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Powermatic 3520A Tailstock Question

C

Clem Wixted

Joined
Mar 17, 2005
Messages
105
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Location
Jonesboro, Arkansas
While trying to mount my live center in the tailstock today, I couldn't get it in seat. So I cranked the handle and nothing happened. Still couldn't get the it to seat. Long story short, the shaft was spinning in the tailstock. There was a short pin in the recess in the tailstock. I found a hole for the pin and rotated the shaft so the pin would seat in the grooved slot on the shaft. I rotated the shaft with the slot to the bottom and was able to insert the pin so the shaft wouldn't spin when I cranked the handle.

Now the question.

How hard should I drive the pin to stay in the hole?

The pin doesn't appear to be tapered. There is a hole in the top of the tailstock that appears to be over the pin. I guess that could be used to drive the pin out if it were ever necessary but I haven't cleaned out the hole to check that.

Thanks for your help,

Clem
 
Clem,

Page 21 of your Instruction Manual shows a dowel pin that appears to come out by driving down from the top. If that pin fell out, tapping it in to just shy of the depth of the groove on the shaft should do the trick. Any tighter would cause the shaft to bind, unless it is supposed to be loose in the groove and comes out when the shaft is removed. A call to the Tech Dept. at PM may be in order.
 
Instruction Manual?

Jake Debski said:
Clem,

Page 21 of your Instruction Manual shows a dowel pin that appears to come out by driving down from the top. ... A call to the Tech Dept. at PM may be in order.
Click to expand...

Jake,

Read the instruction manual for help? 🙂

I uesd to be a technical writer and that should have been the first thing I should have done.

Thanks for the reminder "if all else fails, read the instructions"

Clem
 
Loctite Blue

Clem,

I had a problem with the pin dropping out of the tailstock on the two 3520a's that I use on a regular basis. After various attempts to get the pins to stay in place, the final solution was to put a drop of Loctite Blue on a pin and press it into place by hand. It has been several months since doing this and the pins on both lathes have stayed in place.
 
Thanks, Randy

After I cleaned the pin I put a drop of some green Loctite that I had and slipped the pin into it's hole.

It's holding and we'll see how long it does.

Thanks again for the tip,

Clem
 
One more question..............

In order for the pin to drop out doesn't the shaft need to be over extended? If so, what operation would require consistantly over extending the tailstock shaft? Please don't take this as criticism I am mearly confused. 😕
 
I could hear a pin drop

Jake Debski said:
In order for the pin to drop out doesn't the shaft need to be over extended? If so, what operation would require consistantly over extending the tailstock shaft? Please don't take this as criticism I am mearly confused. 😕
Click to expand...

Hi Jake,

My tailstock was just sitting there with the shaft fully retracted, not in use, when the pin dropped out. The pin is there on the bottom of the shaft, to keep the shaft from spinning when turning it in or out, and is located about midway in the tailstock, under the shaft. The in and out operation only slides over the pin and doesn't have any concern about shaft location.

Can you feel how far the pin is from flush on yours?

Clem
 
Oh!!

Clem Wixted said:
Hi Jake,

My tailstock was just sitting there with the shaft fully retracted, not in use, when the pin dropped out. The pin is there on the bottom of the shaft, to keep the shaft from spinning when turning it in or out, and is located about midway in the tailstock, under the shaft.
Clem
Click to expand...


Clem,

Red faced because I never looked at my machine before posting.

Anyway I first measured the depth of the groove in the shaft, .14"+/-. Then the extension of the pin from bottom of the bore upwards, approx. .085-.090. This was measured with feeler gages, not the best because of the curve of the bore and gages are flat. Then I measured the pin exposure under the shaft housing, again with feeler gages, 0.21. This was a better measurement because the bottom of the housing is relitively flat. Hope this is of some help.
 
Just out of intrest, what does this pin do? 😕
 
Dowel Pin

Kyle said:
Just out of intrest, what does this pin do? 😕
Click to expand...

Kyle,

The pin keeps the tailstock quill from spinning when the tailstock handwheel is turned to advance or retract your live center. The pin fits into a groove on the bottom side of the quill.

Clem
 
that makes scense. i guest i never noticed that on the school lahtes
thanks
 
Kyle,

Lathe manufacturers have no standard when placing the dowel pin, top, side, bottom, etc. In fact some use a threaded stud rather than a dowel pin. My last lathe had a pin mounted on top and to remove it you would use a punch to drive it down and into the tailstock bore.
 
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