3520C On-Off Switch Problem

[Jeff Struewing]

The red-green on-off switch on my 3520C, purchased in June 2018, started going bad after only a month or 2. After stopping lathe, pressing green button would not work. Tapping switch box or letting it snap back with the magnet would usually "fix" it. It got progressively worse over a month or 2 until Powermatic sent a replacement switch and I swapped it out in November 2018. It worked fine until 4 weeks ago, when it failed fairly quickly. The replacement switch sent this time looks to be a different brand and the orientation of terminals 1-4 are a little different. Terminals X1 and X2 aren't marked on the old switch. Powermatic tech support hasn't been super responsive and I would like to just replace it again myself, but I cannot tell for sure whether the brown jump wire between terminals 1 & 3 on the "old" switch should remain with the new one. A picture they sent of the new switch wired up does not appear to show it. Anyone else have similar issues with their 3520C?

 

[Fadi Zeidan]

I had a problem with the switch On my C as well. The lathe would all of a sudden switch into reverse while In the middle of turning. It was scary when you are doing a hollow form and all of a sudden the lathe would come to an abrupt stop and start going in reverse fast with the tool inside a hollow form.

Powermatic sent a contract technician to evaluate and replaced the switch as the cause of the problem. The new switch is different than the one that came with it, but so far no problems.

 

[Jeff Struewing]

Good to hear. Hopefully I can get someone to come replace mine soon - been down for over 2 weeks.

 

[GRJensen]

The red-green on-off switch on my 3520C, purchased in June 2018, started going bad after only a month or 2. After stopping lathe, pressing green button would not work. Tapping switch box or letting it snap back with the magnet would usually "fix" it. It got progressively worse over a month or 2 until Powermatic sent a replacement switch and I swapped it out in November 2018. It worked fine until 4 weeks ago, when it failed fairly quickly. The replacement switch sent this time looks to be a different brand and the orientation of terminals 1-4 are a little different. Terminals X1 and X2 aren't marked on the old switch. Powermatic tech support hasn't been super responsive and I would like to just replace it again myself, but I cannot tell for sure whether the brown jump wire between terminals 1 & 3 on the "old" switch should remain with the new one. A picture they sent of the new switch wired up does not appear to show it. Anyone else have similar issues with their 3520C?

I had the same issue with mine about a year ago. A shot of compressed air into the switch would get it going for a while. Called Powermatic ... tech was very responsive, and sent a new switch (sounds like the 2nd switch they sent you). I recall that the terminals were different, but to be honest I cannot remember how it relates to the wiring diagram in the manual. They should be able to work through it with you on the phone.

 

[Jeff Struewing]

Turns out the jump wire is still needed, so I installed the new one and up and running again.

 

[john lucas]

Must be a different style switch than my 3520A. Mine just has 2 wires and is an off the shelf micro switch mounted in the larger mechanical button.

 

[Greg Norman]

I’ve had that problem twice. The switch is not bad, it’s full of dust. The first time they sent me a new switch, no problem. Changed it out and it worked perfect for about six months. I call Powermatic and the guy told me it was full of dust and to just take it out and gently tap it on the lathe bed to remove the dust. I’m thinking he’s an idiot and said ok I’ll try it. I still had the old switch and was shocked at how much dust came out of it. Now I feel like the idiot, LOL. I just unhooked the switch from the box and gently tapped the switch till the dust quit coming out and it worked fine. They did send me this cover to keep the dust out and I’ve not had anymore trouble with it.

 

[Jeff Struewing]

Interesting. When my second one stopped working, I took the cover off the back and blew it out with compressed air. I did not see any sawdust whatsoever in the box, and nothing seemed to get blown out. But I did not remove the switch from the box itself (until I went to replace it) and blow air on it. I threw the first one away but kept the second, so maybe I have a backup?

 

[Paul Jubb]

Great to know. My 3520C is due to be delivered within the hour. I hope I made a good choice going with this lathe for my first one.

 

[Jeff Struewing]

Probably so - beyond the switch it has been treat to use!

 

[Greg Norman]

Interesting. When my second one stopped working, I took the cover off the back and blew it out with compressed air. I did not see any sawdust whatsoever in the box, and nothing seemed to get blown out. But I did not remove the switch from the box itself (until I went to replace it) and blow air on it. I threw the first one away but kept the second, so maybe I have a backup?

The way the switch connects to the push button assembly keeps any dust from getting into the box, but unfortunately funnels it inside the switch assembly instead.

 

[Ric Williams]

I've had my 3520C for about 3 weeks now and haven't had any problems with the run/stop switches (so far), but the forward/reverse switch stopped working a couple nights ago. I tried blowing it out, but that didn't help. I finally opened the control box and when I wiggled the wire connectors on the back of the switch it started working again and has been fine since. Don't know if it was the connectors or if moving them caused enough wiggle inside the switch to get debris loose. I guess time will tell. I know the crimp connectors make production and repair easier, but they can cause reliability problems sometimes.

 

[Mike Johnson]

They do make sealed switch contacts for the better quality switches manufactured by a number of different companies that will eliminate this concern. Would not be too difficult to seal up one of these cheaper type contact blocks with some CA glue or quality silicone on the housing of the contact assembly. Any of the cheaper made components that are rivetted or have crimped fingers holding the cover over the switch contacts will over time draw dust into these enclosures. All of these electrical devices get warm while running and as they cool they create a small vacuum pulling small amounts of dust particles into the enclosure after every run cycle. You also have electrical and static charges that attract dust particles to these components. A good yearly (5-year) cleaning in these electrical component housings will reduce these problematic issues from turning into a bad situation.

 

[Lou Jacobs]

This is an interesting discussion and I’ll store it away for future reference. I took delivery of my 3520 C about two weeks ago. I was very disappointed that it came on a rough shippers pallet but not fully enclosed. It had clearly suffered damage in transit. This included the on/off switch being broken to the point that the green button was gone. I dealt with the vendor who got Powermatic to replace the entire control head including the cable. I had a hell of a time figuring out how to disconnect the cable from the VFD drive end and replace with a new one. I finally got it done and the lathe is working fine. After having spent the past seven years on a lower end Grizzly lathe, I feel like I’ve moved from a Chevy to a Mercedes-Benz!
I wonder if anybody else has replaced this cable at the VFD end, or is it intended to be replaced only from the remote control box end?

 

[Lou Jacobs]

 

[Paul Jubb]

Lou I'm not sure about replacing the cable but your post made me go out and inspect mine more closely.
It was delivered a while back but my shop isn't ready for it
My lathe had slid off the inner pallet breaking the cardboard box when it was delivered. It seemed to be ok but Powermatic seems to have a problem with their packaging, shipping company or both.

 

[Lou Jacobs]

Paul, check carefully for any damage. Even just scrapes to the finish. Powermatic sent me a can of touch-up paint as well as a new spindle lock and lock guard, both of which were smashed, as well as the control unit. It’s a wonderful lathe, but I figured my experience was an anomaly. Curious to hear that your packaging was also lacking. Hopefully you found everything ok with the machine.

 

[Ric Williams]

I wonder if anybody else has replaced this cable at the VFD end, or is it intended to be replaced only from the remote control box end?

From what I've seen exploring the wiring (I just installed a stop bar on my 3520C), the end at the VFD is definitely the easier end to work with. At least you have some spare parts should you ever need them, assuming that Powermatic didn't want the damaged parts back.

The only damage I found on mine were a lot of paint chips and scuffs, enough that I was a little disappointed, but Powermatic sent my a spray can of touchup paint too.

 

[Lou Jacobs]

Ric, yes, I kept the damaged unit for just that purpose. My problem was that the ends of the modular snap on connectors (I’m sure there’s a technical name for them, which I’m drawing a blank on), were just too big to fit through the hole in the VFD box where the cable enters. After scratching my head for half an hour, and manipulating them every way I could, I carved an extra quarter inch slot in the cable box hole that allowed me to snake them out. I’ve made a patch to close that gap and keep dust out, but I’m sure there’s got to be a better way.

 

[Jeff Struewing]

Well, after 3 years with no problems after my second switch replacement, it started acting up again about 6 months ago - intermittently failing to start when I press the green start button, then the reverse switch stopped working for about 5 weeks. Reverse switch started working again and the on/off was an issue only rarely, but in the last month, reverse hasn't worked and the on button rarely works. I have opened the back and used compressed air several times over the last couple of weeks, yesterday I removed the on/off switch from the box to blow it out further, reconnected all the wires (which I have never found to be loose), but every time I hit the stop button, the first press of the on button doesn't work. Usually after a few snap-backs with the magnet into the slot, it will start again, but sometimes not. I can get an exact replacement of the on/off switch, but especially with the reverse button no longer working, I wonder if there is more to it than the switch. A neighbor of mine with the same machine has had similar problems, anyone else?

 

[Steven Forrest]

I know this is an old thread, but I have one very related follow up question. Got my 3520C (barely) used earlier this year. It's been working fine, but my green go button has just started to be finicky. I gotta push it in pretty hard, and even then it's not always switching on. After reading the above entries, I'll try taking apart the housing and blowing everything out. My question is, do you just peel the foam backing off to expose the screws, then glue it back on when done? I really don't want to mess things up unnecessarily, but if that it how you get into the unit, fine. Thanks in advance.

 

[John K Jordan]

I know this is an old thread, but I have one very related follow up question. Got my 3520C (barely) used earlier this year. It's been working fine, but my green go button has just started to be finicky. I gotta push it in pretty hard, and even then it's not always switching on. After reading the above entries, I'll try taking apart the housing and blowing everything out. My question is, do you just peel the foam backing off to expose the screws, then glue it back on when done? I really don't want to mess things up unnecessarily, but if that it how you get into the unit, fine. Thanks in advance.

Steven,

Someone earlier in this thread mentioned dust. 20 years ago the power switch on my Jet1642 failed (different design than on the new PM). I've examined and repaired many switches over the years - often it is burned or dirty contacts, sometimes the internal spring-loaded mechanism that mechanically flips between on/off needs to be cleaned or lubricated.

So I took apart the Jet switch and discovered that extremely fine sawdust had worked it's way inside and kept the contacts from closing. In this case it was obvious the dust had come in through supposedly tight joints in the plastic switch body. After cleaning inside carefully and reassembling (and testing), I sealed the outside of the switch body. Never had another problem. Still use that lathe some.

Sorry, I'm not familiar with that switch. But many components do have some covering on screws that needs to be removed for disassembly. I usually try to find some similar material to replace it.

JKJ

 

[Lou Jacobs]

I’ve got this machine and have found that keeping the pendant in a gallon sized plastic bag with a twist tie around the cord keeps the dust out. I’ve got to replace the bag every six months or so, but a cheap, if clumsy fix.
And yes, to open the back you’ve got to find the screw locations through the foam padding. I just cut away the padding over the screw heads and left it missing so I can get to them easily next time.

 

[Warren Grill]

I’ve had that problem twice. The switch is not bad, it’s full of dust. The first time they sent me a new switch, no problem. Changed it out and it worked perfect for about six months. I call Powermatic and the guy told me it was full of dust and to just take it out and gently tap it on the lathe bed to remove the dust. I’m thinking he’s an idiot and said ok I’ll try it. I still had the old switch and was shocked at how much dust came out of it. Now I feel like the idiot, LOL. I just unhooked the switch from the box and gently tapped the switch till the dust quit coming out and it worked fine. They did send me this cover to keep the dust out and I’ve not had anymore trouble with it. View attachment 33784View attachment 33785

Just seeing this, when this thread was picked up again.

Is the dust cover, which seems like a great solution to this issue, available for purchase? Part number?

I searched the Powermatic site, but could not locate.

Thank you!

 

[Steven Forrest]

I’ve had that problem twice. The switch is not bad, it’s full of dust. The first time they sent me a new switch, no problem. Changed it out and it worked perfect for about six months. I call Powermatic and the guy told me it was full of dust and to just take it out and gently tap it on the lathe bed to remove the dust. I’m thinking he’s an idiot and said ok I’ll try it. I still had the old switch and was shocked at how much dust came out of it. Now I feel like the idiot, LOL. I just unhooked the switch from the box and gently tapped the switch till the dust quit coming out and it worked fine. They did send me this cover to keep the dust out and I’ve not had anymore trouble with it. View attachment 33784View attachment 33785

It looks to me like they realized the switch needed a proper cover/seal. Greg's post is 4 + years old. The manual doesn't show this cover (Warren Grill, I checked the parts list and diagram in the manual, too), nor do any of the photos I see posted on line. I tried calling Powermatic this morning, but the phone lines are down - I'm assuming weather related issues. I'll follow up when I hear anything. And thanks for your post, too, Lou Jacobs.

 

[Mike Novak]

I just cut a little circle in the foam to get to each screw. Blowing out the switch was not enough, but spraying in contact cleaner did the trick.

 

[Larry Mercier]

I’ve got this machine and have found that keeping the pendant in a gallon sized plastic bag with a twist tie around the cord keeps the dust out. I’ve got to replace the bag every six months or so, but a cheap, if clumsy fix.
And yes, to open the back you’ve got to find the screw locations through the foam padding. I just cut away the padding over the screw heads and left it missing so I can get to them easily next time.

I do the same. The plastic bag has prevented any further switch problems. Its not pretty but it seems to be a cheap/efficient solution.

 

[Steven Forrest]

Here's an update:
I contacted PM - customer service was prompt and friendly. Gave me a list of three actions:
1) with power off, press start and stop switches 20+ times - I suppose to dislodge any crud. That seemed to help, but only a bit.
2) Spray compressed air around the switch/buttons directly. Again, nominal improvement.
3) Remove back and blow out the innards. I did this, and definitely cleared a potentially significant amount of very fine dust. I also repeated 1). (The foam was a non issue - I ended up scraping little patches to expose the screws - didn't have to expose it all. No harm, no foul.)

Final result - better, but still not how it should be. I didn't try the contact cleaner, because I couldn't see the contacts themselves, and I have a long and unhappy history of disassembling things and making them worse. I can live with it, but I wish I didn't have to. I may report back to PM and see what they say. I bought the lathe (barely) used, so no warranty, but they do seem willing to help any owner, original or not.

One last note: I asked customer service about the little rubberized clear cover that appears in Greg Norman's post above. The rep offered to send me one gratis. It just arrived - I haven't installed it yet. But I asked, and she confirmed, that they are including those now on the controls, but they haven't updated the parts list online to reflect that. She literally had a few laying around and sent me one. So, plus for her kindness and responsiveness, minus for PM having an issue that was easily avoidable. We'll see what they say about the partial "fix."

 

[Greg Norman]

Here's an update:
I contacted PM - customer service was prompt and friendly. Gave me a list of three actions:
1) with power off, press start and stop switches 20+ times - I suppose to dislodge any crud. That seemed to help, but only a bit.
2) Spray compressed air around the switch/buttons directly. Again, nominal improvement.
3) Remove back and blow out the innards. I did this, and definitely cleared a potentially significant amount of very fine dust. I also repeated 1). (The foam was a non issue - I ended up scraping little patches to expose the screws - didn't have to expose it all. No harm, no foul.)

Final result - better, but still not how it should be. I didn't try the contact cleaner, because I couldn't see the contacts themselves, and I have a long and unhappy history of disassembling things and making them worse. I can live with it, but I wish I didn't have to. I may report back to PM and see what they say. I bought the lathe (barely) used, so no warranty, but they do seem willing to help any owner, original or not.

One last note: I asked customer service about the little rubberized clear cover that appears in Greg Norman's post above. The rep offered to send me one gratis. It just arrived - I haven't installed it yet. But I asked, and she confirmed, that they are including those now on the controls, but they haven't updated the parts list online to reflect that. She literally had a few laying around and sent me one. So, plus for her kindness and responsiveness, minus for PM having an issue that was easily avoidable. We'll see what they say about the partial "fix."

After cleaning out the switch and installing that cover I haven't had anymore problems. To get mine to work correctly I had to get all the dust out of the switch assembly. You will need to separate the switch from the buttons and lock the ring back, point the lock ring down and GENTLY tap it on your lathe bed several dozen times. Then tilt it slightly and tap it with a pencil or something, tilt it the other way and repeat. I probably spent 20 minutes before I got it all out, it really was an unbelievable amount of dust inside the assembly. It has been trouble free so far.

 

[Steven Forrest]

After cleaning out the switch and installing that cover I haven't had anymore problems. To get mine to work correctly I had to get all the dust out of the switch assembly. You will need to separate the switch from the buttons and lock the ring back, point the lock ring down and GENTLY tap it on your lathe bed several dozen times. Then tilt it slightly and tap it with a pencil or something, tilt it the other way and repeat. I probably spent 20 minutes before I got it all out, it really was an unbelievable amount of dust inside the assembly. It has been trouble free so far.

Greg,
Thank you for the excellent photos and advice. Can I ask, how did you get the unit out in the first place? Here is a pic of my switch unit in place. What's the order of operations to get it out without screwing it up? (I am a past master at screwing it up.) Also, am I correct in assuming that once you have the switch out as you did, popping the cover into place is all you need to do before reinstalling? It seems like the switch has to be out of the housing to properly place the cover.
Thanks so much.

 

[Greg Norman]

Steven,
I took my box apart to get some better pics. I had forgotten the new switch is a bit different from the original, that I used in my last pics. To get the switch out you have to separate it from the button assembly, also necessary to get the button assembly out of the box to install the cover. You need a small flat blade screwdriver to rotate the lock tab. This is much easier if you disconnect all wiring from the switch, but it can be done without that if youre not comfortable removing the wiring. Be careful not to put any pressure on the wire terminals when you rotate the tab. Once the tab is open gently pull up on the switch and it should come out. I had to disconnect the short wire from the reverse switch, just pull up and slightly wiggle it. Pull on the connector not the wire. Remove the bulb from the switch, rotate it counterclockwise and pull it out. Orient the box and wiring so the switch can point down, gently tap it with something to get the dust out. Be patient, it will take a while.
To remove button assembly unscrew the lock ring and push it out. You are welcome and I'll be happy to answer anymore questions if you have them. I'll try to respond sooner next time, had a hard week and passed out after supper last night.
Hope this helps.

 

[Steven Forrest]

One more update:
I followed Greg's advice/instructions. I disconnected the switch assembly - labeled every lead before detaching it, wrote stuff down, etc. This let me get at the locking clip at the base of the assembly, which is easily moved with a flat screwdriver to "unlocked." The brown switch assembly was now free. I could then unscrew the locking ring on the back of the buttons, so I had all the main pieces apart. I blew more compressed air up and around the buttons. I tapped and tapped on the switch, blew it out some more - got a little dust, but not much - certainly not much compared to when I first blew out the pendant housing with the back off. I still didn't see any actual metal contacts - that looked like it was internal, and the only movable parts I could see were the plastic actuators on the back of the button assembly,.
Anyway, I put it all back together (and included the clear flexible button cover from PM). Result: I would say 95% better. Still not absolutely positive with a single touch, but significantly improved. We'll see how long this lasts. For now, I can definitely live with it, whereas before it was really pretty annoying, interrupting the work flow. If things head south, I'll approach PM again and see what they say. For now - Greg Norman is Man of the Hour.

 

[DMcIvor]

One more update:
I followed Greg's advice/instructions. I disconnected the switch assembly - labeled every lead before detaching it, wrote stuff down, etc. This let me get at the locking clip at the base of the assembly, which is easily moved with a flat screwdriver to "unlocked." The brown switch assembly was now free. I could then unscrew the locking ring on the back of the buttons, so I had all the main pieces apart. I blew more compressed air up and around the buttons. I tapped and tapped on the switch, blew it out some more - got a little dust, but not much - certainly not much compared to when I first blew out the pendant housing with the back off. I still didn't see any actual metal contacts - that looked like it was internal, and the only movable parts I could see were the plastic actuators on the back of the button assembly,.
Anyway, I put it all back together (and included the clear flexible button cover from PM). Result: I would say 95% better. Still not absolutely positive with a single touch, but significantly improved. We'll see how long this lasts. For now, I can definitely live with it, whereas before it was really pretty annoying, interrupting the work flow. If things head south, I'll approach PM again and see what they say. For now - Greg Norman is Man of the Hour.

Having been in your shop, I'm wondering if you had to mount the 3520C on the ceiling? There's no room for that beast!

I'm on my second switch, and it has been giving me problems of late. First one replaced under warranty, second out of pocket. I hadn't seen this thread and I'm glad to have picked up some tips.

One thing to try (though I think you're past this point now) is simply tightening the connection screws. This has helped me in the past.

Annoying, because I'd say this is a fundamental design flaw, but doesn't seem to be a high priority with Powermatic. It is an otherwise great machine.

 

[Michael Brown]

Every few years the paddle switch on my jet1640evs does something akin to this. I've been contemplating putting in an e-stop extension on the right side and a smoother on/off cw/ccw toggle...

 

[Steven Forrest]

Having been in your shop, I'm wondering if you had to mount the 3520C on the ceiling? There's no room for that beast!

I'm on my second switch, and it has been giving me problems of late. First one replaced under warranty, second out of pocket. I hadn't seen this thread and I'm glad to have picked up some tips.

One thing to try (though I think you're past this point now) is simply tightening the connection screws. This has helped me in the past.

Annoying, because I'd say this is a fundamental design flaw, but doesn't seem to be a high priority with Powermatic. It is an otherwise great machine.

Don,
I also think it's a bit of a design flaw. They can make sealed bearings - why not a sealed pendant box/switches? Feel free to be in touch if you want to go through the particulars.

Re: cramming it in there, I of course unloaded the Stubby first - they aren't both in there! And yeah, it's crowded, but it's really only meant to hold one person. I have had to allow for the bigger footprint and position it a little more centrally, but I can still move around it (if I hold my breath).

 

[Lou Jacobs]

get the switch out you have to separate it from the button assembly, also necessary to get the button assembly out of the box to install the cover. You need a small flat blade screwdriver to rotate the lock tab. This is much easier if you disconnect all wiring from the switch, but it can be done without that if youre not comfortable removing the wiring. Be careful not to put any pressure on the wire terminals when you rotate the tab. Once the tab is open gently pull up on the switch and it should come out. I had to disconnect the short wire from the reverse switch, just pull up and slightly wiggle it. Pull on the connector not the wire. Remove the bulb from the switch, rotate it counterclockwise and pull it out. Orient the box and wiring so the switch can point down, gently tap it with something to get the dust out. Be patient, it will take a while.

Greg,
Thanks so much for these detailed instructions. I just followed them and was able to insert the dust cover on the switch. Not sure if I would’ve been able to figure it out without your details!

 

[John K Jordan]

... was able to insert the dust cover on the switch.

Hope that works! (The reason I'm hoping is that on the Jet I mentioned the dust got into the switch from the back side. But I'm sure the two switches have different construction.)

 

[Lou Jacobs]

Hope that works!

Fingers crossed John, but I’ve still got the plastic bag cover for the belt and suspenders solution. My switch didn’t stop working. I’ve had the PM dust cover for a month or so, and just had time to put it on today.

 

[Vincent Vogel]

Greg,
Thanks so much for these detailed instructions. I just followed them and was able to insert the dust cover on the switch. Not sure if I would’ve been able to figure it out without your details!

How did you go about getting the cover, I think I would like to have one.

 

[Lou Jacobs]

How did you go about getting the cover, I think I would like to have one.

Call PM tech support. They’ll send it to you.