My N&W class A 1239 (gauge 5", 1 in 10 scale)

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Bill Shields
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Bill Shields »

:mrgreen: That's a hot water faucet...
Too many things going on to bother listing them.
Asteamhead
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends of the N&W,
Today was fine to me for I could assamble all the parts to built a complete tender truck for the first time :D . Just the right wheel sets are still missing. Will be built soon, too.
The cross bars are bolted rather than welded in favour of better access (for adding in the brake rigging!).
The equilisation will allow the axles to move about a generous + / - 5 mm (1/5 of an "). Springs will ad about 2 mm at full load then.
The trucks are intended to turn around the outer cross bar (the big bore) rather than the center :idea: . Thus the wide lateral travel of the long tender ends in curves will be reduced for better connection to locomotive and train. Vertical load will be transferred by means of a central cross bar and sliding plates as common, yet.
Best regards
Asteamhead
Attachments
A T 95 tender trucks, all parts made of stainless steel or bronze
A T 95 tender trucks, all parts made of stainless steel or bronze
A T 95 truck frames
A T 95 truck frames
A T 95 tender truck with wheels (not finished yet)
A T 95 tender truck with wheels (not finished yet)
A T 95 maximum equilisation in position middle up
A T 95 maximum equilisation in position middle up
A t 95 truck frame from below. No welds, just bolts
A t 95 truck frame from below. No welds, just bolts
Andy R
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Location: So. Calif.

N&W class A 1239 tender trucks

Post by Andy R »

Very, very nice.
I like the offset support too.
The equalization will be interesting when in service because of the eccentric vertical load on the truck.
It may behave more like a 4-wheel truck with an idler axle. Time and experience on the track will tell.
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Dick_Morris
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Dick_Morris »

Nice!
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JBodenmann
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by JBodenmann »

Hello My Friends
Very nice and ultra cool Asteamhead.
Jack
Asteamhead
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Andy, Dick and Jack,
Thank you all!
Andy, you are right, the equilization will be supportet by just 4 points to the truck frame. The total load will be distributed to all 6 wheels equaliy, yet.
The people from Roanoke found this construction superior to the standard Commonwealth design at higher speeds. Hope they were right :)
The center axle-boxes will get a bit more lateral play to improve running around sharp curves (of about 30 feet radius).
In the meantime I started milling the 12 axle boxes, more to come soon.

Best regards by
Asteamhead
Asteamhead
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends,
Time to show some progress. First, all the 12 axle boxes were turned, milled and tested by use of some tools in several steps from raw rings of bronze. Starting with the fit for the ball bearings of 32 mm diameter and the front surface :idea: , they were turned and centered again. Thus the rear (inside) fit for the sealing was turned as was the rear side.
Next I milled the two sliding plates in two steps, related to the finished bore and front surface :idea: . The final precision cuts were milled after some testing and adjusting the position of the parts in the vice. Thus the gap between the truck insides and the axle boxes could be achieved precisely at 2 x 0.1 mm (1 / 256 ") to insure for a slight glide without sticking. (The prototype drawing asked for 2 x 1 / 16 ").
The fits for the pair of ball bearings to be pressed onto the axles are intended as very slight press fits :!: to insure easy assembly.
The next steps will be milling the bottom first and then the top head finally. For all other surfaces are finished and rectangular that will be a more easy job :) . A lot of chips could be saved by means of a shovel :)
Not to damage the finished surfaces by the vice, very thin plates of aluminium (taken from Märklin metall) :idea: worked best.
More to come soon.
Asteamhead
Attachments
A T 95 axle box, turning the fit for the ball bearings
A T 95 axle box, turning the fit for the ball bearings
A T 95 axle box, turning the fit for the backside sealing
A T 95 axle box, turning the fit for the backside sealing
A T 95 axle box, testing the fit for the ball bearings
A T 95 axle box, testing the fit for the ball bearings
A T 95 axle box at raw milling
A T 95 axle box at raw milling
A T 95 axle box, precision milling by one final cut
A T 95 axle box, precision milling by one final cut
A T 95 axle box, before final milling
A T 95 axle box, before final milling
Asteamhead
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Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends,
Time again to report some progress. Now, the axle boxes are completed. The axles are turned with precise fits for both the wheels and the pair of ball bearings. I decided to construct slide fits (- 2 to 3 µm) for the outer races and medium press fits (+ 1 to 1.5 µm) for the inner races on the axles.
This will allow removing the axles (with the ball bearings) out of the axle boxes in case of repairs with just little force :) . The ball bearings may then be removed from the open shaft, if necessary. The wheel set is hold together as a unit by means of nuts on the axle and the covers at the outsides. Following the construction of the N&W, the axle boxes got just one edge each at the inside :idea: .
Sorry, but there are no photos of the wheel sets yet, for assembly will be the very last step. Some dimensions are to be checked very carefully before the bearings may be pressed on :!:
The brake rigging will be added in a bit later. Such a lot of parts :shock: to be constructed lasered, welded and milled!

Best regards
Asteamhead
Attachments
Axle boxes at different stages of processing
Axle boxes at different stages of processing
Axle box, precise milling (finish) of the slide surface
Axle box, precise milling (finish) of the slide surface
Axle boxes, milling the seats for the leaf spring
Axle boxes, milling the seats for the leaf spring
Axle box, drilling the threads for the cover plate by means of  a turntable
Axle box, drilling the threads for the cover plate by means of a turntable
Axles, pre turned
Axles, pre turned
Axle, fine turning the press fit for the wheel (step 3)
Axle, fine turning the press fit for the wheel (step 3)
Last edited by rmac on Sun May 22, 2022 8:48 pm, edited 1 time in total.
Reason: Photo Orientation
Asteamhead
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends,
I´m so sorry for I used wrong nos. :? :
The used fits were 10 times bigger than written in my last post of coarse, meaning more standard - 20 to 30 µm resp. + 10 to 15 µm.
The press fit for the wheels by the way is + 20 to 25 µm (about 1 / 1000 of the shaft diameter).
The smallest precise fit for the bearings was made last :idea: (step 4) in favor of better turning the bigger diameters as long as the axle is more rugged. The cosmetic turn of slight tappers to the center will be done after the wheels are pressed on for the same reason.
Be careful making sure, the axle will not be warmed up when turning the final cut. Otherwise the final diameter might not be precise but a bit smaller :o
All the best
asteamhead
Attachments
Axle, precise turning of the smaller fit for the ball bearings
Axle, precise turning of the smaller fit for the ball bearings
Last edited by rmac on Sun May 22, 2022 8:47 pm, edited 1 time in total.
Reason: Photo Orientation
Asteamhead
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Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends,
Some more photos how I built the SKF cover plates of the axle boxes. Maybe helpfull to other modelers?
The (sand-) casted covers made of bronze needed some final precision work. They are sealed by means of an O-ring and hold the outer race of the ball bearing in position. Like the prototype a small thread may be used to add grease for the bearings once a year.
A simple tool to hold the raw covers safely centered in the chuck was milled on the turntable first:idea:
Drills were made by means of a turntable, too at the identical positions :!: as were used drilling the axle boxes before. Thus all covers may be mounted on any axle box :)
When all jobs are done, the small shaft will be cut off on the lathe using the tool for centering again.

Best regards
asteamhead
Attachments
Tool for turning and drilling the covers
Tool for turning and drilling the covers
Cover pressed into the tool for safe turning
Cover pressed into the tool for safe turning
Turning the seat of the cover. The part may be put off for controls and be put in again with no harm regarding precise centering. The small shaft will be used to clamp and center the cover in the chuck of the turntable
Turning the seat of the cover. The part may be put off for controls and be put in again with no harm regarding precise centering. The small shaft will be used to clamp and center the cover in the chuck of the turntable
Clamped in the chuck for precise drilling and final milling by means of a turntable
Clamped in the chuck for precise drilling and final milling by means of a turntable
Covers ready for use
Covers ready for use
Asteamhead
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Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead »

Hello friends,
All parts are done, just 2 leaf springs are missing yet. The axles were finished by turning the tappered shafts before the covers were mounted.
The first truck is ready for use now :) . A load test by about 300 pounds showed some spring action but very low side motion for good stability.
A closer load test by means of a press will follow to test maximum load and load distribution on each axle under less optimum conditions.
The complete clasp brake rigging of mostly lasered levers is still under construction, It will be built in a second step to achieve a working air brake.

All the best by
asteamhead
Attachments
First truck ready for use
First truck ready for use
Truck, upside view
Truck, upside view
6 axles with bearings
6 axles with bearings
Turning the tappered axles. Last step before inserting the covers
Turning the tappered axles. Last step before inserting the covers
Inserting the sealings before puting the axle boxes on the axles. The ball bearings were pressed on and fixed as last step
Inserting the sealings before puting the axle boxes on the axles. The ball bearings were pressed on and fixed as last step
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NP317
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Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by NP317 »

Well done!
RussN
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