grabiron jigs

Started by deemery, December 26, 2021, 02:37:36 PM

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For my B&M batch boxcar build, it was worth investing the time to do jigs to drill holes for NBWs, grabirons, etc.

The secret tool :-) for doing these small jigs is a really small square: I bought one when visiting Japan just because I thought it was cute. Turns out a small square is really useful! I also use my metal digital calipers to scribe lines that are parallel to the long side of the jig, and the little square locates the perpendicular lines. I scribe and drill the holes, then install the alignment pieces. The body of the jigs are done in either .040 or .060 styrene, it's whatever scrap I pulled out of my scrap bin. The key thing is to make sure one long end is smooth, and take -all measurements- from that edge. 

There are two jigs for the grabirons. One is for the ladder on the left side of the end (18" grabirons), and the other is for the grab on the right side of the end and the right side of the body (24" grabirons). Using the same jig for both ensures they're lined up. On the inside, there's a 1/8" square piece along the side and another along the bottom, at right angles. The holes are there to clear the truss rod ends, which I installed before doing the grabiron holes. (Should have done all the drilling first.) I did a similar jig for the truss rod NBWs. 

Of course, the more accuracy you get in the jigs, the better the results. I did throw away one jig that wasn't quite accurate enough. Also make sure to allow enough extra material to hold the jig into place, too often I've cut my jigs too small, where they have the measured holes, but there was nothing left to hold when drilling.

Modeling the Northeast in the 1890s - because the little voices told me to

PRR Modeler

Curt Webb
The Late Great Pennsylvania Railroad
Freelanced PRR Bellevue Subdivision


Gregory P. DeMayo
General Construction Superintendent Emeritus
St. Louis & Denver Railroad
Longwood, FL


 Very cool... sir

I use a small square for everything but storing my coffee. 

Did you ever notice how many towns are named after their water towers ! ?

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