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Old Jul 16, 2013, 12:02 PM
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Build Log
1:8.5 Scale Manitowoc 18000 Lift crane

Good evening,

I have decided to do a build log covering a scale model project that does not normally crop up on RC groups, namely a heavy lift crane. The model will have full RC functionality although the intention is more as a static display model rather than one to operate and play about with.

The project will run for a number of years, and I will endeavor to cover it as fully as I can, but there may be quite some periods of time between posts, depending on the work being done. The first few posts will follow fairly quickly as I bring the project status up to date, after that it will slow down a bit as I get into the build process. Currently the model is in the very early stages of the build, with most of the work going into pre-build jigs/tooling, etc.

Cheers

Tim
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Old Jul 16, 2013, 12:26 PM
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A bit of background:

The Manitowoc 18000 is a 600 metric ton capacity lattice boom crawler crane, which can have its capacity raised to 750 metric tons with the addition of the Maxer superlift attachment. The superlift can either be of hanging type or on a wheeled carrier.

The crane can be equipped with a main boom of up to 128 m (with Maxer) and a luffing jib of 91m on top of a 94m main boom (with Maxer).

As an idea, it can lift 750 metric tons at 10m radius or 45 metric tons at 102m radius.

An impressive machine by any definition and one worthy of a large scale model

Cheers

Tim
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Old Jul 17, 2013, 05:33 AM
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A bit of background regarding the model....I apologise in advance for the long post!

Apart from RC aircraft, my other modelling interest covers 1:50 scale diecast models, specifically cranes. I have a TWH Manitowoc 18000 (Demont colours)in my collection and after a quite a whlle looking at it each day, a nasty little voice started to lurk in my head demanding that to get a real display of detail, a bigger scale is needed. I am sure many of you are afflicted with this unwelcome companion

In any case I foolishly decided to set myself a project that was intended to push my design and modelling skill limits to the max. I initially intended to work to 1:10 scale as it would be an easy scale up from the TWH model and still produce a model of size to satisfy the voice. Additional information could also be had from the Manitowoc Crane Library web page in the form of pdf drawings.

Sadly I came quickly to realise that the 1:50 scale model was not as accurate or detailed as I hoped to use for such a large detailed design. Furthermore, good quality photos showing all the hidden areas were not to be found on the internet.

Just as I thought the project would be stopped in its tracks, I had the extremely good fortune to come across one of the very few Manitowoc 18000's in Europe being serviced locally, with the vast majority of components available for inspection. What is more, the crane in question was the same one as my TWH replica -what is the chance of that!!!

Long and short, I had the opportunity to take more than 1650 high resolution photos and over the period of 80 hours spread over 7 days, I measured the whole thing from top to bottom, inside and out, resulting in 342 A4 size pages of destailed dimensions and sketches.

The project was definitely now on.

Using this new info and the multitude of drawings available from the Crane Library, I started the design using Solidworks. Currently the project has now been running nearly 3 years and the design phase is basically complete. I have put in over 650 drawing hours that has resulted in over 5000 part and assembly files and generated over 2300 unique parts and assemblies.

Design accuracy (at model scale) has been kept to 0.3 mm over 100% of the machine and 0.1 mm over 80 %. Due to choosing standard available plate and tube thicknesses, the acuaracy is out by between 0.1mm and 0.3mm for these parts and affected assemblies.

Initially the design was for 1:10, but due to the general availability for reasonable prices of boom and mast tubing, I went up to 1:8.5 early in the design, the little voice in my head demanding ever larger scales did also not exactly help.

At the beginning of this year when I was costing out the whole production process including necessary new tools, I decided that the costs (and eventual transport weight of the competed model) would be too high and decided to redesign to multimedia.

As from now the model lattice boom sections will be made of Ash round dowels (26mm, 21mm, 13,mm) and pine dowels (11mm, 10mm) and aluminium tube (18mm, 15mm, 10mm). All boom and mast plate sections will be alumnium, the pulleys and sheaves will be aluminium.

The rest of the model will use aluminium for all large plate areas and load bearing structures (pivot plates, sheave mounts, pendant straps, etc). Some smaller plate areas will use GRP sheet in 1 and 2mm. Internal structural support will come from Birch ply in 3, 5 ,6, 10,12 and 18mm thicknesses.

Complex forms such as the track shoes and boom connectors will be cast from Alumilite.

The basisc dimensions are:

Width 118cm
Length (without maxer and boom) 187cm
Length (with hanging Maxer) 300cm
Height to top of backmast 426cm
Height to top of backmast with maxer 563cm
Height to top of boom (120ft min) 471cm
Height to top of boom (240ft max) 901cm
Height to top of boom with fixed jib 1098cm
Weight with Maxer approx 560 kg

A challenging project don't you agree?

Cheers

Tim
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Old Jul 17, 2013, 12:27 PM
R_G
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Very interesting project Tim! I'm looking forward to seeing this crane come to life!

Ralph
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Old Jul 17, 2013, 01:28 PM
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Old Jul 19, 2013, 05:20 AM
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An update on tooling progress:

The plan for this year is to start on the track shoes, sheaves and boom sections. A bit of a strange mix to be sure, but is in fact related to the type of work that can be spread over the year and is needed for next years progress. In this case, much time can be devoted to manufacturing the multiple part pieces (track shoes, connectors, sheaves). It is best to set up for this process and follow it through until completed, rather than complete some, undertake another task and then have to reset up all the tooling, etc.

The sheaves will be turned from laser cut Aluminium blanks (spoke reilef pre-cut) on a small lathe and the other components will be cast (next post).

To enable being able to turn both sides of the sheave and the rope gullet, I had to make a special tool to fit the lathe. This replaces the 3 jaw chuck and I turned it in situ from a large block. It will remain in the lathe until all the sheaves are cut. The blank has the center machined out to 24 mm (for roller bearing) on another lathe and then is mounted on the center of the tool and clamped against a raised back face. One side is cut, the blank flipped and the other side and finally the gullet machined. Have to order the blanks within a few weeks.

Only 82 sheaves to make
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Old Jul 19, 2013, 05:52 AM
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Casting the boom connectors:

Manitowoc have a special form of boom connector that facilitates quick assembly and is a dominant feature of the boom sections. Machining from aluminium would have been very expensive so I decided to try out my hand at casting with Alumilite Polyurethane resin to create the complex forms.

I have never tried this before and came across Alumilte whilst researching the concept on the internet. It is not so easy to acquire in Europe but I manged to get some test kits from the UK. The tensile strength according to the website should be sufficient and test pieces have shown that this plastic is very much up to the task. Most of the loads are compressive, but during assembly and boom raising, the lower connectors will see upwards of a 100kg tensile load. Likewise, the track links will also see 50-80 kg loads when moving.

A master is made of the part in question (good old balsa!) and painted and sanded to create the appropriate smooth surface. A mold form is made from whatever is to hand and sealed against leaks. The master(s) are placed in the mold ready to create a two-part silicon mold.

Normally you would seal the lower part of the master with modelling clay so that the upper part of the mold can be poured and once set, the mold flipped, the clay carefully removed and the lower part of the mold poured. In my case, I mounted the masters in the mold form and poured directly to a set height. Once cured, I treated the surface to several layers of silicon mold release and poured the second part. I suspended some round-ended dowels into the first mold part when pouring-these provided a locating key for the second part.

The mold was left for few days to fully cure and then seperated and the masters removed. Pouring the Regular polyurethane was straightforward, but had to be done quicklly as there was only a 90 second window!

The new parts could be pulled from the mold within 20 minutes (can be within 5, but I wanted to allow for full setting).

All 56 connectors are now made. The track shoe is still only a master as I need to order large quantaties of resin and Silicon and this will have to take place later in the year to spread the costs.

cheers

Tim
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Old Jul 19, 2013, 06:11 AM
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Completing the connectors:

The last stage for the connector manufacturing was to fill the air bubble holes, clean up the part and drill the main pin holes (11mm and 8mm). This was a tricky task as the connectors do not just rely on the pins to join, but also have a butting interface (to take the compressive loads). That meant that when drilled, the holes had to line up perfectly between all parts so that they all made the correct butt contact.

To this end some simple jigs were made and the parts held whilst drilling. A bit of trial and error found the exact location for the jig in the drill to correctly position the holes. That is the beauty of casting - it took a couple of parts to find the correct location and new ones could be recast for almost no cost within half an hour!

The connectors are now ready to be used to assist in setting up the boom section jig.

cheers

Tim
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Old Jul 19, 2013, 06:38 AM
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The last post for the moment-the boom section jig:

I am currently working on a simple jig that will allow me to make all the various boom sections. Once these parts have been created, it will be converted to make the smaller mast sections.

It is basically a rigid box section 2m long that has been fully trued up and is twist free. One end is fixed and the other will be floating to allow section removal and also to suit the different section lengths.

The current stage is awaiting the locators for the connectors. Now that they are ready I can complete the most important section of the jig. The boom chords will be supported by intermediate mounts and held straight and true whilst the lacings are glued in place.

Well, that is it for now. I will add some more updates once the jig is completed and some test parts run to check for accuracy and alignment.

cheers

Tim
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Old Jul 20, 2013, 10:48 PM
Ooga-Chaka Ooga-Ooga Ooga-Chak
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In my part of the world (north central Iowa, USA) it seems we are in the midst of a windmill building frenzy. I've watch several cranes similar to your project lifting the blade assembly as one piece. It is a site to behold.

You have quite the project and I sincerely hope to watch it to it's end

Ken
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Old Jul 21, 2013, 03:20 AM
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Ken,

I have seen a number of turbines turning up over the years when I fly into Des Moines on the way to our factory in Pella. One of my colleagues managed to grab a pic of an installation once and it was being assembled by a 400 ton crawler.

Cheers

Tim
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Old Jul 23, 2013, 10:18 AM
Brighto?
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Search around on Youtube for a guy who excavated his basement using RC construction equipment.
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Old Jul 27, 2013, 02:30 PM
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A quick update.

The boom jig is progressing and I now only have to make some final adjustments to the vertical postioning of the connectors. A test fit of a vertical lacing shows no assembly issues.

Now that the boom chords are in the jig, one starts to get an impression of the actual size of this model!

cheers

Tim
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Old Jul 30, 2013, 01:05 AM
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Really an awesome undertaking. I look forward to viewing your progress.
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Old Jul 31, 2013, 03:28 PM
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Let's hope I can do the undertaking justice!

Not much news, finished fine tuning the jig this evening and I can now start on actually creating the boom section. So far 11 hours have gone into the jig and it is now time to build some crane

Cheers

Tim
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