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Building a PRR 2-10-0 or Hyppo in 1/32 scale live steam build log

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Discussion starter · #21 ·
Thanks Paul for your encouragement. I am a bit put off by the huge amount of work before me and my lack of knowhow in machining and precision work. So I amgoing slow not to ruin everything. I need to think how i will do this and how to do that first...
I got some nice photos of the beast thanks to Dick Abbot who was visiting a friend in the area and offered to make some photos for me. Nice portrait of you and your children I guess. Thanks nevertheless.
 
Discussion starter · #22 ·
Your encouragement prompted meto push on with it. One problem I was facing was that my journal boxes (Canibalised from the mikado tank build) almost fitted my axle slots in the frame. To such a point that I felt that just doing a bit of filing very delicatly checking as I go should permit me to fit them nicely in the frame slots. I know the proper way to do that is to mill these slots; but not being to good at milling and especially, not having many of the necessary tooling (nor the knowhow) to do that accurately; would likely result in some errors, perhaps worse than the very slight filling needed to make these axle box a nice sliding fit in those slots! So I decided to try it out and here is the result:
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The fact is, that the slots were an exact fit for these journal boxes, all that needed to file away was the slight V shape that the water jet cut made. So hopefully it should be very exactly the axle spacing which I wanted. Cross your fingers...
Well anyways this will enable me to make a running test in my sharpest curve on the layout, to see with these (Ex mikado) wheels, if it has enough side play to negociate my sharpest curve : 4 meters 50 radius which comes out to 14 and 3/4 feet. If it works I will push on especially since the 1 I had flangeless center driver (originally the three center drivers, but that is a bit risky).
Next will probably be the turning of the new drivers, which were purchased from Mark Wood (these are for the Virginian 2-B-B-2 jackshaft electrics), which had the right number of spokes and the very large counterweights, although I shall have to modify the shape of the counterweights. By the way if anyone knows who is building these heavy juice jacks I shure would like to see the results, as electrics especially heavy ones are also one of my pet interests. Unfortunatly no other manufacturer made castings with the right number of spokes.
Happy steaming!
 
Discussion starter · #23 ·
Testing for binds and sideplay on the sharpest curve of the layout:
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As the center driver will be blind and I have four drivers salvaged from my mikado build, it made this test possible, before pursuing further. This is essential, as I have had issues on my 1-4-1 R with a frame so tight that it doesn't allow enough side play and on certain sharp curves it derails. As this is a decapod the problem worsens. The chassis passed the test OK, although unsprung and still very light.
 
Discussion starter · #24 ·
Last evening I decided to try to make an axle for the missing 5th axle. as I had some 10mm diameter steel, I made one but as I didn't have a round nose tool to use on it, it turned out rather rough, but it was good exercise in precision work on the lathe. I am still way back in the learning curve. I will get a proper tool and some 1/4 inch stub.and make another one !

Image

Learning the hard way...
 
Discussion starter · #25 ·
Finally as it was another rainy day, I decided to make some experiments with different tools and different positions of the tool in relation to the part being worked on. And succesfully made a new axle; this time with good surface finish and much better dimensional precision.
Here is is in place on the frame.
Image

The first axle which was gioing to be junked anyways, helped me understand how to get a better surface finnish.
I learn as I go...
 
Discussion starter · #27 ·
Hi Victor, this is in 1/32 scale gauge one. As I now own three PRR passenger engines , but no freight engines in live steam although i do have a FAM PRR M 1a which is electric and which I would love to convert to live steam. And although an experienced modelrailroader, I have very little experience, training and knowledge in precision machining,and am learning as I go. Thus sometimes making another part.
 
Discussion starter · #28 ·
After a long period of thinking about how I would proceed, I finaly got around toturning the wheels for the hippo. This was primarily because one of the feature of the prototype which was the very heavy and protuding counterweights.

Image


As you can see in this beautiful photo of the prototype made for me by Richard Abbot these protude a good two,or three inches.

I decided to follow the turning instructions in Mark Wood's site and adapt as I go. It was particularly difficult because the disc which holds the wheel on the mandrel during the last stages of the turning process had to have a deep recess to allow for this counterweight. And I had to make a new one especially.
The other difficulty created by these counterweights was the machining of the part of the boss where the crankpins are, as the counterweights get in the way! I phoned Mark who remembered another builder who had the same problem, and suggested to hand turn the boss- a lengthy and strenuous process:

Image


The photo shows how (at least on a myford super 7) I pulled the belt to cut the boss, in the photo I am about to make a pass of just the angle for the crankpin boss. One tenth at a time.
As the result wasn't a very nice finnish I then filed these flush with the center of the boss which could be done with the lathe. You have to take some advance headway to pull through with inertia. My hands were red when I finnished from pulling the belt.

The rest was fairly strait forward; here I am turning the back of the wheels :
Image


Things got a bit more complicated when I tried my fine scale form tool (puchassed on E bay deutshland) which I had modified to have deeper G1MRA standard flanges (2mm depth flanges), as it broke on the first try. I also had a great deal of difficulty with the wheels slipping in the disk, so had to do a different mounting than that advised by Mark, which before had worked well for me. This was probably because the small diameter of the part of the axle which is inserted in the wheel (4,6mm diameter) is probably too small for a strong screw, also because I didn't turn an axle especially for it at first. Which I later did, and this saved the day. I also had to recess the mandrel a bit as the wheels were pivoting around the inside central boss too much.

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I did nearly everything with my carbide tip tool which is really for boring and isn't made for that, I guess. This is where my lack of machinist training (and hardware) shows up. In this case I set the long side of the tip at the 3° angle to make the tread angle, the nice thing about the carbide tip is that it had a round end about 1 mm diameter making the 0,5mm fillet on the wheels. I turned at a very slow speed with the back gear of 55 Rpms, for this last operation. I turned down the diameter of the tread and then durned down the flange to two mm height. and finnished with a file.

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The wheels at last. The nicks in certain counterweight, happened when I pulled the belt a bit too enthusiastically. But will be invisible as I have to modify the shape of the counterweight a bit. Mine are curved the hippo has straight ones.
 
Discussion starter · #29 ·
Drilling the crankpin holes:
I made a simple jig with a spigot to hold the spigot in the axle hole. And with this drilled the holes for the crankpins on my drillpress and reamed that same hole in After which I inserted one crankpin and was abolutely horrified to see my crankpin go in crooked! This really depressed me enormously and I began questioning my being able to do any model engineering work, not having the training, experience nor probably the proper tools for it.
A few days later having calmed down a bit, I took a good look at what was hapenning and discovered the culprit : The rear wheel boss was right in the way of the drilling and had deviated the crankpin hole near the end; if I inserted a drill bit only partially it would come out perpandicular to the wheel! Eureka!

Image

What I did then was to file out the part going through the boss with a round jewelers file, which was beyond the depth reached by the crankpins anyways. I reamed the holes after that operation and inserted the crankpins on my press.
Mounting the axles with the wheels and quartering them:
I had to ream the wheels a bit with a hand reamer to make a good press fit As the reamer I had was for the Journal boxes and I would have had to buy another. The result was quite good and the wheels turn straight. I then placed the axle inside my quartering tool (made by Metalsmith a long time ago... usual disclaimer) it was too short on account of the oversize counterweights. So first I made a small extension from some 6mm stock I had. Quartering is a sinch with such a tool :

Image


In the photo I show the blind center driver.
And at last I could see all the axles inserted in the appropriate chassis axle slots and test it on my sharpest curves again, it passed nicely.
Image

Next will be the axle keeps and the springing. Watch this space!
 
#31 ·
Yes I agree with David great work here Simon and thanks for the details of what goes wrong and the fix as we all learn more from seeing problems than just a pic with "..here it is and it all went together as expected.." type of post.
I like seeing build posts of loco's and rollingstock.
Russell
 
Discussion starter · #32 ·
Thanks David and Russell :
Actually I haveen't any model engineering training at all, but whish to aquire it as I go in the good old American empirical way. With the help of G1MRA (I have all the Newsletters since 1976, when I became member) model engineer books and articles, and good friends. But it is a steep learning curve. I have post poned learning how to draw with computers, in order to concentrate on aquiring the machining skills. It is partially rendered difficult because I do not have a proper milling machine. I mill on the lathe, with a vertical slide. Although I mastered soft soldering years ago in HO scale, I have just learned recently silver soldering for instance, too. Things like Billes Loco building features on mLs helped me a great deal and encourage me even more. I hope that it will result in a succesful working model of this interesting prototype.
 
Discussion starter · #33 ·
Today, I made the prototype for the suspension and equalisation of the loco. I had wanted to do it with working leaf springs, which isn't the easiest way to go, but I think on this loco the frame is very apparent, and we frenchies find Bar frames quite fascinating and exotic as most of our locos had plate frames. So here is that prototype:

Image


I shall likely replace the screws with hex head ones. Now I have to produce another seven of these and order some more phosphor bronze to make the leaf springs. I will likely have to add some more leafs when I know the full weight of the engine which I am still far away from knowing at this point.
 
Discussion starter · #35 ·
Here is the complete chassis sprung with leaf springs and equalised. As closely to prototype practice as possible.

Image


Here is a close up shot of the arrangements for the rear drivers which are under the firebox and use a special supenssion set up to clear it:

Image


This was my first rtry at working leaf springs made from Phosphor bronze.
I appologise for the slowness of this build, but I am totally new to model engineering and need to think about projects a lot before taking a saw to the metal.
 
Discussion starter · #39 ·
I worked on making the connecting rod knuckles. First I checked very carefully which rod blanks were slotted and which were thinned down to fit inside the other rod's slot. A mistake here could proof fatal. I also drilled and threaded the rods that would hold the small screws making the connection in the knukles.
I then mounted the appropriate rod blanks on my lathes verticalslide to present them to the sliting saw. This slitting saw was mounted in a quick change mandrel (Although I guess it could have been mounted in a 3 jaw, just because it was set up already). My slitting saw is a 2mm thick slitting saw.
I then proceeded to slit the 6 forked ends of the rods.

Image


This proved so easy that I decides to use the same process to do the rods whose ends were thinned down to fit inside the slot.

Image


Great care was taken to thin down the ends with a fairly tight fit (That is one with no slop but free to move easely). Also I adjusted the ends of each slot very carefully so that a good deal of the mechanical effort would be done by this instead of the pin at least in compression.
I also turned two new pins that are a tight fit inside the rod blanks and which screw into the inside end of the forked rods; These are then tapped and slotted for screwing inside the rods.
I peirced the thinned rod blanks and also the outside fork of the forked rods interposing a piece of sheet steel inside the fork to protect the scew threads of the other inside fork 3mm diameter. The thread was M2,5. This by the way copies how Aster does it.
So after a fairly relaxing session I had two rod blanks connected through their Knukles:

Image


I could now proceed to see if my "theory" of having the frame and the rod blanks machined by "water jet" would give a motion on a ten coupled frame with no hard points. As these rods would have bronze bushes, I could drill out the rods progressively (in 0,5mm increments) to final 4mm crank pin diameter as these would later have bronze bushes inserted in them.

The result was quite disapointing! More on how this was remedied later.
Cheers!
 
Discussion starter · #40 ·
Well, I am glad to announce that there is a happy end to this tale: As I tried to adjust the rods to the drivers in the chassis, I discovered to my dismay, some very big differences in distances, which litterally flabergasted me having taken as many precautions to prevent that from happening, as I could. Indeed having built quite a few kits in HO scale and a certain number of Aster locomotives, I was familiar with "tough spots" when puting the connecting rods to an engine. And the more drivers there are the more the problem seems to grow. So I had made a drawing, had it digitalised by a friend, who knows how to do that (I am a dinausor) and had the chassis and the rod blanks water jet cut to ensure as much precision in those distances as possible. I even went to the trouble of enlarging those holes step by step 0,5mm at the change of every drill, to open up those holes to finnished size!
What could go wrong?
In theory not much, so I thought. I had given the whole thing quite a lot of thought, not being a proficient model engineer.
Then disaster struck!
So I started to painfully adjust every crankpin hole in order to eliminate this error. This ment ovalizing at least one crankpin hole and as would happen it was of a considerable amount: Almost 1mm.
Then all of a sudden as the rest seemed to go together as planned, except for that one crankpin bush, it suddenly dawned on me to check the quartering on that driver.

I took it out of the frame and checked and lo and behold, it was out of quartering! Probably a negligence on my part while doing the serie I omitted (or rushed) a quality check... So I quartered it correctly this time. And took out the ovalized bush, made a new one pressed it in and after some minor adjustment the motion turned fairly correctly around!

I alm happy that this turned out OK, as I had given a lot of thought to the process to ensure as much precision here as possible. Especially since the whole process took about over a year getting my friend (who is avery busy engineer) to find time to convert the drawing, then to find a suitable company to get the water cutting done. Then getting on with, it which took me time so aghast was I by the huge undertaking I was about to get myself involved in. So you see : i'm happy!
 
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