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View Full Version : And Shazam! I am cursed no more!!! or My Powermatic 3520b finally runs like a dream!



Joshua Dinerstein
12-17-2009, 2:52 PM
(Sorry I can't resist titles that remind me of the Rock and Bullwinkle show. My Dad loved to watch those with us when we were younger... I didn't get them then but now I have a great appreciation for them. :)

I have contacted both Sean at ToolNut and Powermatic after the tech finished at my house but I wanted to post here too.

First off, I wanted to say thanks to the great people here on the Creek for all of the help and information.

I almost can't say it for fear of jinx'ing it but I do believe my that my lathe is now fixed!!! I had hoped to write this sooner than this but my daughter has been having a few health issues and 3 trips to the hospital later she seems to be on the mend.

Anyway, Eric the new tech from second local company, first first being some less than helpful, came and worked on my lathe last Thursday. The parts came in the day before on Wednesday. He told me flat out that he had never ever seen a parts order come that fast. Powermatic had said they would expedite things for me and I am very grateful that they were as good as their word and did! So Thank You WMH!

Eric was extremely sharp and knew just what he was doing. He started to dismantle the headstock all the while explaining what he was doing in great detail to me. I think my worries and frustration must have shown on my face because he really went above and beyond to show me he was doing and what was going on. He moved quickly and confidently and had the headstock apart in short order.

He did tell me that he had never had it be so easy to take apart. Everything was still "new" and fully greased up with nothing stuck, frozen or corroded. He also told me that he had never had to do this on a lathe that was this new. *sigh* Like I said before just simply cursed.

Anyway, we took the time to look over the spindle and bearings as they came out. I know the tolerances are too fine for most things to see with the unaided eye but I guess I was hoping to see something that was totally whack on it so that I could point to it, tell it was wrong and know that the new one would fix it. There was nothing so Eric moved onto re-assembly. I got to be "helpful" by holding lights and what not. :)

I am sure that in looking back at I was about as helpful as I was to my Dad when I was a kid. Too much excitement I guess at the thought of getting my favorite toy fixed.

Eric had it back together in just a few minutes and we started measuring things. Once again, just like the first spindle that came with it, the important surfaces measured scarily true on the spindle itself. No more than 1/10th of a mil on the main faces. And that seems more like the friction of starting to turn the spindle than anything else.

So we mounted up the face-plate that came with the lathe and it had the same wobble as before. I mean literally the same exact numbers from the same places across the face and outer edge of the faceplate! At this point my heart hit my shoes!

So we moved onto the chuck. Same wobble measured here. Eric was stumped. I was despondent. So we removed the chuck and checked the tightness of the spindle locking nut and looked for motion. Lather rinse and repeat on tests on the chuck and it measured the same. So for good or bad it truly mounting the same as it had on the previous spindle.

With nothing left to try I chucked up a nice big roughed out bowl blank onto my new Vicmarc chuck. It was a trumpet shaped bowl. So had 3 faces. The outer rim, the concave curve to the bottom of the bowl and the bottom surface itself. I think I was too nervous and upset because I butchered the rim on my first cut. Not a catch just the worst possible cut I could make. *sigh* I was watching everything on the lathe but what I was actually doing. But it made me think it we still going operate terribly. So a few deep breaths, a firm grip on my bowl gouge and on the second cut it worked as expected. Then cut the concave curve from top to bottom and then the bottom itself. So once I was back on track I made the 3 light cuts in 1 go.

IT SPUN COMPLETELY TRUE!

Hallelujah! Can you believe it?!!?

Seriously perfectly true. No visible wobble or ghosting. None of the problems I have been fighting before since first setting up the lathe.

I am flat out flabbergasted about that. Seriously I mean it. It measured the same in terms of run out. The exact same numbers on both my dial indicator and Eric's high end one and the exact same as before on the previous spindle. But with the lathe running the wobble was gone!!!

I then did some spindle work and it worked perfectly there as well. Meaning I chucked up a spindle blank and turned the outter edge to true on the meeting faces 10 or so inches from the face of the chuck. Again no wobble or ghosting in the work piece.

So I guess all the comments from so many sources about less than 4 mils is within tolerance were right. I am between 1 and 2mils on the chuck and it works. Just the way I would have hoped from the very beginning.


BIG QUESTION: Can any of you tell me, even if it is just a guess, what could possibly have cause my problems if the chuck seats the same on the new spindle when it is off but wobbles so terribly when the lathe is on and spinning? I ask because I am totally stumped after what I saw for what could have caused that. It has to lie somewhere in the spindle and the bearings as that is what got replaced but what? how? where?

And for the record the guys at ToolNut are the best customer service guys I have ever worked with. WMH gets top marks too! Timberline in Orem not so much. And of course you Creekers are the best. I have and will continue to give Powermatic my highest praise. Pending of course a good answer to my above question. ;)

Joshua

P.S. Being a software engineer I wish we had had the time to replace just one piece at a time. I would like to have known which exact piece it was that was bad. Just for my own peace of mind. But we replaced all 3 bearings and the spindle and with all replaced it works... So at least it got narrowed that far for me.

Bernie Weishapl
12-17-2009, 3:06 PM
Glad it is all worked out Joshua. Now the fun begins.

Richard Madison
12-17-2009, 3:08 PM
Toldya. Spindle and/or bearings. The fact that the chuck O.D. appears to wobble is irrelevant. What matters is what the piece held IN the chuck does.

Glad to hear the problem is solved. Happy Turning Joshua!

Jeff Nicol
12-17-2009, 3:15 PM
Joshua, With everything you have been through it is great that your 3520B is up and running! I still believe that it was in how the threads were cut on the spindle if the were cut at a little bit of an angle you may not ever see it even with all the checking of tolerences. But once the blank is put on the lathe and the forces of it spinning and the gouge catching the wood, I think the threads had a little give in them and when it all snugged up it would put the blank offset a bit, and the larger the blank the more you would see the wobble and the heavier the cut the chance that the faceplate or chuck would rack back and forth when there was a weight shift or a heavier cut that would move the wobble to a different location. To see what Iam talking about get someone to cut some threads with a metal lathe and cut them a little deep and thread on the nut you will be able to wobble the nut as the faces of the threads don't mate up, this is what causes backlash in linear motion units like cross slide tables and metal lathes etc.


Just my thoughts, good luck and keep us posted with the creations from the new lathe!

Merry Christmas,

Jeff

Dan Forman
12-17-2009, 3:53 PM
Glad to hear that everything is finally in good working order. Must have been horribly frustrating for you. Hope your daughter is back on her feet soon.

Dan

Steve Schlumpf
12-17-2009, 4:39 PM
Joshua - my first thought is that I hope your daughter is doing better! Nothing scarier than having something happen to one of our kids!

Glad to hear your lathe is up and running! You can spend time trying to figure out what was defective and why - or put it behind you and spend some quality time on the lathe and turn something! Looking forward to seeing some projects real soon!

Mike Peace
12-17-2009, 4:41 PM
Now you get to enjoy what a PM does really well. Spin wood.

Rob Cunningham
12-17-2009, 7:17 PM
Joshua, glad to hear that your lathe is up and running, but more glad to hear your daughter is on the mend.

Sean Ackerman NY
12-18-2009, 12:45 PM
yeeeehaawwww been waiting for this resolution post FOREVER! Hope you get to rock out with that hunk o' mustard this weekend?

charlie knighton
12-18-2009, 1:47 PM
great to hear that your lathe problems are over

Thom Sturgill
12-18-2009, 2:11 PM
Glad to hear that the daughter getting better, and the lathe is turning true. Hope to see some turnings from that mustard monster, as I look forward to the day I can order one (my shop is in my daughter's garage - I can't get 220v or more room there).

As a one-time programmer, now sysadmin, I appreciate the 'fix one thing' attitude. As a support tech, I learned that it is often better to just get a system into a known good condition (apply patches) and move on.

David Epperson
12-18-2009, 2:44 PM
He did tell me that he had never had it be so easy to take apart. Everything was still "new" and fully greased up with nothing stuck, frozen or corroded. He also told me that he had never had to do this on a lathe that was this new.

BIG QUESTION: Can any of you tell me, even if it is just a guess, what could possibly have cause my problems if the chuck seats the same on the new spindle when it is off but wobbles so terribly when the lathe is on and spinning? I ask because I am totally stumped after what I saw for what could have caused that. It has to lie somewhere in the spindle and the bearings as that is what got replaced but what? how? where?

Joshua

P.S. Being a software engineer I wish we had had the time to replace just one piece at a time. I would like to have known which exact piece it was that was bad. Just for my own peace of mind. But we replaced all 3 bearings and the spindle and with all replaced it works... So at least it got narrowed that far for me.
Most likely there was no "bad" parts involved at all. But like I said before - and the first quoted part basically confirms it for me - the original was assembled with not enough preload on the bearings, allowing them to "roll" (Spirograph style) on the spindle or in the races. His expert reassembly was most likely what cured your issue, not any of the replaced parts.

Ian Parish
12-18-2009, 3:29 PM
Most likely there was no "bad" parts involved at all. But like I said before - and the first quoted part basically confirms it for me - the original was assembled with not enough preload on the bearings, allowing them to "roll" (Spirograph style) on the spindle or in the races. His expert reassembly was most likely what cured your issue, not any of the replaced parts.

I was part of this diagnosis for the past two months, and I think I can rule out bearing pre load. The first technician that came to look at the Lathe, turned the bearing load up to "11". Meaning to diagnose a looseness in the spindle he got out a big hammer and jammed that locking nut for the bearings about 3 times harder than any one should do. At this point the spindle/chuck still wobbled and the bearings were screaming like a bat. Thus the 2nd tech ordered new bearings.

The second true technician thought it was the threads being cut too deep. During his first visit he was able to put the chuck on so it would not wobble, then on another attempt he put the chuck on so it wobbled a lot. This lead me to beleive that the threads were "Too small" and some time the chuck would center up and other times it would be off center causing movement and all sorts of trouble once a big block or wood was added to the chuck.

It is good to have it fixed, and it does run true and nice.
Ian

Leo Van Der Loo
12-18-2009, 4:56 PM
Josh, can you take the workpiece out and remount it in a different spot,---- is it than still running true ????

I do assume it will not.


My assumption is that Chinese made machine has undersized threads on the spindle, so you have too much slop between the threads of your chuck and the spindle thread.

I certainly would not be happy with an outcome like that, having paid a good amount of $$$ for that machine, of course there's this small chance that both the faceplate and the chuck are the culprits, though I doubt that, looks like you will have to live with it or return your machine, good luck on your decision :-(

OK all that like to, you can shoot the messenger, the outcome doesn't change though :-((

Skip Spaulding
12-18-2009, 5:25 PM
Great to hear your daughter is better! Glad to hear your lathe is up and running! Guess you have a lot to be thankful for this season.;)

Joshua Dinerstein
12-20-2009, 2:10 PM
Great to hear your daughter is better! Glad to hear your lathe is up and running! Guess you have a lot to be thankful for this season.;)

I absolutely do. You have no idea. This is my first Christmas with a wife and child. Last year was the first Christmas with a wife. So things just get better and better every year!

While it was a scary no one was as concerned as we were. My daughter Katie had serious diarrhea for more than 2 weeks. 15+ dirty diapers a day is just not normal. Then she started to quit eating. So dehydration became the icing on the fear cake. After two weeks of constant prayer, hospital and doctors trips she started to turn around. While not back to normal she is so much improved that I will take it. Thank goodness for smart physicians and pharmacists. Thanks to the other problems she had diaper rash that wouldn't quit. Blisters and was losing layers of skin! Ouch. Watching her cry as we changed her darn near killed me. We got put onto some stuff that was a real miracle worker on that front.

Scary when a baby loses 10 to 20 % of their body weight. She is putting it back on pretty quickly at this point.

As for the lathe. While I am grateful for that I do consider it the least of the things I am grateful for this season. I turned a cherry branch into a great lidded box shape. Was fun to do. Spun true and worked nicely. The color and figure in the wood is amazing. It did however continue to crack and split as I was turning it. It just didn't really want to stabilize. With every cut it seemed like it released more built up tension in the wood. But still it was a seriously fun piece to work on!

Best wishes to everyone!

Joshua