97 replies to this topic

[Cale]

How about two solutions for the price of one.

First solution. This isn't how Benn did it but it's a possible solution I came up with.





And now solution #2. I'm pretty sure this is how Benn did it using this part in black.

www.bricklink.com/catalogItem.asp?P=43093



Link to Flickr Gallery

Cale

Edited by Cale, 12 November 2012 - 01:26 AM.

[zephyr1934]

Very good designs Cale, but in my earlier post,

http://www.eurobrick...2

I had intended to clarify that the friction pins were out of bounds. My reasoning is three fold, 1) LT12V just did it, 2) I need at least 1.5 studs beyond the wheel to accommodate two rods and the eccentric, and 3) I don't trust the friction too keep it in place long term.

Your first design is the best non-gear submission thus far, it is good enough to win if no one comes closer, but there is room to come closer. My solution will keep the eccentric from rotating on its own axis and it does not use any glue.

So the competition remains open but we will have the 4th and final winner by the end of the contest.

[Cale]

zephyr1934, on 12 November 2012 - 05:52 AM, said:

Very good designs Cale, but in my earlier post,

http://www.eurobrick...2

I had intended to clarify that the friction pins were out of bounds. My reasoning is three fold, 1) LT12V just did it, 2) I need at least 1.5 studs beyond the wheel to accommodate two rods and the eccentric, and 3) I don't trust the friction too keep it in place long term.

Your first design is the best non-gear submission thus far, it is good enough to win if no one comes closer, but there is room to come closer. My solution will keep the eccentric from rotating on its own axis and it does not use any glue.

So the competition remains open but we will have the 4th and final winner by the end of the contest.

Yeah. I should have paid a bit more attention to that. Oh well. You've got me stumped now.

Cale

[BMW]

Hmmm... I get back from a train show this past weekend only to find another one of Ben's reverse engineering puzzles.  The below method achieves the 45 degree quartering in Ben's example.  It should be noted that this 45deg angle is not achievable using the 8-gear method posted, although the 8-gears do produce an angle closer to the prototypical 30 degrees.  Many scale model steam builders prefer a 45degree angle as it exaggerates the motion.

- BMW



http://www.flickr.co...ams/8179288362/

[Duq]

I'd come up with that this morning but as I was excluded from competition I hadn't posted here yet:

Eccentric solution by Duq, on Flickr

[zephyr1934]

I would have gotten away with it if it weren't for you meddling kids! Kudos to BMW, who has sealed the 4th and final spot, he has illustrated the technique I used on v3. Cale, however, has secured the secret 5th place spot (would have been 4th, but he was slow to post) by coming up with my other solution, shown below. So free s/h on an order of rods to both of them as I call this competition to a close. And a special nod to Duq for doubling down.



Before getting to BMW's solution, I tried Cale's solution first on a blind driver but the 3x3 lift arm kept knocking against the adjacent flanged drivers. It should work on the back side of a flanged driver though. Cale's design has one distinct advantage over the other two solutions, you can put a 1/2 bushing on the drive wheel's axle to hold the eccentric assembly in place. My current thoughts are to do just this for my own use and trim the ends of the 3x3 down to 2x2 for use behind a blind driver.

[Locomotive Annie]

Oooooo clever.  Having not really done much with Technic pieces before I couldn't even begin to think how that was done.

[Duq]

My first thought was to use a half bush with teeth but I couldn't find a piece to use behind the wheel. A 3 long version of this would have done the trick but it doesn't exist:

My next idea was to use one of these to go behind the wheel and use an elastic band to keep it attached to the wheel axle:

As I was putting that into MLCad I realised that the L shape of 2 1x2 liftarms would fit.

[Daedalus304]

This was the solution picture I messaged to Zephyr - with some creative guidance from LT12V's amazing model helping with the stand-in gear.



It's kind of funny seeing the answer, because that 3x3 liftarm was actually my first approach that I scrapped because I was unsure if it would clear the rails; I supposed I should have tested it. This gear idea came next, with the gear on the wheel axle slide into the frame a little and the eccentric gear slide into the recess on the driver a little. That helps keep them connected more sturdily and also keeps the axles from sliding.

The design BMW and Duq crossed my mind after during a disappointed tangent about my liftarm idea not working out (should. have. checked. :P ), and then I hopped on here and saw it posted. It's really kind of amazing to see how many different viable methods there are for building a valve gear eccentric - I think this competition is likely going to be the push we finally needed to standardize it (Although I think the real catching point is when we find a way to do it without any modified parts - us purists can be stubborn!). In the meantime I'm going to be hunting down my old technic pin/clips that have broken or worn out clip ends, I don't care for modifying parts but if it's broken anyways I may as well find a better use for them...

[zephyr1934]

Look what I got... just finished today. I hope to try these on for size tonight. The picture shows four different types of rods or bars. The two biggest rods are my normal side rods and are included for reference. The far right show the batch of 3 mm thick valve gear bars, these have cuffs to clear the clips on technic pins. The top left show the 2 mm thick valve gear bars, they have a smaller ring around the pinholes and no cuff (hence they are 1 mm thinner). These two groups of bars are both 2 mm tall (measured in parallel to the plane of the photo). Then the bottom left shows 3 mm thick and 3 mm tall prototypes that probably will not be used for bars, but might evolve into a lighter variant of the driver rods.

Note that the three-hole rocker bars were just to get the holes in the right place. The final versions will probably have a little more elegance to them.

[Locomotive Annie]

Ooooooo cool bananas! Those valve gear parts look like they're going to be very useful indeed.  Having access to a range of such great steam loco specific parts is going to be sooooooo good

[roamingstudio]

Id be interested to know whether you are using a makerbot type device; have your own other 3D printing or reusing something expensive or from a company? When I get a little better organised I too will start getting some.

[zephyr1934]

It took a little longer than anticipated, but I've tried the 3mm thick valve gear out and I am quite happy with the results. I've uploaded detail shots of all the new bars here, and they will be visible once moderated.




First, I simply updated the v2 concept to use the new bars (click on the image to see the individual frames once the folder is moderated)



If you look closely, you'll see that I've also updated the cylinder in preparation for v4.




Ultimately I plan on putting these under a new 4-8-4, but for now I borrowed by Milwaukee Road S3 to try the rods out,



here is a shot of the previous drivers next to the new drivers



This locomotive design uses 9v motors for the pilot and trailing trucks and the drivers are simply dragged along behind the front motor. As such, the cylinders have to be fairly wide to clear the motor on curves and you do not have much space to actually build the cylinders (I did not think to get a detail shot of the cylinders, but I will try to do so soon). In the end it came out to be just under 11 wide. I tried to take an unflattering photo of the build, but aside from blurry shots, I couldn't find an angle where I thought the valve gear protruded too much (see examples in the folder once moderated)

I would caution that it is hard enough to make a steam locomotive run well with just side rods and connecting rods. So I would recommend that you do not wander too deeply into the valve gear until you are comfortable building and adjusting technic constructions.

The running gear in v4 might look simple enough, but it was actually a fairly complex build. As noted in an earlier post, I cut down a pair of 3x3 technic half beams to 2x2 to anchor the eccentric behind a blind driver (you could probably keep it unmodified behind a flanged driver). I also cut down a technic axle pin with towball to connect to the eccentric (inspired by LT12V). Using the 3mm thick valve gear bars, the bar connecting to the eccentric and the rocker bar have the cuff turned to the inside of the locomotive- to keep the pin heads from knocking against the side rod. Then the final bar had the cuff turned away from the locomotive to facilitate connecting to a black 2 long technic beam behind it. The end point of the valve gear and the side rod differed too much to use the 2 long valve gear bar to connect the valve gear to the piston as I did in v2.

The valve gear look great at slow speeds (click here for a short movie) and I've run the locomotive for a few hours without any trouble. Since PF does much better than 9v at slow speeds, I suspect PF is where the valve gear will really shine.

roamingstudio, on 17 November 2012 - 09:41 PM, said:

Id be interested to know whether you are using a makerbot type device; have your own other 3D printing or reusing something expensive or from a company? When I get a little better organised I too will start getting some.

I use a third party for the fabrication, but then I inspect all of the rods and do finishing work to ensure they will run well. My biggest problem is variability in the hole diameters. I've often contemplated attempting other connectors (e.g., a technic axle or axle hole) but given the variability in the holes, I don't think that would be feasible at this time. It is amazing what the difference of 0.1 mm will do.

[LEGO Train 12 Volts]

WOW! Wonderful upgrade ...and useful new molds of piston rods!
Your stuff get better and better ....I'm a little bit jealous of your huge stock!

[Locomotive Annie]

I should hang my head in shame Benn because everytime I see your lovely Milwaukee Road S3 I can't help thinking of it as being the 'piano locomotive'.

Marvellous to see the video of the new valve gear in action.  Now I find myself trying to choose an NZR tank locomotive with outside valve gear that I would like to build.  One of the larger classes, but not so large it wouldn't be seen on a sleepy little twiglet of a branchline..

[LEtsGO]

It's amazing to see the animated bars moving. I like the way you did this project very much.
Some years ago I was asked by my son to try to build a german type steamm engine, tried to do my best but unfortunately did not have proper wheels so tat's what came out

[zephyr1934]

Thank you all for the kind words.

LEGO Train 12 Volts, on 24 November 2012 - 07:06 AM, said:

WOW! Wonderful upgrade ...and useful new molds of piston rods!
Your stuff get better and better ....I'm a little bit jealous of your huge stock!

With these new valve gear bars I'm working on something like 20 new parts (I'm going to see if I can push both the 3mm and 2mm thick bars all the way out to 8 long). I can TOTALLY see why rods and bars just are not feasible in terms of small scale production without the rapid prototyping.

I just tried the 2mm rods on v3 and they look real sharp and it works fine, but the technic pin is a limiting factor (you don't want a pin sticking back from the valve gear knocking against the side rod). So the 3mm rods will be better in some applications (e.g., the rocker bar in v4). I want to rebuild the frame for v3, hopefully add a motor and then I'll post photos with the 2mm rods.

I hope to make the bars available in Dec so that folks can start playing with them. More on these developments soon.

Locomotive Annie, on 24 November 2012 - 09:30 AM, said:

I should hang my head in shame Benn because everytime I see your lovely Milwaukee Road S3 I can't help thinking of it as being the 'piano locomotive'.

Heh heh. At first I was wondering what the heck you were talking about, but yes, from the side view the running board really does look like a piano keyboard, doesn't it. As soon as you get some elevation you see through them and it looks more like the grillwork I had intended. I wanted to get the band of silver there and keep the running boards "light". Her sister, my A3 (the middle locomotive in this shot) is worse, but the checkered flags gave me the thin white stripe necessary for the profile shot. Ah compromises.

LEtsGO, on 24 November 2012 - 05:42 PM, said:

It's amazing to see the animated bars moving. I like the way you did this project very much.
Some years ago I was asked by my son to try to build a german type steamm engine, tried to do my best but unfortunately did not have proper wheels so tat's what came out

Wow, that is a very nice locomotive. Given the fact that you used mostly basic brick and plates it is fantastic (none of this cheese slope cheating the laws of physics stuff). I'm guessing you built it around 2000 or earlier. It looks comparable to the cutting edge designs prior to BBB wheels (excluding the occasional steamer that had machined driver wheels). I think Dan Siskind had similar driver wheels on one of his designs of that era. My first engine from about that time was an 8 wide diesel switcher with rubber tires and similar basic brick design- although it might be a little clunky, it has nice detailing given the resolution and I still proudly display it on a shelf in my office.

[roamingstudio]

Coming back to middle wheels for PF motors; the question is how would you attach Zephyr's custom rods? I too would love to reuse this design but I fear that BBB wheels (small size) dont have an attachment point for a connecting rod; which would mean that you would need to create a custom wheel; or use a CAM shaft brick. So Zephyr / BBB: Any chance of making a wheel set for PF motors which would allow a middle - and suitable connecting rods.
As skaako demo'ed in this old thread

Actually thinking about it - the middle wheel should not even be flanged... no wait.. actually we would need flanged and blanks with holes.

@Zephyr: Actually seriously thinking how much would such a custom mould cost - I could easily see myself helping to set up some production of these as im sure there would be plenty of trainheads taking benefit. Perhaps even a custom deal with Ben Fleckes?

Edited by roamingstudio, 28 November 2012 - 04:54 PM.

[monai]

roamingstudio, on 28 November 2012 - 04:49 PM, said:

Coming back to middle wheels for PF motors; the question is how would you attach Zephyr's custom rods? I too would love to reuse this design but I fear that BBB wheels (small size) dont have an attachment point for a connecting rod; which would mean that you would need to create a custom wheel; or use a CAM shaft brick. So Zephyr / BBB: Any chance of making a wheel set for PF motors which would allow a middle - and suitable connecting rods.
As skaako demo'ed in this old thread

Actually thinking about it - the middle wheel should not even be flanged... no wait.. actually we would need flanged and blanks with holes.

@Zephyr: Actually seriously thinking how much would such a custom mould cost - I could easily see myself helping to set up some production of these as im sure there would be plenty of trainheads taking benefit. Perhaps even a custom deal with Ben Fleckes?

you can use the medium size wheel  from BBB, b ut you must levigate or cut the blind wheel not to touch the flanged ones.
See
http://www.brickshel...y.cgi?i=4422173

Sergio Monai

Edited by monai, 28 November 2012 - 05:42 PM.

[roamingstudio]

Thanks Sergio; I thought it would look too overpowering using the medium wheel set from BBB but it seems i'm wrong. Adding the offset using a custom technic washer should not be a problem; although whether this places undue strain on to a custom rod would need to be checked.

[JopieK]

Very nice tutorial like posts!!!

[Commander Red Hat]

There are some very useful ideas in this thread and I love the way your custom rods look!

I do think the price is slightly steep, if you need a few rods to upgrade one big steamer then the total runs up quickly.
But I understand that making these costs time and effort, which of course makes a price. Maybe it would be possible to give a bit of discount when somebody orders 6 or more for a single model, kits for particular engines perhaps?

In some pictures the finishing of the rods looks a bit crude, will the final product have a smooth finish?

[Locomotive Annie]

Zephyr's rods have a very fine granular surface because they are made by 3D printing, but crude they certainly are not.  These rods are very precise in their sizing and look absolutely spot on in every way.  The price is what is is because they are a low volume production item and considering the wide range available; - which includes some fairly uncommon spacings and offsets as well as the more usual types, - I think they are very reasonably priced.

[zephyr1934]

roamingstudio, on 28 November 2012 - 04:49 PM, said:

Coming back to middle wheels for PF motors; the question is how would you attach Zephyr's custom rods? I too would love to reuse this design but I fear that BBB wheels (small size) dont have an attachment point for a connecting rod; which would mean that you would need to create a custom wheel; or use a CAM shaft brick. So Zephyr / BBB: Any chance of making a wheel set for PF motors which would allow a middle - and suitable connecting rods.
As skaako demo'ed in this old thread
...
@Zephyr: Actually seriously thinking how much would such a custom mould cost - I could easily see myself helping to set up some production of these as im sure there would be plenty of trainheads taking benefit. Perhaps even a custom deal with Ben Fleckes?

monai, on 28 November 2012 - 05:42 PM, said:

you can use the medium size wheel  from BBB, b ut you must levigate or cut the blind wheel not to touch the flanged ones.
See
http://www.brickshel...y.cgi?i=4422173

Sergio Monai

For the moment I do not have an eloquent way of attaching rods to the small train wheels that come with the PF motor. Short of drilling a hole for a technic pin in the wheels (I'd do it from the backside, using 60483 connected to the existing axle hole as a guide), the best I've got is using a 2 long thin technic beam, e.g., LEtsGO's drivers above or a technic crank e.g., my little Porter (I borrowed this idea from someone else).

I MIGHT be able to figure out some way to clip on to BBB small wheels, but that would be a lot of work to get a satisfactory connection so it is way down the road. I doubt there would be much demand though, since you lose the traction of the bands on the lego small wheels.

Modified BBB medium wheels solves the connection point problem, but still does not address the traction problem (some folks have machined a grove into the BBB wheels but it is non trivial).

As for the rods, I already have the solution for BBB medium drivers. I made a 4 hole 10 long connecting rod (do not adjust your set, yes, this is in white, it is for a customer who wanted to paint it). This design is not yet in my store since I have no idea how to keep from confusing customers with the subtle differences between my normal rods and this thin design (and whenever it does hit my store it will be in gray).



and it can also be fabricated without the thin grove, yielding the middle rod in the picture below,



Note that this wheel spacing only works if you modify the BBB medium wheels as was done in bricklink user ulimy's example noted above (ulimy does some great work). These rods can be fabricated with larger spacing between the holes for non-modified wheels as well as the larger wheel designs (e.g., here).

Returning to the small wheels for a second, while talking about three axle trucks/motors, recall when the RC motor first came out the bands would slip. Then Cale/SaveTheAggie solved this problem using thicker o-rings purchased from a hardware store. Although it would appear that lego has solved the slipping band problem that the original wheels had, with three axle trucks the thicker o-rings still offer an advantage when placed on the outer axles. I used this technique for the powered 3-axle trucks on my SP Pacific tender (with wider wheelbase than you would have in a PF motor) and it lifts the center axle (without the thicker o-ring) sufficiently off the track that I have not had problems in curves or switches.

Commander Red Hat, on 28 November 2012 - 09:53 PM, said:

There are some very useful ideas in this thread and I love the way your custom rods look!

I do think the price is slightly steep, if you need a few rods to upgrade one big steamer then the total runs up quickly.
But I understand that making these costs time and effort, which of course makes a price. Maybe it would be possible to give a bit of discount when somebody orders 6 or more for a single model, kits for particular engines perhaps?

In some pictures the finishing of the rods looks a bit crude, will the final product have a smooth finish?

Oh, I totally hear you. I would agree that the prices are high, but that is where they need to be. I am able to distribute the fixed fab costs over many rods by fabricating a lot of rods at one time, but even totally eliminating the fixed costs, the unit cost of fabrication per rod is still high. Not to mention the time put into design and finishing. I am not getting rich. So these rods are for the individual who is looking for that detail on their locomotive.

This is the finished product, so yes, the surface is matte and a little grainy when viewed close up. I wanted to show the detail shots so there would be no surprises. Given the price, I want to do all that I can to ensure the customer is getting what they expect. I personally think it looks tons better than pinning together a bunch of shorter technic half beams (which is why I made these for myself in the first place) and they are particularly handy for the long spans past 7 studs where you previously had few alternatives this thin.

No problem if these rods are not for you. If you are on the fence, I'd suggest starting with a single locomotive, e.g., as Duq did, and see how you like them. Then, if you find you do like them and have big ideas, certainly we can talk off-line.

Locomotive Annie, on 29 November 2012 - 01:54 AM, said:

Zephyr's rods have a very fine granular surface because they are made by 3D printing, but crude they certainly are not.  These rods are very precise in their sizing and look absolutely spot on in every way.  The price is what is is because they are a low volume production item and considering the wide range available; - which includes some fairly uncommon spacings and offsets as well as the more usual types, - I think they are very reasonably priced.

Thank you Locomotive Annie. I would agree with both you and Commander Red Hat on this one.

[roamingstudio]

Those living in Belgium and Luxemburg may be interested to know that Staples are going to be introducing a 3D printing service... which could be cool.
http://www.engadget....inting-service/