Engines > From Plans
Another Pennsylvania A3 Switcher
JCvdW:
Thanks Per and Chris for checking in. Silver soldering the boiler still looms somewhere in the distant future...
The truck side bars were cut from mild steel sheet using an angle grinder, and then milled to size on the mill. The mill vice was too small to hold the pieces, so a temporary vice was devised using a few lengths of cold rolled flat bar that were on hand.
The bending jigs suggested by Kozo made bending the side bars straight forward. The sharp edges of the v-slot in the jig were rounded on the belt grinder to prevent marks on the side bars.
The jig to cut the sloped slots in the bolsters was made from mild steel. To mill the 3 degree slope on one side of the jig blocks, a wooden jig was first made on the table saw with the blade set at a 3 degree angle.
Stainless steel coil spring wire was sourced from a local spring manufacturer. The coil springs were then turned on a mandrel in the lathe as described by Kozo. It took longer to select the correct gearing for the required pitch, than it took to actually make the springs.
And finally the two trucks were assembled, with all parts numbered, as suggested by Kozo!
Next step is painting, before starting with the frame. I am unsure about this. The side bars fit tight in the bearing block slots and will most likely not fit if painted first. Inserting the bolsters will however require disassembly after painting, which may also be problematic. Any advice will be appreciated.
Kim:
Sorry, I seemed to have missed one of your posts in August! You've made a lot of great progress and have some fine looking trucks there!
As for painting, I masked off the notches in the journal boxes where the arch bars fit, and of course, all of the sliding portions of the columns and bolsters. But I painted all of the arch bars. I didn't seem to have any problem making things fit after painting, though I may have had to sand down a little on the edges of the bars to make them fit if the paint was too thick. I don't remember for sure, but that is certainly something I've done on this build. I am using powder coat rather than spray paint though, and powder coating adds a bit extra thickness. If you're spray painting, I can't think that it will add enough thickness to cause you too much issue. If so, just sand a bit off so it will fit :embarrassed:
Wonderful looking trucks for sure!
Kim
Admiral_dk:
Another great step forward - looks good :ThumbsUp:
Per :cheers:
JCvdW:
Thanks Kim for your painting suggestions, and Per for checking in. Two months later and the trucks are finally painted! During this time I also replaced the spindle and gearbox bearings of my RF-45 clone milling machine, but the main reason why painting took so long, is procrastination - I do not particularly like painting.
I first experimented with rattle can paint, hoping for a straightforward and simple process, but could not achieve satisfactory results. In the past, I had good results with 2K automative spray paint, but this is quite a tedious process, as curing time may be 24 hours or more.
To make things a bit more attractive for myself, I first made a counter top spray booth which takes care of over spray and noxious fumes. It consists of an extractor fan from a domestic oven, some filter material and a few pieces of styrofoam taped together.
I then made an oven that reduces curing time to around 30 minutes. The oven consists of a temperature controller, two 125 W lamps and a styrofoam box.
The spray booth and oven make life much easier, especially the short curing time. Progress can now be made quickly. Suddenly painting is not so bad!
The final result:
As suggested by Kim, the edges of the bars had to be sanded down to fit into the slots of the journal boxes. This was then re-sprayed after partial assembly. The sliding interfaces between the bolsters and columns were also sanded down, and is now covered with oil. This will hopefully prevent rust. The wheel rims were sprayed with 2K clear coat.
The screws will be replaced by scale bolts to be ordered from Knupfer in Germany.
Kim:
The trucks are beautiful! Great job on the painting. :ThumbsUp: :popcorn: :popcorn:
And the paint booth & drying oven are great additions. Love the foam construction too! Very nice!
Kim
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