3520A VFD replacement?

[Jake_Debski]

Has anyone had to replace their 3520A VFD since the newer 3520B was introduced? The original drive is listed as obsolete on some vendor sites. The replacement has the same model# with the exception of the A suffix being replaced by a B suffix.

The Powermatic parts dept. wants almost 2-1/2 times the money for their replacement as do a couple of outside vendors. But since Powermatic only goes by their in-house part #'s it becomes difficult to compare apples to apples.

I would appreciate any insight as to the difference between the A and B drives both in cost and or installation.

Thanks, Jake

 

[robo hippy]

Jake,
It would be 10 or so years old, and they might have made some changes. The only difference I know of for sure is that the older ones did not lock you out so that only Jet/PM could service them or change the speed ranges and torque. I changed mine a couple of times with help from PM before they sold out. 3520A minimum speed almost 0 to 1500, and 0 to 3000. B 50 to 1200, and 50 to 3200.

robo hippy

 

[Bill Boehme]

I think that the reason that the newer inverters are more expensive is mainly due to the newer device being more sophisticated. I think that the older unit were just basic volts/Hertz speed controllers and the newer units are sensorless vector controllers -- meaning that they attempt to sense speed and torque by measuring current. I believe that the Brand of the older units is Delta (no relationship to Delta Woodworking, Delta Airlines, or Delta faucets). I think that the Delta model number can be found on the controllers and then you can probably find a manual online even though the product has been EOL'ed.

I have manuals for Delta model series VFD-A/H, VFD-B, and VFD-S.

If you make a note of all of the settings for your controller, you can reset the controller to get rid of any lockout passwords and then reprogram it to suit your needs. Needless to say doing so voids your warranty and if you really are not quite sure what you are doing, the inverter will confirm this suspicion.

I suspect that your model might be: VFD015B21A which is the VFD-B series inverter for a three phase 230 volt 2 HP motor operating on 240 VAC single phase input power.

 

[Jake_Debski]

I suspect that your model might be: VFD015B21A which is the VFD-B series inverter for a three phase 230 volt 2 HP motor operating on 240 VAC single phase input power.

You are correct Bill that is the model #. Both you and R.H. have most of the facts that were explained to me by couple vendors.

I located a controller for the A model, and the current B model is readily available. The price is in the $300 dollar range with shipping for both of those. On the other hand from the manufacture the dollars are much larger,$600+ without shipping.

Thank you both for the information I will order the B model.

Jake[/QUOTE]

 

[robo hippy]

Contrary to what they will tell you at Jet/PM, running at less than 50 rpm will not damage your motor at all. I use those speeds for sanding my warped bowls, and others use them for some of the thicker finishes that they don't want to have drip marks in. The motor runs cooler than when I turn. Mostly because there is no load on the motor. It is a feature I made sure to keep when I got my Robust.

robo hippy

 

[Bill Boehme]

You are correct Bill that is the model #. Both you and R.H. have most of the facts that were explained to me by couple vendors.
.....

Thank you both for the information I will order the B model.

Jake

Jake since you are buying a new unit, you will probably get the user manual on disk. If not, let me know and I can send you a user manual on a CD for the cost of postage. If you have a LOT of extra paper and ink on hand, you could print out the manual, but it is pretty hefty. I get the "A" and "B" manual sizes mixed up -- one is just shy or 200 pages and the other is just shy of 300 pages, but I can't remember offhand which is the larger.

Contrary to what they will tell you at Jet/PM, running at less than 50 rpm will not damage your motor at all. I use those speeds for sanding my warped bowls, and others use them for some of the thicker finishes that they don't want to have drip marks in. The motor runs cooler than when I turn. Mostly because there is no load on the motor. It is a feature I made sure to keep when I got my Robust.

robo hippy

Yes and no. They are probably hedging their bets because it depends on what you want to do at the very slow speeds. Sanding shouldn't be a problem, but if you were to put the maximum torque load on the motor for more than a brief period, it would get very hot because the current through the windings would be close to the rated full load current. And, at 50 RPM the cooling fan is not producing any cooling air over the motor. You can be pretty sure that if they opened the operating envelope to a wider speed range that there would be owners who would not heed any admonitions about what could be done at the minimum speed. The motor probably has thermal overload protection, but the thermal overload switch doesn't prevent damage, it just minimizes it. The effects of thermal damage are cumulative so eventually if someone regularly runs the motor until the overload trips, the wiring insulation and the glyptal varnish on the laminations will degrade and lead to early motor failure. Before that happens, however, the thermal overload device will probably fail which means a trip to the motor repair shop since these devices are buried down inside the motor wiring.

The type of controller used is nominally rated for operation over a 10:1 speed range, but it depends on the motor as to how much of that range is usable for normal operation.

 

[Jake_Debski]

Bill and R.H.

Thanks to R.H. for his personal experience and Bill for fleshing out and adding to what R.H. had said.

Bill I will accept your kind offer should the vari-drive not come with a disk.

Again thank you both,

Jake

 

[Bill Boehme]

I have been helping a friend troubleshoot a problem with his Powermatic 3520B lathe after he installed a remote START/STOP switch. The symptoms made it appear that the remote switch operation was becoming intermittent.
We suspected that wood dust was entering the switch and getting between the contacts. We addressed that potential problem a couple days ago by putting a rubber glove over the switch toggle, but by sheer luck, I think that we stumbled onto the real problem -- loose wires inside the power plug. I noticed a loose screw on the power plug and then figured out that it was incorrectly assembled. Next, I found that the leads were barely making contact with the terminal connections inside the plug. I rewired the plug and now we are waiting to see if the problem returns.

What does this have to do with the original question? Two things:

1. Sometimes the cause of a problem is not what we think is obvious -- in this case a recently installed remote switch.
2. I printed several pages from the inverter manual to verify that it was wired correctly. In the process of searching through the manual, I discovered that the inverter is just the basic volts per Hertz model. While that seems to be adequate for this lathe, a better option is to consider getting the next step up -- a sensorless vector inverter for better low speed operation.

 

[john lucas]

The first thing I'm going to do after I retire in 4 weeks is to finish the installation of my new remote switch. after rebuilding the Powermatic remote about 4 times I gave up and purchased a high quality sealed switch and got some better wiring to hook up. I got busy at work and it's been laying there ever since.
I tried some jury rigged dust prevention methods but it still seemed to get into the switch and cause problems. I'm hoping my new switch will solve the problem. I'm still considering moving the on off so it's all remote but in reality just turning the speed down until the lathe stops would also work.

 

[Bill Boehme]

John, that is very good information because it helps confirm from what I have seen that there is a basic design problem.

My friend has installed two of these units -- Powermatic sent him a complete new replacement after the first one pooped out after a few hours of use. The second one did not even go as long as the first.

He then replaced the paddle switch with a heavy duty lighting switch which also quit working. This was odd because the switch was rated for 30 Amps and the actual current is just a few milliamps. It did not take too long for me to notice that the lighting switch has rather large gaps at the top and bottom of the toggle that allows dust to get inside and foul the contacts. Our interim fix was to cut up a latex glove to cover the switch toggle and seal the edges with tape. The next step might be to buy an environmentally sealed switch.

 

[robo hippy]

Makes me wonder if Brent English (Robust Lathes) could do a second business of aftermarket converters, and remote switch set ups. The set up on my Beauty is far better than the one on my old PM.

robo hippy

 

[Jake_Debski]

Makes me wonder if Brent English (Robust Lathes) could do a second business of aftermarket converters, and remote switch set ups. The set up on my Beauty is far better than the one on my old PM.

robo hippy

R.H., having turned on an American Beauty for a few days I believe the above statement(s) are correct, but lets not forget that that quality comes at a cost many turners, myself included, simply cannot justify. (read that as afford if you wish)

Buying a remote set up from Mr. English sounds like an interesting prospect.
Thanks for the thought.

Jake

 

[Bill Boehme]

Makes me wonder if Brent English (Robust Lathes) could do a second business of aftermarket converters, and remote switch set ups. The set up on my Beauty is far better than the one on my old PM.

robo hippy

While it sounds like a nice daydream for a wonderful project, I think that it would seem more like a nightmare to Mr. English. It would be a huge amount of work for practically no profit.

It is easy enough for a manufacturer like Powermatic to make this accessory for their lathes since their focus would be on one or two models and only a few variants on those models (such as 3520 original, A model, and B model). Given the selling price and their actual cost of materials and NRE, Powermatic isn't doing it for the money. Things like this help develop customer loyalty.

Why aren't dozens of small after-market companies building these simple devices? After all, it's just a box, a magnet, a switch, a length of wire, and an instruction manual. Well by far, the most difficult and expensive of the above items is the instruction manual. Preparing instructions that cover a number of the various VFD's used on lathes would likely be a daunting task. And don't forget that pictures are essential, too. Brent would just need to buy one of every model lathe to which the mod could be applied.

Finally, relying on the average person to correctly wire up even a very simple device no matter how good the instructions is risky business. There is no limit to how badly even a very simple task can be botched. Maybe some day lathe manufacturers will come up with the clever idea of having peripheral ports where accessories can be plugged in (like our computers are configured). Imagine something like a bunch of USB ports on the back of the headstock where remote ON-OFF switches, speed displays, speed controllers, coffee makers, etc. can be interfaced to the VFD. Maybe somebody will come up with this idea and then make it a standard feature on all variable speed lathes. Until then, rolling your own is the best option.

 

[Jake_Debski]

Bill and R.H.

Well gentlemen the 3520A is finally up and running. The new drive is installed and with the help from a chapter member who, prior needing help programing the drive, I did not know is an electrical engineer. So as the saying goes all is well for now.

Again thanks to both of you for your suggestions and advice.

 

[Roger Wiegand]

Why aren't dozens of small after-market companies building these simple devices? After all, it's just a box, a magnet, a switch, a length of wire, and an instruction manual. Well by far, the most difficult and expensive of the above items is the instruction manual.

I think you underestimate the cost of business liability insurance. Mine costs $850/year (the cheapest I've found anywhere) and I don't make any physical product. I'd hate to think what it would cost to insure an electrical product you might sell a few dozen of.

 

[Bill Boehme]

I think you underestimate the cost of business liability insurance. Mine costs $850/year (the cheapest I've found anywhere) and I don't make any physical product. I'd hate to think what it would cost to insure an electrical product you might sell a few dozen of.

I agree with you about the cost of insurance, but that wasn't a topic that I mentioned. The snippet that you quoted is a rhetorical response to Reed's post. The technical support expense alone would be staggering. There are plenty of other expenses as well.

 

[Mike Johnson]

When a person finally gets around to replacing a VFD on any piece of equipment that was made a decade or more in the past you are usually left with sourcing a new design as technologies and designs change on a constant basis. You can purchase a generic VFD these days and most of them will readily adapt to the components used on most lathes. There are a number of videos on YouTube that take you through the entire process of wiring the VFD, the input devices, feed back devices and remote E-stops etc.

 

[John Jordan]

Makes me wonder if Brent English (Robust Lathes) could do a second business of aftermarket converters, and remote switch set ups. The set up on my Beauty is far better than the one on my old PM.

robo hippy

He won't touch it because he doesn't want to have to support someone that is incapable of the simplest installation. See how nicely I phrased that? LOL
He did one for a Stubby for me, but I had to promise I would support it, and I sell a lot of Robust lathes.

John