|T O P I C R E V I E W
||Posted - 01/02/2012 : 11:37:07 AM
Greetings all. Welcome to my next project. On this one, I will be taking the proverbial hammer to a Bachmann On30 2-6-0. My inspiration for this project is a Brooks Locomotive works Mogul built for the Quincy and Torch Lake Railroad, a copper mining railroad on Michigan’s Upper Penisula. Drawings for this engine were in the Aug. 1985 issue of Railroad Model Craftsman. Pictures and more information on both the engine and the neat railroad can be found here:
The Bachmann engine is a little bit smaller, the wheel base is about 80% of the prototype’s and the drivers are a bit smaller, 39” vs 42” but I think the proportions are similar and, well, I’m not really trying to model this engine, just model a similar one that looks as if it could have been a sister engine built by Brooks for my Iowa coal road.
The Bachmann engine is a long tried and true good runner. The engine I started with was a basket case I bought at swap meet. Someone had already started something on the engine. It was in pieces and looked like the person had narrowed the frame slightly. There seemed to be an awful lot of slop between the frame and drivers (more than 0.08”). But the price was right (really cheap) and I figured for the price on the engine, if nothing else the wheels and motor would be useful. But I liked the challenge of seeing if I could make anything of this. Any of you that might have read of my previous build would know I’m nuts so…
My first problem with the engine is that the frame is a more or less solid block of metal. Locomotive frames from this period were much more open with the area between the ashpan and the cylinders being almost airy. Also while the model is based on a prototype that had a long firebox that went to the end of the cab, the Q&TL engine had a shorter firebox (or longer frame) and thus had a more open cab. To represent this I shortened the motor block and the frame leaving about 1/8” of metal behind the gear slot. This cut did obliterate the screw that secures the motor block and frame just behind the gear box. However, there is another screw just ahead of the gear box and there is so much metal here that the chances of there being enough flex to cause problems is pretty remote. To test this before I cut, I removed the rear screw, hooked up power to the motor and while running tried to manually separate the pieces. I wasn’t able to move it with more force that it should ever see, so I feel this won’t be a problem in the future.
Now to open up the frame. What I’m about to do will seriously weaken the frame. However, I believe the frame will still be far stronger than is needed to support the weight of the engine, keep the wheels and gears in alignment and pull the loads expected. After making these cuts though, one wants to be sure to avoid any hammering on the frame (as in prick punching hole centers for drilling) and to make sure there is direct support when putting force on the frame. If the frame is accidently bent slightly, I found that gently sqeezing it in a vice will bring it back into alignment.
OK, here goes: I first drilled 1/8” holes through the frame on either side of the axle slots leaving 0.08” of frame material across the top. I then cut out between the holes with a jeweler’s saw. The cut frame was filed smooth, each section being supported in a vice while filing. This is what I ended up with:
I then made frame overlays from 0.04” styrene. When trying to make two identical pieces like this in brass, the usual method is to cut out two brass blanks, solder them together, cut/file the piece and then heat and separate them. Well, obviously, this isn’t going to work with styrene. What I did was cut out two plastic blanks, clean them very well with denatured alcohol, then stick them together with Scotch double stick tape. I then squared up an edge and end, and laidout and cutout the overlays. When done, I carefully separated them using Goo Gone to cause the tape to release and clean the adhesive. you might notice that some of the lower bars are irregular, unknown to me as I was filing them to shape, they were flexing in the vice, I'll fix this later.
I epoxied these to the frame block. After they were in alignment, I clamped them and let the epoxy cure for 24 hours. Then I cut the axle slots out, using care to not mar the bearing surfaces.
Next is to figure out how to collect power from the drivers and hold them on. I have some ideas, time to see if any work. Thanks for stopping by.
|15 L A T E S T R E P L I E S (Newest First)
||Posted - 04/11/2013 : 7:17:56 PM
¡¡¡ Simply amazing Bill !!! [:-thumbu] [:-thumbu] [:-thumbu]
||Posted - 04/11/2013 : 6:55:34 PM
I just walked through this thread - great stuff! I'll be watching for updates.
||Posted - 04/11/2013 : 3:27:49 PM
||Posted - 04/11/2013 : 2:36:43 PM
Greetings all. Thank you for your comments, compliments and attention. I really appreciate it.
On to the air valve bodies and access plugs. Here is what I’m trying to represent:
You may have noticed in previous pictures, after I notched for the air manifolds, I cut away the tab of the 0.020” end between the notches. I did this to make it easier to make it look like the valve bodies were actually cast with the rest of the air cylinder.
The plugs were started by turning a piece of 0.050” rod down to 0.030” this was sliced off, leaving a small domed cap.
Two pieces of 0.020”x0.080” strip were cut, and a 0.020”x0.030” notch was cut on each end and the ends rounded off. Centered on the 0.060” offset, 0.032” holes were drilled on each end. The plugs were cemented into this. After the plugs dried, they were sanded to thin them and bring them to the same thickness and the excess stub cut off. 0.040” hex was then bored 0.025” and thin slices cut off. These slices were cemented on top of the plugs and sanded to the same thickness.
These assemblies were then centered on each end of the air cylinder and cemented.
The valve bodies themselves were represented with short lengths of 0.060” ½ round that had been laminated onto strips of 0.015”x0.060” cemented onto the ends of the air manifolds. I forgot to take pix of this as I was doing it, but here is one from the finished air pump.
The lower attachment brace was a length of 0.15”x0.060” strip centered on the cylinder.
That finishes the air cylinder. Next will be the cylinder heads.
Thanks for stopping by.
||Posted - 04/11/2013 : 12:19:16 PM
Me too. Lurking and learning.
||Posted - 04/11/2013 : 12:17:40 PM
Beautiful work! Continuing to follow along with great interest ...
||Posted - 04/11/2013 : 12:06:28 PM
Greetings from soggy Iowa. Hope you all are surviving whatever the weather is throwing at you today.
Continuing on with the air cylinder. The area between the valve bodies is finned like the rest of the cylinder. I tried to represent this, though in retrospect I doubt it was worth the trouble, most of what I did was lost when I drilled the holes for the air inlet and outlet. It is a pretty small portion of the pump really. It was good practice working with really small bits of styrene anyway.
I started off by cementing lengths of 0.10” square strip to the area between the valve bodies spaced in line with the spaces of the air cylinder.
I then took some 0.010” rod and scraped it to thin it and cemented it in the grooves between the strip.
Later I drilled a shallow hole to accept a short slice of 0.050” rod bored 0.030” to represent the airline attachment points. As you can see on this later photo this obliterated most of what I just did. Oh. well.[:-indifferent]
More to come…
||Posted - 04/04/2013 : 09:25:35 AM
Greetings from sunny Iowa.
Continuing with the air cylinder for the 9.5 inch air pump. After remaking the air cylinder and vowing this time to leave it on the bolt until completed, I moved on to the valve housings. These are basically check valves that control the flow of air through the air cylinder. Facing the pump, the receiving valves are on the left and the discharge valves are on the right. Since this is a double acting pump, there are valves on both sides (upper and lower) of the piston. This is what I’m trying to make:
And from the back (sort of)
Sorry, about the poor framing and poor focus, it was a pretty tight fit to get that picture. Also the caked on grease doesn’t help much either.
The air manifolds are two rectangular blocks that run the length of the air cylinder. The valve housings are half round shapes on the side of the manifolds and only run about 6 inches from the top and bottom of the air cylinder. On the prototype, these and the lower mounting bracket are all part of the same casting as the cylinder. On the cylinder head side of each valve housing is an access plug that allows the removal of the air valve. Maybe I can save the rest of the thousand words and just give a drawing to show what I mean.
At this point the air cylinder model has no front or back, therefore, marking the chord on the end of the cylinder to locate the valve bodies becomes easier. My best estimate is that the air manifolds are about 4 inches square give or take and extend about an inch beyond the back of the cylinder. Therefore, I marked a 0.060” chord on one end of the air cylinder using a piece of 0.060” styrene strip and marked 0.080” in from each side of the chord using a pair of dividers. I then mounted the cylinder in my drill press vice with the chord parallel to the top of the vice jaws. Then I carefully milled notches into the cylinder until I met the lines.
I cut two 0.080” square pieces of styrene to match the length of the air cylinder minus the 0.020” ends and marked a line 0.060” in from each end. This will be the location of the valve housings. On the prototype this area is ribbed as well. However, I couldn’t figure out how to do this so I tapered the valve housing area so at least it was filled in and met the ribs on the cylinder. Then I cemented the manifolds onto the cylinder.
And that was enough fun for one day.
Thanks for stopping by.
||Posted - 03/26/2013 : 10:36:52 PM
Triple WOW!!!!! ~mike
||Posted - 03/26/2013 : 7:21:29 PM
Make that a double Wow!
||Posted - 03/26/2013 : 4:43:43 PM
Some really neat craftsmanship here.....
Good to see you back at it!
Looking fwd to the finish.
||Posted - 03/26/2013 : 4:31:27 PM
Bill, welcome back.
All I can think to say is WOW.
||Posted - 03/26/2013 : 3:57:23 PM
I have made a tool holder for my lathe that allows me to use cutting tools I filed out of 1/8” steel rod. This has really improved the speed and accuracy of the lathe work over using files.
I turned the fins and ends to 0.260” diameter and the spacers to 0.230”. I used very light cuts until the stock was round and then measured often to make sure I didn’t turn too far.
After the turning was done, I combined the turnings onto a single 00-90 bolt. First a 0.020” end, then a 0.010” spacer then a 0.005” fin etc…until all 12 fins, 13 spacers and 2 ends were on the bolt.
This was then lightly brushed will plastic cement. If too much cement is used at one time the 0.005” fins will melt. It was at this point that I learned that it’s best to leave the assembly on the bolt until the fin support and the valve bodies are cemented on. Without these I found that the cylinder could come apart as one tries to remove it from the bolt. In the process distorting and thereby destroying the assembly. More turning practice for me.
Until next time Friends.
||Posted - 03/26/2013 : 3:28:44 PM
Thanks Arthur. Its good to be back.
I’ll start with the lower air cylinder. Probably the most distinctive feature of this air pump is the finned air cylinder. As far as I can find, this was the only single cylinder air pump with fins. When I measured the prototype I found that the fins were ¼” thick and the spaces were ½’ thick and ¾” deep. The top and bottom of the cylinder were about 7/8”. The air cylinder measures 12.5” in diameter over the fins. There are 12 fins (does this count as rivet counting?). My first thought was to try and turn this, however, with my rather crude lathe, I decided against it. Instead, I decided to build this up from layers of turned styrene sheet stock.
First I laid out the discs on 0.005” styrene for the fins, 0.010” for the spacers and 0.020” for the top and bottom of the cylinder. I drilled the disks with a #61 drill and tapped 00-90.
As you can probably notice, while I scribed a center line I wasn’t too concerned if the hole was a bit off. As long as it was close, this will work itself out in the turning.
The disks were then roughed out and threaded onto a 00-90 bolt and washer. Then locked down with a nut and washer.
Here are the fins and ends on the bolt. Since they are the same diameter, they could be turned together. The spacers were turned separately.
On to the turning…
||Posted - 03/26/2013 : 2:27:25 PM
Bill, welcome back. Good to see this thread come back to life.