How to remove this stuck tapered pin?

[Friendly non murdering Sword]

On my Deckel FP1 the gearbox for the X and Z feeds has a little problem that I wanted to address. Everything is pulled apart and the problem is already spotted, a worn thrust washer causes misalignment of the drive dogs for the Z-axis feed and so when the Z-feed is not turned on the feed is still engaged, wanting to move the table in Z.

Things could be so easy... I have looked it up in the manual and there are only two tapered pins holding the whole feed shaft in place. Remove those pins, pull the axis apart, machine a new washer and put everything back in place.

But like seemingly everything else the previous owner pulled some super shady things on this one...

One of the tapered pins was spot welded in place, so something must have caused problems before or this was just his solution to the above mentioned problem. I tried to grind the spot weld away with a dremel but I had no luck so far. In the second picture is the thicker side of the tapered pin and you can already tell there is something going on with the tapered hole... as if it had been redrilled multiple times? What is also odd is that the pin is crooked inside the bore, see picture three. I can't imagine it was bent by hammering on top of it, it looks like the whole pin and bore is crooked? I have no idea what is going on here...




Here is the thinner side of the pin. I tried to grind away the spot weld with a dremel, but I still can't get it out...



I guess the only thing left is to drill the pin out? It it s a 4mm pin and I would punch mark the thicker side and drill with 3mm, and 4mm if needed? If have never done this before and I am still hesitant to do this. There are no more spare parts for this mill and if I mess something up I am in even bigger trouble.

So what do I do, besides approaching the previous owner and punching him in the face?

 

[rabler]

I've had to drill out taper pins before. They are usually made from soft steel so will drill easily enough. If you do have to resort to drilling, I suggest trying to just drill enough to free the weld spot completely and then drive it out, even if that requires a drill slightly larger than the pin. Sometimes a little gentle heat cycling will help loosen the pin.
Regardless, definitely worth using a taper pin reamer and cleaning up the hole before reassembly.

 

[kd4gij]

I would grind the small end flat center punch and drill with a slightly larger bit to just below the surface. then drive it out

 

[SLK001]

My guess is that the tapered hole is so buggered up that it is no longer the proper taper, so a previous owner had to keep hammering the pin back into place, until frustration got to him so he welded it in place ("That'll fix it!"). I would drill from the small end all the way thru, then drive the old pin out. Upon reassembly, you may have to abandon the old tapered hole and just rotate the pin location 90º or so and just redrill, then ream to a common taper size.

 

[tq60]

Welded on small end...good.

Plenty of meat on big side, better.

Step 1. Try to grind off top of weld with die grinder.

Use dye or sharpie to paint the surface as it should wick into the area between pin and gear, you need to know when weld is removed.

You may need to carefully center punch then drill a bit to remove just the end and hope weld not deep.

Get the biggest hammer you have and just gentle drop tap.

The energy transferred is far more than had swing of small hammer and if lucky it may come loose.

Next, CAREFULLY drill and tap the large end for fine thread screw.

Use an Allen head set screw as these are usually higher grade screws.

Fine a 1/4 drive socket that will fit over the pin and thread screw into pin through a washer over the end of the socket through the drive hole.

Add washers to get enough of screw in threads and possibly pull pin.

Not too tight to avoid stripping, but tight enough to pull.

With punch and hammer tap the opposite side again.

If you get all of the weld it will come out, propane torch to apply heat while screw applies force.

Good lock!

Sent from my SM-G781V using Tapatalk

 

[Friendly non murdering Sword]

Alright folks, worst case scenario. I managed to properly f*ck this one up.

There are two tapered pins that hold the shaft in place so before tackeling the above mentioned one I decided to get the other one out. It looked to be in way better condition however I couldn't tap that one out either. So I decided to practice drilling this one out first and everything went good. I drilled it all the way through and that was enough to drive that one out easily:



After that I tried the above mentioned and from the start I noticed this material was a lot harder than the one before. Either the welding caused hardening in this area or the pin isn't made out of soft material. I smoked the first drill and had just gotten a tiny bit in. With the second it started to get easier and I got in maybe half way through... when the drill bit broke on me.

Somewhere in there is the drill bit burried:



A little panic attack later I decided to drill from the other end with a slightly larger drill bit and I got to maybe half way through the bore when I noticed I hit the stuck drill bit. I tried to knock the tapered pin out in hope there may be enough material removed but I wasn't lucky.



So my last idea is ordering some carbide dremel tools and grinding the drill bit away? Or are there any other suggestions? Anyways I had enough for now and I'm out.

 

[Shootymacshootface]

Don't be afraid to grind a small flat spot on the gear to help start a new hole.

 

[Lo-Fi]

That's certainly a dilly of a pickle you're in there.
No movement if you get a punch in either side now?

 

[SLK001]

Get some carbide burrs for your Dremel tool and start grinding the drill bit out (or EDM, if you have one!). From your photo, you're in fairly deep, so once out, you should have enough material out that you can now drive it out. I don't think that the pin is hardened, because of the amount of bending that has occurred. Maybe you hit the shaft?

 

[pdentrem]

Diamond grinding bits well for this type of problem. Use lube to keep things cool.
Pierre