Fixing a Power Feed and How They Work!
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- čas přidán 24. 09. 2021
- This episode on Blondihacks, I show how a power feed works while I fix mine! Exclusive videos, drawings, models & plans available on Patreon!
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Hey everyone! As many noted below, what I called a “smoothing cap” on the micro switches is actually a metal oxide varistor. However I was correct about its application- to suppress transients from the switches.
**sniff** **sniff** They grow up so quickly! (In the best Dave Jones impression you can imagine!) Lol
U so clever
hahaha
"An impressive exercise in cost-cutting" - Great way to describe the nature of the electronics on that device!
Did you two coordinate power feed weekend?
@@rpavlik1 I was wondering the same thing, having watched one... and then the other pops up! ...both videos by total CZcams legends too!
Quinn is one smart cookie...Have fun over at Metal Bash with the guys,, Wish we could go, but work has piled up and pay's the bill's :)>.
@@bearsrodshop7067 Yes, Quinn is not only smart - she explains her thoughts and process with unusual clarity, and finds ways to keep it fun! I'm sure it will be a great weekend. Maybe you can make it to the next one!
Yup, I remember those dimmer circuits. With an SCR, it's a half wave dimmer that can only reach half power for AC devices. There is an old trick of using the SCR to short the output of a bridge rectifier, and putting the load in series with the hot AC lead to that rectifier to get a full wave AC control from the SCR, they did that before Triacs were a thing. The Neon bulb fires at a known point (around 90v) on the AC slope, and an RC circuit in series with it varies the exact point in relation to the incoming AC so you get somewhere between 0 and 180 degrees of conduction angle, sorta PWM modulation of the power line, that controls a load. BTW, those neon bulbs age and their firing point moves, which can cause issues with the circuit. (maybe that's why it's been getting worse. New bulb?) Also the Neon bulb's firing point varies with light, so the circuit will work differently when the bulb is shielded from outside light (so it's interesting that they tried to use it as a power indicator!) As you pointed out, the bulb can be replaced with a proper diac diode (sorta kinda two zeners back to back in series, cathode to cathode or anode to anode).
You probably could find a replacement potentiometer that would electrically work, but with a shorter shaft. Then you could drill and tap the shaft and an extension shaft, and then insert a headless screw (threaded rod) with lock tight to extend the shaft. Simple machining problem!
I’m impressed by the breadth of you technical knowledge Quinn. Having your understanding of electronics in your bag of tricks is great, good for you. Thanks for the explanation and congratulations on making a working “pig’s ear” out one that didn’t. Cheers, Will
AvE on speed dial! Made my day!
Perhaps the contamination on the carbon disk was the lubricating grease used on the entire assembly? There used to be electrically insulating grease used in components like that. I would enjoy watching your re-design and modification of the control circuit.
16:50 I've fixed lots of old pots in a similar way, but I bend the brass springs so the wipers contacts a less worn track of carbon. Excellent sleuthing there.
Hi Quinn, I have a 230 volt version of this drive. There is not a no volt release switch so the drive will restart after a power failure even if the mill spindle does not. I also did not like the 230 volt supply being directly switched by the table travel limit switches which are close to any cutting fluid used. I built a control unit with an integral NVR switch, a 230 to 24 volt transformer and three 24 volt ac relays. This is fed it with 230 volts from the mill main supply switch and is also interlocked it with the mill NVR stop/start control switches. By including a 230 to 24 volt transformer I reduced the switching voltage on the table travel switches to a safe value. With some thoughtful design this extra control box can be disconnected and the various cables easily relinked to put the set up back to your configuration. BobUK.
Even Sprocket knows you're not really fixing things unless you have bits left over the first time you put it back together.
The traditional watchmaking apprenticeship involves being given five watches and being told to take them all apart and put them all back together. When you can do that and build a sixth watch from the left over parts you have passed. If all the watches work you have passed with honours:-)
Indeed, in several shops where I worked, we called that "cost reduction."
My boss from our old machine shop added a large amount of odd parts to this new "plane o mill" that was being assembled by our Metal Fitters dept. Very funny when they couldn't work out where all the odd parts went. We had painted some of the parts to match exact colour of the new machine.
My experiences of repairing things like this tell me that I will be back into it sooner rather than later. Cleaning pots is only a temporary fix, they will never be as good as when new. However buying a replacement but with a shorter shaft will be an exercise in making a longer shaft to suit.
That may indeed be next
@@Blondihacks And now you cheated by just getting a new mill with a new powerfeed ..
I love the BOLTR style video. Especially the explanation of the circuit. Definitely would watch more of these.
How does one even know all that stuff ?
I‘m seriously even more impressed with your electronics knowledge than with your Maschinist excellence - which is very impressive in its own right! 👏🏻👏🏻👏🏻👏🏻👏🏻👏🏻👏🏻👏🏻
You might enjoy the electronics projects on her blog, her homebrew computer and arcade pinball machine are both pretty epic
@@rescdsk Already on it.
Thanks a lot 😃
8:00 The lightpipe might not be just to provide an indicator. Neons sometimes don't light in total darkness and need some ambient light to start the strike.
Good point!
Right, I've seen that effect on power strips that have a neon indicator lamp that is old... maybe replacing that neon bulb would be the fix!
Some have a taste of radioactive gas in the neon to help ignition. Maybe 2 or 3 axial lead diacs in series would work.
It wouldn't be engineering if your workaround didn't require another workaround.
Great video, analysis and further comments. Thank you for teaching me.
The neon lamp should make no difference to the direction, the two microswitches should normally be used to reverse the polarity going to the DC motor after the SCR circuit. The difference in power in one direction is more likely to be in the motor or else something mechanical.
17:15 One of todays equivalents is Servisol super 10 switch cleaning lubricant. Magic stuff, it cures the scratchy pots/sliders on amps and mixers etc.
I’ve had good luck with some of the products from DeoxIt. Pretty easy to get a hold of too.
CRC also makes a contact cleaner which is not expensive, probably similar to the RS stuff, and available at Quinn's local Canadian Tire.
@@LenPopp I don't think there are very many Canadian Tire stores in California :)
@@Steve_R their loss
It is so refreshing to see an informative video from someone very knowledgeable that does not rely gimmicks or a a running diatribe of expletives.
Amazing explanation. I really love your in-depth way of going in to the smaller things which also counts, all your videos are like that which is phenomenal. Thank you for your time and effort keep up the good work and keep well.
Chinese products spend a lot of time at sea on their trip to North America. The excessive grease is there for corrosion protection.
The grease they use also stinks. I call it "Eau De Harbor Freight".
Shenzhen #5!
Thanks for the video. Circuit looks like a half-wave SCR phase controller GE SCR Manual ca. 1970. Possibly no EEs were harmed (or even employed) in the many revisions of that PCB over the decades. The blue disks are not capacitors- they are MOVs (metal-oxide varistors) to help reduce arcing. They "wear out" eventually and tend to fail short.
I rebuild a lot of old radios. Deoxit is the best thing to use to clean contacts. Love your videos.
Hi Quinn,
It is the nature of DC and AC brush/commutated motors to run at different speeds in in one direction. It has to do with the compromise position of the brushes to achieve the best torque at a desired speed and direction. For symmetrical speed the brushes can be rotated about the commutater with a constant field position. Not possible with the way your motor is built. Really enjoy the videos, keep them coming.
I agree, and you can get the same asymmetry with a permanent magnet motor if the field and brushes are misaligned. I don't think it has anything to do with the neon, as the 'dimmer' circuit will see the same polarity all the time. Assuming a series-wound motor, the reversing is almost certainly done by swapping the direction of the field winding (or brush/commutator) with the two microswitches.
@@mikerudin8261 exactly right. Her motor is probably a parallel wound motor as it needs torque not speed. Series wound motors are typically used in vacuum cleaners and other machines where the load is firmly attached at all times as they can exceed safe speeds if unloaded. A parallel wound motor will not reach destructive speeds as the back EMF will limit the speed unlike its series wound counterpart and can still be bidirectional with field reversal. Still. The speed control circuitry is pretty cheesy, I would have used a constant current field variable voltage setup personally. That would give a more constant torque curve across the range of speed.
Great video! I loved the AvE style tear down / inspection and the TOT-esque rebuild music. Thanks for sharing
Had a similar problem with my mill. I added a 200 ohm resister. to the 'A' pin on the resistor (I think,- it was a while ago and I have forgotten ) and it runs so much better at the low speed end where I use it most. It now runs smoother at these speeds and also has better control, by needing more twist of the knob to get the RPM to change.
Good idea!
I really enjoyed this. Looks like many of my "I've never done this, but maybe I can fix it if I can get it apart, but regardless, I'm learning something new." I'm impressed by your electronics knowledge.
I'm impressed as usual. You are a smarty! I have to think you own an analog multimeter which would have been better at showing inconsistencies in the potentiometer.
Knipex Pliers Wrenches 😍😍 my faves!
If you have room to do it, putting a zip tie through/around a spring will keep it from springing-spronging into your face.
Deoxit is the modern thing
You have the nack of making everything look easy 😃could the speed difference be anything to do with how the motor brushes bed in.
Yeah, I built some controllers like that, around 1972. Not touched on SCR's after that since now we have much better parts and can embed a small cpu for total control. Thanks for sharing.
I recently had my ASONG AS-235 apart---a similar unit. The trace to R5 welded itself out of existence and left a smoking resistor in its wake. Some notes: The pot (RV24YN 78S B501) is available but mostly the 20S version, which has a shorter stem. The custom one is 78mm long and not available to the public. There's a CRC contact cleaner and Deoxit D5 is a favorite with electronics repair people---usually no disassembly required for pots. I traced the circuit and found that the neon bulb is strictly an indicator. Mine may be different from yours but I think the neon bulb is a way to avoid having any low-voltage section on the board but have a little light anyway. Neon is probably the best choice, if the voltage is set, because it is relatively low power and heat compared to the alternatives. It looks like the SCR is getting triggered by an RC network. The trigger circuit is directly between the gate and cathode and charges from the half-rectified mains (after it's taken a detour though the stator windings). The time constant is set by the resistance of R4 in combination with the zener-pot-R2-C2 circuit. I think that subcircuit kicks it the way an diac would. Not sure about that. ANYWAY, I tried to figure out R5 from stills of your video but just couldn't do it. Thanks for the video. It always makes me feel less insane when I see someone else doing similar things.
Good one Quinn. My Bridgeport II power downfeed speed controller has lost it’s mojo.
I’M GOIN IN😂😂 Thanks for the motivation.
Proper old school electronics there. Brought back memories. Noisy pots used to be the bane of my life!
Blimey that is an absurdly large reduction for a single stage gearbox.
A good electronic contact cleaner was "Tuner Wash," for cleaning the manual UHF and
VHF rotary channel selector switches. It worked well on relay contacts, automotive ignition points, and similar, too. IDK if they still make it, but if anyone runs across it, it's good stuff.
Be careful with TV tuner cleaner, it often contains a light grease to lubricate the mechanical contacts. A better choice might be De-Oxit, which cleans but doesn't lubricate.
Dear Blondihacks! Thank you for your video! I had a problem with my Chinese 'Bridgeport' which has the same cross feed drive. It kept going slower and slower until it eventually died!! I stripped the drive down but because of your examination I managed to save time trying to get the variable resistor out! I removed its cover and rotated it a number of times blowing it out clean with compressed air! 😊 Thank you!
This is great Mrs. Hacks! I had to rip apart mine last year and replace the board. (One of the resistors had fried so badly that I couldn’t identity it). I tried fiddling around with getting some of the other parts off as well but didn’t make nearly as much progress as you. Mine has a similar problem where it won’t travel at slower speeds. So, I’ll add cleaning my pot to my list of to-dos.
Loving your videos.
Hello Quinn,
A good repair... and well explained, I often wonder how the aftermarket power feeds worked.
Take care.
Paul,,
I'd love to build one that reads the spindle speed and can calculate the feed per tooth on various cutters but my Arduino-fu is not strong enough. A project for an electronics nerd like BH maybe?
@@mattagnew206 Clough42 has you covered there with his electronic lead screw project
@@MattOckendon That's a bit more than I need, but it is an interesting project.
I have that old Radio Shack Micronta multimeter. 20+ years and still going strong! One year it was left alone and the batteries all let out their innards into the compartment. A quick wipe with damp paper towels and its back in action.
I am glad you opened that up. I have some of those and always wondered what was inside. All of the adjustment is all on one end on mine. After a half turn you don't get much speed change at all.
Wow. You really know your electronics! Nice work.
Fabulous video, a great delight and motivator to tackle stuff that challenges in so many different directions. Thanks for sharing!
I love this video! Please do more electronics explainers like this; you are so good at articulating your problem solving and though process that I learned a lot from this video.
Thank you very much for this video. I have one of these drives on my Taiwanese mill and although it's still working well after 14 years you never know when it will need surgery. The only trouble I've had with it has been perished rubber boots on the main switch and push button. I replaced them with rubberized material cut from fingertips of cheap work gloves, held in place wit hot melt glue.
Now I want to see you rebuild this thing. Dunno how practical that would actually be, though.
I might be inclined to replace it with a servo or stepper instead.
Oh my god what a punish just to get at a faulty Pot. Kudos to you Quinn for persevering.
Great job! I'm impressed, but then again I've never doubted you!
I have one of these. In the UK they are sold with a separate transformer box to drop our 240 volt mains power to 120 volt to run them. I have a manual for mine with a drawing, and could email you a copy if you wish. I knew it was a thyristor with a neon lamp type circuit as the manual has a circuit diagram. Great work and excellent presentation as ever.
Quinn, enjoying your videos.! My first comment though. I know about electricity but not electronics... Down to earth description and explanations of the power feed. By the way, with 53 yrs machining experience I'm impressed with your work habits and attention to details. Thanks for your time and sharing! 👍😎
I've never been inside one of these, although I've used many in my day. Very interesting, clearly good electronics experience, I've worked electronics almost sixty years, never ran across the use of a neon light instead of a diac. I learn something new every day! Thanks.
Yep couple others saw that 400v MOV across that pot. Plumbers silicon grease for faucets will restore that damped spin on those pot shafts for everybody's fyi.
Your channel is really great. Many thanks for all those hours you put into it.
Your overall knowledge of everything is amazing, yet another great video, thank you.
It's nice to see come electronics on the channel too. An analog multimeter is handy to have around for testing pots.
I have a new ALSGS table actuator for 230VAC. Type ALB-310SX
In it, the neon lamp is only used as a power-ON control in the switch. The forward and reverse microswitches reverse the field of the motor. The potentiometer gets a half-wave as a constant voltage and controls a tyristor that limits the rotor voltage of the motor.
There is no trigger diode or DIAC built in. The speed is the same in both directions.
Hi Quinn, I went back and checked my Power Feed adjustment on the Drive Wheel clearance. Sure enough I could feel the Motor when it was in Nuetral and manually feeding. Readjusted and it’s a lot better. Thanks for a very interesting Video. I’ll know what to look for if mine develops a problem.
Your range of knowledge is remarkable.
Thanks for the video, Interesting and useful. I have a similar unit on a 1999 mill. I thought my "power light" bulb was broken. I did not bother to take apart since otherwise working. I will now be comfortable with the light apparently not working, well not producing photons, but it seems to be in the AC to DC conversion.
Dave.
Yay!! It's Blondihacks time! (Sorry I was late, I got caught up rebuilding the headliner in my mom's jeep)
Good job and explanation as usual. I have found that an analog meter tends to reveal intermittent connects better than a digital meter. I too have a vintage can of RS tuner cleaner which might only be a temporary solution inn your case. When this pot acts up again, you could investigate the possibility of cutting the shaft off and making a coupler for connecting to a replacement short shaft pot. It might not be bad idea to also replace the neon indicator lamp.
So cool to have an electronics video related to machine tools! ❤
Hi Quinn. I had a similar problem with my power feed. I found an exact replacement at Travers Tools. This part might be made cheap but they sure aren’t sold cheap. Just over $100 got me back up and running. I’m not an electronics guy at all but I’m going to clean up the old potentiometer and keep it as a spare! Thanks for the great video!
I've watched this video about 5 times now. My power feed as totally packed up. Thanks for the dicetion
Impressive understanding of electronic circuits 👍👍👍.
Man that device is huge! Was looking for something small when I got my Grizzly clone but ended up building a $45 contraption with a nema stepper motor, seeduino and a driver. I can go super slow and way too fast if needed. Been using it for two years without any hickups.
Yah, it really doesn’t need to be this large for a mill this size. It’s quite a bit overpowered. But, they’re cheap I guess.
@@Blondihacks cost engineering. If there are two models that can share a motor, that’s a whole supply chain you don’t need. The smaller model is overpowered, but what the hey.
I love your knowledge of all things! It would be very interesting to to you replace the light with a diac/triac solution. After I watched your latest video I looked this up. Thanks
I thought I was the only one who still has that old Micronta meter in (mostly) working order.
40 years and counting on that thing. It just keeps going
Great problem solving! For improvised power feed on my manual bench mill, I just use a cordless drill. It's super controllable and advantage is, you can also use it on Y (cutting) and Z (just to make it easier to lift the head for tool changes etc). Same applies to the lathe - it's great for the cross feed.
And power compound on the lathe!
Wow, I am impressed that you know so much about electronics. Great video. I would make sure that the tapered gib is locked in with both end screws and the gib isn't trying to lock in going towards the small end of the taper. I would have bet the gib was binding up.
Yay! Finally incorporating electronics on your channel! More. Please!
Caig Labs Deoxit D5 in the spray can would be the replacement for the old radio shack contact cleaner. It's a miracle for anything with contacts that get intermittent. From audio equipment with dirty pots and jacks to that maglite that won't work unless you whack it against the table, it cleans contact surfaces and keeps them from getting dirty again for a long time.
Quinn , Great video , when I take a machine apart and I see it has a spring that does something ? does not matter what. I run a thin piece of safety wire through it to keep it from flying away and taking The shims and other stuff for a test flight off the bench (learned that the hard way ) I will use a sharpe and make a witness marks so I know how it goes back together after weighting for parts .. stay well
Very interesting to see it disassembled and reassembled. Cheers from Australia
Thanks for the timely reminder about contact cleaner it's just what I needed to give new life to my 35-year-old guitar 🎸🎶
You sure know your Electronics! I am impressed, you have many talents!👍🏼👍🏼😊
Since you suspect the neon is causing the asymmetry in feeds, I would be curious if reversing it would make a difference.
I was wondering that too. It’s not obvious to me how the motor direction relates to a difference in circuit condition over at the neon lamp.
I understood very little of that, and was fascinated! Clearly I need to watch more of your videos :)
I learned years ago that you can clean electrical contacts by dragging a dollar bill between the two faces of the contacts. The fibers in the bill are mildly abrasive and can help remove contamination.
Deoxit contact cleaner and improver. They still use it at the laser mine where I introduced it.
Really useful stuff. Examination component level 👍👍
Electrical talk usually goes so far over my head they can see it from the ISS, so well done for getting at least some of it
into my tiny brain . Looking forward to seeing more .
Maybe an external ten turn pot. Nice to see there are people out there that aren't afraid of component level repair.
Enjoyed this episode. Thanks Quinn.
That potentiometer looks very much like the potentiometer that was used to set the flaps position in my friends ultralight airplane 😅 It was also not linear at all and the flaps worked in about the same way as your power feed 😂. It was almost impossible to find a replacement pot but after weeks of googling and searching on ebay suddenly a guy in israel appeared and sold the exact same pot on ebay so we ordered three of them. The guy sent them and the package bounced back three times because he didn’t fill out the correct export forms, but on the fourth try the package got through, the pot was installed and the plane still flies this day. 😃👍🏻
At the opposite end of this, one of the bridgeport's at work has the old 8f Power feed. It was Stone dead but I managed to resurrect it and it works great. I think they chose each component based on how expensive it was to manufacture. I'm happy I got to work because I was tired of cranking handles. The power supply uses the whole column of the machine as a heatsink. In the summertime I think you could roast marshmallows
Well done Quinn,you’re really clever.👍👍
Entertaining and informative as always. Keep up the good work!
Cant wait for the new board to be made ;)
Great fix and video!!
I know you've said in the past that you think electronics projects are better in blog form, but I thoroughly enjoyed this video! I'd love to see more electronics from you too.
I paused the video and tried to reverse engineer the circuit... and I was puzzling, I saw that 10W toaster oven, err, ceramic wire-wound resistor, and I've seen neon bulbs in oscillators, and even incandescent bulbs to balance in-rush current, but I wondered how that would play into a motor control, I hadn't yet connected the dots, my brain didn't go to "dimmers" but once you said it I was "Ah HA!" that's right!!! Now it makes sense!!! And I was very happy to hear you talking about some power switching electronics: triacs, diacs, and SCRs, I know of about them, but I don't work with them (I do mostly digital and op amps)... Still, just hearing about them again took me back to my days in college electronics courses in semiconductors. Thanks for the electronics "refresher" of sorts... Cheers!
Loved the explanation - thank you!
Radio shack contact cleaner is amazing. I think i have also used up my can that is 10+ years old.
I have found 3 good alternatives for cleaning electronic contacts.
1. Isopropanol alcohol, 90+% is better for electronics. 70 can be used but takes longer to evaporate. clean with canned air
2. Electro Klene by Stoner, this is alcohol based, evaporates with no residue
3. Deoxit red & gold. this will leave a residue, but it cleans and restores electric connections. especially gold plated ones. It does leave a reside that you have to clean off with alcohol.
I believe the smoothing cap across the switches is actually a MOVs to reduce arcing when the switch opens. Try replacing the neon bulb with an NE2. All electronics has them 5 for $1.00. If you can get them to ship first class mail it should only be a dollar or less for shipping.
The newer neons tend to not be made as well as the old ones. Fran Blanche has an old clock with neons that needed replacing (they were run at fairly high current), so she got some new ones only to find that they started to degrade in just a few days of use!
For contact cleaner I use MG Chemicals 409B Electrosolve Zero Residue Electronic Contact Cleaner. This works really well. I've fixed a number of old switches with this.
Hey Quinn, the modern day equivalent of the Radio Shack contact cleaner is called DeoxIT. by CAIG. There are several different formulas available. I believe the "fader lube" is the one to use on pots. Good luck on your future electronic projects with dirty pots.
Quin I went back and rewatched this video yesterday because I accidently plugged mine into 220-volts and it is a 110-volt unit, I am writing just to say thanks for pointing out that is a regular power feed in it bolted to the horizontal adapter. I have 2 of the regular units so I should be able to make a swap. When I bought mine, I paid in excess of $400 usd from PM. The ones I got from Vevor are the same units rebranded. Also, I have found repair parts for mine are not too hard or too expensive. I am going to take it apart and hopefully it just smoked the breaker, but I will not know until i do the autopsy. Anyway, thanks for the detail you provided.
The over greasing is to prevent corrosion while products languish in distribution in the high humidity of Guangzhou and Shenzhen ports.
I'd love to see you design and build a new board!
I've worked on a few of these frustrating and scary repair projects, where you have to disassemble 90% of something to get at what you suspect is the problem part. :-) You also _hope_ your memory is good enough to remember how all of the screws and clips and springs go back together. And, you hope you don't accidentally break some little plastic tab or other feature which would render the entire device scrap. :-) I was getting nervous when you were prying apart that potentiometer, hoping that a bunch of little plastic fragments didn't fall out of it. But, in the end, you succeeded! Bravo!
Hello Quinn.
As always a very interesting Video. I paused and rerun the Video multiple times trying to identify as much as possible to diagnose the Speed difference.
You said you bed it is the neon Bulb. But this circuit would be powered the same Way for both directions. The Switching is done by reversing either the Stator Windings or the Brushes of the Universal Motor to switch Directions. Have not seen it on Video, but have you also checked the NC to COM Switch contacts ?
Maybe i am totally wrong and You ha a much better View of the wiring, but i assume the Problem is in the switches.