More Madill Madness

[Beekster]

This morning I well and truly crossed the Rubicon, and I must say the crossing was totally unopposed. Here's that $103 3D-printed track frame from Shapeways as it arrived:

This morning I cut it apart and trued up the sides:

Then rough-cut some .125" square stock and superglued it into the hollow spaces:

When the superglue is cured I will trim with a scalpel and make another couple of passes with the True Sander to keep everything square and smooth. After that, I will add .020" sheet stock and sand everything smooth. This is the direction things are going, with the printed center section on top of my new one to show the additional width (more or less). I can decide how wide I want the tracks to be and sand the center section down to dial that in, then glue the track frames to it and ensure that everything sits flat and square.

No problems cutting the frame apart with a razor saw; just worked slowly with running water to clear away the residue so the saw wouldn't bind up. The whole operation really couldn't have gone any easier.

[mustang1989]

WOW!!! I've spent my fair share of money at Shapeways as well and to me it was worth every penny. Those tracks are drop dead gorgeous. Good stuff dude.

[Beekster]

May 17, 2022 11:53:33 GMT -6 mustang1989 said:

WOW!!! I've spent my fair share of money at Shapeways as well and to me it was worth every penny. Those tracks are drop dead gorgeous. Good stuff dude.

I feel the same way.  This particular piece makes me cognizant of the fact that big things can warp, so you have to be careful about that.  In this case, the fix was easy with the right tools.  For something like a car body or truck cab or the service body that's supposed to fit the 1/35 Meng F350 a bent part might be a lot more trouble to fix.  Won't know until I buy one, will I?

Getting this far now has me thinking about how to do finish work.  There's quite a bit of detail here that would repay careful painting, so this might have to be painted as a subassembly before it goes into the hull I will build.  That hull will probably also be painted, at least the sides and bottom, before final assembly.  I will have to work out how everything goes together and in what order stuff gets attached and whether or not it gets painted first.

[Dukemaddog]

Congrats on crossing the Rubicon. I'm still on the other side since all your pics come up with a blue square saying "imgbb.com service unavailable". I guess I'll have to wait till the Forums sort out again...

[Beekster]

The slightly widened track frame is now back together:




And some mock-ups with the original hull, the engine, and the winch bay to start looking at proportions:







Compared to #70141, my track frame isn't as wide between the treads nor are the treads themselves as wide. But they are a few inches wider than VVSS Sherman tracks, about like HVSS. And the CG is definitely lower, which is desirable. I will make another hull of this same width, or maybe .020" wider. On 70141, the inside edge of the track is really close to the hull side:


The single layer of .040" stock isn't nearly stiff enough, so I will double that. Though I'm certain the thing has slab sides, I need to do some engineering work. This his how the track frame sits right now:


That gap is obviously unacceptable. I believe that a combination of building up the bottom of the excavator frame and relieving the hull sides & bottom to allow clearance for the down-angled sections of the track frame will be required. That said, the bottom of 70141's hull is pretty darn low:


Obviously, operators aren't really concerned about moving cross-country or getting hung up on an obstacle.

[JCON]

Looking good Beekster!!! Nice work!!!

[Beekster]

This is where things start to get really interesting. My objective is for this machine to be in travel mode, on a trailer built for it (the one seen in the M911 thread; yes, I will eventually complete them). If the yarder is to be on the trailer, it must be able to ascend the ramps to climb onto the trailer deck. So, let's talk about this mock-up:


The tracks are up against the ramps and about to start the climb. The floor piece with the engine, is already touching the ramps at the back. The LEGO stack represents a radiator. You can see that I have a bit of a clearance problem with a simple full-with floor back here. This is because my track frame isn't as long as that on my reference vehicle, relative to everything else. See here:



The winch bay lines up with the front bedplate just about centered over the track run, which is what I will have to do too. That puts the most mass right on the center of the track frame. You can see that #70141 has a stubby rear floor ending just forward of the tracks, with heavy beam extensions to carry the engine & radiators. I will have to do that too; as the machine climbs trailer ramps that will be in the clear space between them.

I have to assume that #70141 has an intact track frame inside it, similar to this rebuilt machine that stuffed the frame inside the original Sherman-shaped hull, with patches welded on the sides for strength:


Referring back to my mock-up the yet-to-be-built PTO housing will have to be flush against the back of the track frame and, of course, the rear bedplate. Lining the winch box up there does put the front bedplate about where it should be for proper weight distribution. The PTO will be about a quarter of an inch thick, and the bottom end will mate with the engine bellhousing.

If you hadn't noticed before, you will now see that there are puzzles within puzzles within puzzles to be solved here. Next step will be to cut that floor panel back to fit just inside the tracks and add corresponding side panels. There are similar issues to deal with on the front of the machine, but less severe. These things are always backed onto a trailer with the spar sticking out aft, and the end won't hit the ground without a really serious down angle since it starts at least eight feet above ground level.

[Beekster]

Though the weekend was largely obliterated by obligatory yard work and the airshow, I did manage to get the hull pretty much together and the frame that supports the superstructure box in front added to the winch box. This is what it looks like at the moment, with the rear of the winch box lined up with the back face of the excavator frame (for PTO clearance, when that gets built). The base frame is fragile and I've busted it once already, but it adds necessary stability when evaluating positions & proportions.








So far, so good, but a few things are becoming apparent. First is that the hull looks rather lopsided. More on that in a moment. The second is that when I start looking at the proportions of what is yet to be built, that my hull is still too short relative to what must fit on it. My track frame is probably a good three scale feet shorter than the reference machine I'm looking at, with a narrower track width. That makes judging proportions more challenging. Look at this side view of #70141, and that box in front of the front superstructure:


Let's guess that the box is about 36" wide, and as you can see it doesn't reach the front of the hull. Here's a box cobbled up from scrap that's three feet wide:


Mine extends forward about a quarter of an inch, not optimal. Well, I knew that I would have to adjust things as I went. So, the superstructure box is 48" from winch bedplate to its front face (thus the size of the frame beneath it), so maybe the front box is smaller and more like 32". To support it, I still need to add an angled section to the hull to extend it forward and provide clearance as it comes off & on a trailer. Which brings me back to the lopsided issue. At the back, I can extend the floor & sides by .406" and still have easy clearance to the trailer ramps. Why that measurement? It's simply a piece of .250" and .156" stock glued together. That extension is in progress, and what do you know? The hull edge to track face at the back is .355" as modified, and .357" at the front. There's some wiggle room in where the track frame sits but when all is said and done the two overhangs (before angles are added) with be within a scale inch of each other, even with losing a bit of material when I sand the back square. That's even enough for me. The angles will probably be different front & rear. At the back, the extension should be sized to support the vertical stanchions supporting the upper deck, so I need to get started on a framework for that to work out where those vertical supports need to land. Puzzles within puzzles..

[Tim]

Had to look a yarder up. These machines are awesome! You do excellent work on these things! Watching with great interest.

[Beekster]

May 24, 2022 16:52:26 GMT -6 Tim said:

Had to look a yarder up. These machines are awesome! You do excellent work on these things! Watching with great interest.

They are unsual beasts Tim, but here in the Pacific Northwest they are still a pretty common sight.  Several manufacturers made them over the span of maybe fifty years, either self-propelled on several different tracked chassis or on an 8-wheel truck derived from a mobile crane.  A couple of the smaller types could be mounted on the back of a standard truck, including a very early Madill unit on an M26A1 soft-cab Pacific tractor (Dragon Wagon).  Others are mounted on a standard flatbed semitrailer and moved by a heavy-haul prime mover tractor.  Lots of opportunity for creative modeling, if you can get enough documentation to do it.  I'm still hunting for photographs & documentation for that Madill unit on the Dragon Wagon; got a Tamiya kit & Trackz soft-cab conversion in the stash, reserved for it just in case.

[mustang1989]

Really puttin' on a show here with all the mods and tricks. Love every update.

[Beekster]

Minor progress. The hull extensions are complete, save for the brackets that will support the yet-unbuilt deck structure. I've made a laminated lump of thick strip stock to start on the PTO, reworked the engine mounts, and cut I-beams for them to sit on and mocked things up to look at proportions. This seems workable.








You'll also notice two holes in the floor of the hull up front. I figured that some way of getting water out of the thing would be useful, so that's what the holes are for. I will punch small disc covers for underside and add those with bolt heads later on. I won't cut a hole in the hull because there will be no sightline under the engine, but I will fabricate an appropriate belly plate for under the engine, too. The cutout for the PTO has been started; it will have to extend aft a ways and probably deeper down the side too before all is said and done. Oh, and I've tightened up the gaps where the excavator frame exits the hull, too. I will paint the track frame separately and paint the hull inside & out before the track frame goes in for good. Then small pieces will be cut to fill in over the top of the frame legs, sanded smooth and touched up.

[JCON]

Love the madness!!!

[Beekster]

So, long time no update on this or anything else. Sigh...

We're coming up on 13 inches of rain in the last three months, well over twice what we ought to have. No more drought, but the weeds love it and (unfinished) work eradicating them to prepare for other landscape projects has consumed far more time than I would like. But I've snuck in time at the bench where I can.



I've got a rattle-can coat of black on the track frame now, which will require an airbrush session to cover the details inside. I've roughed in the shape of the PTO housing and worked out the fit of the engine/PTO assembly relative to the winch bay. That required adding .080" of height to the hull walls and tweaking the dimensions of the cutout on the right side of the hull for the PTO. There's a little more work to do there to tighten up the gap there.

This stage is all about proportions. These various subassemblies have much to be done to them yet in terms of details, but for now the work is ensuring that everything fits together like it should. The hull needs to have the angled extensions built which will support the back of the top deck. Measuring that up requires the deck to be started so I know what I'm working with. Here it is upside-down, with a rough opening cut for the Tag drum's line to exit upwards to the spar:

More openings will be cut, for the hydraulic oil tank and possibly for the brake cooling water tank. That one will be rectangular on this model, it and will either sit atop the deck or be recessed into it. Haven't decided on that yet. I might also need a hole for the exhaust pipe to exit. But cutting the hole for the Tag drum and grinding a clearance arc in one support member was required to fit the deck properly on the rear winch bedplate.


Here the deck is held up more or less in the right position, next step is to measure up & fabricate the hull extensions.

You may notice that this deck is shaped a bit differently. Several yarders I've seen have had the rear extended like this; mine is about 18" longer in scale. Yarder #70038 had this feature, along with other interesting things like the air cleaner and exhaust pipe atop the deck, and the fuel tank apparently moved aft a bit.







Here's another machine with an extended deck:


Nothing is standardized with these things beyond the configuration it had when it left the factory. Individual operators made these changes later; while Madill probably accommodated some customization during production the relative rarity of deck extensions convinces me that that particular modification, when it appears, was done locally and not at the factory. My version is representative, I think.

[ARMORGUY]

All I can say : this is mindblowing.

[Beekster]

Obviously long time no progress on this, or any of my other projects. Summer got consumed with major landscaping projects, a very nasty summer cold, a road trip vacation, and sundry other activities. This is where we stand today:






Doesn't look like much has changed, does it? That's largely true, but the photos are a little deceptive. I don't have exact views for comparison, but judicious sanding work and addition of material on the edges of the cutouts in the middle have moved the track frame forward by a good .060" or so. I've also fabricated the angled back sections of the hull that will support the deck above and the framework for the fuel tank and engine bay door. Up front, I've started adding details similar to #70141. I'm satisfied with the overall proportions now having shoved everything (track frame, engine, and winch box) forward on the hull by a few scale inches. Everything just looks more centered, so the end result won't look so tail-heavy once everything behind the winch box is complete and the spar is sticking out towards the front. Since I took these images earlier this morning; I have added a couple of I-beam cross braces to the hull at the front of the track frame to stiffen the structure. The top one is level with the top of the hull sides and might get drilled through or relieved on the bottom to route some hydraulic hoses.

At this stage, I think that I need to get going on completing the engine bay by building the radiator stack, exhaust fan, and plumbing for the turbo-to-radiator stack (intercooler) and intercooler to intake manifold. I will also have to figure out where I want an intake air cleaner to go and how to plumb that, as well as the exhaust pipe. The latter might come up straight through the top deck. We'll see.

[JCON]

Welcome back brother!!!

[JED]

Welcome back