More Madill Madness

[Beekster]

Today I've been playing with the winch box. I made a bunch of mistakes with the first yarder, which made spooling on the running lines an absolute nightmare coated in gold-pressed latinum. For one thing, I left way too much side-to-side play in the drums, which contributed to lines running off the drums and tangling around the axle shafts. This time, I will shim both sides so that there's minimum sideways play for these drums. I've also been more careful about ensuring that the flanges are round, and that they spin without a lot of runout. So, this is the start of shimming:




My Skyline gear is three laminations thick; I used only one for the first yarder. The second image shows the real thing. I think that three laminations is too much at nearly 6x scale inches thick, so I'll slice them apart and use only two.. Seeing this close-up makes me dissatisfied with how well I lined up the teeth, so that needs to be rectified. Still to come will be shims on both sides of the Main & Haulback drums and on the front of the Skyline drum so that they all sit the same distance out from the rear bedplate. I will fabricate the guards to match, eventually.

Not evident in this view is the use of some thicker stock for the bottom plate and the side plate on the other side, .020" versus .015" on the first yarder. Makes a noticeable difference in stiffness, and the visual difference is trivial. I might bevel the top edge of the side plate; I might not.

[JED]

Taxing work to say the least!!

[Beekster]

After all the troubles with the die-cast, I decided to just spend money and get what I really need: a detailed excavator frame. Behold:


Cost is $103 all in, but it should be worth it. It's a detailed piece, with accurate tracks. Once it's here, I'll see if the yarder chassis I've started will work with this. The dimensions are pretty close, though this piece is a wee bit narrower. If I have to build a new chassis, so be it.

[JCON]

Cool!!!

[Beekster]

I sure hope so, Joe! I expect that there will probably be some areas of the running gear that betray the fact that this is a 3D print and not a unit assembled from pieces (themselves printed or not). With any luck, some file work under magnification and perhaps some dirt accumulation will help.

Just my luck, I forgot to take my phone with me when I went swimming this morning. As I left, a dump truck was stopped at the light right in front of my parking space, towing a trailer with Hitachi excavator on it (bigger version of the Hasegawa kit). I would have had nearly a minute to shoot some useful reference images, but no. Oh, well...that's what I get for being a bit rummy this morning, not having got to bed until well after midnight. The wife and I attended the Journey concert in Portland last night, the show was opened by Toto. Our high school bands are still rocking it.

[Steve Ski]

All I can say is, WOW! The amount of detail taking place is incredible, Beekster. That must be a 3D print on the tracks, correct? Depending on the resin used in printing, what will the clean-up entail? My gun deck was a pain to clean up, but I know there are resins used that are much easier to clean. I understand it depends on the size of the structure to be printed, but I'm by no means a 3D print aficionado.

I may be late to the supper table, but I'm in on this build.

[Beekster]

Steve, the material is the Fine Detail Plastic from Shapeways. The track frame was originally designed in 1/50 scale (model railroad "S" scale?) for a Gradall excavator. I asked the designer to rescale it for 1/35, and he obliged. My big Shapeways order won't get here until the middle of April, so I won't know how much cleanup is required until I have all the stuff in my grubby paws.

This piece will be considerably lighter than the die-cast frame I first tried to use, which should be an advantage--the mass of the track frame won't distort the shape of the yarder chassis. the only question is whether or not it will be strong enough to support the mass of everything above it. There's a lot of styrene in one of these projects, and I'm making this one incrementally heavier than the first one by using thicker stock in places to make life easier. I also expect to have to add some fishing weights in the engine compartment, to counterbalance the spar. This rig will be done in transport mode.

[Beekster]

More work accomplished on the winch box. I've made bearings for the shafts where they might be visible from some angles. Probably not, once the guards are made and installed, but better safe than sorry. I didn't do this on the first yarder, mostly because I knew that with the spar up and all that rigging there was no possible sight line. There might be with the spar down. I have also adjusted the thickness of the Skyline gear and shimmed the backs of the Main & Haulback drums so that all three drums have only a few thousandths of fore & aft play on their respective shafts. This will prevent the trauma I went through on the first yarder with lines twisting as they spooled and getting caught up behind the guards and tangling around the shafts.








Believe it or not, I will have to shoot some paint on the drums and the inside of the winch box before too long, though I will get the guards done first. There's a crossmember to be installed near the top of the angled section of the bedplates, but the Main & Haulback drums beyond it can't be inserted past that structural element. So the area beyond that crossmember, drums and all, has to be given at least a first coat of color before the crossmember is installed. The Skyline can remain removable for quite a while yet, until I build the sponson. Then it too has to go in for good.

[JCON]

Quite the thought process to get it done...

[Beekster]

Mar 31, 2022 9:29:08 GMT -6 JCON said:

Quite the thought process to get it done...

Indeed, Joe.  That's the essence of building something as complex as a yarder, thinking things through...however long that takes.  And as satisfied as I am with the first one (which got a bunch of oil & grease staining done this morning), I intend to learn from my mistakes and make the second one more robust.  And perhaps by explaining it all in excruciating detail I can perhaps encourage others here to be ambitious and to avoid the problems (all self-induced, of course) that I've dealt with.

[Beekster]

Christmas in April! And we had snow last night in Hillsboro to prove it!

My big Shapeways order arrived today, and I could not be more ecstatic about what was inside. The excavator frame is exquisite, simply exquisite. It's a little narrower than the die cast, so it's back to the Chopper tools to make a new hull. Not a big deal; I suspected that might be the case. I took more photos, but they didn't come out well. The frosted high-detail plastic doesn't photograph well, so you won't be able to see how really nice it is until I get it cleaned and spray some primer on it.




Also in the goodies are these snatch blocks. The large & medium ones will make for perfect yarder bling. I will order more of these, and probably some in 1/24 as well just to skew the available sizes larger:


And finally, these two rolling blocks are a revelation. Not only do they swivel, but they are nearly dead ringers for the ones I made for the powered guylines on the first yarder project. I will order another set, and craft the end of the spar to use these instead of my own creations. They were something like $16 before shipping, and at that price I can't go wrong.

[Beekster]

PLayed with exposure settings a bit and got some photos that show the detail on the excavator frame better:








There is a slight fly in this ointment; the frame has a slight twist to it. It isn't apparent here, but it is when placed on a glass-smooth surface or a trailer bed. Probably nothing to be done about that; any attempt to correct it would likely break the piece. I think I'll contact the designer, and ask if a little hot hair dryer treatment would be enough to soften the material and work the twist out.

[JED]

Looks pretty good stuff

[JCON]

Looks good!!!

[Tobi]

Holy flying cow! I'm a little late, but I'm seeing engineering arts here.

Regarding the Shapeways parts, I received advice to either prime them soon for protection, or store them away from light, because on exposure they seem to become even more fragile and brittle than after printing already.

[Beekster]

This is a closer look at my conundrum with the excavator frame. These four photos show the problem clearly. In the first two, the weights on the right-side track hold it flat, and the gap on the left is visible at the front:



Now the frame has been turned around, the weights are on the left-side track, and the gap is visible on the right side:





So here's what we know: One, each track run is straight on the bottom because it can be made to sit flat. That means that the warp is somewhere in the rest of the frame. Two, this material is really brittle so great care must be taken with it. Three, there's been no response to my query about using heat to try to make the material more malleable...though a response might still come. I need to be patient. Four, what is the basic shape that forms the center of the excavator frame? It's a square. A shape easily fabricated from styrene stock.

You can probably sense where this is going. If heat might damage the brittle material, there's no way to fix this without surgery. You're thinking, "Beekster is loony. He just spent $103 on a 3D-printed part and is considering cutting it apart." And you would be right. This epiphany came to me while doing my work in the pool this morning.

The problem isn't with the track runs, it is with the rest of the frame. That shape is simple and easy to replicate. The part looks to be hollow inside, which makes sense because the object with designing something like this is to make the walls thick enough to print but not so thick as to waste material, which adds cost. If it's hollow, I could fill the cavity with styrene stock and superglue. Since we know that the track runs themselves are square, a separated track run modified as described could be carefully sanded on the True Sander, to ensure that the exposed styrene mating surface of the frame is vertical. This would allow for a standard styrene join with a new center box that would add strength. A new box could be wider, tailored to the chassis box I've already started on, so the entire track width could be altered as desired. Or a new chassis and box could be fabricated, wider than the original.

I'm not decided on doing this, and I want everyone here to pick apart my reasoning and add your insights. In the meantime, if we get some clearing this afternoon I'll spray some rattlecan Tamiya primer on it for UV protection.

[JCON]

I would build as is and use the groundwork to get it to sit in it so it looked level... much less work and pain!!! Lol!!!

[Tobi]

Basically spoken, every material is responsive to heat, I surely don't have to tell you that. But the Shapeways high detail stuff is very delicate from my experience. I had designed me some gratings, not larger than about 0.5x1 inches, and though they were printed flat, I had to adopt them into a resin body which was slightly warped and that could not be cured. So I made the hot water treatment and it worked to a very small degree, plus I had a breakage on one edge of the two gratings. So 50% success rate in my case and that with very, very thin part thicknesses.

Looking at the size and the complexity of your part I would say if you try the same like me, brace yourself for a nerve-racking work of blood and sweat and with insecure result. My opinion.

Joe's argument on the other hand is tempting, it's only I for myself couldn't live with it. I would take the hard road and start the surgical work. And everything that can be substituted by standard styrene due to its geometry I would leave off and replace, until I have developed enough trust into the long term behaviour of the printing, also in hindsight to glue, paint and thinner compatibility, possible later evaporations, and so on. In my modeler's life, there were some nasty surprises.

[Beekster]

Tobi, my thinking is evolving in line with yours. I've used this same 3D printed material on other projects, and thin sections are very brittle. I haven't had issues with painting it; one unfinished project has been primed and had paint on it for a few years now with no problems. That said, I have had problems with certain paints reacting badly to some weathering methods, so I'm cognizant of the risks. The frame got a liberal coat of primer yesterday, so it's protected from UV exposure now. Like you, I'm disinclined to live with the problem and conceal it somehow. It's dry enough for light handling, so I'll take the calipers to it and make notes on dimensions. I'll make the central box, then make a final decision about how to proceed. Don't be surprised if I procrastinate a bit on starting surgery. Sometimes I have to steel myself for work of that sort. In the meantime, the center box and work on the winch bay will keep me occupied while I think.

[Beekster]

More work accomplished on the winch bay lately. The interior work is now complete and you can see the large crossmember that ties the structure together beneath the spar, as well as the guards around the ends of the winch drums. The irregularly shaped ones on the inside face of the rear bedplate aren't quite prototypical; changing shaft diameters to something closer to the real size changed the amount of room I had to work with. Some machines had these guards removed (!!!) or replaced during their operational service, so I'm not way out of line with these for a rebuilt unit on a new excavator chassis.









The outer two drums can still be removed to get paint in there; the center one cannot. I can pull the shaft out so that it wiggles around in there, which is what I'll have to do when painting. I'll use a brush to get the inner surfaces that are nearest to that drum and airbrush the rest. For that, I will wait until I have more of the subassemblies done...stuff like the left side sponson, the guyline outrigger on the right side, the front cap for the Skyline shaft, and so on.