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PRR T1 kitbash from 2 Hudsons


rbrown7713
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That's a shame that the rods were the wrong length. They look really good to me. With the roller bearing, that's over the top! Nice attempt anyways.

I overlooked that you had bought an O scale engine. I thought it was G.

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I cooked my own goose by installing bearings in the rods, as it made them very tight requiring the exact length of the rods as the distance between the axles.  Most models use bushings and are very loose for that reason.  I corrected the lengths now and the rods are finished and the correct length.  My next venture, if I can is to replace the axle bronze bushings with bearings, but I don't know if that will be possible. That's nice to hear that the O gauge dash 8 smokes well Jerry.  Bob.

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Finally an item that eased my installation.  I have machined the driving wheel axles and now the driven wheel hubs had to fit the id of the bearing.  I went to the local hobby shop and bought some 1/4" brass tubing and the id. was perfect, but took a little sanding on the OD of the tubing to fit it to the id. of the bearing, much easier than having to machine the entire bushing out of raw stock, works well. Here is a picture.  The initial testing of the fit of the rod while rotating seems to be perfect without any binding, hope the other three rod setups work as well.  I have located some flanged axle bearings that I will attempt to incorporate into the mix, hoping to eliminate having to worry about oiling the axles and also maybe a little less roll friction, we shall see.  The bearing size is:  7mm x 11mm x 3mm, requiring to ream the axle hole to 11mm from 10mm.  I think it will work. Bob.

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Need help, does anyone know what thread size the rod to wheel machine screw size is for the one gauge Hudson.  I got one 4-40 to go in with some oil, but I am having a hard time with the others.  Is it a special thread?, it seems awful tight.  Is it metric? If it is metric, it is very close to a 4-40, any help would be helpful, thanks, Bob.

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Some of the screws on my O scale MTH engines are metric. I really don't know about these for sure? I would guess they are. Chuck or Ray might know? Can you match up with the originals?

once you find out, you should probably chase them if you have a matching tap if they're buggered up.

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I think I have seen where the right side wheels are threaded different than the left (reverse threads) on an O scale model? I have no memory left!

If you do get any binding feel while spinning the flywheels when you're done, make your tolerances slightly larger. I believe most have slop because the geometry isn't perfect.

I'm trying to help!

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I am going to attempt to run a 4-40 tap through them and then in final assy. I will use lok tite, that's the only thing that I know to do so far.  I know that there are different  thread ratings  as far as tolerance and tightness,  and I am beginning to think that this is one of those  cases.  The original screw diameter is .109 and the new diameter is around .112, so that is part of my problem.  Maybe the best thing and easiest is to run a die on the new screws that I have, I will see if that will work. Bob. 






 

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Well, I found a chart that compares metric screws to NC threads and they state that a 3mm .5 pitch screw is the same as a 4-40 screw, so what I am running into is the tolerances of the screw itself.  The screw diam. out of the Hudson is actually 2.77 mm and the 4-40 screw is 2.86mm, so I will go down to Ace hardware and see what diam. their 3mm screws are, maybe I will get lucky. Bob.

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Here is what I have been doing the last 3 hours.  I traveled to 3 different Ace hardware stores and compared the size of 4-40 bolts and 3mm .5 metric bolts and here is what I have found.  The 4-40 bolts varied from .109 inches to .113 inches.  The metric bolts varied from .1125 inches to .116 inches, so sorting through these bolts, I think I have some bolts to work with.  Even with the smallest of these sizes, the threads in the Hudson wheel to rod attachments are still tight, so I will be working on the bolts to bring them down even smaller in size so that they will go in easily.  I screwed one in with too much pressure and the fitting in the wheel spun and I don't want that to happen again, that's not fun, so here I go. Bob.

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I solved the mystery of the tight threads, I think. Part of it was the loktite that they used at the factory and also tight threads.  I used trans. fluid and tried to run a screw down and it loosened a bit and on some I had to take the wheel off and run a tap through some of them and that did the job, all have new screws. Here is where I am at with the model right now, waiting for some rod slides from MTH. Bob.

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These builds get to a stage where I get impatient. I always rush forward to get the thing running. Even now that this isn't even mine, I'm excited to see it run. Looks like she will be rewarding on the quality of the build!

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What I've ran into over the years is the Challenger plastic drivers are 4-40 and say like the Big Boy metal drivers are metric when it comes to the crankpin screws. So maybe since the Hudson uses plastic drivers as does the Challengers then maybe both are 4-40?? Don't know just wondering. Don't get on them to hard as the inserts will spin if tightened too hard or if permanent loctite is used. I use the blue threadlocker myself.  

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I talked to Ray and you are confirming what he said minus naming a 4-40 screw and yes, some of the inserts did turn, well I ended up removing the two that had turned and used ATF fluid and first ran a screw through them and removed the loctite substance and that helped.  On some of them, I had to use a 4-40 tap and now all is well. Bob.

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I, up until yesterday, was faced with a problem with a urethane mold for the boiler or body of the loco.  The problem was that when using a urethane mold, what you pour is what you get.  You can't come back later and add details, such as rivets or any other detail, but with an epoxy and glass mold, you can.  I have never mixed mold mediums, I don't know why, so with this mold, the outside will be epoxy and glass cloth, allowing me to add details, and the inside of the mold will be urethane.  That way, the details, such as attach points on the inside of the Hudsons will be maintained and solve my problem..On the inside, there are mounts for the electronics, screw anchors to attach the body to the frame, and they will be maintained.  I just thought that I would share this thought and I don't know why I didn't think of this before. Bob.

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