mandrels

[cd18524]

When I put my #2 morse taper pen mandrel in my jet midi lathe and turn it on, I have some wobble in the end. Not a lot, but enough to plainly see. I have three new mandrels (woodcraft, rockler, and arizona silhouette)and they all do the same thing. When I bring the tailstock up and lock it in place the wobble seems to move to the middle of the mandrel. The tailstock is far from to tight and the knurled knob is not tightened. The headstock and the tailstock of the lathe line up perfectly and there does not seem to be any play in the headstock. I think I put everything in there. Can anyone give me any pointers?????

Chris

 

[JimGo]

Chris, check out http://www.woodturnerruss.com. He has some great recommendations for what to check and how to correct these kinds of problems. But, off the top of my head, it sounds like you might have junk (technical term) in the taper or on the tapered end of the mandrel that's not allowing the mandrel to seat perfectly.

 

[johnson]

There is a rubber reamer on the market that is made to clean out the morse taper sockets. I couldn't believe the crud that came out the first time I used it. It doesn't take a very big piece to throw off the mandrel. .oo5 at the headstock can make quit a bit of runout at the other end.
Dale

 

[wudwrkr]

Chris,
Are you using the standard live center that came with the lathe? If so, that will not work with the mandrels. The point of the live center that comes with the Jet is a 30 deg taper, the mandrel end is at 60 deg taper. This will cause a wobble. You can get a 60 deg live center from littlemachineshop.com for $12.95.

You can also get wobble if the mandrel has a bend in it. The link that Jim posted should help.

Good Luck!

 

[GregD]

Chris, I would say you have (junk)in the taper or on the tapered end of the mandrel that's not allowing the mandrel to seat.
One question that's not quite clear. On all three of your mandrels, are you using the same morse taper to insert or do they each have thier own? In other words, are you screwing in the mandrel shafts to the same taper end or does each mandrel have it's own taper end. Does that make sense?

 

[Ron Mc]

Dave,
Are the live centers listed all 60 degrees? I can't find any info on their site.

 

[mschem]

Ron-
My understanding is that for machining (metalwork) 60 degrees is the standard taper. In any case, the one from Little Machine Shop is just right. I was amazed at how much truer my setup ran when I made this simple change.

 

[AirportFF]

Originally posted by Ron Mc
<br />Dave,
Are the live centers listed all 60 degrees? I can't find any info on their site.

I couldn't find anything either.

 

[wayneis]

Roll your mandrels on an flat surface like a table saw top or bandsaw top and see if it rolls freely. If it does then your problem is like everyone else said. You can also make a cleaner to clean the crud out. Take a piece of wood and mount it between centers and turn a taper that slides in your MT, keep it kind of rough not sanded smooth and it'll pick up crud. You can also you the tool that you were born with, oh stop it guys get your minds out of the gutter, I'm talking about your little finger and a rag.

Wayne

 

[JimGo]

I use a paper towel rolled in an MT-type shape, with some DNA on it. I bet automotive detailing clay would work well too.

 

[wudwrkr]

Chris they all should be 60 degrees. The one I have is #1189 and works just fine.

 

[woodwish]

I remember a similar thread a long time ago. Someone suggested wrapping a single layer of an old towel around a #2 MT (like your mandrel) and soaking some solvent (I used some acetone I had handy but DNA is probably a safer choice) on it. Then put in the headstock while turning by hand. I wasn't having any problems so I didn't worry about it. A week or two later I was out in the shop doing some cleaning and maintenance so I figured I would just see what was in the headstock- wow, what a load of grease and sawdust I got out of there! Now I do it pretty regularly, and I am amazed everytime.

As far as the degree of the live center vs. the angle on the end of the mandrel- logic tells me that only the tip of the live center should touch the center of the mandrel, that's why they are both tapered. It seems to me that the standard live center and standard mandrel should still work perfectly fine, I have done it for hundreds of items on a mandrel with no problem. I haven't tried the other live centers so maybe I have not seen the difference. It works fine for me now, I see no need to change it. []

 

[knottyharry]

Chris,
You have some really good suggestions here.
Also, is this a collet type fitting for the mandrel?
If it is don't tighten it too tight....that can move it also.
Snug is good, just so the mandrel doesnt' slip.
And just finger tight on the nut.
Also, when you put the tailstock up to the mandrel, get it close and lock it in place. Then turn the wheel to bring the center up to the mandrel. Let it touch and start to spin. Then lock it.
You aren't supporting a lot of weight, too much pressure from the tailstock isn't good either.
Harry

 

[cd18524]

First off, thanks to everyone for your replies. I did try cleaning the morse taper before I posted the original questions, but it wasn't a very deep cleaning. I will do a real good cleaning tomorrow and see if that is the problem. As far as the live center. I do have the original one that came with the jet, maybe I will have to order the 60 degree (thanks wudwrkr). All three of the mandrels have their own morse taper and all three mandrels seem to roll just fine on a flat surface. Thanks again for all the tips. I will keep you updated.

Chris

 

[Randy_]

Originally posted by woodwish
<br />.....As far as the degree of the live center vs. the angle on the end of the mandrel- logic tells me that only the tip of the live center should touch the center of the mandrel, that's why they are both tapered. It seems to me that the standard live center and standard mandrel should still work perfectly fine, I have done it for hundreds of items on a mandrel with no problem. I haven't tried the other live centers so maybe I have not seen the difference. It works fine for me now, I see no need to change it.....

Ray: If it is working for you that is all that counts. But your logic does miss the point. In a metal to metal contact, the contact surface is actually supposed to be on the shoulder and not on the tip. Works just like a Morse taper which you will note has no point or the taper in a drill press. Many folks have ruined their 30° wood point when using it with a metal pen mandrel having a 60° dimple. Not quite sure why you haven't had a problem; but count yourself lucky.

 

[mschem]

Woodwish-
I agree with Randy that the bottom line is what works. I seem to recall that one or another of the mini lathes is a woodworking oddball in that it comes with a 60 degree center - presumably to match standard pen mandrels. Perhaps you have one of those. I have personal insider information about how quickly a mismatched angle can wear the center point to ruin - but, by pleading the Fifth, I refuse to name the dummy that went through 2 points before finding out about machining centers.[B)]