# Roundhouse parts question



## scoobster28 (Sep 15, 2008)

The progress on my DACRE is slow and certainly not steady, but I am to the point where I need to order some Roundhouse parts or make them myself. For anyone who has built or taken apart a Roundhouse engine, can you tell me:

FIRST: For their frame spacers (FS - Frame spacer 1/4" square brass), is it drilled and threaded on the ends, or just square stock that the buyer must drill and tap? I plan on using 3-48 screws instead of B/A or Metric screws, and I wonder if I order the frame spreaders from Roundhouse will they be essentially useless with my screws?

If I were to make them myself... well actually, have a friend help me make them.... I would probably drill and tap for 3-48. But, it would certainly be much easier to buy them ready-to-use.

SECOND: Can someone measure their axles? I need to know the entire length of the axle, as well as how much at each end is squared off for the counter-weight. I plan to use Roundhouse wheels and counter-weights, but they are designed for 1/16" thick frames. My frames are 14g steel, which is slightly thicker. With my wheels gauged for 45mm, I need to calculate if there will be enough clearance room for the wheels. So, Once I know the length of the axle, I can subtract the wheel gauge and then divide in half, and then subtract the counter-weight and frame thicknesses and see how much play room I have.

[(Axle Length) -(Wheel Gauge = 45mm)] / 2; then subtract (Frame Thickness) - (Bushing Lip Thickness) - (Counterweight Thickness) 

IF not enough, then I will need to remake my frames from thinner stock. Not the end of the world, but not desirable either.

Or, a clear picture of the underside with a ruler would serve in a pinch.

Thanks.


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## Cougar Rock Rail (Jan 2, 2008)

This is really testing my memory but I'm 99.9% certain that the frame spacers on my Billy kit were predrilled and tapped for BA screws. 

Keith


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## Cougar Rock Rail (Jan 2, 2008)

I just checked the RH website and you may want to have a look at the online Billy kit instructions: 

http://www.roundhouse-eng.com/pdf/hbk1.pdf 

It looks like they might use M3 screws for those frame spacers now... 
I suggest you email them directly--they are great people... 

Keith


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## scoobster28 (Sep 15, 2008)

Cougar, 
Thanks for the link. It is really helpful. I have emailed Roundhouse, and await their response.


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## Larry Green (Jan 2, 2008)

Ask Keith said, the folks at RH are great with questions like these. About the frame spacers, they come tapped for 3mm(?). I retapped them deeper for 4-4-0 when modifying my SR 24. If your frame stock is going to be thicker, how about taking twice the extra off the length of the spacers, leaving the outside dimension the same as from the factory. This should handle the clearance issue, won't it? If you prefer to retap the factory spreaders, use a smaller #3 clearance hole when drilling the frames to maintain alignment. 

My RH engine was easy to rework and all parts have good, basic design. I have the feeling that you, as I did, want to eliminate their use of slotted head screws and use closer to scale hex bolts instead. 


Larry


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## scoobster28 (Sep 15, 2008)

Larry,
I like your thinking, but I am not sure if reducing the frame spacer too account for the increased frame width will fix the problem. The real issue is that from the outside edge of the wheel to the outside edge of the counterweight there is only so much room to be had. If I could move the wheels in closer (like 32mm, as the original plans suggested) it would work fine. Picture the axle stubs coming out of the Roundhouse wheel/axle assemblies. On that stub I need to fit a counterweight, the frame thickness, the thickness of the axle bushing protruding from the frame, and have a little clearance room between all of these pieces.

I should reach out to Llyn Rice, because he might have a stock Roundhouse axle lying around that he could measure. I am not sure if the SR&RL #24 axles are different from the regular Roundhouse line.

Regarding your other comments, I want to use 3-48 hexhead bolts if possible. I wonder if it is possible to retap the frame spacers to 3-48 OVER their existing 3mm holes. Of course, if that doesn't work I might need to ask Mark Landgraf to help me make new ones! He has helped me build my 1.5" scale Allen mogul tender.


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## Larry Green (Jan 2, 2008)

I guess my idea doesn't change the clearance relationship with an outside framed engine. However, have you considered shaving a bit off the RH axleboxes equal to the increased frame thickness? Next, the OD of a 3-48 bolt is loose in the 3mm tapped hole, but if you drill the spacer deeper and use longer new bolts, it will work fine. That's why I mentioned putting #3 clearance holes in your new frame. Also, the 3mm threads could be drilled out to 0.125" to their existing depth and a brass tube bushing inserted to maintain a more snug fit at that point. I suggest you go ahead a buy the factory spacers and give them a go. When I had the chance to visit the factory last fall, I seem to remember them on the parts pegboard and everything was reasonably priced. Also, Llyn's Lady Anne chassis was assembled the last time I saw it. 

Say hello to Mark for me--we know each other from ALS.


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## scoobster28 (Sep 15, 2008)

Larry, 
I think I will order the parts and the drill them longer and thread the "newly drilled" portions for 3-48. That is a great idea. If that doesn't work I will think about plan B. Since my screws are 1/2" long, and it is unlikely that Roundhouse drilled/tapped the frames for 1/2" long metric screws, it should still allow for some room at the end to bite into the new areas.


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## mocrownsteam (Jan 7, 2008)

If you use 4-40 hex head bolts all you need to do is run the 4-40 tap into the frame spacer holes. The BA size that RH uses is just about equivalent to 4-40. I've been using their spacers for a long time and I picked up on this dodge quite a while ago. 3-48 is kind of, in my opinion, an odd thread size. Most common are 2-56 and 4-40. Just my opinion for what it's worth. 

BTW, you couldn't find a nicer group of folks to deal with than RH. They have always been a great resource for me. If they don't list a particular part that you need more often than not they will be happy to supply it to you. 

Mike McCormack 
Hudson, Massachusetts


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## scoobster28 (Sep 15, 2008)

Mike, 
I am trusting you! I just ordered some new 4-40 hardware to replace the 3-48 stuff and hope that it works. I just need to make sure that I don't bottom out the tap in the hole and strip all of the threads I just cut!


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## Larry Green (Jan 2, 2008)

Mike & Ben, I did the 3mm to 4-40 thing (easiest), but the heads are large. Ben's use of 3-38 would help that. Re: common usage, we modelers can do what we like, and I seem to remember that the relative strength of a 3-48 tap to a 4-40 one favors the former (root dia./ od). Even in my 1 1/2" building days, I avoided 4-40, favoring 3-48 and 5-40 as appropriate. Again, do what works for you. Nobody has commented yet on the large hex heads on the frame of my Belden Falls #12 2-6-2. 

Larry


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## macbookman13 (Jan 22, 2008)

The 4-40 tap does work very well. I just did a RH conversion and replaced many original fasteners with 4-40 bolts and the joints are quite secure.


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## scoobster28 (Sep 15, 2008)

Can someone take a nice clear shot of the underside of their Roundhouse engine so that I can see how big the axle bushings are? In all of the pictures I have seen I have not actually noticed them, and that might be because they are small. I am having a problem because my frame members are 0.0785" thick, not the 0.0625" called for. This means that they are 0.014 too thick. Roundhouse has advised me that this additional thickness will cause binding of the parts. I am trying to figure out if I can make them work, or modify them (turn the flange portion thinner). Otherwise, I might need to redesign them. 

ANYONE with any pictures? Thanks.


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## HeliconSteamer (Jan 2, 2008)

IIRC, the bushing flanges on RH locos are actually flush with the inside of the frame and then project out behind the cranks. In fact, there is a large amount of side play in the axles of all of my locos with Roundhouse outside frame chassis. I'm not exactly sure where the binding would be since the internal frame spread would be as built and the bushes already project out behind the cranks. The only change would be less projection beyond the frame, right?


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## scoobster28 (Sep 15, 2008)

Harri emailed me and said:

"If you intend using our frame spacers and axles, you will have to make your own axle bushes as ours require the frames to be 1/16" thick. If you use our axle bushes on thicker material (14g) they will be too wide to fit between the outside cranks."

I asked for clarrifiation on this statement but haven't received it. I can understand what he is saying if they were to fit in from the OUTSIDE and thus protrude OUTSIDE, but I read somewhere (I cannot find it now, maybe I imagined it) they they went in from the INSIDE. 

If they do go in from the outside, I can fix the problem by filing/turning the different of the frame thickness (0.875-0.625) from the outside edges of each part of the bushing that protrudes from the frame, or by making slightly longer axles which will allow me to space the cranks farther out from the frame.

Other ideas, which I probably won't do, include:
1. Using muriatic acid to strip the galvanized coating, which should take off about 0.004 from the total thickness of the metal.
2. carefully file away the portions of the frames where the cranks spin around, to give them some more clearance room.
3. File the cranks thinner to clear.
4. Remake the frames with 1/16" metal (I want to avoid this as I like the extra heft that 14g gives the engine.)
5. Make new bushes somehow.


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## Larry Green (Jan 2, 2008)

Sounds like time to collect your parts and start. I'm sure the slight extra in frame thickness can be accomodated one way or another when you actually see the parts going together. 

Larry


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## mocrownsteam (Jan 7, 2008)

Larry is right. Test fit everything together and see what you have for clearances. In the chassis kits RH supplies washers because you can end up with too much slop between the bearing and the back of the crank. What Harri is saying isn't registering with me. True, if the space between the two "outsides" of the frame (got that?) is wider because of thicker frames you will have less space (slop) between the outside of the frame and the back of the crank. You don't want the cranks rubbing against the frame. Use some thin washers to keep the cranks from rubbing against the frame. There should still be plenty of slop so that you will have a none issue. 
Whew! The bottom line is test fit up everything and see what kind of a problem, or not, you have. I suspect you will be fine if you have thin washers between the cranks and frame so the cranks are not rubbing. I have used 1/8" frames with RH parts and they work fine. Let us know how it works out. 

Mike McCormack 
Hudson, Massachusetts


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## scoobster28 (Sep 15, 2008)

_"True, if the space between the two "outsides" of the frame (got that?) is wider because of thicker frames you will have less space (slop) between the outside of the frame and the back of the crank. You don't want the cranks rubbing against the frame. Use some thin washers to keep the cranks from rubbing against the frame. There should still be plenty of slop so that you will have a none issue."_ 

I believe that you are correct, but until I have the parts in hand it is tough to say. I have ordered some of the parts from Quissenberry Station, but with the hectic schedule Royce has I am not sure when I will get them. Until I do, there are other portions of the project I can work on. 

Anyone know a good source for 3/8" brass angle? I cannot find it online or in any store, hardware or hobby, and was thinking I might just need to cut a brass sheet into tiny pieces and bend them in a brake or over an anvil.


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## Taperpin (Jan 6, 2008)

Ok Ive measured the Frames /Bushes /axles etc.. on aLady Anne kit.

The side play on this example assembled is 0.012" very small variance from axle to axle..

your 14G frame material has added 0.032" to the width over the bush faces.. 


2 ways of correcting this problem.

[1] mount the bushes in lathe and remove 0.062" from each thrust face..although this will reduce the bearing area and perhaps the bearing life ,its not much and you may not notice any difference , we dont work our toys hard! 

[2] Reduce the frame stretchers length by 0.032" ..this may be the best way if no lathe is on hand..and will retain the bearing area.as designed.

The bushes are pressed in from inside the frames so the inside is flush with frame surface.


Gordon.


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## Larry Green (Jan 2, 2008)

Ben--re:3/8" brass angle. I checked Small Parts, and they do not list it (they stock milled brass angles from 3/16" and SMALLER). 

What thickness do you need? I have some bronze angle, 1/8" x 3/8" x 3/8". If you can use it, it's yours. 

Larry


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## scoobster28 (Sep 15, 2008)

Larry, I sent you a PM. Thanks! 

Taperpin: This is some very useful information. Thank you too!


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## Shay Gear Head (Jan 3, 2008)

Special Shapes shows 5/16, 3/8 and 1/2 Angle, all .0280 thick.


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## mocrownsteam (Jan 7, 2008)

Glad you had a kit to measure Gordon. That's a lot less "slop" than I've seen in Lady Anne kits. I wonder if they have changed the length of the stretchers at RH? In any case I agree with you that the easy way out is to reduce the length of the frame stretchers. No sense mucking about with the bearings if you don't have a lathe. 

Mike McCormack 
Hudson, Massachusetts


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## scoobster28 (Sep 15, 2008)

Thanks for the head's up about Special Shapes. I talked to them yesterday and they did indeed have what I was looking for, but only in 36" lengths, and with shipping it would have been over $20. Since I needed less than a foot, I was only going to go that route as a last resort. Plus, while they are carried/distributed by K&S Engineers, hobby stores I talked to (3) yesterday couldn't match the part number (A12) that Special Shapes told me matched their angle, thus I would have to order direct from them. 

However, a generous forum member has some of what I am looking for and so this immediate need has been met. Yey!


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## Shay Gear Head (Jan 3, 2008)

The K&S stuff at hobby stores is very limited in the sizes they can carry. They do NOT have the complete Special Shapes line!


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