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RC models by Robert Holsting

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  Cabin, and general body.

Once the main core is done, and various other details are falling into place, it's time to start looking into the main body of the carrier.
As always it begins with a few thoughts on the white-board... and the following collections of images:



Album: LTM1500_Body




Album: LTM1500_Cab




Album: LTM1500_Rear




Well... let's build it!

  As usual I'm building stuff like this in 2mm plastic plates. Here are the four basic parts!

The huge hole towards the back is for the turntable later on.

  Holes were drilled in the plates and in the core, and M3 thread was cut, ensuring a good fit of the deck.
(Except the two front-most one's. They will accommodate the resting bracket for the crane boom later on, mounted from below, so these two holes are smooth bore.)

Also the cut-out over the outriggers have been made. It will be possible to access the inside mechanics of the outriggers this way.

  A small close-up of the outrigger cut out.
Notice the eight holes in the middle. These holes are for the head of the screws holding the outriggers. I do not want something that central and load-bearing to be mounted in plastic, as this might deform under stress, leaving the screws loose!

  Then the front of the raised area was put on.
This will be the highest point of the carrier.

  A small tip, requested by visitors: How do I ensure that long pieces of plastic are straight?

I sand it with sandpaper fitted to a board like shown.
By sanding with only a light pressure using this idea leaves you with a very straight edge.

  A bit later, the first structures around the cut-out for the outriggers were made.

  A close-up of this structure. The holes in various beams are for wires, hydraulic tubes, and what not later.

Also shown is the now counter-sunk screws for the aluminum edge, which will later hold the rubber curtains.

  And with all that done, it was time to play a bit!
Here's my Scania and my custom flatbed, dropping off six of the eight axles for the crane.

It is time for a little get-together...

  Family reunion!
This is the first time ever that the crane meets the family.

Everything in this picture is in scale 1:14, except the tank. It's 1:16.
The crane will be a BIG monster!

  I then went ahead and made the main upper body. Since I'll put a lot of electronics and what not in hidden compartments, I wanted the lids to be removable.
Here's the rear most lid, middle and front lid.

Notice the index libs. That feature, and two counter sunk screws will hold the entire top in place.

  Here's the rear most compartments. Holes inside the structure are for wires, tubes and such.

  ...and the lid in place.
Inside space is 20mm high, and about 100mm wide.. Plenty of space!

  The enclosures over the outriggers are fitted with my signature method: Steel strips and magnets.
The steel strip is glued on to a plastic strip inside the outrigger top, and the magnet is glued on to the lid.
An index lib holds everything in place.

(I need access to the outriggers for maintenance and service, thus the removable lids.)

  A few details that I found on most of my images. The little tank's air (?) lines will be fitted nicer later, here only shown as illustration.
The air tank is made from a plastic tube with a couple of 2mm plastic sheet glued on each end, filed and sanded to shape. For now it's held in place by only one strap, cause it'll be removed when everything is to be painted, and that I can get paint into all little places.

Notice the two 2mm bolts on the vertical bracket.. On the real crane this bracket can be adjusted, so'eeee..... yep!

  Here's the middle section of the top lid.


  ... and the front top lid, now in place between the finished outriggers enclosure tops.

  The center of the space right behind the drivers cab is quite detailed, so let's get to work!
Instead of making three removable doors in the top lid of this area, the doors were engraved into the one-piece, removable top.
Four holes were cut for future ventilation of this big, perfect space for electronics, batteries or whatever ends up here.

Some models of the real crane has this configuration, so what you see is not my imagination, but a true copy in scale.

  Aluminum netting was fitted to the lower side, and overall I'm happy with the result.

More details are in the making, not done at all! :-)


  Shortly after that, a few details were added to the same area: (Supports for the crane boom later on)

The round cones towards the left in the picture were made from a hub cap for a Scania R620, cut in half and finished off with a 1mm plate.
The little rectangular shapes are simple strips of plastic.

  The other hub cap went inside the hole in the forward section, meant to look like a small cap on a tank within the structure.

Also new: The tank in the background. The top was sanded to be slightly rounded, just like a real tank. 1mm strips simulate mounting strips, and a round structure, based on parts from the countless leftover pieces from kits, mimic the tank cap.

  The large space within are too good to loose, so the top comes off, offering a great spot for electronics, batteries, hydraulic or similar later on.
Index libs on the lower side of the tank top ensure a secure fit when mounted in place.

  The smoke stack is quite unique, so I had to make it from scratch as well.
A round plastic tube as roughly shaped into an oval using boiling water (HOT water softens most plastics, making it possible to shape them slightly), and four oval disks were cut.
Three of those were stacked on two long threaded rods, so the smoke stack can be bolted to the floor.

  The finished smoke stack in it's future home!

Some chromed brass tube was cut into the different pipes.
The top one's were glued using epoxy, while the bottom one's were not.

  The bottom tubes are loose, so the smoke stack can be removed AND flex if struck by something (crane?) without braking everything apart.

You gotta plan for the unplanned, right? :-)

  The two air intakes were made from an old piece of vacuum cleaner tubing (the black plastic tube) and the normal white 1mm and 2mm plastic.

  The finished air intakes in their future home!

Note the small pieces of gray tube added in this image, going from each air intake and to the center console.

  -and that completes the front of the main body engine area!

  It will have to await paint until more of the carrier is done, and ready for paint.

  Compared to the original carrier, it's close!
One piece of work is still to be done: The little wall between the high part and the low part of the center console are supposed to be full of slots for cooling.
I have to add those to the model as soon as I figure out how to cut them.

Compare this image with the next one. In this picture all is closed... all tops are in place.

  -and in this image, everything is open, all tops removed! Conclusion: LOTS of space for electronics, hydraulics and what not..

I also added the little door in the side of the upper structure, here shown ajar in the front left corner of the carrier. I think that the volume control will go in here later, after all it is right next to the speaker box...

  One of the final details: The cooling vent.
I cut it on my CNC using a 2mm end mill, but not without problems. As it can be seen on the first attempt, the 2mm plastic melted at first. By constantly blowing debris away, the second run went much, much better!

  The area with the vents was cut and adapted to fit the crane body, adding another great detail!

Now work will focus on the drivers cab, and why not build a solid base for that first!

  A sheet of 3mm aluminum plate was used for the base on which the drivers cab will be built.

The front of the plate was bent upwards, and the corners cut off reducing the width. (The front is not as wide as the rest of the crane.)
This plate will be visible, and will form the footboards. It will also protect the plastic cabin from being crushed, should the crane strike the ground in bad terrain, or during manual (miss-)handling.

  Four metal spacers ensure strength, and correct placement.
All screws on the lower side has been counter sunk to prevent them getting stuck on something.

  The front edge was filed so that the bumper uses the 3mm plate for support, a feature that makes the bumper much more impact resistant!

  And then: Back to the white plastic!
I want to make the drivers cab in two parts; inside stuff and the outside shell, making removal for service and access to the inside easy.

First the raw basics of the inside stuff.

  .. and then the first steps towards the outside shell!

  The doors must be able to open, so the side pieces must be cut open to allow a door later.

  This is the two parts: The inside part on the left, and the outside part on the right.
The two parts are held together by hidden bolts.

  Inside part and outside part put together, and then placed on the chassis. Doors and windows frames will follow!
The front wind shield will be held in place by a genuine rubber strip, shaped as an H, just like in a real car!

The lights on the roof have been placed for demonstration only, I am not sure I'll include the two small chrome one's...

  A small test of the H-profile rubber seal in model size!




  Corners sanded round, and various work. Planning doors...

  And here you go! The doors. Notice the hinge, and the track around the inside of the window frame.
A 1mm transparent plastic window goes in later, followed by a 1mm white plastic cover on the inside of the door.
(Making a sandwich with the glass in the middle...)

  Getting there....
There will be one more windshield wiper later on, but I have a little problem with the consistency of regular snail mail service..

Notice the funny protectors (?) on the corners of the cab! I made those from a 1mm plastic sheet. They will be black later on!

  The new top markings for the cab! A small white LED will go inside this tube, and wires extend through the roof to the inside of the cab.


  Notice the back side of the bumper: I had to build an enclosure for the bumpers back side, hiding front lights and turning signal lamp.

  And that's it! I forgot to open the small service door right behind the drivers cab, but it opens as well.

    One small detail: The hook must be tied to something when the crane drives around, so I made this to put on the front bumper.
It's 2mm brass, cut on the CNC using a 2mm end mill.

    Left is only to solder it using silver solder, and of cause paint later on.

-and that completes the cab for now! Inside details (seats, instruments, working indicators etc.) will follow, but first everything must be painted yellow and grey.

    I now turned to some of the pending metal work: The rear plate.
A 3mm aluminum plate was cut to shape. (Shape copied from pictures)

    Small test-fit!

  Now the fragile plastic structure is a bit better protected, and one more important piece of work is done!

  The rear plate will add strength to the rear end, and form a base for the bumper, rear lights, and a cabinet holding the most important electrics:
Key switch "on/off", power source selector, charge plug, external power input, hour counter, and such. I'll return to this later, in a separate chapter.

  A small view to indicate how the rear plate is fitted to the same area that will be occupied by the rear support legs.

  Rear bumper and tail lights!
The hole in the bumper (center) and the larger hole about 90mm above it, is for future wiring, and will be hidden by a compartment.

  Glass was painted for the tail lights, and the tail light house got a layer of silver paint.
The silver paint should prevent the LED in shining through the plastic house..

 

Then the glass was glued to the house using epoxy.
When I later spray final color over the whole thing (masking off the glass), the paint will ensure that no false light escapes the tail light housing.


  Small jump in time: Cabinet finished. No big deal, just plastic work as usual.
Also notice the little license plate holder to the left of the cabinet.

If you thing that the rear end will look funny, don't blame me! The real thing is often configured this way..

  The cabinet opens, and a 5mm edge at the bottom ensures that any content (tools?) will not fall out etc.

The cabinet will also hold something else! Make sure to visit the section called "On/off, power selector, hr counter, charge" for details!

  Here the entire assembly lies on it's back, showing the hole in the center of the bumper, and the hole in the bottom of the cabinet.
Wires to lights will exit the bumper, and enter the cabinet, travel up to the upper hole inside the cabinet, and through that hole continue into the carrier, where electronics will be located. (No wires (or anything else for that matter) can go on the other side of the base plate that makes up the rear end, cause all space is taken by a set of support legs.)

  Notice the hole in the upper edge of the license plate holder, and the small hidden hole through the side of the cabinet.
A small SMD LED will illuminate the license plate, and wires will be routed into the cabinet to the other wires later.

That pretty much completes the rear end. I do need to fabricate some stronger spacers to sit between the main bumper, and the shorter bumper at the cabinet doors. The hexagon spacers shown here are just for illustration, and not nearly strong enough for actual use.

  On with metal work: The support for the turning table.
I got hold of some 40 x 80mm aluminum square beam, 3mm thick. Excellent!

  I cut of one side, and mounted the rest on the steel core.

  A temporary plastic spacer between the two supports illustrate a nice way to make it even stronger!

  Here the plastic deck has been fitted to show you how it's going to work.
The turntable can now rest on both the steel core, and the two supports towards the sides.

  A couple of plastic covers were made, screws hidden within the structure.
Cardinal rule where possible: If possible; no visible nuts, bolts or screws, unless they are part of the model.

  The space between the decks aluminum edge and the white plastic cover of the support will be used for the rubber curtain that will hang from there.


  I could not find any rubber thin and flexible enough, but I did find this black fabric, normally used on dresses and stuff.
Price was less than dkk 10,- pr meter.

(How come that the girls can get away with prices like that in their hobby, while our hobby tears a burning hole in the pocket every time? hmm...)

  The plan is to place a 10x2mm brass bar under the aluminum and the fabric.
The bolts that holds the alu on to the main body plastic parts will extend through the whole "sandwich", and thereby squeeze the fabric in place.

(The image shows a short sample, not the final piece with the correct measurement.)

  The height of the aluminum edge will be cut to about half, but this image does illustrate the "rubber" curtain in place.
(The image shows a short sample, not the final piece with the correct measurement.)


  I noticed that some LTM 1500 in the real world have a support structure that the main cylinders can rest in, when the crane boom is removed. The cylinders would rest on top of the outriggers without these structures, and that is a no-go.

  Two identical aluminum brackets were cut by hand, and a brass U profile formed the base.
M2 bolts allow the aluminum brackets to be removed while the brass base remains, should it be desired.

The aluminum mounting bracket in the middle is bolted to the steel chassis below the plastic.

  The black tube illustrates the left side main cylinder resting in it's bracket, with the main crane boom removed. The angle will be slightly different when it is hinged on the crane base though.


That pretty much completes the main body top, front, rear and in between. The only things that remain is cutting holes for motor, gearbox, and fitting / painting various details. Those things will be shown in later chapters.


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