Lathe

[Linmax]

Help - The lathe on my Mark V repeatedly throws whatever I mount off the machine. The seemingly obvious answer is that alignment beterrn head and tailstock is off but I have very carefully made the alignment per the instructions in the manual and I have used other alignment techniques as well. Nothing is loose so ther is no play on either side. The wood is securely mounted but what happens is the pin on the tailstock cuts a groove out of center (which I have very carefully marked) and continues to cut its way out of the wood and then the wood goes flying. Does anyone have any experience with this problem or can offer any suggestions? I'm out of ideas. Thanks for any input you can offer..

[edflorence]

I am guessing the tailstock center is a dead center. If it is, switching to the live center should make all the difference.

[jsburger]

Can you post a picture of what you mean "the pin on the tailstock cuts a groove out of center (which I have very carefully marked) and continues to cut its way out of the wood. The dead center should be seated in the stock so that the round cup is embedded in the stock. Same thing for the drive spur. The 4 wings need to be embedded in the stock.

Use a rubber mallet to drive both centers into the stock so they mark the wood very well. Then mount the centers and the stock.

[garys]

You are getting too much vibration from something. If your wood is badly out of balance when you start, set the Shopsmith to the slowest speed to start. That should slow down the vibration. And, drill a small deep hole for the tail side of the wood so the pin is seated full depth into the wood before you start.

If the machine itself is out of adjustment, that could cause it too. As already mentioned, a live center should work better than a dead center.
As long as the drive center pin is aligned with the pin on the tailstock, the lathe should work just right.

[JPG]

The center pin is only to allow centering. The outer ring is what holds the workpiece centered.

[everettdavis]

Please check the Lathe Turning section in the Shopsmith Academy at this address to insure you have the right components, and they are set up as shown.

http://www.shopsmith.com/academy/latheturning/index.htm

• If you're working with hardwood, drill 1/8" diameter holes, 1/2" deep in the center of both ends of the workpiece, and saw diagonal kerfs 1/8" deep. This will help seat the drive center.

• Mount the drive center on the main spindle and the cup center in the tailstock. Position the power plant so that the centers are about 1" farther apart than the length of the workpiece, and lock the power plant in position. Warning: Be sure the speed dial is set on “Slow.”

• Wax or soap the end of the stock that mounts to the cup center to help it turn smoothly. Hold the stock against the cup center; then extend the quill and mount the other end on the drive center. Press against the quill feed lever to be sure both the spurs and the cup are engaged. Do not release the tension. There is also a Live Center #2 Morse Taper cup as an option

• Then lock the quill in place.

Warning: The spurs of the drive center and the circle of the cup center must penetrate into the wood at least 1/16" in order to mount the stock securely on the lathe.

Everett

[roy_okc]

Adding to Ed Florence' suggestion of getting a live center, you will want one with a Morse Taper 2, or MT2. You might look at a kit that allows you to change the point with various tips.

[Linmax]

Thanks to all for your comments and suggestions. I have added a picture to better illustrate what is happening. The rounded piece is pine (or similar soft wood) and was purchased as a round dowel with a 2" diameter. It split in half as it was ejected from the lathe. The square piece is made from laminated 2 x 4 cut to a 3 1/2" square. Nether piece was touched by a tool, I mounted them and turned the lathe on simply as a test, which both failed as they were thrown from the lathe. The turning speed was relatively slow (within suggested speed range) but not at the slowest speed.

The problem is always on the tailstock side. Are you still of the opinion that a live center will fix this issue?

I should add that both pieces were securely mounted. Is it possible to have the wood mounted too tightly? It spins relatively easy by hand so it wasn't binding on the tailstock side......

[JPG]

Again - the center pin is ONLY for centering.

The cup(ring) is what keeps the work piece mounted.

The first pix shows no indentation of the cup.

The second shows the cup indentation, but not following the path the center pin took when dismounting.

The cup is what the workpiece rotates against, NOT THE PIN.

A live tailstock center will NOT work with only the pin contacting the workpiece either.

[jsburger]

Thanks to all for your comments and suggestions. I have added a picture to better illustrate what is happening. The rounded piece is pine (or similar soft wood) and was purchased as a round dowel with a 2" diameter. It split in half as it was ejected from the lathe. The square piece is made from laminated 2 x 4 cut to a 3 1/2" square. Nether piece was touched by a tool, I mounted them and turned the lathe on simply as a test, which both failed as they were thrown from the lathe. The turning speed was relatively slow (within suggested speed range) but not at the slowest speed.

The problem is always on the tailstock side. Are you still of the opinion that a live center will fix this issue?

I should add that both pieces were securely mounted. Is it possible to have the wood mounted too tightly? It spins relatively easy by hand so it wasn't binding on the tailstock side......

Your problem that has been already said more than once is that you are not seating the cup center in the stock correctly. The pin is only for centering. You must have the circular cup embedded in the stock.