Regauging a 7 1/4" Minnie Project

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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Wed Nov 08, 2017 9:02 am

I purchased a 7 1/4" gauge Minnie locomotive project a few years back that has been left dormant way too long. Upon inspection several things needed attention in the running gear, valve gear and boiler. I will elaborate in future post.

We recently bought winter property in Florida and upon inspection I have decided to tear it down and regauge it to 7 1/2".

Rob

10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Wed Nov 08, 2017 10:34 am

First upon removal and inspection of the cylinders. The packing glands were using O-Rings which I dislike due to wear out and having to disassembled everything to replace. So I converted to packing glands for graphite packing material.

Second, there were no cylinder drain cocks and the drain ports were not machined in. I will note the cylinders are the same as used on my Allen Ten Wheeler, so I had prints and knew what was needed. So machined in the ports and made a set of automatic cylinder cocks.

Next I noticed the bores were machined very well, but had not been honed to smooth the tool mark ridges. So I honed them.

Next the cylinder heads were not machined to correct thickness, which means the cylinder to piston clearances were under size and the brass covers would not cover right. So machined them to proper dimensions. Then I made brass cylinder jackets and machined and mounted the cylinder cover blanks to fit.
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Wed Nov 08, 2017 11:03 am

Next up was removing the main driver axles and cleaning the hardened grease from the needle bearings, the project had bee stored for several years so that was expected. This is that laminated frame locomotive design so a lot screw removal to get at the bearings.

The axles fits to wheels were way to lose for Loctite and one had been knerled as well. The lube passage had not been cross drilled to get lube from the hole in the axle center to the bearings either.

New axles were made to be 1/4" longer and to fix poor fit issue. Still require locking compound due to the free construction not allowing wheels and axles to be preassembled. The derivers are keyed to the axles for alignment.

He a pic of the old axles.
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Wed Nov 08, 2017 7:03 pm

Painted the frame from the cab deck forward. It was now or never before driver and axle assembly.

A trial fit of the drivers and old side rods came out great. Drivers roll without any binding.

Also added the regauged pilot truck and trailing axle.

Shorting crank pins is next to be done to work with the regaging.
Attachments
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Fri Nov 10, 2017 4:07 pm

Today's progress.

Crank pins shortened for the regauging.

Stevenson's valve gear eccentric strap rod lengths checked. The red dimension in the picture was off by 0.041 to 0.387 inches over size. Reworked and ready to put back on when the time comes.
Attachments
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dnevil
Posts: 189
Joined: Fri Aug 03, 2012 10:19 am
Location: Springtown, Texas
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Re: Regauging a 7 1/4" Minnie Project

Postby dnevil » Fri Nov 10, 2017 6:58 pm

About 18 months ago I contacted Bill Oberpriller and received permission to harvest and reproduce his website for the Minnie project. I hope it will be a help to you and other Minnie owners/builders.

http://ibls.org/mediawiki/index.php?title=Bill_Oberpriller%27s_Minnie

Happy steaming!
Daris
Daris Nevil
IBLS Secretary
North American Region
http://www.ibls.org

10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Sat Nov 11, 2017 11:32 am

Daris, that's great to hear. I only got a partial set of plans with the project. So additional information will be helpful.

Rob

10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Mon Nov 13, 2017 7:22 am

Here's a couple of Minnie completed pictures that were on the above posted link.

I have the ballon stack from the first pic and the metal cab from the second.
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BillOberpriller_and_MinnieII_640x479.jpg

10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Mon Nov 13, 2017 7:54 am

While I am waiting for rod material to arrive. I got the blast pipe fittings made and the inlet fittings set up in the saddle.
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Mon Nov 13, 2017 5:49 pm

Rest of today was spent on correcting the defencies in the Steven's valve gear links. A lot of time consuming fiddly work.

Drilled and put in dowel pins on the rocker arms and lifting arms. They were just set screwed. Added oil holes to the swing links and rocker boxes. And did trial for to get position of the outside rocker arms on the shafts for drilling there pin holes.

Also measured and sketched out the valve rods and made the adjusting coupler nut. The builder had it set up for a single rod passing through a bar in the slide valve that also has a set screw to secure and adjust it. Using set screw attachments as primary fastening are failures waiting to happen.
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Wed Nov 15, 2017 7:23 pm

Today's progress, fished the valve rods, adjustor couplings, made stainless valve stems and T nuts for the valve
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10 Wheeler Rob
Posts: 1386
Joined: Tue Mar 21, 2006 2:44 pm
Location: East Hartford, CT

Re: Regauging a 7 1/4" Minnie Project

Postby 10 Wheeler Rob » Sun Nov 19, 2017 10:30 pm

Got drivers a fixed to axles with Loctite retaining compound, mounted the cylinders and cut gaskets for cylinder heads and steam chest.

The close fit between front drivers and cylinders required trimming the cylinder covers so they can be installed over the valve head and clear the wheel flange. Trimed area does not show after assembly because its hidden behind the cylinder.
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