Handling or Adjusting for Run Out

[Flute Maker]

Hi All,
I turn long thin spindles for making flutes(25 to 30 " long with 7/8 , 3/4 or 1 " bores)....I dont have a modern lathe but an older Craftsman with the tubular bed. I basically take 2 pieces of stock and rout half the bore of the flute in each and glue these together. Then I insert a mandrel which goes through the entire length of the flute .It is a 1/2" rod which is threaded on one (live center end) and it has inserts in each end to fit the size of bore I am turning...The opposite end jams up to the chuck .I noticed when I turn my first piece this way I had some runout.How do you guys deal with runout? Thanks A Bunch !!

 

[4yanks]

You've not included much information on the nature of the problem. Have you measured runout at the spindle? If so, I'm not sure the lathe is worth the effort to fix it. Have you attempted to line up the center point of the spur center and the live center to see if they line up? If they don't you can shim either the tailstock or headstock to bring them into alignment which may help. Another possible problem is whip. This occurs when the stock (and your mandrel flex due to centripetal force). If that is the problem you could try to steady the stock with your non-tool hand (this works for me) or invest in a steady rest. Could it be that your mandrel isn't centered? You may be able to measure this by chucking it up without stock to see how it behaves. Finally, I would attempt to determine if the chuck itself is the culprit. I hope this has been helpful.

 

[Flute Maker]

Thanks,
I do need to recheck the line up of the live center and the chuck plus I do have another chuck on order. I turn these spindles down thin and noticed one side (when looking at the bore on one end)was a little thicker than the other. This was the first piece using the mandrel and I am relatively new to turning...I do have a lathe steady rest that works pretty good....

 

[walnutjerry]

Mike---------I had a lathe like the one you mentioned. I could never count on the turning to be concentric. That single rail and the way the tailstock tightens leaves too wide a margin of error. The tailstock does not have to move very much to or fro for it to be off center.

The solution????????----------maybe a machinist lathe. An impovement??????? A Powermatic or Oneway.

Good luck with figuring it out----I never did.

Jerry

 

[Mike Davis]

I have seen some of those smaller lathes set up a vibration that can be either in sync with the speed or a sympathetic vibration that is half or a quarter of the speed. When that happens the stock will be closer to the rest once per revolution or half the time or 1/4 the time.

Anyway the effect is that the finished product will be out of round and center will be toward one side.

Sometimes you can dial the speed to a point that cancels the vibration. But, then you have to have variable speed which most of the small lathes don't.

Really the only answer is to buy a better lathe. :swoon:

Sorry if that is not the answer you were looking for.

 

[sssfox]

I have done something similar to what you are doing.

I have the same lathe and I bought what is called a "screw center". It is a #2 MT with a screw on the other end. Sears sells them for around $6.

I put it in the spindle and drill a hole in a small piece of wood and screw it on. Then, I turn the wood to be a tight fit on the bore of the flute. This way, it is guaranteed to be concentric to the spindle. I jam the flute on the wood spindle and hold it in place with a live center in the tailstock. My flutes have a 1/4" hole in the tail end so a standard live center holds it easily. Since your flutes are larger bore, you may need to turn a tapered piece to fit between the end of the flute and the live center.

Hope this helps.

 

[Mike Davis]

For the flute I made I noticed the cone tailstock was splitting the wood. So, I made Plugs for both ends that butt up against the end of the wood rather than pushing it apart.

 

[Flute Maker]

For the flute I made I noticed the cone tailstock was splitting the wood. So, I made Plugs for both ends that butt up against the end of the wood rather than pushing it apart.

Mike, That is how mine is . My mandrel 1/2" dia , 32" long with 1/2 " 13 threads on one end and none on the other... I have three bore sizes...The one I use most is 7/8"...The pieces for both ends are turned from 1 1/2" stock down to the bore dia and they both have a shoulder that stops them ..The length of the inserted part is 3" ....Tailstock end is threaded and has a dimple for the live center.....On the drive end the chuck holds the 1/2" rod and the other piece just slides into the bore and jams up to the chuck...

I know my lathe is not the best but it will have to work for now..With the mandrel setup would you think that the alignment of the chuck and tailstock be accurate with them being tied together so to speak? Thanks

 

[Mike Davis]

I don't use a mandrel, never have. So, I can't say if that is better or worse.

I made my plugs in my Stronghold chuck, they are very well centered.

I don't think the alignment of the head stock and tail stock is as important as them being parallel. What I mean is the tip can be high, low or to one side and it won't matter as long as they are not skewed. In a metal lathe you offset the tail stock to turn a taper, but the cutting tool is sliding on a rail so that the offset tail stock forces one end closer to the cutting tool. That does not make it non-concentric nor wobbly which are the too most common complaints about wood lathes. No, since you move the tool by hand guided by your eye the tail stock could be an inch offset and you could still turn a perfect pipe.

I think far more important is the weak base, flimsy ways and flexible head and tail stocks make all of the problems in a wood lathe. Get a rock solid lathe and all of your problems disappear.

If you can't buy a better lathe you can beef up the one you have. Mount it on a heavy solid oak beam at least 10 x 10 inches, reinforce the ways by clamping blocks underneath or having a heavier pipe made for it or filling the pipe with concrete if that will not interfere with the function.