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DFMiller
01-21-2012, 05:14 PM
I have some taper pins to extract from Mill to remove it to make it right. . Looking for suggestions.
The pins on the column to base seem to be tapped M4 on backside. So I guess I need to make up a puller. Google tells me they are called extractable taper pins. What have others done in the past?
The rest of them are not tapped and are almost flush with surface.

Thanks
Dave

T.Hoffman
01-21-2012, 05:26 PM
The blind hole taper pins I've tinkered with have a threaded portion sticking out. Simply screw on the appropriate nut, and that pulls the pin.

DFMiller
01-21-2012, 05:40 PM
These have a female threaded hole not a male thread. I wish it was that simple.
I will have to make some little gizmo.
Thanks
Dave

Davidhcnc
01-21-2012, 05:58 PM
A slide hammer will pop them and make you smile:)





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Black_Moons
01-21-2012, 06:07 PM
Just find a machine screw that fits em, And then put a nut and washer on the screw.

Try not to use your cheapest grade negative 3 chinese machine screws for this.

Screw the screw in as deep as you can, maybe back it off 1/2 turn so its not bottomed out (Unneeded stress on threads), then while holding the screw steady, use a wrench to tighten the nut (if the taper pin is recessed, Else you need another larger washer with a big enough hole for the taper pin)

Once the taper pin comes out a tiny bit, you can just grab the screw head and pull it out by hand.

Alternatively, use a small crowbar on the head of the screw (no nut needed, a washer is a good idea if you don't wanna mangle up the screw) and idealy place a small plate under the crowbar heel to keep from damageing the paint.

DFMiller
01-21-2012, 06:10 PM
Thanks, good ideas.
Time to find my M4 SHCS.
I think I bought some recently.
Dave

macona
01-21-2012, 06:11 PM
Taper pins are soft do you can drill and tap them if necessary.

lakeside53
01-21-2012, 08:26 PM
+1 on the slide hammer... often better then just "jacking" with the 4mm screw - the shock frees them. Use a quality SHCS (they are typically equivalent to grade 12) ) as the threaded grip.

Tait
01-22-2012, 09:18 AM
Thinking ahead to when I might need to do this:

Is there any call for penetrating fluid prior to pulling?

lakeside53
01-22-2012, 12:54 PM
No. Taper pins are "metal on metal". Done right there is no gap at all. Done wrong - they don't hold.

Tait
01-22-2012, 03:32 PM
Makes sense. Thanks.

DFMiller
01-30-2012, 01:30 AM
Finally got them out. Got the first one out using a SHCS a spacer and a nut.
The nuts I got from Fastenal were really poor material, after stripping 5 on the second pin I picked up a slide hammer.
After I made up a adapter to fit the collet and modified the hammer so it would properly hold the adapter, It took some effort get the second one out. It was really in there.

Did I say I hate Crappy tools, this one had on the front of the box xxx tools USA. It was a 5lb unit. The barcode said China. And it was a poor copy. They made it so the collet for holding the pullers only engaged a couple of threads. After cutting off the reduced section that was useless it was usable.

After some more dissembly I can start working on machining and adding some Turcite.

Dave

dp
01-30-2012, 02:27 AM
The possibility exists that the pin has been girdled over time and all the holes don't line up any more and the pin is distorted. This is especially possible if the pinned components work against each other. You should at least plan on that and consider buying ahead of time a new reamer of the correct taper when you order your replacement pin.

DFMiller
01-30-2012, 07:26 AM
Dennis,
I was hoping not to replace the pins. ;-) just put them back in. I will have a better look at the one that did not remove easily.
The machine is less than 4 years old.
I have assumed the pins are used to enable the parts to be returned to the same location after reassemblly. But I don't really know.
Thanks
Dave