Turning Using Tailstock Center For Support Is P***ing Me Off

Only trust a co-axial indicator to do this, any other is subject to gravity.
 
T Bredehoft said:
Only trust a co-axial indicator to do this, any other is subject to gravity.
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Never heard of this type of indicator before, found a good YouTube video on using it,
.

Thank you. I always learn something new on here.
 
I have a suggestion. The Sherline live center may be off, and I know without a doubt that the tip of the live center can be misaligned with the morse taper. Use a test bar with accurately drilled centers and put one end in a dead center at the headstock end and use the live center at the other end. Use a dial indicator and index the live center (rotate the live center in the socket) to minimize deflection. There will be a position where the live center will show minimal run out. Mark the live center and ram so you can always put the center back in the same position every time you need to use the center.
 
You need to put the dead center in the tail stock turn a piece and check it until you do this you will only be guessing at best. I have seen live centers that were the cause of much frustration.
also do you have the square alignment bar under the head stock.?
Tomh
 
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I also have a fairly new 4400, without the DRO though. I also had problems, The live center was not center. Clean the tapers, insert the dead centers, and check. Now use the dog to hold a piece and turn it between both centers. Then check to see what run out you get. If everything is good, then place your three jaw on the spindle and try another test cut. Check to see how it did. If good then replace the dead center in the tail stock with the live center and try another cut. See what you get. It does not take much to cause this problem.
Another problem could be what are you using to drill the center, If using the drill chuck that can cause you to drill center a bit off also.

Be sure to put oil on the dead centers. and recheck often. .

Also I have had it where I though it was good on the center but as it spins, it smoothed the item out, and became loose. thus when trying to turn, it was deflecting away from my tool, causing this problem.

Note: I have a second set of fresh pointed centers that I use just to check the alignment as I also due some tapers on purpose, Thus Have to put the head stock back and check it.
I have though about ordering an extra tail stock, or finding one on ebay and making a fully adjustable tail stock to fit mine. T

I hope this helps you out.
 
If you are turning a taper between centersbecause of deflection due to tool pressure (lack of support or wrong tool geometry), you would get a barrel shaped turning. If you get a straight taper, it is an off-center tailstock.

Bob
 
Tom, from your photo it appears your turning from roughly the middle of the shaft to the headstock and seeing the taper. Set up a piece of stock as you have done but take a light cut, say .005 from the tailstock all the way to the headstock. Check the diameters at the ends. If they are the same the tailstock is in alignment, and your taper is due to the shaft flexing. If the dia at the tailstock is different than at the headstock then you have an alignment problem.

Greg
 
I have an old 4400 that has a badly worn tailstock ram. When turning shafts I have put a rod between dead centers, turning with a lathe dog. Then shim the tailstock at the ways with brass shims until a test cut shows that the diameter at the headstock and tailstock are the same. Tedious, but it works. Takes about 1 extra beer per part :)
 
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