3/4 and 1" Scale Couplers - Running Off Into the Woods Again

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Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods A

Post by Carrdo »

Keith,

You are right. It is the coupler body which is hollow. I looked at the 1941 loco Cyclopedia and upon careful examination of the drawings there, the knuckles are indeed solid.

I did not drill all the way through the knuckles as I did not trust the castings to be uniform enough for the drill to come out the other end where I wanted it to (for looks).

Also, I had some previous exciting adventures with small, deep drilling right through the all steel knuckles with the Al. Grigg type couplers which have 1/16" dia. holes. Sooner or later (and without warning) the drill is going to jam and break right at the worst depth (about 2/3's of the way through). I got the pieces of the first drill out after hours of struggle but when the second drill jammed and shattered no way!

Al. Grigg must have run into this problem as well as he didn't drill all of the way through the knuckle on most of his original couplers.

Rob,

What is on the photo is most of what is on the print but I can take a photo of it all. PM me on this.
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods A

Post by Carrdo »

Keith,

Just finished talking to Richard. Apparently, some years ago he was in Fort Erie where Canadian National 6218 Northern is located. He was taking photos of the locomotive when a swam of wasps flew out of the hole in the front knuckle of the locomotive. Upon closer inspection, he could see that the knuckle on this engine was indeed hollow and the wasps had built a big nest inside of it.

He agrees that hollow or not one would not want to carry a knuckle very far.
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LVRR2095
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Location: Maine, USA

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods A

Post by LVRR2095 »

Don....Wasps and Hornets are a constant problem on the railroad!
Whenever we used a wayside telephone (a thing of the past now) we would always flip in a lit fusee first, to chase away any stinging insects!

Keith
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods A

Post by Carrdo »

The more I looked at the drawing for the knuckle tail piece the less I liked it.

Then I thought, how would I do this to make it stronger if one had to start from scratch?

Came up with the following. It allows one to push lock the knuckle using a straight pin with no slot or use the existing slotted pin as per the drawing (but made from steel instead of brass) which allows the knuckle to open and lock by raising and lowering the pin slightly.

Still, it is not a spring loaded snap design as per Al. Grigg. This is another reason why his coupler bodies are half castings. The internal snap design which he uses requires a split coupler body.

Anyway, I wasn't 100% certain my method would work so started with one tail piece.

The first operation is to set the mostly machined knuckle casting up as shown in the first photo on a rotary table. Then plunge mill the locking slot cavity. See the second photo. The amount and location of the material to be removed from the knuckle tail piece can be seen when the knuckle is in the closed position in the coupler body and one looks down at the tail piece through the locking pin hole. A long needle was used as a scriber to scribe the tail piece material to be removed.

Next, two circular step segments are milled in the end of the tail piece and then the outer end of the tail piece (if needed) using the same rotary table setup. See the third photo. This leaves a central projection which is a clearance fit to the lifting pin slot so the tab left on the tail piece can slip back and forth through the slot in the lifting pin.

The forth photo shows a finished machined tail piece (including the locking cavity) compared to one not yet machined with the rotary table plug used to locate and hold the knuckle in place.
Attachments
84 Setup for Plunge Milling Tail Piece Lock Cavity .jpg
85 Formed Cavity.jpg
86 Circular Milling Tail Piece Steps.jpg
87 Finish Milled Tail Piece with Unfinished One .jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods A

Post by Carrdo »

When all the coupler parts were re-assembled, everything worked so well I was delighted!!

However, the struggle was not over as the two finished machined couplers would not mate in the locked position. Far too much metal remained on the machined knuckle and coupler body castings for them to lock together in the closed position with the lifting pins installed.

Spent today belt sanding, die grinding, hand coarse filing, riffler filing, hand finish filing and then blending and sanding/polishing to remove all of the excess/interference metal but finally the job was done with the knuckles fitting together with minimum clearance. See photo.

The couplers can now be dead locked or the lifting pins raised slightly for unlocking and re-locking the knuckles. The tail pieces are left virtually solid making them as strong as the metal will allow. The only weak spot is the slotted lifting pin as seen on the original drawing but a full diameter solid pin (without a slot) can be used as permitted by the machined cavity in the tail piece.

I liked my idea so much I am going to use it on the Al. Grigg couplers which I have. This will mean producing new patterns for a single piece knuckle and tail piece instead of the two piece silver soldered design which Al. used. It is just more delay and $$$ to spend.
Attachments
89 Finished Couplers Coupled Together.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods Again

Post by Carrdo »

After sitting idle for the last 2 years and 95% finished, I finally decided to make the last fixture for the 3/4" scale Al. Grigg couplers which I am machining.

It is a rivet swaging fixture which will swage the 1/32" dia. commercial brass rivet which goes through the coupler lifting pin shackle. I think that the photos are self explanatory so...

Would you believe it but I have over 60 single sided pages of machining notes on the machining of these couplers but this includes all of the construction details, notes, photos, sketches/drawings of every new fixture/part made, all of the custom gauges needed and the special tools used. It also includes (as sketches) all of the modifications Richard carried out on his Al. Grigg couplers.
Attachments
182 The Coupler Lifting Pin Shackle and Brass Rivet.jpg
183 The Lifting Pin Shackle Rivet Closer Parts.jpg
184 The Rivet Closer Assembled.jpg
185 The Rivet Closer Set in Place.jpg
187 Swaging the Miniature Brass Rivet.jpg
Last edited by Carrdo on Tue Apr 05, 2022 9:13 am, edited 2 times in total.
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: 3/4 and 1" Scale Couplers - Running Off Into the Woods Again

Post by Carrdo »

If you use the Chaski search function for the thread "3/4" Scale Coupler Update" under my author name also, you can read the two threads together as this thread contains all of the things Richard (RET) did to modify and upgrade the original Al. Grigg coupler design (modified the original coupler knuckle/lifting pin to make it stronger) using a CNC approach.

My original approach was to make my A. Grigg couplers exactly as Al. did originally - manually and not deviate from his original design except that the silicon bronze coupler body casting halves were silver soldered together and I believe that Al's were soft soldered together (I may be wrong about this), as Richard has a very expensive and excellent heat treating furnace which was utilized.

I did it this way because I wanted to prove to myself that I COULD do it.
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