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Erector set part number JU rod clamp

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BGHansen

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#1
Yet another reproduction Erector set part thread. This one is for part number JU rod clamp used on the Hudson locomotive model. The part was made from 0.020” thick steel, ½” wide. It wraps tightly around a 5/32” rod and has an 11/64” hole through the end for screwing to other parts. Yup, here’s another history lesson . . .

The A. C. Gilbert Company came out with the Erector Hudson model and sets in 1931 and sold them through 1937. They are prized by both Erector set and toy train collectors. The completed model is about 28” long and was built from many specialty parts with just one use. It surprises me that the company came out with such a complex toy to manufacture during the Great Depression. There are thousands of them out there (I own or have owned 8 of the sets), so people back in the day were scrounging up the $15 - $25 to buy the sets. A complete locomotive currently brings between $750 - $1000 depending on condition.

Lots of ways for making this part. I’ve made a couple in the past by gluing a paper pattern to sheet metal. Punched and sanded the edge to the line, formed the part over a drill bit shank. Also considered making a punch/die for knocking out blanks. Make a nest for my Roper Whitney punch press to locate the part and punch the through holes. In retrospect, that might have been a better way to make the part than what I came up with . . . Decisions, decisions as I’ve got to weigh the time to make tooling vs. how many parts are needed. In this case, I figured the “World’s supply” for the JU rod clamp would be around 100 parts, so opted for a different method.

I made a fixture for transfer punching the two holes in the blank. Cut strips of 0.018” stock on my Tennsmith shear to just over ½” wide. The punch fixture has a rabbet cut in the base so the blank can be slipped up to the stop, then held in place by hand while the two holes are transfer punched. I punched the holes with a Roper Whitney #5 hand punch.

Instead of making a punch and die to form the outline of the blanks I settled on a CNC routine on my Bridgeport mill. Made a holding fixture out of a block of aluminum.

I can comfortably stack up 15 blanks, screw them to the holding fixture and run the CNC routine to cut the shape. The routine takes about 45 seconds to make a trip around the blanks.

Made a forming tool for bending the flat blanks into a “U” shape from a piece of 5/32” thick strap steel. Formed a radius on the end with a stationary belt sander. Then drilled/tapped an 8-32 hole for a locating pin. Probably overkill on my part as I could have eyeballed centering the blanks on the radius and folded over the sides by hand. Learned a little geometry lesson as my first locating pin was an 8-32 set screw. Problem is, once the part was bent over the form I couldn’t get it off the tool!

Thought about just grinding the screw down, but I was taught that screws are for retaining, not locating. So threaded a 5/32” rod and used it as the locating pin. Form the parts by setting one blank hole on the pin, then fold over the fixture by hand. The fixture is ½” wide so I flush up the sides of the blank with the sides of the fixture to make the bend square.

Last step is to slip the “U” shaped blank over a piece of rod stock turned to about 0.005” smaller than 5/32”, and squeeze the part down with a pair of pliers. The JU rod clamp should clamp tightly onto a 5/32” rod when the screw is tightened, hence the underside mandrel for forming the end.

Thanks for looking!

Bruce

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hman

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#2
Fantastic work as always. Finishing question - do you plan to tumble deburr/polish the parts before offering for sale? Or are the plier marks OK?
 

BGHansen

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#3
Fantastic work as always. Finishing question - do you plan to tumble deburr/polish the parts before offering for sale? Or are the plier marks OK?
Hi John,

I polish them with a Scotch-brite wheel. Curiously, the original parts have the same tool marks, but I doubt they made them like I do!

Bruce
 

hman

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Wow! Talk about paying attention to fine details ...

You're da MAN!
 

Eddyde

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#5
Bruce thanks for the great writeup!
 

BGHansen

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#6
Wow! Talk about paying attention to fine details ...

You're da MAN!
Naw, my dad is the man. He taught me early on that it's either correct, or it's a POS. He used a yardstick for the visual aid; if the project is done correctly, it'll be used this long. Then he'd hold his thumb and forefinger about a 1/2" apart; "this is how much time you will spend on the project to that scale". If it's wrong, it'll be used this long (thumb and finger firmly pressed together). I have him to thank for being somewhat anal on making stuff, never had a complaint about quality as a result! Always good to go to a show and see someone I sold something to and not have to dodge them because I gave them a piece of junk.

Bruce
 
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