I live in Canada and my 7 by 12 mini lathe by King Canada Tools has the exact same POT I assume if not all the Chinese made mini lathes are all built and wired the same only with different color branding on the body. I found your video inspiring and very informative , as I looked at mine and I almost lost hope of attempting to replace mine. Once I order and receive my new POT I will follow this video to the letter and have a feeling of great relief knowing for future POT failures what to expect . Well done my friend you have inspired many of us , thank you so much my friend.

Thanks for answering my question about using a momentary switch and a non-switching pot. That's what I had in mind b/c the OEM switch is difficult to find or it's very expensive (~$25 US). Now I know it can be done. Appreciate it!

Perfect timing as I actually am holding the new switch in my hand and preparing to install it.pretty straight forward job and your video reinforces that,Thank you and by the way the old switch lasted about 1 year with heavy use

@SteveJordan

7 жыл бұрын

Hi Thanks, When my first one broke, I was actually quite relieved at how easy it was to replace. I took one of the old potentiometers apart and was surprised that they can actually last a year or more! The switch arm mechanism was made of a brittle plastic! But like you say it is very straight forward to change and its great that you can get the spares easily. Regards, Steve

It's good to know this is available in case I should need it for my mini. Thank you Steve.

@SteveJordan

7 жыл бұрын

Hi Jim, thanks that's ok.

Ehi Steve, minute 8:17 - i also had the same problem with my potentiometer, and - as at that time wasn't able to find a potentiometer whose switch was closing in anti-clockwise position, i built up a piece of printed circuit board with a normal linear potentiometer of 4,7 kohm, a microswitch ( type with a little wheel ) and a lathed round piece of steel, coaxial with the potentiometer itself, with an half bore in the outline circle, just to get in the wheel of the microswitch. It works, but - due to the poor room inside the box - i was compelled to adjust the things so that the speed was increasing in an anti clock-wise rotation ( crazy !!! ). After some time i got the whole box cracked ( after years of punching on the emergency stop ... ), and - after attempting to get a new one from Ali Express ( and negative help of italian postal service ) - i fixed all the electronics into an old box from Teko i had in my house by many years ... and happily fixed that box with the help of four exagonal bolts on the lathe ... So also i changed the crazy speed increasing in a more human understanding, i intend increasing speed in normal CLOCK-WISE rotation ... To do so, I had only to invert P1 and P3 on the potentiometer, and change position of the "shaped" wheel on the potentiometer itself, but it was easy. In the future i will not need any special potentiometer with special type of switch, but only simply, linear potentiometers of 4,7 kohm ... Best regards from Italy.

Thanks for sharing this video Steve I’m a bit late I know lol but you just helped me change mine and now I’m up and running again all the best mate stay safe god bless

@SteveJordan

3 жыл бұрын

That's great. Thanks for the feedback. Regards Steve.

I'm on my 4th pot since buying my mini lathe 2 years ago and keep a bunch of spares I got from eBay. My motor seems to be laboring lately so I hope you make a video on motor replacement (brush and brushless) someday.

Hi Steve, good video. Do you have the link to download the instructions for the KB circuit board?

Tks !! Tôi cũng đang có 1 con máy bị như vậy

good job Man , I found they don't last long to !

@SteveJordan

7 жыл бұрын

Hi Shawn, Thanks.

Hello! Excellent video. I have a question - my lathe is very similar to yours and the RPM 'floats' randomly. What could be the issue? Thanks in advance

Hi Steve, thanks for this video. My mini lathe was running lumpy through the range of speeds, only really running smoothly at maximum revs. A set of instructions stated that the pot would be knackered if the lathe ONLY ran at maximum. It also stated that lumpy running would probably be the brushes. I checked those and found all OK. Having watched your video I bit the (inexpensive) bullet and ordered a pot from Amadeal. I've just installed it and now all is sweetness and light :-)

@SteveJordan

6 жыл бұрын

Hi Nige, Sorry for the late reply. Great that you managed to change it. I have found that the potentiometer sometimes doesn't last long.I have had a few of them now, but the one I had last year seems to be lasting well. Thanks for watching...Regards Steve

@zorro587

6 жыл бұрын

Hi Steve, slightly off topic here (but I couldn't see an email address for you) but do you know of any wiring diagrams, to component level) for the mini lathe? My RPM readout packed up a while ago and I've found a blown-apart voltage regulator on the small board that the readout and pick-up plug into. If I can get a part rather than having to get a whole new board I'll give it a go. Thanks

Acid flux? NOOOO! That's probably a major reason why the pots are failing so quickly... Also, you could use a standard counter-clockwise open switched pot, find a low voltage rail on the circuit board, and use a relay to invert the switches operation. Then you could use a conventional pot of higher quality.

@binness

7 жыл бұрын

Yes I spotted the use of that flux as well, however it is not even a minor reason for the pot failing, acid type flux should never be used on the circuit board itself as it is a corrosive and will destroy the circuit, but used where he did on just the pot clearly it had not burned through the connection, and given they don't last long anyway, it is unlikely to cause a problem, I would say it is a touch of the cheap components used in these kind of lathes in order to keep the price down.

mine god steve, l hope this one works for 10 years.

Hello Steve, what do you think about opening the broken switch and to replace it with a tiny limit switch ? Mine never broke, now I'm using a three phase inverter and a small three phase motor, with vector control and a brand new panel just for speed and direction. cheers

@SteveJordan

5 жыл бұрын

Hi i converted mine to belt drive with VFD and 1hp 3 phase motor now. I was the best upgrade I have done. No more trouble with the electronics that I had in the past.

hi I wanted to ask for the 2 wires of the motor that I have one white and one blue that do not have the terminal as they go connected to which side the white goes thanks a lot

Or a normally open push button momentarily on switch so you have to be pushing the button to change direction.

Steve, Well if the switch mechanism is too flimsy then there isn't too much you can do about that. But you know it is likely there will come a time when you can't find these potentiometers. That might be a long time away. However, if you keep one of them that broke in the open position. It can come in useful. If you absolutely had to, you could then add a normally open momentary push button switch. You would connect the two wires gong to the terminals on the pot to the momentary switch. That way you would turn the pot anticlockwise to lowest position then push the momentary button and change directions. That would work but it would be a two hand operation it seems. Not good but it could act as a work around if it became necessary. Hopefully it will not come to that. With my old equipment I am always needing to find these types of work around.

@johncoops6897

Жыл бұрын

Potentiometers are a 100% standard component, always available. The problem is that the switch is rated for small radios, not for this kind of application. The obvious solution is to separate the switch from the speed control. Since there is already a switch on the top of this lathe, he can just use that to control the lathe. It's much better to have the switch separate from the speed anyway.

You could always use a standard potentiometer with a "normal" switch by designing a simple circuit in line with the switch using a PNP transistor and a 2k resistor on the gate. You could enclose the entire thing inside of some shrink tube so no circuit board is needed.

@SteveJordan

7 жыл бұрын

Hi Ian. I have only very basic knowledge of electronics, so I wouldn't know what to do with info like this. Thanks though as it maybe of use to someone reading the comments. Regards Steve

@ianide2480

7 жыл бұрын

My instruction is not quite complete but it is still a very simple circuit. Your switch is ON when a "normal" switch is OFF. So you determine which wire looses voltage (and/or signal, call it what you want) when you start advancing the knob from the ON position to OFF; you can find this by using a DC voltmeter easily enough. Now toss in a "normal" switched potentiometer and hook up everything except that one wire that you just discovered. Get a small piece of wire and attach that to the now blank switch contact. What you should have left is the original wire and a new wire from the switch. The old wire that used to go to the switch will now go to the COLLECTOR pin on the PNP transistor. The new wire that you added to the switch will now go to the EMITTER of the transistor. From the EMITTER to the BASE pin of the transistor you will solder a 2k OHM resistor...... Now the part that I left out, run a 20k OHM resistor (this number just isn't that important but you do want it to be a bit higher than the other resistor, 15k or even as high as 30k will work fine) from the BASE pin to ground. Any ground on the current circuit board should be easy to find. The total circuitry is 2 new wires and 3 very cheap components. 1/4 watt resistors are fine and any off the shelf PNP transistor will do the job, a 2N2222 will handle up to 50v. The entire thing should cost less than $5 and you shouldn't have to mess with this circuit ever again, because now you have the same amount of wires attached to the potentiometer, and if it fails again your process for changing it stays the same.

Steve, If the potentiometers are of a weak design you could "as you say use one from China" This could be made to work properly by introducing a secondary relay to reverse the action of the potentiometer "off position". That is when the China potentiometer contact opens in the off positon you could then use the added relay to close the contacts on the board. Just a thought to solve the problem.

@SteveJordan

7 жыл бұрын

Hi Glenn, The trouble is I have very limited knowledge when it comes to electronics. I don't know anything about relays really. I only did this video because I had to change this component so many times, that I was forced to learn what I have shown here. When I came to changing the potentiometer the first time, I was actually really worried I might mess something else Up!

Your plastic guard in the back of your control panel is getting bad, get a "For sale" or "No trespassing" sign from Walmart, The thin plastic ones. Cut out a new one. These are about the same thickness and work great. I even wet sand the paint off the signs and use them as shields in places where you don't have to look through them. Plus they are cheep. I love your videos. Norman

@SteveJordan

7 жыл бұрын

Hi Norman, Thanks. I know the signs you are talking about. That's a great idea thanks! Regards Steve

To solder: Make a MECHANICAL joint. This will mean preparing fresh ends on the wires, and passing them through the tags on the potentiometer. Then a small amount of solder on the iron, place the iron on the tag, then feed in more solder until the work is done. The soldering in the video is, shall we say, "a bit iffy"!!! :-( Definitely not "mil spec"!

@SteveJordan

7 жыл бұрын

Thanks for watching and giving the correct method of soldering. People may be interested in the correct specification when repairing a lathe.....Regards Steve

Hi Steve, brilliant video as always, I've implented many of your upgrades on my mini lathe with great success thank you. On my mini lathe the motor has recently started to hunt/pulse, have you got any suggestions what the problem might be please? Thanks Dave

@SteveJordan

6 жыл бұрын

Hi Dave, Mine sometimes does that. Its a bit temperamental. The problems I've had with mine were mainly with the potentiometer. They don't last long and I think the carbon contacts get dirty. Mine has just broke in the switch mechanism again. I have just bought a Maplins potetiometer that can be converted on the switch mechanism and used on the Mini Lathe, which are only 1.50 pounds to buy. So I will show this at some point. Other than that if your motor has brushes, the commutator may need a clean? Regards Steve

@dave51104

6 жыл бұрын

Hi Steve, I've just found this, somebody has suggested to fix this fault "turn the IR pot control on the speed control circuit board anticlockwise 1/8 of a turn at a time until the hunting is corrected. Make sure the power to the lathe is off when making the adjustments" Any idea what he is talking about as I think there is more than one the PCB?kzread.info/dash/bejne/dGmMxMFmgZzVkajM.htmlttps://kzread.info/dash/bejne/dGmMxMFmgZzVkajM.htmlttps://kzread.info/dash/bejne/dGmMxMFmgZzVkag.html

@SteveJordan

6 жыл бұрын

Hi Yes I have altered the circuit board pots before, but after a while the board packed up altogether. I bought a new board from www.amadeal.co.uk but have left the pots exactly as in the factory set. The reason for this is that I checked out the circuit board makers site, where you can get all the information about the exact board and adjustments one can make to it. Apparently there is a very fine line as to where the pots are set up and where an alteration will cause the boards to fail. I think I had turned up the pot that increases the motor torque a bit too much and this blew the board. So after buying a new board I decided to leave everything as it is factory set. I do have the motor slightly hunting on occasions and sometimes the motor torque seems to be a bit temperamental, but these usually come right especially as the machine warms up. I maybe wrong but sometimes I think it maybe caused a bit by the operating condition in the workshop, as in the summer I don't notice any faults. I will find the makers details from USA later so you can see the circuit board instructions for yourself. Regards Steve

@SteveJordan

6 жыл бұрын

Hi Dave further to my last reply....This is the USA maker of my circuit board where you can download a PDF file of instructions for the exact board. www.kbelectronics.com/kb_manuals.html The circuit board on mine was listed as KBLC-240, but the same one is now listed, (a different serial no), on their site under the title section 'VARIABLE SPEED DC DRIVES'.......... See the KBIC series Drive Installation & Operating Instructions, there for all the details

Steve, Are they putting a large current through the contacts of the potentiometer. If so it may be too much for the contacts on the potentiometer.

@SteveJordan

7 жыл бұрын

Hi Glenn, I'm not sure what current goes through it. Its not the actual contacts that are faulty. The arm that has the contact on seems to be made of a very brittle plastic. Its after many uses of the switch that the mechanical plastic arm breaks.

I would buy a better potentiometer drill out the rivets turn the switch around and rivet or screw it back together and then install it.

4K7 is a 4.7 kilo ohm pot - ie. 4700 ohms.

Can you please show pictures of ALL the wiring . Im trying to change out the forward /off/ reverse switch and I need to see how it is wired . It would help out alot

@SteveJordan

2 жыл бұрын

Hi Michael, I haven't got the board anymore. I converted my lathe to a VFD with a 3 phase motor so it's completely different now. Regards Steve

I am in the process of changing the pot on the same machine. Unfortunately one of the leads from the switch at the back of the pot has become detached at the end opposite the switch. One lead is still attached to the smaller of the two circuit boards but I do not know where the other one goes! Any help here would be appreciated.

@SteveJordan

5 жыл бұрын

I can't find my old electronics boards for this one at the moment so I don't know. I will see if I have a photo.

@iantaylor8187

5 жыл бұрын

Hello Steve. Thanks for the reply. Problem solved yesterday afternoon by courtesy of Hugh at Amadeal. He was able to find a similar control box. The lead had popped out of the forward/reverse switch which unfortunately as you know has a possible 12 terminals. Thanks again...... Ooooh! keep up the good work on the videos. Excellent stuff.

Just reposition the Forward Reverse selector switch so the rotating chuck provides isolation. If the Chuck's spinning your won't be able to change rotation... so that flimsy zero selected switch would be unnecessary. An electrical interlock isn't difficult... A zero speed switch with a timer for a second or two of anti bounce would do it. I'll see if I can grab one or draw up a simple circuit to do the fwd rev using relays instead of the drum switch. If you have a B472 potentiometer too it's a 4.7K ohm

@SteveJordan

2 жыл бұрын

I got rid of the original Chinese electronic parts in the end. I now have a VFD and three phase motor control which is excellent for this lathe.

@WireWeHere

2 жыл бұрын

@UCEpeQtxhVUTtMZzBpdegp-w Well that's where my comment got to. I was working on it and got distracted and forgot about it... Looks like I hit send. Sorry, I was planning on adding something useful for your rotation change enable switch. They seem to last most people about a year. Bourne wire wound potentiometers are what I like to rely on for customers. I've never had one fail. The 10 turn ones are helpful for fine speed control on things like a welding turntable. The simple way to have a protected zero speed rotation change is to tie fwd and rev selector switches each to a relay and an on delay timer in parallel. The relay's normally closed contact disables the motor until a parallel timer contact closes when the timer times out. This enables the motor again and the potentiometer need not be turned down, the speed will remain as is. The timer setting just needs enough time set to allow a coast down from full chuck speed. A schematic diagram would be much simpler. This is just an idea for anyone who may be interested. There's many ways to automate.

@WireWeHere

2 жыл бұрын

@@SteveJordan VFD's are greatly improved now. It's helpful to adjust your belt drive ratio so you're using all the rpm the motor has available. AC motors have always been the first ones to complain about low rpm work but their winding details are getting better all the time. Cheers.

Hi. Great video. I’m in the same situation. Do you have the part number for this potentiometer? Than you in advance.

@SteveJordan

2 жыл бұрын

Hi I don't know the part number and have a long time since converted my lathe to vfd 3 phase. If you contact Amadeal.co.uk you should be able to buy one from them. That's where I used to buy mine. Sorry I can't help you further. Regards Steve

@SteveJordan

2 жыл бұрын

I have just looked on the Amadeal UK website and they still sell the mini lathe potentiometer. Regards Steve

@dennis198007

2 жыл бұрын

Thank you. That helped a ton!

Can I use a pot that's rated higher than I need? ie. my controller requires a 5k pot but all I have is a 20k pot. will it be harmful?

@SteveJordan

7 жыл бұрын

Hi Billy I do not know much about electronics. I'm pretty sure it wont do any damage, but I think you will find that the normal speed range of the lathe wont be obtainable using a different rated pot. Regards Steve

@ianide2480

7 жыл бұрын

A circle is 360 degrees. You will reach 5k ohms resistance at 360 degrees when using a 5k pot. On a 20k pot you will reach 5k ohms at 90 degrees. So in essence you will loose some resolution in the speed control. Which will make fine control more difficult. Anything above the 5k range (5.1k-20k ohms) will do nothing at all and will be ignored by the controller. Of course this example assumes 360 degrees. A single turn pot only has about 300 degrees of revolution. So your fine control of speed will be even less. BUT, it will indeed work in a pinch, just don't use less than 5k or you will never reach full speed.

if you turn a custom knob with a tab, it could operate a separate microswitch.

@SteveJordan

7 жыл бұрын

Hi Thanks.....That is a great idea!!