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Old 11-14-2017, 04:58 PM   #1 (permalink)
 
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Default Dead center problem

Recently I purchased a #1MT 60 degree live and dead center from woodturningz. The live center fits fine but the dead center wobbles when it's inserted into the headstock.

I put my live center in to my headstock to see if it was a problem with the lathe. The live center fit fine with no play.

I contacted woodturningz to see if I was doing something wrong. They sent me a new dead center today and I have the same problem. When I insert the dead center I can wiggle the center from side to side in the headstock.

Is there something I'm doing wrong? I don't want to contact the company a second time if it's something I'm doing wrong.

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Old 11-14-2017, 05:33 PM   #2 (permalink)
 
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Is the dead center longer? Does it have a tang on the end that could be bottoming out? This is more common in the tailstock though.
Does the dead center fit in the tailstock?
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Old 11-14-2017, 06:19 PM   #3 (permalink)
 
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Is the female taper in the headstock clean?
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Old 11-14-2017, 06:27 PM   #4 (permalink)
 
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The headstock taper is indeed clean.

The dead center does not fit in either the headstock or tailstock. I don't recall if the center is longer or not I will have to check when I get home.

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Old 11-14-2017, 06:43 PM   #5 (permalink)
 
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Please post the part numbers from the Woodturningz website.

Also, consult the manual for your lathe to determine the spindle specifications.

Sometimes the headstock spindle and the tailstock require different MT.

For example, my lathe tailstock is MT2 while the headstock spindle is MT3.

On a big lathe I have, the tailstock is MT3 and the headstock is MT5.
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Old 11-14-2017, 07:24 PM   #6 (permalink)
 
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The item number from woodturningz was DEADCENT1.

I did check the manual before ordering the part and the spindle is a MT1.

The dead center is however a bit longer than the taper of the live center. Is it feasible that trimming some metal from the back end of the center would fix the issue?

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Old 11-14-2017, 07:59 PM   #7 (permalink)
 
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Look into the shaft and see if there is a step at the end of the Morse taper inside. If so grinding off the tang should fix it. Out of curiosity does the dead centre fit the tailstock okay?
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Old 11-14-2017, 08:07 PM   #8 (permalink)
 
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Also, Morse tapers do vary.....perhaps not the actual size but apparently the length is an issue. When I turn a wooden Morse taper for a mandrel/ jig, etc, it will fit the lathe I make it for very nicely but when taking it to my other lathe, the Morse taper mandrel does not seat fully as in your case.

Perhaps grinding the tail end will make the difference.
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Old 11-14-2017, 08:12 PM   #9 (permalink)
 
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Quote:
Originally Posted by Curly View Post
Look into the shaft and see if there is a step at the end of the Morse taper inside. If so grinding off the tang should fix it. Out of curiosity does the dead centre fit the tailstock okay?
Curly, read post #4, where he states that the DC does not fit the TS. :) . This is puzzling because he also said that both the TS and the spindle are MT1. . It could be just a matter of the length of the spindle taper compared to the length of the DC taper.
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Last edited by magpens; 11-14-2017 at 08:41 PM.
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Old 11-14-2017, 08:28 PM   #10 (permalink)
 
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Quote:
Originally Posted by Wagner11 View Post
The item number from woodturningz was DEADCENT1.

I did check the manual before ordering the part and the spindle is a MT1.

The dead center is however a bit longer than the taper of the live center. Is it feasible that trimming some metal from the back end of the center would fix the issue?
I was thinking that this part that you got from WTZ was actually a PSI part but it is not.

It is possible that trimming off the back end may allow it to fit. But I would be very wary of doing this .... only as a last resort .... because grinding the steel could be a very laborious process. I have heard it recommended that the tang at the end of some centers can be ground off but I would think it would be a very tedious process.

I believe, from viewing the WTZ picture, that yours does not have a tang (flat piece about 3/4" long at the smaller end of the center).

Have you tried probing into the spindle taper and measuring its depth and comparing that measurement with the tapered porton of the center ?

You can actually calculate the angular taper of the center:

Measure the largest diameter of the center = Dia1
Measure the smallest diameter of the center = Dia2
Measure the distance between the above two measurement points = Lgth

Angular taper in degrees = arctan{(Dia1 - Dia2)/2xLgth}

Most small pocket calculators will handle this without any trouble and should by default give the result in degrees (other units are possible, like radians). The arctan function might be labelled on the calculator key as Tan-1 (where the -1 is elevated about a half-character height above the "n")

Now somewhere recently I posted a link to a table of angles for Morse Tapers. I will find that and repost here by editing in a few minutes.

When you get the calculated answer, you really haven't made much progress because you already know it is a MT1 ...

Back in a minute or two. . Here is the table I found on the website specified:

https://littlemachineshop.com/reference/tapers.php

and I posted it in post #4 of this thread:

MT0 Pen mandrel

I would encourage you to try to measure the depth of the taper on your spindle and compare that with the measured length of the taper on your dead center. And then try to deduce whether grinding off the small end of the dead center could help.

You could also try making a MT1 taper out of wood and see how far you can insert it into the spindle. You don't need to be too accurate about the shaping .... of course more accurate is better .... and just use a disc or belt sander to shape the wood.

This is just a shot at trying to figure out what to do next.
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Last edited by magpens; 11-14-2017 at 08:38 PM.
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