cold blooded Powermatic 4224

[Sherril Blackmon]

I have had this machine for about 10 years and I love it when it works. I can only describe as cold blooded; that is, when it gets cold (below 50 degrees Fahrenheit) the spindle doesn't turn.

I can jog it using the panel on the inverter but that is the only way I can get it to turn.

I've never tried to get it started (after it is warmed up from a heater) without unplugging it and allowing it to reset.

My gut says it has to do with the inverter since that is the only part that is non-mechanical but that flies in the face of what I know about solid state electronics which often will work if they're sprayed with a cooling spray.

I do believe I have other issues as well. Lately, since I have had the door for the inverter open, I have noticed that I can run it for a while but when I turn off the power, it gives an "oc" (or is that "0c") error code. Also, I believe the rundown braking is a bit quick; I've been reading where others have set theirs to 5 to 8 seconds; mine goes from 1500 rpm to a stop in less than 2 seconds.

Another possibly salient point is currently I am using the remote cut off to start and stop the machine; the main switch is bad and I have some on order.

I really have no clue as to how to set the programming for the inverter.

<<My latest thought is to pull the inverter out in order to clean it on the inside of its chassis.>> So, I did it (quite a challenge); I took the front cover off and blew it out with a can of compressed air; now it is throwing a 'ol'/ or '0l' error code.

I feel like I'm digging myself a hole and covering myself as I go.

Any ideas would be helpful.

Sherril Blackmon

 

[Emiliano Achaval]

Interesting, looking forward to seeing the answers, we have some very knowledgeable turners here.

 

[Dave Landers]

The manual for my Delta VFD on my PM3520b says "oc" is "Over Current - Abnormal increase in current", and "ol" is "Overload - The AC motor drive detects excessive drive output current". Somewhat similar to each other.

My first thought (from your title and first paragraph) was gummed up grease in the bearings (spindle and/or motor shaft) seising up when cold. I expect you've checked this, but loosen the belt on the pulleys and see if things will spin.

But over current/overload could also be due to an issue with the motor or the VFD itself. Good luck!

 

[Mark Jundanian]

Sherril, I don't have any specific info to offer you. Maybe you've already reached out (and I know it's out of warranty), but if it were me, I'd call Powermatic and at least find out what the error codes mean, and maybe discuss the problem in general.

I can jog it using the panel on the inverter but that is the only way I can get it to turn.

Could you explain what you mean by jog? Have you tried giving the hand wheel a spin by hand to get the motor going?

 

[Mark Jundanian]

I see Dave knows the codes. I'd still see what Powermatic would tell me.

 

[Don Wattenhofer]

Another possibly salient point is currently I am using the remote cut off to start and stop the machine; the main switch is bad and I have some on order.

The normal start up of a VFD controlled motor is to accelerate by starting at zero volts and zero frequency and proportionally increasing both over a period of time called accel time. I don't know how your lathe is wired but if the start up is not originated at the VFD it is likely that you would get a fault such as "oc". The best bet is to fix the main switch and then see what happens.

 

[Richard Coers]

I'm with Dave. Often simple answers are the best. A real simple fix would be putting it to bed with an electric blanket on it.

 

[Sherril Blackmon]

Sherril, I don't have any specific info to offer you. Maybe you've already reached out (and I know it's out of warranty), but if it were me, I'd call Powermatic and at least find out what the error codes mean, and maybe discuss the problem in general.



Could you explain what you mean by jog? Have you tried giving the hand wheel a spin by hand to get the motor going?

The inverter panel has a button captioned "Jog." By jog I mean that I pressed that button and the spindle turned.

 

[Sherril Blackmon]

I'm with Dave. Often simple answers are the best. A real simple fix would be putting it to bed with an electric blanket on it.

I'm running out right now to purchase that electric blanket

 

[Sherril Blackmon]

The normal start up of a VFD controlled motor is to accelerate by starting at zero volts and zero frequency and proportionally increasing both over a period of time called accel time. I don't know how your lathe is wired but if the start up is not originated at the VFD it is likely that you would get a fault such as "oc". The best bet is to fix the main switch and then see what happens.

When the switch is delivered and I put it in I'll let you know if that fixes anything.

Sherril, I don't have any specific info to offer you. Maybe you've already reached out (and I know it's out of warranty), but if it were me, I'd call Powermatic and at least find out what the error codes mean, and maybe discuss the problem in general.



Could you explain what you mean by jog? Have you tried giving the hand wheel a spin by hand to get the motor going?

It is fairly easy to turn by hand.

 

[Sherril Blackmon]

The normal start up of a VFD controlled motor is to accelerate by starting at zero volts and zero frequency and proportionally increasing both over a period of time called accel time. I don't know how your lathe is wired but if the start up is not originated at the VFD it is likely that you would get a fault such as "oc". The best bet is to fix the main switch and then see what happens.

Don, that is great information. Over the years I have had some experience with motors ( I was an aviation electricians mate in the Navy) so when you tell me about the VFD controller it makes sense. And, since I have that information I will be more likely to get the lathe fixed.

You guys are really great. Sincere thanks to all of you.

 

[Sherril Blackmon]

The manual for my Delta VFD on my PM3520b says "oc" is "Over Current - Abnormal increase in current", and "ol" is "Overload - The AC motor drive detects excessive drive output current". Somewhat similar to each other.

My first thought (from your title and first paragraph) was gummed up grease in the bearings (spindle and/or motor shaft) seising up when cold. I expect you've checked this, but loosen the belt on the pulleys and see if things will spin.

But over current/overload could also be due to an issue with the motor or the VFD itself. Good luck!

Thank you so much for the information. This goes a long way to getting the lathe up and running.
Your suggestion about the gummed up grease might ring the bell. I'm checking that now.

 

[Marvin Jones]

While researching new bearings for my spindle and motor, I found that basically there are four types of ways ball bearings typically contain grease. Open, regreasable, shielded, and sealed. Open bearings are packed and the seals are not contained in the bearing, regreasable have a keeper usually a metal c clip that holds the shield and is easily removed to clean and replace the grease, shielded bearings have a plate crimped in that cannot usually be re installed (others tried and said they could not do it) and of coarse I tried found my bearing dry (my fault) cleaned and regreased and found I bound the bearings after reinstalling the shield, and lastly the shielded bearings which I found it is relatively easy to remove and reinstall the shields after cleaning and greasing and watched several videos of this being done.
When I ordered new bearings, I ordered sealed bearings because I found my bearings in great shape, spun absolutely smooth after washing with solvent and blowing them clean with air. I removed both side shields to clean and inspect and could not see any damage, just almost dry. (noisy when running. Since I won't be spraying PB Blaster inside the headstock to clean out all the accumulated dust and debris, I expect these bearings to last beyond me, but knowing me I want to be prepared...

 

[Mike Johnson]

If the VFD is faulting on over current starting up, you could possibly spin the spindle by hand at the same time you start the lathe.
This would reduce the start-up current that the motor/vfd is incurring on the initial start of the motor.

 

[Bill Boehme]

I have had this machine for about 10 years and I love it when it works. I can only describe as cold blooded; that is, when it gets cold (below 50 degrees Fahrenheit) the spindle doesn't turn. I can jog it using the panel on the inverter but that is the only way I can get it to turn.

If you are able to use the inverter panel switches to jog the motor then I would think that the inverter is working fine. My first thought after reading your description of the behavior is that one of the controls located on the headstock (potentiometer and switches) would be the most likely cause of the problem. From what I have seen, Powermatic uses the cheapest switches and pot they can find. I would use a multimeter to check out those components when they are cold and again when warm.

... My gut says it has to do with the inverter since that is the only part that is non-mechanical but that flies in the face of what I know about solid state electronics which often will work if they're sprayed with a cooling spray.

My opinion is that the use of cooling spray such as Freeze Mist is more likely to create problems than identify them. While using cooling spray might have been an acceptable troubleshooting aid back in the vacuum tube days, I would not use it on solid-state components.

... I do believe I have other issues as well. Lately, since I have had the door for the inverter open, I have noticed that I can run it for a while but when I turn off the power, it gives an "oc" (or is that "0c") error code. Also, I believe the rundown braking is a bit quick; I've been reading where others have set theirs to 5 to 8 seconds; mine goes from 1500 rpm to a stop in less than 2 seconds.

You need to download the owner's manual for your Delta inverter. The ramp time is a simple parameter change.

If you haven't done so yet, I think that you should remove the drive belt so that it isn't contacting either pulley and then turn the motor pulley to see if there is any resistance or noise. Also, turn the handwheel to verify that the spindle turns freely and there is no noise coming from the bearings.

... Another possibly salient point is currently I am using the remote cut off to start and stop the machine; the main switch is bad and I have some on order. I really have no clue as to how to set the programming for the inverter.

The remote switch is simply in series with the switch on the headstock. They are connected to one of the logic inputs to the inverter. The Powermatic switches are notorious for failing because they aren't environmentally sealed. This allows dust to get into the switch.

... <<My latest thought is to pull the inverter out in order to clean it on the inside of its chassis.>> So, I did it (quite a challenge); I took the front cover off and blew it out with a can of compressed air; now it is throwing a 'ol'/ or '0l' error code.

If a microprocessor device such as a VFD is malfunctioning, It's unlikely that blowing out the dust will fix the problem unless it's so full of dust that the fan can't draw sufficient air to cool the power switching devices.I would say that it is OK to use a shop vac or a shop air compressor, but not canned "air" which contains hydrocarbon alkanes, like butane, propane, and isobutane, and fluorocarbons like 1,1-difluoroethane, 1,1,1-trifluoroethane, or 1,1,1,2-tetrafluoroethane.

 

[Mark Jundanian]

but not canned "air" which contains hydrocarbon alkanes, like butane, propane, and isobutane, and fluorocarbons like 1,1-difluoroethane, 1,1,1-trifluoroethane, or 1,1,1,2-tetrafluoroethane.

Could you explain why canned "air" is bad? Environmental effect? Damage to equipmemt?

 

[Larry Komroff]

I am thinking, if it is not a switch or pot, is it either a relay or fractured/cold solder joint inside the VFD.

 

[Bill Boehme]

Could you explain why canned "air" is bad? Environmental effect? Damage to equipmemt?

The hydrocarbon alkanes in "canned air" have the potential to dissolve or soften the conformal coating on the printed wiring board which could leave the printed copper"lands" exposed. The conformal coating serves as both an electrical insulator and protects the board from the corrosive effects of tannins in wood dust. Canned air also can cause thermal shock if any liquid in the canned air is sprayed on the circuit board.

 

[Bill Boehme]

When I ordered new bearings, I ordered sealed bearings because I found my bearings in great shape, spun absolutely smooth after washing with solvent and blowing them clean with air.

I don't recall the reason, but I read in ball bearing engineering manuals that "thou shalt not spin a dry bearing with compressed air". It possibly might cause the bearing to overspeed.

When regreasing a bearing, the average person usually assumes more is better. Actually, more is much worse because of the increased hydraulic pressure of a fully packed bearing increases friction dramatically which raises temperature dramatically which causes the oil and soap to separate and suddenly you have a hot dry bearing. I think that the maximum fill for open and shielded bearings is about 25%.

Replacing a shielded bearing with a sealed bearing may not necessarily be the best thing to do. The rule of thumb is to replace a bearing with the same type. Sealed bearings typically are rated for a lower top RPM than shielded bearings. Sealed bearings have more friction and run hotter than shielded bearings.

 

[Sherril Blackmon]

I believe that Powermatic will give you the settings if you call them.

I didn't ask for the settings but relative to the symptoms I gave them (roughly what I mentioned in my original post) they suggested to replace the cable between the inverter and the motor (14/4 cable).

If that doesn't result in a fix, then, they think, there is a problem with the motor.

Before I replace the motor, I will tear it apart so I can check the bearings, etc. (I like to tinker.)

Bill, I imagine we have met. I worked at the Woodcraft store in Hurst until the COVID thing came up. I am 76 and we have my stepson who has MS and won't get vaccinated in the house and I just couldn't take the chance.

By the bye, what are the specs on the potentiometer (if you know them off your head.) I have to open the panel on the headstock to replace the power switch but wanted to order the pot beforehand so I could replace both at once. (I have not yet tested the pot but I figure I haven't lost much by replacing it. That is, unless I by the Powermatic part which is listed at $72+. Took my breath away.)

Right now I'm operating under sensory overload from all the information you guys have provided.

Thank you all.

R

 

[Joe Kaufman]

I worked for a manufacturer of electronic equipment whose systems were very costly, irretrievable and a had a designed service life of years. Using compressed air on a Printed Circuit Board would be grounds for termination of employment. Some of the reasons, introduction of undesirable compounds and the potential of static electricity discharge damaging or weaking components. This may be extreme but something to consider.

Consider a shielded bearing. There is no mechanical seal, moisture, dust and dirt can be forced into the bearing by compressed air. So, is it a good practice?

 

[Marvin Jones]

The context of using compressed air was after removing the bearings from the motor shaft and all bearing shields was to remove all grease, debris then check the bearings for wear. One of bearings after cleaning with solvent (gasoline) still had something lodged in some place I could not see or there was damage that was not visible. I used compressed air through both shield areas to finally get whatever was in there pushed out then the bearing spun freely by hand. To me this proved that after 16 years of service, the bearings were not perfect, but still good.
There really is a reason behind all of this. I wanted the ability to disassemble the bearings, clean and repack if needed and I found that sealed bearings can be serviced as easily as those with the 'c' clip keeper. This day and time, I'm sure that I will do what I did this time and just order new bearings but being a little older and seeing lean times in the past, who knows what the future will bring, this is an alternative.
The other issue that concerned me, that Bill mentioned, was sealed bearing heat. After reading that this is usually an issue with higher RPMs along with prolonged run times, I don't think the slower speed that I turn will, hardly ever over 1000 RPM will cause an issue.
I now use a dry spray graphite on all bare metal surfaces instead of an oily spray that collects dust. The spray looks like flat black paint and the banjo slides so easy on it, as does the locking system. I should no longer wash grease from bearings.
As just a kid, first started doing any type of hub repacking, bearing cleaning, I took a hub to the car wash thinking this would be a great way to clean out all the old grease and grime. On impulse, I put an exposed bearing on my finger and just touched it with the pressure wand...at least I had the sense to hold the rotation somewhat perpendicular to my body. It sounded like a hail storm all the bearings bouncing off the metal walls and ceiling of the car wash so...NO sir! I did not spin the bearings with air......

 

[Bill Boehme]

The reason that I know what not to do is often a result of doing what I shouldn't have done.

I knew a co-worker who was considered to be rather close to his money. Like most of us back then he washed greasy bearings and gritty engine parts in gasoline. After the gasoline was as black as coffee and full of grease and grime any "normal" person would pour it on the ground behind the garage, but not Harold. Gas was 28¢ a gallon ... too valuable to waste by pouring it on the ground. So Harold would get a funnel and pour it back into the tank of his car. And, the gritty stuff at the bottom of the pan? Well, that's gasoline too so he would just tip the pan over so that it all went back into the tank. When asked about the gritty stuff being poured into the tank he said, "that's why they have a filter in the line to the carburetor". How can you argue with logic like that?

 

[Bill Boehme]

I didn't ask for the settings but relative to the symptoms I gave them (roughly what I mentioned in my original post) they suggested to replace the cable between the inverter and the motor (14/4 cable).

If that doesn't result in a fix, then, they think, there is a problem with the motor.

Before I replace the motor, I will tear it apart so I can check the bearings, etc. (I like to tinker.)

Bill, I imagine we have met. I worked at the Woodcraft store in Hurst until the COVID thing came up. I am 76 and we have my stepson who has MS and won't get vaccinated in the house and I just couldn't take the chance.

By the bye, what are the specs on the potentiometer (if you know them off your head.) I have to open the panel on the headstock to replace the power switch but wanted to order the pot beforehand so I could replace both at once. (I have not yet tested the pot but I figure I haven't lost much by replacing it. That is, unless I by the Powermatic part which is listed at $72+. Took my breath away.)

Right now I'm operating under sensory overload from all the information you guys have provided.

Thank you all.

R

Sherril, I moved your post back to this thread because you had posted in a thread that has been dormant since 2012 (nearly ten years ago). When surfing the forum for information it's often easy to get lost in time, but it will save others a lot of confusion if you make sure that you are in the thread that you started.

 

[Marvin Jones]

I worked for a manufacturer of electronic equipment whose systems were very costly, irretrievable and a had a designed service life of years. Using compressed air on a Printed Circuit Board would be grounds for termination of employment. Some of the reasons, introduction of undesirable compounds and the potential of static electricity discharge damaging or weaking components. This may be extreme but something to consider.

Consider a shielded bearing. There is no mechanical seal, moisture, dust and dirt can be forced into the bearing by compressed air. So, is it a good practice?

I worked for a manufacturer of gasoline for 25 years and one of the positions I found myself in was the rotating equipment foreman, I was there long enough to find it to be very interesting work, we had hundreds of pumps, blowers, compressors, about every sort of rotating equipment imaginable, 99% had sealed bearings. Most were air cooled, some were liquid cooled though most of large ones had intricately designed plain bearings. Most moving a flammable substance. Being a welding, piping, carpentry kind of supervisor but a major tinkerer, much of the technology used was fascinating and was offered a position in the bearing vibration analysis department and had I been a younger man, would have went for it, too close to retirement age to start over. I really lacked the mechanical background needed and soon moved to maintenance planning, became a senior planner before retiring.
I did learn to use calipers, indicators and micrometers...

 

[Sherril Blackmon]

I am still working on the lathe.

Followed Powermatic's advice and replaced the cable from the inverter to the motor. Alas, no success; ran it with no load for about 20 minutes and when I shut it off, it threw the "oc" error code.

My next step is to drop the motor to see if there is anything obviously wrong that I might correct. If nothing else, I suspect it has "some" dust inside.

If that is not fruitful, I'll be looking for an electric shop (in the DFW area) to bench test the motor.

 

[Larry Komroff]

I am still working on the lathe.

Followed Powermatic's advice and replaced the cable from the inverter to the motor. Alas, no success; ran it with no load for about 20 minutes and when I shut it off, it threw the "oc" error code.

My next step is to drop the motor to see if there is anything obviously wrong that I might correct. If nothing else, I suspect it has "some" dust inside.

If that is not fruitful, I'll be looking for an electric shop (in the DFW area) to bench test the motor.

Sherril, any progress on the VFD/motor issues?

 

[Marvin Jones]

I'm probably not going to use the correct terminology with this question, not even protending to know anything concerning VFD troubleshooting so this is an 'I'm wondering' question. Sherril stated his lathe stopped really fast when he hit the stop button. I'm assuming excess voltage was created and would be directed toward the braking resistor. My question is, would there be a large spike of voltage or current created at a two second stopping time and would the VFD see this as a OC occurrence? Thinking like a carpenter...sorry. I'm thinking that I would change the braking time first thing.

 

[Darryl Fective]

I had all kinds of issues with mine. Frequent OL messages, sometimes just a no-start condition. Powermatic's tech also told me to replace the wiring between motor and VFD. I replaced it all the way to the plug and still no resolution. I removed the motor and took it to a local electric motor shop. The guy laughed when I said it was 3 hp. He pointed out that it had a 6A rating (more in line with a 2hp) and was curious about the VFD. I removed that and sure enough, it had a sticker that said 2hp max output.

I ended up buying a 3hp Baldor motor (used on eBay) and a new VFD. It still would give me occasional problems because of the junk switches they used are not dustproof at all. It's a real bummer when you have a window of time to turn, but end up tearing apart a switch to get your machine working. I finally replaced both with simple light switches. No problems since.