Installing trip pins on MTL 903

[Jbub]

For those who have used the 903's, how do you get the trip pin on the knuckle. The first one I tried snapped the knuckle off where the hole is. Also, is it necessary to weld the lid on with a hot soldering iron?
TIA
Jason (Jbub)

[Chris333]

I simply change the 3 to a 5 and that works for me 

I press them in with a pair of flat jaw pliers. They are square so make sure you line them up correct. And I weld the box with an exacto blade heated with a lighter.

[Jbub]

I simply change the 3 to a 5 and that works for me 

That might be the case for the next set

[gbcaboose]

If your talking about press-fitting the trip pin into the coupler, I always take a small file and file the ends of trip pins to an angle and they go in much easier.

Mike

[randgust]

I hold the top edge of the knuckle against a firm surface - I like the front edge of my workbench.  Grasp the trip pin with a good set of grip longnose so that the push is in line with the top of the pin.  When you push it in the hole it has a 'backer' against it then it won't go in too far, or won't stress the edge of the knuckle against the shank, either.

I've never broken one doing it this way.

[djconway]

I can not over enphasize removing any burrs on the trip pin before trying to press it into the knuckle.
I use a little piece of nicrome wire, a normally open spot swirch and a 9 v9lt battery, touch the wire to the box hit the button and it's welded.

[Jbub]

Thanks for the replies everyone.  I think this will help. If you have any other tips on building these feel free to post. I do have the assembly jig which does make getting that nasty spring in there a lot easier.

[nkalanaga]

Like Chris333, I buy the 905s.  Never could get the 903s to work consistently, even though I've been assembling 1025s since the very early 70s.  For the 903s I did get together, I didn't weld them, and I never have welded the 1025s.  Just screw them on.

[Santa Fe Guy]

Yep, file the ends of all trip pins before assembly. Saves a lot of heart ache.
Rod.