Custom Steam Locomotive Rods

[zephyr1934]

Shortly after discovering Big Ben's Bricks, I found myself dissatisfied with any of the alternatives for driver rods (connecting and side rods) on brick built steam engines. Out of determination, I have produced driver rods that are compatible with BBB and Lego's steam engine wheels for my own use.

After some tinkering, I'm now offering these rods for sale to the AFOL community as well. These parts are designed to be driver rods, they are a little thicker than a plate and a little thinner than a 1/2 Technic beam. This odd thickness is deliberate, the rods are designed so that they should not rub against the rim of the wheels. The rods float on the pin cuff- compatible with 3/4 pins or full Technic pins. So now you can paint the rims of your driver wheels if you are so inclined.

Given the wide array of possible configurations and the limits of my pocketbook, I have opted to fabricate these custom driver rods using rapid prototyping technology. As a result, the possibilities are literally endless, e.g., half stud offsets for BBB small drivers should be feasible.

My store only contains those driver rods for which I have completed designs and fabricated at least one copy. Other configurations are feasible, contact me via Bricklink messages and we can discuss (I can't guarantee that I can make everything, and in any event, expect a longer lead time on new parts since I will have to design it).

The surface of the driver rods is a little rough because the fabrication technique, but it is hardly noticeable except when you are extremely close up. There are only a few fabrication colors to choose from- gray, black and red and I cannot adjust the colors. Fortunately, the gray is pretty close to light-blay. I have not yet tried the other colors for a match to lego colors, I suspect they will not be as close as the gray, but I will probably do a test run soon. As such, black and red are only available upon request (again, contact me via Bricklink messages).

Visit my Bricklink store to order the rods or find more information about production. These are a labor of love.

Many more examples and prototypes can be found in my brickshelf folder. There you will even find a tutorial for modifying an Emerald Night.

www.bricklink.com/store.asp?p=zephyr

[zephyr1934]

The custom rods offer much greater flexibility, e.g., you can span more than seven studs while keeping the rod under half a technic beam. So you can build narrower steam locomotive designs (when retrofitting, I was able to make one of my engines one stud narrower). Unfortunately, some existing MOCs were designed for full technic beams and cannot easily be modified for the narrow rods.

When I started fabricating the rods I thought I would have to skip over my most recent steam locomotive. On my little 0-6-0 switcher both the side rod and connecting rod were so long that I had to use full beam width constructions for the rods (as per the prototype, the connecting rod attached to the rear driver). I thought I came up with a pretty good all Lego solution. Unfortunately my design has the cross head/cylinders at 8 wide (the same width as the side rods) so the connecting rods were at 10 wide. My custom rods are half as thick, but the connecting rods still had to be beyond the cross head, i.e., wider than 8 wide. I did not want to redo the cylinders, so to use the new rods I would need a half stud gap between the side rod and connecting rod.

I came up with a solution for this retrofit problem. I've added an extension to the backside of the connecting rod on one end. At this point the rod is now almost a full stud wide. Inside of this extension I put a grove so that it could accept a pin either at the midpoint or all the way through. So now I could use a standard pin to pass through the side rod and into the extension on the connecting rod, clicking in at the halfway point. The new connecting rods would now be at 9 wide on this locomotive.

On the other end of the connecting rods, I still had a full pin connecter that I could not eliminate, creating another retrofit problem, but this one was easier to fix. I simply made a washer that was essentially a one long rod with a single hole. Pop it on the outside and it keeps the connecting rod in place.

Even with the half stud gap, I think the solution looks better than the full width, all Lego connectors I was using previously.

Although my store only lists the extensions on 12 long connecting rods (the only design I've fabricated so far), these extensions can be added to any of the rods.

[SavaTheAggie]

I eagerly await my bank account having the sufficient funds to have some fun with your new stuff. I can't wait to try it.

--Tony

[zephyr1934]

I've finished my latest fab and have packed up orders tonight. They should hit the mail Fri.

I've also just added five new rod configurations to my store. All of the additions are slightly unusual lengths or spacings, e.g., note how the middle hole in this example is 1/2 stud off-center.

[LEGO Train 12 Volts]

_{I love these stuff!}

[Cale]

Oooh! So many steam locomotives that could be built with these. It's good to see these gaining in popularity. So when are we going to solve that valve gear problem?

Cale

I've finished my latest fab and have packed up orders tonight. They should hit the mail Fri.

I've also just added five new rod configurations to my store. All of the additions are slightly unusual lengths or spacings, e.g., note how the middle hole in this example is 1/2 stud off-center.

[zephyr1934]

Oooh! So many steam locomotives that could be built with these. It's good to see these gaining in popularity. So when are we going to solve that valve gear problem?

Cale

Yeah Cale, I might have enough rods in that photo to equip your active fleet (grin).

Valve gear is still on the horizon. Certainly if there is interest from others, speak up. What would valve gear have to have to be of interest? My current thoughts are to modify a rod to have the eccentric come off, use features similar to a lego bar to get up to the valves. I already have around 20 different rod designs without the valve gear (everyone puts the wheels in a slightly different place). So with the complexity of the valve gear, I would want a one size fits most solution for the vertical and horizontal displacements.

What might be best is to figure out how to do a mostly lego valve gear design so that individuals can scale it up or down as they need too, and then just figure out what features the rods would need, e.g., adding a clip point for the eccentrics. Would simply incorporating a clip point on the rod be sufficient and the rest could be lego?

Benn

PS, and thank you to everyone who has encouraged my efforts with the rods either on or off line.

[monai]

Yeah Cale, I might have enough rods in that photo to equip your active fleet (grin).

Valve gear is still on the horizon. Certainly if there is interest from others, speak up. What would valve gear have to have to be of interest? My current thoughts are to modify a rod to have the eccentric come off, use features similar to a lego bar to get up to the valves. I already have around 20 different rod designs without the valve gear (everyone puts the wheels in a slightly different place). So with the complexity of the valve gear, I would want a one size fits most solution for the vertical and horizontal displacements.

What might be best is to figure out how to do a mostly lego valve gear design so that individuals can scale it up or down as they need too, and then just figure out what features the rods would need, e.g., adding a clip point for the eccentrics. Would simply incorporating a clip point on the rod be sufficient and the rest could be lego?

Benn

PS, and thank you to everyone who has encouraged my efforts with the rods either on or off line.

Perhaps they can help:

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=3432870

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=383419

Sergio

[Locomotive Annie]

Perhaps they can help:

http://www.brickshel...y.cgi?i=3432870

http://www.brickshel...ry.cgi?f=383419

Sergio

Wow! That BR01 locomotive is amazing. Make sure to read the PDF which tells how he did it.

[zephyr1934]

Fine, go throwing gauntlets at me (grin). When I talked about the idea of valve gear with Cale, I was thinking I could come up with some "standardized" set of valve gear that many people could use. I have seen just how varied different designers build their engines (e.g., the numerous new rods I recently added with unusual spacings). To keep the design "light" I was assuming I would need to develop my own hinge mechanism. With all of the degrees of freedom, there is no way I could come up with a standardized design. I have about 20 different rods in my store for this very reason. It is unlikely that there will ever be such a large selection of rods without using a similar fabrication technique.

The two examples from Sergio are fantastic, but if you look at them you will see that they are vastly different. They really underscore the fact that the valve gear design cannot be decoupled from the locomotive design.

So in response to the renewed interest in valve gear, I started tossing around different ideas to put an additional attachment point on the rods and let the individual builder take it from there. But nothing really struck me as being robust enough.

Then I realized that the narrow rods open up a whole new dimension. Where previously large engines would have all Lego rod assemblies that would be two studs wide per side, each side can now be just one stud wide. So using that second stud space previously needed for the rods, I could put the valve gear. Borrowing ideas from Carl's design (most notably, omitting the eccentric) I've come up with the following quick model. It uses a 3 long technic pin off of the main driver and rods that are already available in my store.

You should be able to see the whole gallery once moderated. I recommend loading up the first four pictures and step through them to see the mechanism at work (hint- be sure to step through them a second time since the first load time might be slow while buffering). There is also a blurry video.

This design is not the end all, but it shows what can be done. If there is interest, I can put it in to LDraw (sans custom rods and I'll explain whatever is not included).

If there is sufficient interest in valve gear I would probably make thinner rods for the valve gear (that would take a major redesign but is doable). At this time I'd keep the pin connectors, so the ends would be the same size.

If you are interested in playing with your own valve gear ideas, I'd suggest using full technic beams to build a prototype model like this one and work out the lengths needed (e.g., imagine this little model only with full width beams in place of the rods). My rods can fit a little tighter than technic beams since the mid-rod is narrower (I don't think this particular design would work using all lego, even if you did not care about the overall width of the model).

=========

PS, here's an animated gif...

Edited October 23, 2012 by zephyr1934

[Duq]

I've ordered a set of these rods to fit on my BR65 and I have to say I'm quite happy with the result:

BR65 Before and After by Duq, on Flickr

[zephyr1934]

I've ordered a set of these rods to fit on my BR65 and I have to say I'm quite happy with the result:

...

BR65 Before and After by Duq, on Flickr

Wow, very nice! The engine was great to begin with. I like the painted rods, that could be mistaken for a nice O or S gauge locomotive. I've been contemplating doing similar on one or more of my engines (only in black) as was done on the prototype.

Meanwhile, I've been busy in the back room. I did a small test fab in red. The color is close, but the holes did not come out to my satisfaction. So more tweaking. If I can work through the kinks I hope to soon have a call for beta testers interested in purchasing red rods. Nothing is definite yet and no time line, more info as it evolves.

Inspired by LT12V's unbelievable work, I've continued working on the valve gear mechanism posted earlier in this thread. I've made two new prototypes that I'm quite happy with and will be posting as soon as I have time to photograph them. Now that I have the dimensions, I will be fabricating the first round of prototype valve gear parts soon (looks to be 8 new parts in two different styles for a total of 16 different parts).

In my tinkering, I came up with an all Lego solution to get the eccentric in the design. I will soon be tossing down a reverse engineering challenge to you to figure out how the eccentric crank is done. Definitely for the sheer glory and hopefully with a store discount as a prize if it is it within the EB TOS (anybody know if offering a store discount to an impromptu reverse engineering challenge is within the EB TOS?)

[rebelego]

Great! I have had this idea for years, but never got the time to implement it.

Guess I will buy some of these rods. I currently use rods made from an ice cream box.

[roamingstop]

Seems when I get some time I will revist using these custom Rods for the EE 3/3 designs

The main difference being that the attachment points are built above the actual rod (look at the front wheel). Of course once this is solved; it opens up the whole world of accurate modeling of the Crocodile series.

Depending upon the build variation of the crocodiles, the two large drivers a coupled with a fixed rod; with the distant third driver coupled onto a linked mechanism (i think your existing rod's do most of this)...

A combination with BB's medium driver wheels would also be nice for the EE 3/3 where the spacing is not 2 studs - there is a thread somewhere about why the spacing is non standard; and it relates to using a 2x2 plate at 45 degrees (i.e. spacing is 1.415 studs).

[Locomotive Annie]

Discovering BBB wheels and Zephyr's side rods has been a wish come true. I'm presently waiting for an order of BBB's wheels and Zephyr's rods to arrive so I can complete my single Fairlie loco. The prototype had outside valve gear, but I won't be attempting to represent it unless I strike a really wet day where I'm so bored I can't find anything else to do. The problem is that the prototype wasn't a large loco and the valve gear is quite delicate looking so hanging Technics bits off the side of the wheels will just look plain daft.

[zephyr1934]

The main difference being that the attachment points are built above the actual rod (look at the front wheel). Of course once this is solved; it opens up the whole world of accurate modeling of the Crocodile series.

Depending upon the build variation of the crocodiles, the two large drivers a coupled with a fixed rod; with the distant third driver coupled onto a linked mechanism (i think your existing rod's do most of this)...

Neat stuff. Sure, I can make an "L" shaped rod with an extra hole above the rod for an attachment point. I had contemplated that as a possible solution for the valve gear. I could probably even do a half stud up if that is better for your design. When you're ready, I'd suggest that you figure out your rod dimensions using technic beams and then I can take it from there. The only hard part is making sure we are speaking the same language when talking about the spacing. One easy way to clearly communicate the spacing you want is to illustrate it on a baseplate. Pick a row and pretend it is the rod you want fabricated. Put 1x1 bricks where you want the holes (or use jumper plates if you want half stud offsets) and get me a photograph. Uneven spacing is not a problem either. The one thing is that new designs like this may take a little extra time.

Discovering BBB wheels and Zephyr's side rods has been a wish come true. I'm presently waiting for an order of BBB's wheels and Zephyr's rods to arrive so I can complete my single Fairlie loco. The prototype had outside valve gear, but I won't be attempting to represent it unless I strike a really wet day where I'm so bored I can't find anything else to do. The problem is that the prototype wasn't a large loco and the valve gear is quite delicate looking so hanging Technics bits off the side of the wheels will just look plain daft.

If everything works out with my valve gear designs, I shoud have a much lighter option (I'm aiming for a 2mm wide rod, where technic beams are 8mm wide). So keep watching these skies, I will also post images and photos of the work in progress as soon as I can.

Meanwhile, thanks again for your support.

Benn

[zephyr1934]

As promised, here is version 2 of the running gear

Click on the link to see the individual frames. At this point it is all Lego except for the drive rods. Note how I've used technic half beams to work out the geometries. Everything beyond the pivot points will ultimately go away. I will be replacing the technic beams with custom valve gear bars. For now I am keeping the pin connector, but will be attempting to make 2 mm thick bars. I'm trying two different versions of the bar: 2 mm tall on the left and 3 mm tall on the right, in comparison to a 9 stud long connecting rod in the center.

This first fab is to see if the bars are durable enough and If they are, there is still a little more work to do, e.g., dressing up the rocker bars.

Meanwhile, I pressed on to version 3 of the running gear (can you see the LT12V's influence?),

Again, roughed out in Lego to later be replaced with custom bars and click on the link to see the individual frames.

Look closely, you will notice I used an eccentric

This assembly is pure, unmodified lego (though like LT12V, I will ultimately trim the pin portion off of the axle pin in the photo).

So now the challenge goes out to anyone interested- reverse engineer this eccentric. The competition is for the glory. If you think you've got it working you can post here or contact me via Eurobricks messages. The first correct answer will get free shipping and handling on an order of custom rods in my bricklink store or up to $5 off s/h if you order other items too (assuming that is allowed within the Eurobricks TOS). The contest ends when we have a winner or I'm ready to make the bars publicly available.

[Locomotive Annie]

So now the challenge goes out to anyone interested- reverse engineer this eccentric. The competition is for the glory. If you think you've got it working you can post here or contact me via Eurobricks messages. The first correct answer will get free shipping and handling on an order of custom rods in my bricklink store or up to $5 off s/h if you order other items too (assuming that is allowed within the Eurobricks TOS). The contest ends when we have a winner or I'm ready to make the bars publicly available.

Ooooooo that looks to be a tricky one. I take it that glue isn't an option for an answer.......

[LEGO Train 12 Volts]

It seems we've started a new frontier!

I like the new piston rods on Duq's locomotive and I like the new valve ...thanks for your credits!

[zephyr1934]

Well that took about an hour to get a working solution (and one probably better than mine). LT12V gets the first place honors, Congratulations! But that shouldn't be surprising since I cribbed off of his brilliant work in the first place. Fortunately the reveal was over the messages, so I'll leave the challenge open for 2nd (and further?) and will offer the same prize for 2nd (possibly further).

Ooooooo that looks to be a tricky one. I take it that glue isn't an option for an answer.......

Correct, no glue (for heaven's sake, "glue" is a four letter word don't you know? Then again, so is "lego"), and to clarify the design, there is at least a full stud clearance between the wheel and the eccentric to accommodate both the side rod and connecting rod. So the friction pin solution in LT12V's picture above would not work for this design.

[JopieK]

It would also be nice to have a peg for PF Train motors to connect wheels in the middle and thus decently mimic the red motors from the past...

but then the long side as a cross axle. or but then 1 instead of 3 in length (red would be best, but black is also nice ;))

[roamingstop]

Eccentric being the technic engine cam shaft? Long enough to go through the wheel but then joining to an axle inside? Sorry brain not in right gear.

As to crocodiles; first i have to clear up overstocking of my own designs and older mods and have a decent clear out - i prefer design process compared to running trains. My signature has links of some things for sale

[zephyr1934]

Well that took about an hour to get a working solution (and one probably better than mine). LT12V gets the first place honors, Congratulations! But that shouldn't be surprising since I cribbed off of his brilliant work in the first place. Fortunately the reveal was over the messages, so I'll leave the challenge open for 2nd (and further?) and will offer the same prize for 2nd (possibly further).

I've had two more successful submissions, the first came from Duq, pointing to LT12V's solution that was posted on bricklink, below. Since having an encyclopedic knowledge of other people's tricks can be just as handy as inventing it yourself, I would call that a win. The next came from Daedalus304 and looks like he independently reinvented the same technique. Both Duq and Daedalus304 are have qualified for the free shipping on an order of rods or $5 off s/h of a bulkier order from my store.

Daedalus304 solution is not yet public, but because it only shows the critical components it might be easier to absorb. I'll try to remember to link to it when it does go public.

So far all of the solutions have used the same paired 8 tooth gear trick. I will call that approach closed for this competition. However, I did not use any gears in my solution. So I will leave the competition open to one more winner if they come up with a different working technique (previous winners are excluded from winning this competition a second time).

-----------Edit-------------

One potential hazard I see with the paired gears is that if there is a technic hole right next to the driver's axle hole, the gear could slide into it and get stuck. Here's Daedalus304 solution, same idea as above, but with most of the locomotive cut away.

-----------------------------

It would also be nice to have a peg for PF Train motors to connect wheels in the middle and thus decently mimic the red motors from the past...

but then the long side as a cross axle. or but then 1 instead of 3 in length (red would be best, but black is also nice ;))

Now that is an interesting idea. I don't think I could fabricate pins, but I'll scratch my head and see if I can come up with something else that would fit and would be sufficiently durable (but it will be a little while, since there are several other efforts already in the queue).

Eccentric being the technic engine cam shaft? Long enough to go through the wheel but then joining to an axle inside? Sorry brain not in right gear.

As to crocodiles; first i have to clear up overstocking of my own designs and older mods and have a decent clear out - i prefer design process compared to running trains. My signature has links of some things for sale

The technic engine cam shaft only reaches 1.5 studs, though as you can see in the detail photo, the outside consists of a 2 long half thickness technic lift arm on a technic axle (mimicking the form of the technic cam shaft). The hard part is figuring out how to rotate it 45 degrees while also securing it.

And sure, no problem, my comments about your crocodile rods would apply to anyone. I want to get the holes in the right spot if I can. The reason why no one has produced rods in the past is the vast number of different designs you'd need. So in that sense, the rapid prototyping is ideal. Unfortunately though, there are few economies of scale to be had, which is why the costs are as high as they are.

Edited November 12, 2012 by zephyr1934

[Locomotive Annie]

That method with the two 8 toothed planetary gears gave me a real 'Wow!' moment that hasn't quite left me yet. And it's still not the actual method you used Zephyr?!

[LEGO Train 12 Volts]

I'm happy to try the new rods!

Compliments to the other users that have solved the quest ...I think the best solution could be a new mould of BBB wheel with an axle hole oriented at 45°!