A Real Dirty Job

Where users can chronicle their builds. Start one thread and continue to add on to it.

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Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

Finishing the brake shoe profiles.

The rear side of the brake shoes are three tangent circles two of which are 1/4" dia. centered on the two 1/8' drilled holes and the third circle being 9/32" diameter and tangent to the others (as per my layout print).

To lay them out correctly, I made up a 1/8" dia. plug to fit the two drilled holes having a small centered divet in one end. One leg of the machinist's divider seen in the first photo was set into the divit and the circles scribed. Then, the plastic circle template was employed to locate and scribe the intermediate 9/32" tangent circle.

After that, it was only a matter of careful belt and drum sanding to remove the surplus metal down to the layout lines. I have drum sanders down to 1/4" dia. which are run in the drill press at high speed. Drum sanding throws grit and makes quite a mess so a thorough cleanup afterwards is warranted.
Attachments
351 Laying Out The Rear Brake Shoe Profiles.jpg
352 The Finished Outline Profiles.jpg
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NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: A Real Dirty Job

Post by NP317 »

Good thing you chose to make brake shoes with simply geometry...
RussN
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

The final deep slotting operation on a brake shoe. The one I had been dreading.

The setup and slotting operation as seen in the photos. After all of the work done to date, if I messed up now... so I checked the clamping system three times. It took the full depth of the extra large 1.5" diameter Woodruff cutter to finish the curved bottom slot and I ran the new cutter very slowly (approx .60 rpm) with a very small DOC (about 0.003" per pass) with conventional milling as there was some backlash in the rotary table.

I could not have been happier with the results and everything fits together just as it should.
Attachments
352 The Setup for the Final Deep Slotting of a Brake Shoe.jpg
353 The Final Deep Slotting Operation.jpg
354 Afer Final Slotting.jpg
356 It All goes Together.jpg
357 Another View.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

One more photo.

I have had enough of this tense rotary milling for today.
Attachments
358 It All Goes Together.jpg
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NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: A Real Dirty Job

Post by NP317 »

Whew!
Nicely done.
RussN
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

Thank you for the compliments Russ.

Every time I look at the Langworthy/Yankee Shop Hudson, I see more things which I could fix up or should change.
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

Finished.
Attachments
359 It All Fits.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

The mounting of the brake shoe assemblies to the leading truck.

The initial fitting indicated that the brake shoe assemblies would fit the truck frame as though they were made for each other - no problems at all.

I just had to machine the mounting nuts, bolts and washers. Other than being very fiddly to assemble, everything proceeded very smoothly.

Then I saw the original builder(s) had made a classic mistake when drilling and threading the frame brake lugs. The frame brake lugs are slotted. Instead of tap drilling through both sides of a brake lug followed by clearance drilling the front face of a lug and only then tapping the rear lug face, they had tapped drilled and threaded both sides of a lug. This means only full length threaded mounting bolts can be used. This way, the brake hanger arm pivots on a bolt thread instead of on a smooth pin surface. Not good. An easily made mistake if one is not paying attention.

As a result, the lead truck had to be completely disassembled again down to the frame and set up as shown in the photos for aligning the frame to the fully through threaded brake lugs followed by clearance drilling the front face of the brake lug only. A few hours of setup and checking work for about 5 seconds of drilling.

The new brake lug pins will be made multi-diameter (smooth on their 1/8" and 9/32" diameters to fit the 1/8" reamed hole in the brake hanger arm and the 9/32" clearance drilled face of the brake lug) and will be 5-40 NC threaded on their end only so as to be able to screw into the threaded rear side of a lug.

After this, I should be able to show how nicely it all goes together.
Attachments
360 The Brake Shoe Mounting Hardware.jpg
361 Aligning a Brake Lug in Preparation for Clearance Drilling the Front Face.jpg
362 Clearance Drilling a Brake Lug Slot Front Face.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

Everything was going so well and I was so close to finishing - would my luck hold out? Well, it didn't quite.

First thing I noticed was the original machined slots in the brake lugs were a bit too shallow. So out came the file and I filed the the brake hanger slots a shade deeper until the hanger arm eye ends just rotated freely on the hanger pins. I had to be careful here as the slots were just about as deep as they could be and not compromise the strength of the brake lugs.

I knew that everything was going to be very tight on the brake shoe end as the brake shoes have to be able to swing back and forth a bit. And quess what; everything that could interfere with their operation did interfere. So, I shaved all of the brake mounting bolts, washers and pins as much as practicable. Holding all of these multiple items securely to shave them down became an exercise in frustration.

Then, there are about 8 different ways to orient the brake hanger pieces, all of them look correct until one has installed the complete assembly and then they aren't. I must have taken things apart and re-oriented them 15 times until it all came out correct. And of course all of the smallest pieces were dropped at some point or another or just disappeared.

Everything now works as it should but...

If I ever have to do this again, I will alter the brake shoe design so the rear slotted face of the brake shoes is threaded so that I can use shorter multi diameter threaded mounting pins (as was done on the frame brake lugs). This change will also eliminate all of the rear brake shoe mounting hardware.
Attachments
363 A Brake Shoe Assembly Installed.jpg
364 So Little Clearance on the Brake Shoe Bolts.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

It is now all together but there is still a problem.

I did solve the brake shoe clearance problems by repositioning the mounting shoe hardware nuts and washers to the front of the brake shoe from the rear surface. I would prefer to see the brake shoe mounting pin heads only but since this works...

I also had to take a little more off the main frame around the frame brake lugs to allow for full axlebox vertical travel due to interferance with the outer drop equalizers and from a couple of the raised flanges around the axlebox openinings to allow the ends of the equalizers to fully align with and drop down into the locating slots milled into the top of the axleboxes.

With everything now together, there is a mispositioning of two of the brake shoes which can be seen in the second photo. This problem will have to be fixed.

I will first check to see that the wheel spacing is on gauge and/or perhaps the brake lug slots were not machined truly square, parallel or to the correct offset from the truck frame or the original lug drilling was not square - lots of possibilities here.

Anyway, I am happy with the results so far but it will be another pyrrhic victory.
Attachments
365 It is All Together but There is a Problem.jpg
366 Two Brake Shoes are Mispositioned.jpg
LIALLEGHENY
Posts: 363
Joined: Sat Jan 11, 2014 12:36 am
Location: Bohemia, NY

Re: A Real Dirty Job

Post by LIALLEGHENY »

Carrdo,

I have been following your work for a while now....very nice indeed! I must add that I am convinced you have a second set of machines that you actually do the work on. Your mill is way to clean....I guess it is for photo purposes only. :D :D :D
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo »

I decided that the most straightforward way to solve the two misaligned brake shoes was to machine a couple of offset brake hangers.

I found that the problem lay with the brake lug slots which had not been offset correctly at the time the original brake lug slots were machined. I was not going to widen the existing slots as a solution due to there not being enought metal in the brake lugs themselves to do this.

A photo of the two additional half machined brake shoe hangers which involves some careful layout and milling work to get this far with a rough starting block.

Yes, most of the time, I do clean up the mess before taking a photo.
Attachments
368 The Partially Machined Offset Brake Hangers.jpg
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