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Old 01-03-2024, 10:14 AM
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Default VFD problem again

At work yesterday I had an VFD break on the drill press. The Drake drill press was bought new in 2015. It came equipped with a VFD for reversing the motor, for power tapping, and speed control.

Mid January 2022, the VFD went out. Display just flashed and could not do anything. Boss checked into it, and not knowing much about VFDs wanted to only replace it with OEM stuff. To replace it was $450, for a 1-1/2 HP motor.

I had just set up a cheap VFD (under $100) for my home mill, so I had an idea of how to program it, or figured I could figure it out. So I had no problem installing new VFD and programming it.

So less than 2 years, and it goes out again. Now I’m tempted to just hard wire the motor directly to 220 3 phase, because it’s an expensive short lived VFD, even though it’s a good name brand supposedly.

But boss has a new one coming in tomorrow.

Anyways, I think I might have killed this one accidentally, so thought I’d share my experience here, so hopefully someone else will learn what not to do.

I was drilling 11/16” holes to tap 3/4-16 threads.
I had drilled a 7/16” pilot first, and then the 11/16” bit was catching and chattering, so I was slowing the RPMs down with the VFD, and with light pressure the bit caught and stalled the motor when I had turned the VFD down too far to have enough torque to turn the bit.

Now I have a F042 error when trying to start the motor, which translates to a UW short to the motor wires.

I checked the ohms of the motor leads, and they all were within .4 ohms of each other, and then switched two leads to the VFD, and I got the same error. If the problem was with the motor, I would expected a different fault code.

The book said if fault continues, then is internal to VFD and needs to be replaced.

It would have been better for me to have the drill press in the lowest possible belt speed, which I did try to change, but belts are super tight, and there was no slack available to easily change it, so I said I will just depend on VFD to slow it.

The VFD manual notes not to stall the motor when using, otherwise the motor can overload the VFD and burn it out.

Bottom line, when using a VFD in the bottom speed range, remember your motors do not have the available torque at lower RPMs to do the same amount of work as when it it running faster.


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  #2  
Old 01-03-2024, 10:19 AM
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Here is a link to the manual online in case anyone wanted to see that.

I’m open to suggestions/ learning how to make sure this does not happen again. I know when I read the manual, I only seem to comprehend 1/3 of it and what it is capable of doing, so I can maybe use some one to explain some things in layman’s terms. At least the bad things to watch out for.

https://literature.rockwellautomatio...m001_-en-e.pdf


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Old 01-03-2024, 11:50 AM
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I'm not up on all the VFD stuff, but this sounds remarkably like the problem I used to have with the little Sherline mini-cnc lathe speed controllers. Also, it was a pretty simple fix inside the unit. If the boss is replacing it anyway, you might want to save the old one rather than tossing it in the trash bin.

What was happening on that machine was that when the motor stalled, it would fry one or more of the diodes on the board. Opening the cover up and looking for a burnt spot was about as simple of a diagnosis possible. The parts were easily swapped out among units, or new components installed in their place. Sadly, I got pretty damn good at doing it in a hurry.

Link to post (hopefully)
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Old 01-03-2024, 03:08 PM
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Originally Posted by dubby View Post
I'm not up on all the VFD stuff, but this sounds remarkably like the problem I used to have with the little Sherline mini-cnc lathe speed controllers. Also, it was a pretty simple fix inside the unit. If the boss is replacing it anyway, you might want to save the old one rather than tossing it in the trash bin.

What was happening on that machine was that when the motor stalled, it would fry one or more of the diodes on the board. Opening the cover up and looking for a burnt spot was about as simple of a diagnosis possible. The parts were easily swapped out among units, or new components installed in their place. Sadly, I got pretty damn good at doing it in a hurry.

Link to post (hopefully)

Sounds familiar. I now have two of these broken VFDs. I saved the old one. But that one had total different problems. I even plugged that one back in to see if it fixed itself sitting in the box for 2 years. It didn’t.

But was thinking I might be able to make one out of two. Then have a backup for next time. Or just a good one for one of my home tools. . At the moment it is garbage to my work, but we are busy enough, boss doesn’t want me wasting any more work time on it.


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Old 01-03-2024, 06:40 PM
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If the overcurrent is set properly it shouldn't fry the VFD , when you get the new one , set the FLC a little lower to protect the VFD .
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Old 01-03-2024, 09:20 PM
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That is an expensive drive. Allen Bradley, you can buy better you can't pay more.

https://industrialrepair.net/ these people can fix that thing. the most you will pay is half of a new one. pick up the phone when you get the repair quote and work your charm and get it fixed for less.

P103 is where you set your overload, you are correct name plate current limit is at or near 60hz. the lower speed at the current limit will pop parts, as you have experience at.

A448 is interesting for a faster trip it is defaulted to 0 or turned off.

In your case P104 may be handy as it will not allow you to make the motor go slower than a certain speed no matter how low you turn the pot down. I'll bet now you can turn the pot to 0 and the motor will stop. You do not want that. set to 30hz and go from there.

A410 a413 can be preset speeds, these are defaults but you can change. You could have some toggle switches or rotary switches to set speeds and mark as tap 1 for small taps and 2 for med taps and such or whatever you may like to have.

A442 turn it down a lot, it is set for 150% of the drive rating with motor at or near 60hz. Turn down until you get quick trip outs. then bump up slightly.

A461 is one to understand as well.

Most OEMs buy and furnish a drive based on motor size alone. it is all factory defaults and no or very little customizing the programming of the drive. Some OEMs will send you their program and some not. Once you get their programming of a drive you can adapt to most any drive.

That's all I have as far as a basic understanding of the parameters. AB typically give you this and expects the technician to pay for more training or on the phone help.

When provided a choice, ABB and Yaskawa are my preferred drives, they have better end user support and better more complete information in their user manuals. Not the quick start manuals, the entire manuals.

Now if you want a choice of drive or no drive and drill press operation at the flick of a switch we can go over that if you want.

Scott
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Old 01-04-2024, 08:59 AM
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I have the same lift only I replaced the harness with a hook, and my son adapted it to run with a 20 volt dewalt battery. Ours came from the dump!
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Old 01-04-2024, 09:50 AM
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Quote:
Originally Posted by toprecycler View Post
H so I can maybe use some one to explain some things in layman’s terms. At least the bad things to watch out for.

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Brian, You have to set the overloads as yooper said, and there is one question I have. I see your nice big On/Off switch, and my suspicious mind says you are switching the 3 phase output. This will kill your VFD
On/Off has to switch the power from the control buss on the vfd.

Also I always use a VFD about 40% larger then needed, and back down the overcurrent protection to my needs. I just bought a 10hp vfd to run a 5hp motor. They are cheap now. My last chinese vfd on my drill press has been turned on for 8 years, and every time I step on the foot switch it runs.
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  #9  
Old 01-04-2024, 10:05 AM
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I was always in the club of trying to run the vfd near the middle of it’s range. I run the two I have at 60 Hz all the time. The grinder I’m so used to a fixed speed it makes no difference to me, and the mill I use the mills speed adjustments same as any other. Once in a while I get an error on the mill, simply because I don’t have a braking resistor, and I either forget and hit the brake, or have enough load from tapping etc that it stops quicker than the vfd likes.

Automation Direct has lots of online info and videos about vfd’s, plc’s, and lots of other stuff, I’ve called them and have also ordered from them in the past. Prices are decent and they deal with the shipping and border issues coming here to Canuckland.


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  #10  
Old 01-04-2024, 11:26 PM
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Quote:
Originally Posted by digr View Post
I have the same lift only I replaced the harness with a hook, and my son adapted it to run with a 20 volt dewalt battery. Ours came from the dump!

I got this lift from an assisted living home in the scrap. I didn’t get the battery or charger at the time. Three month later I got called back for more stuff, and there was the battery and charger. I brought it into work to help load bigger items on the mill, which is just 5’ away from overhead crane system.

Boss offered to buy it from me, but I wanted to retain ownership of it, for when I need it at home again. This way, I don’t have to ask to borrow it, I can just take it back.

It has saved my back and a lot of finger pinching situations using two people to try to lift some awkward piece.


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