John Hammonds

[John Hammonds]

I'm a sporadic hobby woodturner who just joined the forum and just want to say "Thank You" for already saving me time and money. Last weekend I was just starting to rough out a large red oak bowl blank on my Powermatic 3520B. I hit the Stop switch to move the tool rest and as the piece was coasting down I heard a loud "pop", saw some smoke rising from the inverter, and then realized the 30 amp feeder breaker had tripped. Not good. The inverter on my 6 year old, sporadically used, expensive lathe was fried. So I searched the web and found a thread on your site dealing with the issue. I saw Doc. Green's post and that was a big help but I really really wanted to access the .pdf that Mr. Crumpton had posted so I could get the program parameters for the changeout. So, not being a "joiner" by nature, but needing the info, I joined. Armed with the "insider" info I needed to effect repair, I ordered an OEM inverter from Galco and saved about $300 over what PM wanted for the same part (albeit pre-programmed). Now I twittle my thumbs and wait for UPS, then on to replacement, and hopefully back to turning. So, again, thanks very much.

As far as turning goes, I prefer to turn bowls, mostly natural edge and hefty. Attached is the only pic I had on file ... it's out of sycamore and turned thinner than I normally do. I occasionally turn candlesticks and rolling pins just to see what spindle turning is like and to practice with that skew thing ... I'm not gonna let it beat me. My wife makes me turn the rolling pins for presents ... and she uses them to roll her pie crusts and pizza dough so I get something out of it too. Woods I've turned: sweet gum (love it), wild cherry (my favorite), sycamore, weeping willow (too pourous), cypress, hickory (makes nice rolling pins), black walnut, red oak (but vacuum chuck won't work because too pourous), pear. I get my turning material from the woods and do my roughing with a chain saw. If you're in the area and need some domestic turning wood I'm willing to share.

Thanks again.

 

[Dave Delo]

Agreed......but the 3520B is 2HP machine. Have mine on a 20 amp breaker.

 

[Bruce Schoenleber]

Agreed......but the 3520B is 2HP machine. Have mine on a 20 amp breaker.

Mine too is 2hp, I thought there was a 3hp option. Either way, a 20 amp breaker is the spec'ed circuit.

 

[John Hammonds]

Thanks guys for the responses. I hope I haven't gotten too technical for an introduction message board but, since I started it ....
I've talked to some of my old power plant electrical expert buddies and, like me, they think one or more electrolytic capacitors blew in the VFD. The loud pops and smoke are pretty sure signs. I'm told a blown capacitor could easily trip the 30A breaker but I might know more when I dissect the old VFD. It's interesting that the first pop I heard happened on motor coastdown. It's apparent that the large out-of-balance blank caused the motor to become a generator which can cause an over-voltage condition in the VFD (not uncommon) and may have led to explosion of an aging capacitor. I've read (on this forum) that increasing the deccereration time can prevent this over-voltage condition and I intend to experiment with decceleration rates with this new VFD.
That said, I did check the integrity of the circuit wiring and ohm'd the motor wiring phase to phase and phase to ground. It all checked out fine. But I won't really know if the motor's O.K. until I run the post-maintenance test. At the nuclear plant we would have run a meggar test on the motor but I don't have that ability ... so ... nothing to do now but power it up. Regardless, the VFD is fried and must be replaced first.
As to breaker size, the PM manual does recommend a 20A and that's what I installed in my old house. This shop/garage already had a 30A 240V dedicated circuit with 10 AWG wiring so I just used it. Am considering swapping to a 20A while I'm at this.
I'm retired ... can I just get back to turning???? Anybody want to come help with the VFD installation???

 

[Bill Boehme]

Welcome to the AAW Forum, John and I am glad that we had information on the Powermatic inverter that helped to save you some money. Before you power up the new inverter it might be good to see if there was anything external to the inverter that caused it to smoke. Another possibility is that the fan failed or it got full of dust. Opening up the failed unit to do a quick postmortem might give you useful information about what led to the failure.

EDIT: I see that you already have done a good check of the external circuits. The capacitor failure scenario sounds plausible. Some inverters use a braking resistor to dissipate the power when the motor is dumping its stored energy back into the inverter, but I don't believe that the Delta inverter on the Powermatic has a braking resistor nor even has provisions for adding one.

Are you the same John Hammonds that I saw on the St. Mary's web site? I was doing some web searching on coronary stents. I had a triple CABG nineteen years ago and I am getting ready for some tests to check on a partial blockage in the "widow maker" artery.

 

[John Hammonds]

Hey Bill,
Yep, I'm that guy. I'm downright famous in the Athens, GA, area. I've been on billboards, TV commercials, radio, magazine back covers ... all having to do with my heart attack in 2016. I walked into the St. Mary's ER with 100% blockage in my LAD artery ... the widowmaker. They slapped a stint in me and I'm still tickin'. The Good Lord just wasn't ready to call me home yet. Hope and pray your tests go well and they find and fix whatever is there.

Funny thing, my highschool Spanish teacher (from 1970) tracked me down last year from the info on the St. Mary's site ... and she's in San Antonio, TX. Looks like I'm famous even in Texas, my old home state.

 

[Bill Boehme]

Glad that you're still kicking. Folks aren't supposed to survive a 100% blockage of the LAD artery. When I described my symptoms to my cardiologist he wanted to schedule me for a nuclear stress test the next day, but not surprisingly, since it wasn't an obvious emergency to the folks in charge of scheduling, they put me down for next week.

 

[John Hammonds]

Yeah, I know about those scheduling folks. Problem is there's too many of us baby boomers and too few doctors. But we're blessed to have the best medical care in history. Hope they get to you soon and all goes well.

Now, in the realm of the trivial, I got my new inverter already today. Ordered it late Tuesday and only used UPS ground ... that's service. Galco even put a candy bar in the box with their wrapper on it ... sweet advertising. When I called them about the Delta inverter before I decided to buy I even got to talk to humans ... and they cared ... and they knew their product. I'm impressed. Hope to install and program tomorrow when well rested ... got to do this carefully.

And my equipment issues continue. Bought a 1hp Rikon grinder from Highland last month and it now has premature bearing failure. Both Rikon and Highland are standing tall but I still need to go through swap out and re-setup.

Hey, if you get the time to read this, how about giving me your opinion on CBN wheels. Are they worth having or overkill?

 

[Bill Boehme]

CBN wheels are the cat's meow. You will be amazed how smoothly your grinder runs and the difference in sharpening with a grinder that doesn't vibrate is really impressive. They are even significantly better than perfectly balanced matrix wheels. And, they don't throw grit all over the shop. But, you still need to capture the metal dust. Rare earth magnets seem to be the most popular way to do that.

 

[John Hammonds]

Excellent. I just happen to have some rare earth magnets that I used to use for dog training. I'll tell the wife that I need the CBN wheels to go with the magnets ... kinda like shoes & a purse. It could work.

 

[Gerald Lawrence]

As an afterthought for me, you could also use the magnets from computer hardrives. I had torn up several when I got rid of the old machines and just realized that the magnet could be separated from the metal plate with a sharp blow on a chisel. Oh do not let them stack as will be very hard to seperate.

 

[Bill Boehme]

.... Oh do not let them stack as will be very hard to seperate.

No kidding! I have a stack of about thirty of the nickel sized rare earth magnets. The magnetic force is so strong that I can almost pull nails out of walls with it. And, I think that the FAA has issued a NOTAM for a magnetic disturbance in my area.

I've gotten a few blood blisters from getting my hand pinched when trying to separate a magnet from the stack.

BTW, Gerald, you really are phrugal ... disassembling hard drives to salvage magnets. I thought that I was phrugal, but I'm just an amateur.

 

[Gerald Lawrence]

No kidding! I have a stack of about thirty of the nickel sized rare earth magnets. The magnetic force is so strong that I can almost pull nails out of walls with it. And, I think that the FAA has issued a NOTAM for a magnetic disturbance in my area.

I've gotten a few blood blisters from getting my hand pinched when trying to separate a magnet from the stack.

BTW, Gerald, you really are phrugal ... disassembling hard drives to salvage magnets. I thought that I was phrugal, but I'm just an amateur.

Just trying to protect my privacy

 

[John Hammonds]

Making progress. Installed the new inverter. Programmed it with the help of my 30-something daughter who grew up in the digital world and it runs great. New inverter even has an internal fan and the original did not. The fan's a bit noisy but it does remind me to unplug the lathe before leaving the shop.

Highland is paying shipping for return of the bad Rikon grinder and refunding purchase price. Plan to go to Woodturning Wonders and pick up one already fitted with CBN wheels.

Bill, what would you recommend for grits?

 

[Bill Boehme]

Bill, what would you recommend for grits?

Being a southern boy (I'm actually Billy Ray ... southern boys need two first names, you know), you caught me off guard and I thought that you were asking about grits for breakfast. Just in case you were, it's hard to beat pork sausage and tomato gravy.

If you mean grits for CBN wheels, once upon a time 80 and 180 were what everybody recommended. More recently, finer grit have become available and 400 seems to be very popular for the fine grit. Not positive about the coarse wheel, but 80 might still be a good choice although I've heard that some people are using 180. I'm sure that Ken Rizza can tell you what is the best combination. I still have Norton 3X wheels on my dry grinder because I mainly use my Tormek to sharpen turning tools. I bought a 1000 grit CBN wheel for my Tormek from Ken at the SWAT symposium last fall.

 

[John Hammonds]

Well, sorry for the curveball, but you did take me back to fond memories about the kind of grits we eat. I was an Air Force kid (Father from Texas, Mom from Mississippi) and my grandfather was a railroad man in Meridian, MS. He worked 52 years for the Southern Railroad. On a trip with him as a boy I ate grits for the first time in a diner in New Orleans. I had to ask what they were and if I was supposed to eat them. But I tried them, liked them, and still do. With my grits though I am, as with most things, a purist. I like 'em plain and mixed in with my over easy eggs ... yum. Sausage & tomatoe gravy? ... man, that's livin' dangerously.

Greatly appreciate your input on the other grits. I had read some forum comments in that vein including yours and Gerald's and was looking for a bottom line before I bit the bullet. I did call and talk to Ken Rizza and plan to pick up the grinder next week at their warehouse ... they don't have a showroom as it turns out. I almost went with the 80/180 setup but since I'll have another grinder with 80 and 120 Al oxide wheels on it I decided to go with 180 and 350 on the CBN's. I think that will be sweet.

Thanks again to you and Gerald for commenting in the thread. I think I'm on the way to getting back to turning and with sharper tools.

 

[Glenn Lefley]

You will love those cbn wheels. I only have one 180 . But it's sweet. Perfectly balanced.

 

[John Hammonds]

Yep, sharpened a few tools on the CBN wheels and can now confirm they are SWEEEET. Have done everything so far on the 350 grit wheel. Thought it was going to be real slow but nope, plenty fast enough for me. Even reshaped a 1/2 inch bowl gouge on it and, again, plenty fast enough for me. Sharpening is much more controlled and even enjoyable. Tools are way sharper too ... the chips don't lie. Many thanks to Ken Rizza at Woodturner's Wonders.