that one direction is working a little better. One can still run such motors in reverse, but only with reduced speed/ voltage and power. So check for sparking when using the motor is reverse with the highest 2 voltages.

author: Verge
author_rank: Contributor
timestamp: February 22, 2025, 08:13:24 pm
content: Quote from: BeBuLamar on February 22, 2025, 10:50:18 amThrough a relay any size. Arduino has 5v. But it's big anyway... just for a speed ramp. ... for safety though... but I thought there should be something simple to implement this.Quote from: Ian.M on February 22, 2025, 01:29:10 pmWhew. so yes, bad news with the DPDT.Initially I was thinking to replace the device's on/off switch with a center off one. Rotary knobs I avoided for missing the center issue.Now I am thinking to keep the original switch and to install the DPDT higher up in a box of it's own so it can't be accidentally pressed.Your suggestion is well noted as I am planning to build a similar device with a cheap? strong silent motor (which I haven't found yet) Best bits for that one. So you think this one is poor quality?I think i've bought this one:https://fr.aliexpress.com/item/1005005928055004.html?spm=a2g0o.productlist.main.5.59091e20Y8JVSC&algo_pvid=fa0f831a-f2d4-4978-ba87-c82f61a3d6d8&algo_exp_id=fa0f831a-f2d4-4978-ba87-c82f61a3d6d8-2&pdp_ext_f=%7B"order"%3A"6"%2C"eval"%3A"1"%7D&pdp_npi=4%40dis%21EUR%212.05%212.05%21%21%212.10%212.10%21%402103917f17402539106688503e8d20%2112000034888671711%21sea%21FR%214841011536%21X&curPageLogUid=nE32djF9B7E7&utparam-url=scene%3Asearch%7Cquery_from%3AOn the motor there is a shield (welded) so I can't read but on the case it says 12-24V (in 5 steps on the transformer), 96W 9A... 9.7A... 96W with 24V is about 5 A.... I don't know it should be close to these specs.I was thought that devices that reverse an electrical motor would be growing on coffee machines in this age... As I was writing I got the ideea of emergency stop type button, with on/on. Could this be done?Quote from: Kleinstein on February 22, 2025, 07:51:28 pmGood advice. I have no idea if this has brushes. Does this apply to brushless as well?It is one bit I have that is in reverse the biggest of all but I was thinking that maybe I can pull more life out of the polishing bits if I run them in reverse. It's no big deal but it would be nice to have this option.Overall... do you think it can be done with just a safely installed good quality dpdt switch?

author: Verge
author_rank: Contributor
timestamp: February 23, 2025, 02:26:31 pm
content: What do you say about this guy?DC Motor Speed Controller 9-60V, PWM Controlhttps://www.temu.com/fr-en/high-power--motor-speed-controller-9-60v-pwm-control--reverse-versatile---aluminum-alloy-easy-setup-for-switch-motor-speed-regulator-12v-24v-36v-48v-60v-20a-g-601099850562900.html?_oak_mp_inf=ENT6xLin1ogBGiA1NDIzN2UzODc4YWY0OTUxOWU1NjZlNjRiOTNjN2UxZSDF582S0zI%3D&top_gallery_url=https%3A%2F%2Fimg.kwcdn.com%2Fproduct%2Faisc_image%2Ffancy%2F2024-12-13%2Fdd07d58d-4f16-4fce-b0ac-0b2435440f35.jpg&spec_gallery_id=5184889739&refer_page_sn=10009&refer_source=0&freesia_scene=2&_oak_freesia_scene=2&_oak_rec_ext_1=NzY5&_oak_gallery_order=1002710572%2C711122459%2C548109463%2C933983755%2C1562477897&search_key=pwm&refer_page_el_sn=200049&refer_page_name=search_result&refer_page_id=10009_1740305430887_e6ua6j8nzn&_x_sessn_id=q6xxjln3zm

author: Ian.M
author_rank: Super Contributor
timestamp: February 23, 2025, 02:39:21 pm
content: Four wires to the reversing switch means it doesn't reverse by controlling a H-bridge, so it almost certainly doesn't implement controlled acceleration/deceleration profiles. Flick that switch a bit too hard and you'll be violently 'plug' reversing the motor. The higher the rotational inertia of the chuck and workpiece, the more likely it is that the controller will fail or something will break loose.Also, why not tell us which mini-lathe you actually have? There may be existing, safe and well tested reversing controller options for it.

author: Langdon
author_rank: Frequent Contributor
timestamp: February 23, 2025, 02:56:08 pm
content: This option works, but requires a ludicrously oversized switch and some very thick wire with lotsa solder.First, your motor should have 3 ceramic disk bypass caps: one across the motor terminals, and 1 connected to each motor terminal and the metal motor chassis.Next, you need a 4-way light switch.Connect the two power supply wires to the four-way switch.Connect a diode (fast or schottky) across the switch terminals the power supply wires are connected to, with the cathode connected to the positive side.Now, just connnect the motor with heay-guage wire to the other switch terminals.NOTE: For best performance, the wires connecting the switch and motor should be as short and thick as possible.NOTE2: While connecting the diode across the switch terminals, it may cause the diode to overheat; to avoid overheating, solder the diode to a PCB, keeping lead length as short as possible and benting the leads to spread the heat over a large copper pad area.NOTE3: To protect the switch, consider soldering 2 24V zener diodes and 2 fast/schottky diodes to a PCB, with the cathodes of all 4 diodes connected together. Connect the anode of each zener to the anode of one fast/schottky diode; connect each motor terminal to the anodes of a zener–fast/schottky pair.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 23, 2025, 04:39:45 pm
content: Quote from: Ian.M on February 22, 2025, 01:29:10 pmThe OP wanted to accelerate/decelerate the motor with the Anduino. To do that the Anduino must do some source of PWM switching an SCR or something like that. I would use a commercially availabe DC motor drive which has reverse capabilities. Many of these drives when commanded to reverse rotation won't do it until the motor comes to a complete stop.But if the OP simply wants to be able to run the lathe in either direction I would simply add a DPDT switch after the power on/off switch then when using the lathe turn off the lathe. Wait until it stops completely. Swith the DPDT switch to change direction then turn the on/off switch to on.

author: Ian.M
author_rank: Super Contributor
timestamp: February 23, 2025, 04:52:16 pm
content: Yes, a *SEPERATE* DPDT reversing switch is usable if the operator doesn't **** up and operate it with the lathe running. However our O.P's predilection for asking us if the cheapest/nastiest piece of far east cr@p is suitable for this application, doesn't inspire me with confidence that they've got the self-discipline not to **** up! Call me prejudiced . . .Also, we still don't know if the lathe has a threaded spindle nose with no locking pin so 'plug' reversing it could result in chuck + workpiece detaching and bouncing round the room. I *HOPE* its a very small micro-lathe as I wouldn't care to be in the same room as even a 4" chuck 'on the loose'!

author: Langdon
author_rank: Frequent Contributor
timestamp: February 23, 2025, 04:58:50 pm
content: What type of motor is this?Would a spindle (like G-Penny) be a good option here?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 23, 2025, 08:19:48 pm
content: The motor on this lathe is probably a brushed DC motor. These can be quite good, although brushes always have their disadvantages. Main disadvantage is the limited life of the brushes and the collector, but this does not have to be a big issue for hobby type machine. A bigger problem is that the motors on these lathes quite often tend to be of quite low overall quality. Burned out motors for no apparent reason is relatively common with the cheap chinese stuff.Spindle motors such as the G-Penny are usually induction motors that run at frequencies of up to 400Hz or even 800Hz. They can be used with extra gearing to get the speed down from 24000rpm to something more suitable for a lathe. I am now in the process of designing a CNC router around this principle. I have a G-Penny water cooled spindle motor, and I'm planning to have an around 1:6 reduction with multi-V belt as an option to drive a BT30 spindle. So I can use small mills at high rpm, and bigger mills at a lower rpm. I have not built this yet though. A disadvantage of induction motors is loss of torque at lower rpm. With a lathe you want high torque (full power) at low rpm.Industrial servo motors are another option, and available in power ranges to many kW, but they are relatively expensive (although a G-Penny with frequency inverter is also not a cheap option. I paid around EUR400 for a set for motor + VFD. Such servo motors are PMSM / BLDC. But PMSM is optimised more for linear resolution, while BLDC is more about power efficiency and has more torque ripple, but this is not very important for a lathe.Apparently putting a BLDC motor on such small lathes is a common upgrade. You can buy a 600W to 800W BLDC motor and controller combination for around EUR 100. The intended use for these motors is for industrial sewing machines, but the motors will drive a lathe just as well. There are a bunch of variants on Ali, but I've never bought such a motor myself. I assume there are quality differences.

author: Verge
author_rank: Contributor
timestamp: February 23, 2025, 08:23:40 pm
content: Quote from: Ian.M on February 23, 2025, 02:39:21 pmNah... It's just a cheap VEVOR I've customized to have dremel flex option.In the future I wish to build this system from scratch with a silent motor, more powerful so I'm preparing that actually.Quote from: Langdon on February 23, 2025, 02:56:08 pmWhew... I saved your comment in .txtQuote from: BeBuLamar on February 23, 2025, 04:39:45 pmYes. I was thinking putting the dpdt in it's own case(for security) as I will chose the rotation at the beginning of the project and leave it like that.Quote from: Ian.M on February 23, 2025, 04:52:16 pmTrue, but if it says 26A it will probably work for 5A. China wants LOVE, Economic shock would be murder in the streets but they are impertinent though, they lie in your face, fake reviews, set up false accounts with exorbitant prices to drive consumption of inflated prices... yeah... they are fake, they are not trustworthy, but they are cheap... free delivery for 10 euro bill (of already half price stuff)...China to France... I have to wait a month it's true....Quote from: Langdon on February 23, 2025, 04:58:50 pmBeautiful, me too I've seen medical use motor 230 euro most silen there is... I would love to buy it but...Do you have any knowledge let's say 200w silent motor dc or ac?Quote from: Doctorandus_P on February 23, 2025, 08:19:48 pmYes! I have 2 of the same model - grace of the client service.Quote from: Doctorandus_P on February 23, 2025, 08:19:48 pmThank you. Wood carving is my secret mistress so I'm researching the most silent option and I am prepared to chip 150 for the motor itself, but it will have to be the dream machine. 150w minimum and quiet. I.ll probably make it a case like computers have but in the car exhaust pipe style.One lathe squeaks a bit and jerks from time to time (I've turned it into a mini flex machine) - I am expecting that the second will fall too so I am starting to prepare now. On this one I can make all the experiments.Is there a way to tell without looking at the specs if a motor outputs the same in both directions?

author: Langdon
author_rank: Frequent Contributor
timestamp: February 23, 2025, 11:30:11 pm
content: What about an AC induction motor?Flywheel?

author: Langdon
author_rank: Frequent Contributor
timestamp: February 24, 2025, 12:14:48 am
content: Quote from: Verge on February 23, 2025, 08:23:40 pmYou are racist.Not everything from China is bad.The computer you are using is at least 50% made in China!LAOA is a Chinese company that makes great tools.There is so much good Chinese stuff.Also, there is some pretty crappy French stuff too:Despicable Me 4The Little PrincePeople in rich countries (like France) are entitled; people in poorer countries (like China) usually are not.

author: themadhippy
author_rank: Super Contributor
timestamp: February 24, 2025, 12:19:35 am
content: Quotehave you tried em? in a spicy crispy coating there rather delicous

author: Langdon
author_rank: Frequent Contributor
timestamp: February 24, 2025, 12:34:23 am
content: Quote from: themadhippy on February 24, 2025, 12:19:35 amNever tried them, never will!

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 24, 2025, 01:02:48 am
content: Quote from: Langdon on February 24, 2025, 12:14:48 amSorry but he didn't say anything about China.

author: Langdon
author_rank: Frequent Contributor
timestamp: February 24, 2025, 02:44:46 pm
content: Quote from: BeBuLamar on February 24, 2025, 01:02:48 amYeah he did!"True, but if it says 26A it will probably work for 5A. China wants LOVE, Economic shock would be murder in the streets but they are impertinent though, they lie in your face, fake reviews, set up false accounts with exorbitant prices to drive consumption of inflated prices... yeah... they are fake, they are not trustworthy, but they are cheap... free delivery for 10 euro bill (of already half price stuff)...China to France... I have to wait a month it's true...."

author: Langdon
author_rank: Frequent Contributor
timestamp: February 24, 2025, 02:57:15 pm
content: Quote from: Verge on February 24, 2025, 10:45:34 amAmazon also has products that are not as described; they just conceal it better.Ebay is a total nightmare.Aliexpress is no worse, they are just worse at hiding it.The stepper driver I bought from Ebay took months to arrive.The 2 from Aliexpress took a week.Quality is questionable for both; but the drivers from Aliexpress are arguably better.How could you ever dare to:Rate women solely on appearanceClassify appearance by ethnicity.Be such a racist, mysogynistic jerk.

author: Langdon
author_rank: Frequent Contributor
timestamp: February 24, 2025, 05:28:51 pm
content: What's wrong with good ol' split-phase induction motors and V-belts?They last forever.They have poor power factor, but a simple capacitor can correct that easily.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 24, 2025, 05:33:07 pm
content: Quote from: Langdon on February 24, 2025, 02:44:46 pmYes sorry didn't see that. But he is into buying Chinese products. For me China makes products ranging from the best to the worst but I try not to buy made in China stuff if I can. It's difficult though.

author: Verge
author_rank: Contributor
timestamp: February 25, 2025, 10:45:57 am
content: Quote from: Langdon on February 24, 2025, 02:57:15 pmHa ha, yes and no... what you do is called false analogy and dichotomization (exaggerated).Postage takes how long it takes. "drivers from Aliexpress" - I doubt Aliexpress has worldwide drivers - All big sites are dominated by Chinese traders but once I hit a French UK or German site (the prices are bigger but honesty is (almost) guaranteed - trustpilot enforced."Rate women solely on appearance" There are 7 races. - 7 basic models. I say I like Italian sport cars more than German ones. Yes, German one have better engines... I like the Italian more. How do I dare to do this? Perche il cazzo sale così!!!"Classify appearance by ethnicity." I didn't but I do now: native southamericans have thick hair and tend to be hairy all over but they have a type of almond eyes that I like - also square shoulders. Archaic societies tend to have more fat people that show overweight in their mid 30's. You can have that, I don't mind - for me.... as personal taste cannot be debated, I'll choose a painting of a geisha to have on my wall. That doesn't mean that redheads are forbidden in my bed broh'."Be such a racist, mysogynistic jerk." - Amphetamine/cocaine intake for prolonged period of time might generate psychotic delusional events. Immediate rehab and Anger Management therapy recommended.P.S. I can't be mysogynistic ... I love BITCHES!_____________________________________________________________________________________________________WORD !_____________________________________________________________________________________________________Quote from: BeBuLamar on February 24, 2025, 05:33:07 pmHere in Europe It used to be that German and Austrian devices were the absolute indubitable best. After everybody moves their factories to Asia some fell, some didn't. It's a pity that one has to develop an extra sense to evaluate quality LOTTERY STYLE based on provenience and appearance one plays a game trying to get that halved price. Because sometimes it does work and one gets the full product at a lower price but it also happens that the promo video was a bit more than slightly exaggerated and we get the product and feel cheated.I want to vent out too: LOOK!2 weeks ago I bought a Flexshaft with drill (Amazon)https://fr.aliexpress.com/item/1005005856834511.html?spm=a2g0o.productlist.main.109.1f0e7983Mjztdl&algo_pvid=77455586-f0ec-49a8-8ad2-5236c3d407bf&algo_exp_id=77455586-f0ec-49a8-8ad2-5236c3d407bf-54&pdp_ext_f=%7B"order"%3A"5"%2C"eval"%3A"1"%7D&pdp_npi=4%40dis%21EUR%218.50%218.49%21%21%218.69%218.68%21%40%2112000034594058038%21sea%21FR%214841011536%21X&curPageLogUid=fxAupNkX6aHK&utparam-url=scene%3Asearch%7Cquery_from%3Athis model type c - It looks tip top - slim machined in aluminium 15 euro.I got it the transfer tube was sliding out. I tied it and began using it. After a week the bit started rotating in void. The wire connection to the pen enlarged - I have to open the pen. but it is encapsulated not screwed so I force the rotating axe out. I brake a safety ring and it's out. The tip of the axis is a round hole that has been pressed into a square to accommodate the square(ish) wire that rotates it. That was not properly pressed and the wire was turning inside what had to be a square.The pen is tip top ... except that pressed square. inside an encapsulated device. that costs 1.5 work hours.- now I drilled another hole in the pen at the safety ring level an I will try to insert a homemade ring through there. so +2 work hours...I've also bought 3 other models because I really really need that device proper and I'm hoping that from 4 I will always have one working.

author: Verge
author_rank: Contributor
timestamp: February 25, 2025, 10:52:34 am
content: And another thing...what is the male female ratio in the pro bono makers communities?

author: Verge
author_rank: Contributor
timestamp: February 25, 2025, 12:15:44 pm
content: I've read this :"Furthermore, for greater noise suppression, I tell soldering your motor with three capacitors."What do you think of this?voltage-dependent resistor (VDR) - do they induce a small speed ramp?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 25, 2025, 06:54:52 pm
content: Quote from: Verge on February 25, 2025, 12:15:44 pmA VDR won't create a speed ramp.

author: Simon
author_rank: Unknown
timestamp: February 25, 2025, 07:33:49 pm
content: Verge, I'm locking this rather than banning you. The next time it's a ban.