Lathe Problem

[Stevej72]

I've had my lathe for about a month now and I think I figured out that the headstock spindle is not straight.

When I turn my pens they are even with the bushing on one side and the other side is above the bushing. The bushing closest to the headstock is not too bad. It get worse the further away from the headstock that you get.

At first I thought it was a learning thing. Then I thought that I had a bent mandrel. Now I have 3 mandrels and they all to the same thing. I have cleaned the arbor and inside of the spindle.

If I measure on the arbor I am off about .002, in the middle of the mandrel about .012 and at the end of the mandrel it is close to .050.

I hope all this rambling makes some sense and hopefully I used the correct words to describe the parts I am talking about.

Thanks, Steve

 

[Tea Clipper]

Are you using a 60deg live center? What you describe would not be unheard of from a 30deg center like the stock one on a Jet for example. Which lathe do you have?

 

[ken69912001]

Is this measurement with out your tailstock cotacting your mandrel or touching. I had the same problem and figured out my revolving center on my tailstock was off center. Got a new taistock and still the same problem. Guess I'll have to buy an expensive tailstock.

 

[leehljp]

I am still learning things myself and cannot give you a definitive answer, but I read something here in the past few weeks and then experienced it myself. I had a similar problem as you a couple of times during the making of 9 pens for a wedding. I backed off on the pressure of the nut and the problem went away. The real problem is that there can be a couple of problems and if you adjust one problem the other can still be the culprit.

Once I get beyond the edges and get a round blank, I back off on the nut pressure a tad. It did make a big difference for me. I don't get the amount of time that I would like in pen turning but I am beginning to get a feel for my machine and hear the subtle differences in speed, tightness of the live center, and even tightness of the nut. Once I had the live center too tight but I could tell that by the sound. Actually it is part feel and part sound. I have been around machinery and motors for over 50 years and picked this up kinda naturally. Applying it to lathes is different but similar. I have read here a couple of times from people who say to get to know your tool - the sound and feel. And that comes from lots of experience.

I believe it was Pipes just recently that thought he had a bent mandrel, but I don't remember what his solution was.

Oh, as Ron mentioned - do you have a 60° live center? Most wood lathes come with live centers made for wood stock, not metal mandrels. That makes a big difference; and if you are applying too much pressure there, you will get the resulting problem that you decribe.

 

[jcollazo]

I had this same problem with my month old Jet Mini..... until yesterday. First I went to my local Woodcraft to see if they had a 60° live center in stock. They didn't, but the lady there said that the center was not the problem... the stock Jet center was "made for making pens". She said it was most likely a bent mandrel or the head stock was out of alignment, yadda yadda yadda.[!]
I went back to my car, called my daughter to get the phone number for the Little Machine Shop (littlemachineshop.com) and gave them a call. A little over an hour later I was happily turning a non wobbly pen with my new $12.50 60° live center.

That center makes a major difference!

Joe

 

[low_48]

You would be suprised how much the ends of the blanks will make a difference with the mandrel. If they are not square to the insert, overtightening the nut will bend the mandrel. Also over tightening the tailstock will easily do it. Just snug up both of them. If the mandrel is bent; With nothing on the mandrel, bring the tailstock up and just tighten it enough to hold the mandrel. Lower the speed of the lathe to it's lowest speed. Put a pencil on the tool rest and VERY slowly bring it to the center of the turning mandrel. As it just brushes the mandrel, pull the pencil back. The small mark left on the mandrel is the highest (or closest to the tool rest) spot. Rotate that mark to the top and tap it with a hammer. Bring up the pencil in a new spot. Keep doing this till the pencil mark goes all the way around the mandrel, or as near as possible. It takes some trial and error but you will get it straight.

 

[Stevej72]

Thanks for the replies. My lathe is Turncrafter Pro from Penn State. I'm not sure if my live center is 60 degree or not as I can't see anything stamped on it and it doesn't say in the catalog.

I did take the live center out and cleaned it and when I put it back together I am only off a little more that .002 in the center and less than .001 at the tailstock end.

I did use a pencil to see if my mandrel was bent and it is. I will try and straighted that tomorrow and I think everything will be right.

I may be tightening the nut and tailstock up too much as well, and will be more carefull of that.

Thanks for the help!

 

[leehljp]

Steve,

By not tightening the nut enough, your chisels with catch and stop the blank from spinning. There are three problems with this one scenerio.
1. Chisels not sharp enough.
2. Taking too big of a bite/ or impatient. (Hey I want to get started with the shaping quick [] )
3. By inexperienced logic, the next step will be to tighten a little too much, which can cause your problem. But the actual/original problem can be 1 or 2 or both. DAMHIKT [)]

A 60° live center is not a pointed as a wood turning live center. The 60° center will fit perfectly into the indention of the mandrel. A wood turning live center will be obvious that it is not filling the full indention of the mandrell.

 

[Tea Clipper]

You have a 60° center - I have the same lathe as you do. As the other guys have said, don't overtighten the nut, and keep in mind that the tailstock is there for support and should not be applying any excessive force.

 

[Johnathan]

The farther you get from the headstock the more this problem can happen. Make sure you are not pressing with the tools. If your tools are sharp you shouldn't have to work to get it to cut. You really need to get a 60 deg live center and it sounds like you might have one, make sure you're not bending your mandrel by over-tightening.

 

[GBusardo]

Hi, You might also want to clean out your Morse Taper holes. Cleaning them has helped me a lot with this problem.
Gary

 

[Scott]

Originally posted by jcollazo
<br />I had this same problem with my month old Jet Mini..... until yesterday. First I went to my local Woodcraft to see if they had a 60° live center in stock. They didn't, but the lady there said that the center was not the problem... the stock Jet center was "made for making pens". She said it was most likely a bent mandrel or the head stock was out of alignment, yadda yadda yadda.[!]

Joe

I had to laugh at this! First because it is so wrong, and second, because it is so typical! I have ruined the points on a couple of Jet live centers, plus a couple of mandrels, because they were not a 60 degree taper! [}] I'm glad Joe knew better than to listen, and got a decent live center!

Anyway, you've received some great advice! Try these suggestions, and I bet something there will work. But if you still have problems, you may have a spindle that is off. If so, get a cheap dial indicator and a holder from Harbor Freight, check the run-out, and with this proof you can get them to replace your lathe.

Good Luck!

Scott.

 

[Stevej72]

I do have the dial indicator and holder from Harbor. I'm not sure where to check the runout. If I check it at the location in the picture the run-out is just slightly less than .002. How much is too much?

<br />

 

[woodmarc]

AH HA!
The center!
Finally!
I am also experiencing the same as Steve. I, too, hooked up my DI that I use for my tablesaw and the runout on my Jet Mini was not measurable at the headstock. I then went and bought a new mandrel. The problem persisted. the new Mandrel it dead on straight. Less than .002 at the end of the mandrel shaft. HOWERVER!!!.... I am using the stock live center that came with the lathe. When looking at the center, the point is a little chewed up.
So now for the big question. What are your recommendations for a good live center. What are you opinions on the various multi tip centers.

I have had my eye on the Nove center at CSUSA.

 

[woodbutcher]

I highly rtecommend the Oneway live center. It is in the area of $90.00 but at that point you have completely eliminated live center issues. I have 3 lathes and all are equipped w the Oneway. You also get a couple cones and a knockout bar to change the replaceable tip. You have to blunt the tip so it will properly seat on the mandrel shoulder. Hope this helps,
Jim

 

[scubaman]

Originally posted by woodmarc
<br />
So now for the big question. What are your recommendations for a good live center. What are you opinions on the various multi tip centers.

I have had my eye on the Nove center at CSUSA.

That'll work. Any of the 60 deg. live centers will work. For low cost, I'd suggest one from littlemachineshop.com, I've used one of these for several yers now. It's perfectly adequate. You can also get ome from Grizzly or Harborfreight. Be aware that many of these are not meant for the speeds a woodlathe can go up to (mine goes to over 5000 RPM) and in some cases the bearing grease will liquefy and run out.

 

[woodmarc]

Thanks for the recommendation. placed my order this evening. Now i can get down ot business, an not worry about out of reound blanks.

 

[Randy_]

I have the one from "TLMS" and it has been just fine!! At $13, it is a heck of a good deal relative to the Oneway for $90. I you get one, be sure to get the 1189. It is the standard duty center. the also have a heavy duty center; but it is 4 big, heavy metal turning and "WILL NOT" not perform well for pen turners!!

 

[Randy_]

Originally posted by Scott
<br />.....I had to laugh at this! First because it is so wrong, and second, because it is so typical! I have ruined the points on a couple of Jet live centers, plus a couple of mandrels, because they were not a 60 degree taper! [}] I'm glad Joe knew better than to listen, and got a decent live center!

I'm glad you can laugh, Scott. That kind of total ignorance on the part of a employee of a woodworking store really pisses me off.[!][!] I, too, bought a new JET mini and immediately had problems with wear on the tip of the stock live center. Fortunately, like Joe, I came to IAP right away and Fred put me on to the Little Machine Shop. One order and end of problem......#1189 live center, $12.95.

BTW, I tried to order some replacement tips from JET and was pleasantly surprised to find out they were only $1.65; but was "SHOCKED" [:0][:0] when they wanted to charge me $19.95 for shipping and handling!!! Needless to say, I squealed like a pig stuck with one of those points. They did finally come down to $9.95 for shipping; but by then someone else at IAP pointed out that many Woodcraft stores sell the replacement tips for $1.99.(Mine did!) Ironic, isn't it?? Woodcraft is the store where Joe got the faulty information in the first place!!![][]

 

[knottyharry]

Steve,
If you put your drive center in the headstock, and the live center in the tailstock, and push them up next to one another... do they line up? Are the points in line with one another?
If not you should be able to adjust the alignment to some degree. You can loosen the cap screws on the headstock and move it a little.
ALL wood lathes come with a center designed to be used with wood for the tailstock, like has been mentioned.
You should have the metal 60 degree live center for the mandrel.
Also, when you tighten the live center of the tailstock....you want it to spin at the same speed as the mandrel...if it is too loose, it will burn up the tip. Just watch it when you move it into position and see if it looks like it is turning at the same speed. Then adjust it if necessary.
Harry