What were the engineers thinking?

[TheOldHokie]

For anybody that cares about the actual issue I replaced the original long cap screws and nyloc nuts with shorter ones and standard hex nuts that are fully tightened. I have not had a repeat of the problem.

Dan

 

[Joisey]

I had to remove a roll pin on an excavator bucket pin once. Mind you, the pin was about 9/16" outside diameter and about 5" in OAL. PO damaged the bucket such that one end of the pin was mostly inaccessible, thus the only way the pin was coming out was by making a hole in the other side, then trying to beat it out. It had to be beat out that way because the "other" (open) end was mushroomed over severely.

It would NOT come out, no air hammer, no hammer and pin punch, it didn't want out. The options were then (1) torch it out, (2) drill it out far enough to beat the bucket pin hard enough to bust the remained of the roll pin off, or cut the entire pin mount off and weld a new one on.

Found out real quick that the roll pin was undrillable, if that is a word. The pin was harder than the drill bit. A $40 cobalt 1/2" bit wouldn't touch it, rather the roll pin chipped the edges of the bit.

Tried to torch it out but there is so much dirt and junk down inside it, that it made it a whole lot less fun to deal with. Eventually got most of it hot, then had my coworker hit the bucket pin with a BIG air hammer, which sheared the hot roll pin enough to beat it the rest of the way out.

So on that job, the customer was quoted $62 to replace the pin and bushings before the machine was seen (plus parts). Shop tech (me) got about $9 of that in commission. But it cost me a $40 drill bit. But the positive side of that is, I learnt some things!

These things can really be stuck, and they can take some time to get em out.

Oddly, just a few weeks ago I had a dowel pin break off of a camshaft/drive sprocket assembly, and I could not believe it, but no bent valves! Pulled the cam out, thought "hmm...how am I gonna get that out". Figured it was harder than hammered hell. Why not try anyway. Grabbed 1/8" drill bit, started in, and it was as soft as butter. Nabbed a LH drill and it caught it, then just pulled it right out. 5 minutes-maybe. Dowel pins are normally pretty hard. Maybe case hardened...dunno...that one was soft! I think that was the luckiest I've ever been in my mechanic'ing life.

External clips are ok, but I've seen them come off and/or get broken. Not often, but it happens. They do spin with the pin which I like.

Late reply, I know. To remove a roll pin that is "stuck" take a steel rod that will fit snugly in the hole of the roll pin. Put it in the hole in the roll pin and then clamp your ground from your arc welder to a clean surface, put the end of the steel wire in your stinger and set your welder to about 80 amps. Turn the welder on and then off, abut 3 seconds. Remove the rod from the roll pin. If it was done correctly, you just removed the temper from the roll pin. Now you can drill it out. If not, rinse and repeat. More amperage may be needed, depending on the situation.

 

[Bri-Guy-GA]

Not sure if this has been suggested, but could you weld a nut to the underside of the flange and use a bolt and lock washer on top?