New to me

Forum for discussion relating to the M2/M3 and M16 US Half Track
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Jerry Carducci
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New to me

Post by Jerry Carducci »

Well, I know what I'll be working on after my King Tiger! I am fortunate to to have come to have a US Half track kit, partially started.

This will be a long term project I believe but an enjoyable one.

Jerry
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M2.jpg
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Robert E Morey
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Re: New to me

Post by Robert E Morey »

Nice! Lucky find!
Bob

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Re: New to me

Post by Jerry Carducci »

I've decided to let my King Tiger sit for a while; I need to decide what I'm going to do with details on the tail plate. I need to make/find a column light
and decide what I want to do with the armored exhaust covers... plus and worst of all I need to decide how I want to finish the painting...

So, this half track is a nice diversion .

I dismounted the track skeletons/roller chains, sprockets, idlers and little return rollers. I dismounted the differential and stripped
it down to the basics. One of the half shafts somehow was not running true however not on the outer part, rather on the end that engages the differential gear. I used my larger lathe compound to bend into near truth +/- 006" as in began nearly .100" out of truth. The other side was true.
My original reason for taking these pieces apart was the terrible amount of rust on the parts. Not only did they look terrible the rust caused
several parts to be really stuck together. In any event the rust is gone now and the most vulnerable parts primed. With luck they won't rust again.

While looking over the differential parts I pondered how easy it would be to build a braking system to assist steering where the large cylindrical parts are but to be really effective both side of the differential would need to be powered. As they are not and that the full sized machine didn't have a steering component on this axle I simply moved on. I'll limit my changes to sealing the differential against dirt intrusion.

Having the tracks off it was time to clean the residue of the original rubber loops and the adhesive from them. First I cleaned off a fair amount of grease from the chains using first kerosene, then acetone. Next was to remove the master link and stretch out the chain in order to clean the links.
I thought at first 'this is going to take forever!'. then I came across a better idea. I clamped the chain out in a straight line on top of a pine board,
applying a clamp on each end. Then with a very effective portable grinder I have; this time equipped with a fine steel wire brush I proceeded to whisk
away all the residue in a matter of mere minutes for both chains. This was for the underside. To clean the outer side it was simply a matter of holding the chain in my bench vise and using the same wire wheel to clean that face. While disassembled I also ground the master link pins to a bare minimum, but evenly in accordance with Armortek's original advice of many years ago. When I did the disassembly I'd noticed scoring on the idler and sprockets; one track became stuck when attempting to run the motor so hopefully this pin grinding will help resolve that issue.

Once the chains were clean I once again replaced the master links and again washed them in acetone to remove any residue and last bits of grease or oil. I believe they are ready to have new loops installed.

Next will be to clean up the frame, repaint all the parts in OD and reassemble the frame. I plan on making a top and bottom cover for the gearbox/'transfer case again to protect it from dirt.

Jerry
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L1_rollerchain_05.jpg
L1_rollerchain_04.jpg
L1_rollerchain.jpg
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Re: New to me

Post by Jerry Carducci »

Some might ask why I had to clean up the base roller chain, removing the remains of the original loops. I'm only seeing the
aftermath of this, I didn't actually see the original loops or what actually had happened to them. The previous owner removed the failed loops before sending the model to me. I was only told they had seriously degraded.

My working theory is they must have been attacked by oil or grease in a possibly hot, humid environment- not sure which of these conditions caused the failure but my money is on the grease/oil. Some synthetic rubbers don't respond well to oils or grease; petrochemicals will cause failures of certain rubbers. Better to be safe than sorry. I'm going to try dry lubricants when I want lubricate the roller chain. I might just use powered graphite.

So I described my cleaning off the rubber remains left on the roller chain in my previous post in preparation of mounting the new loops.

I've performed a trial fit of one loop. I can already see how stiff the assembled tracks will be!

Today I disassembled most of the chassis in preparation of priming and re-painting in OD. Going to go through all fasteners used.
At the moment the chassis is completely in pieces...

I'm extremely picky about how I build things; bordering on intolerant of any way but my way (!). My one overarching tenant is I strive
to build a thing only once.

Jerry
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Adrian Harris
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Re: New to me

Post by Adrian Harris »

When I bought the original demonstrator back in 2017, the tracks had perished to the point where they had become fixed in the outline of the running gear.

2017-05-16_09-55-06.jpg

2017-05-16_09-55-36.jpg

Bearing in mind this kit was released in 2007, that makes the tracks around 10 years old.

I went through the same process of stripping them and found an engineers scraper chipped the old Loctite off the chains quite nicely.

I cleaned them up with a wire brush in a hand drill and then installed the new loops.

This one had washers between the sprocket cages and the drive gear, to give a little more clearance.

Adrian.
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Jerry Carducci
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Re: New to me

Post by Jerry Carducci »

Adrian Harris wrote:
Tue Apr 16, 2024 8:34 am
When I bought the original demonstrator back in 2017, the tracks had perished to the point where they had become fixed in the outline of the running gear.


2017-05-16_09-55-06.jpg



2017-05-16_09-55-36.jpg


Bearing in mind this kit was released in 2007, that makes the tracks around 10 years old.

I went through the same process of stripping them and found an engineers scraper chipped the old Loctite off the chains quite nicely.

I cleaned them up with a wire brush in a hand drill and then installed the new loops.

This one had washers between the sprocket cages and the drive gear, to give a little more clearance.

Adrian.
Yeeeeaaap, rubber, synthetic or other doesn't last forever. Especially under tension of any sort, with without sunlight, heat, chemical
interaction; it all ends up the same. It can last a really long time with the right conditions but models aren't often the right conditions.

That said a set of Panther tires (umm tyres) I cast from poly urethane 'rubber' 35 years ago are still very much viable, wouldn't make a very good
track tho, far too stiff...and fiddly to work with.

On the other hand I made road wheel tires for a series of 1/10 Pz III models using heat vulcanizing rubber- that stuff used in the US to build
new outer layers ("recaps") on commercial truck tires- "Rubber rope". I molded them slightly undersized so they would grip the wheel body. A case of
being under slight tension. Within 6 months many had failed, cracked, split. No ozone protection was my theory. For similar tires molded
for a Hetzer and yet others for other Panthers from the same heat vulcanizing rubber (I've been using it for for quite a while) that were merely held
in place by the wheel design- these have lasted so far nearly 20 years.

There it is.

Jerry
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Re: New to me

Post by Jerry Carducci »

Continued cleaning parts of the half track. Made cover plates for the axle/differential; I'd mentioned this early on as I didn't like it being open
to dirt. when it comes time to reassemble the axle I intend to seal it as thoroughly as possible.

Mounted the rubber loops on the roller chain. Very stiff.

Began priming parts as the weather has been warming up; the SEM self etching primer dries rather quickly and I shoot the parts outside.
As usual for larger parts, greater numbers of parts I use my trusty old deVilbiss I've had for 50+ years; with new seals and keeping it clean I
think it will last forever....

I need to repair some parts of the bogey assemblies, some pins fell out of the arms. I'll prime those bits next.

Once I have the parts primed and painted I plane to fully reassembly the chassis, at least as much as possible and test it for function. I may make
thin (.010") steel spacers as per what Adrian mentioned to provide even a bit more clearance for the master link. I've carefully ground the master link pins as much as I dare but a bit more clearance would be extra insurance for the sprocket parts' survival...

I noticed when I posted my photos they rotated. I'm simply too lazy to correct them!

All you folks at the Open Day... go get an ice cream cone to make the day perfect! Everything is better with Ice Cream!

Jerry
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This trusty old thing has been involved with painting just about every model I've painted since getting it in the 1970s. A real workhorse. Happiest at around 40-50psi.
This trusty old thing has been involved with painting just about every model I've painted since getting it in the 1970s. A real workhorse. Happiest at around 40-50psi.
Nothing is immune to table service!
Nothing is immune to table service!
primed parts_03.jpg
Everything is fair game to serve as a table to hold drying parts. Hard to believe there's an RS7 under all this...
Everything is fair game to serve as a table to hold drying parts. Hard to believe there's an RS7 under all this...
primed parts.jpg
Cleaned, and ready to go.
Cleaned, and ready to go.
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Re: New to me

Post by Jerry Carducci »

Made some progress on the M2. Finished priming the parts and set down the first OD coat. Will re-coat as needed when frame with some chassis components are reassembled.

Decided that the running gear will look a bit better with castle nuts. Such in 5mm aren't the easiest to find but located them in England (fancy that!)
ans so ordered some. However, since I believed a more flat (short?) version than what I think I'm getting would look better, that prompted me to appropriate some regular
5mm nuts and make my own castellated nuts. I began late yesterday afternoon when I made one and decided I liked it and decided to make more. Not having the best night's sleep, due to some form a sinus- allergy(?) I woke up at o'dark 30 and wasn't able to get back to sleep so I headed off to the shop where I ran off a bunch more nuts....

I'm sure many of you have had similar episodes!

Anyway I hope to begin re-assembly of the chassis shortly.

Jerry
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Od is such a lovely color!
Od is such a lovely color!
OD parts_01.jpg
Tracks
Tracks
Have (spray) gun, will travel!
Have (spray) gun, will travel!
Nuts!
Nuts!
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Peter Silcock
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Re: New to me

Post by Peter Silcock »

Lovely kits to build these half tracks. I couldn't get on with the rubber tracks/chain so converted mine to aluminium (not particularly scale but much better running) together with other mods and reduced the final gear to 30 tooth. This results in far better running and you can actually push the model along it's so free. Sadly down to my last 3 unbuilt ones!

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Re: New to me

Post by Jerry Carducci »

Peter Silcock wrote:
Sun Apr 21, 2024 2:52 pm
Lovely kits to build these half tracks. I couldn't get on with the rubber tracks/chain so converted mine to aluminium (not particularly scale but much better running) together with other mods and reduced the final gear to 30 tooth. This results in far better running and you can actually push the model along it's so free. Sadly down to my last 3 unbuilt ones!
So if I understand your modification; you changed the final gear ratio from ~ 2.6:1 (15t driver/40t driven) to something slightly less than 1:1 for a faster overall speed? Pardon if I have the ratio incorrect. I would have thought a lower ratio, if possible, would be better for driving but perhaps with
steering reliant on just the front wheels this is an exception.

Jerry
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Re: New to me

Post by Peter Silcock »

Sorry Jerry typo mistake. I reduced the gear to 34 tooth not 30. Involved a new X member as well. Whether you would get any benefit from just this mod without all the alterations to the tracks etc I don't know.

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Re: New to me

Post by Jerry Carducci »

Made some progress on the reassembly.

When I read from others that the completed tracks on these are difficult to install I said to myself; "how bad could it be?"

These are without a doubt one of the more difficult track systems I've worked with. I tried all manner of approaches and got
little for them save bloody fingers and a paint job that in some areas shows the level of violence required to mount the tracks.

The tracks are mounted. They were stiff beyond imagining..if I hadn't been able to clamp the chassis frame securely in my
bench vice I don't know how I would have been able to do this by myself...

The return roller on one side has a damaged shaft, as I received it, so I have to make a new one. I like my castle nuts on the boogie wheel shafts; I should add other detail there, to the wheels, but I'm going to restrain myself. I'd made some 20 castle nuts- as I intended to only put them on the outer
shaft ends. In the process of compressing both track tensioners, as per original instructions, 'something' happened to them and they refuse to extend to original length so the tracks appear loose but that's pretty hard to believe.

When I had reassembled the tracks I paid attention to the master link. I ground down the pins as far as I'd dared to avoid them damaging the running gear. I'd also made sure the master link was facing outside, away from the chassis as the instructions called out. In spite of this the master link gets caught in the idler, each time I could see a small chunk of aluminium hung up on the pin as it gouged it from the idler- it physically got hung up while running. I'm going to try to soften the edges of the master link pins to stop this damage; when I ground them I ground them perfectly flat but that left a sharp edge. The idler is one piece as far as I can determine; a very nicely made part but I can't do much to make more clearance for the roller chain. The sprocket being in multiple pieces could have spacers made but my furtive run tests don't point to this part as being an issue.

As for test running. So far I'm unable to test the drive with tracks mounted as it draws better than 10 amps sitting on blocks; tracks raised. This causes the fuse of my bench top test power supply to fail. I'll try a battery of some sort- it requires a 12 volt power source.

So, I have more work ahead of me...

Jerry
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tracks_mounted2.jpg
tracks_mounted.jpg
boogie.jpg
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Re: New to me

Post by Jerry Carducci »

Peter Silcock wrote:
Tue Apr 23, 2024 12:49 pm
Sorry Jerry typo mistake. I reduced the gear to 34 tooth not 30. Involved a new X member as well. Whether you would get any benefit from just this mod without all the alterations to the tracks etc I don't know.
Sooooo Peter, tell me more about these aluminium tracks you spoke of! Do you have photos?

Jerry
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Re: New to me

Post by Robert E Morey »

i like to see that too- alternate type of track. :P
B

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Re: New to me

Post by Jerry Carducci »

I was able to do a brief, very brief run test of the chassis. I ended up directly plugging the motor into a 30Ah Lipo pack i have.

I was surprised at the modest speed on the system despite the 24 volts supplied; mind the motor, an EMD PM44-38-2-24-4300-1
was marked 12 volts. It would never run the chassis at 12 volts no matter how much I wanted it to! There was a inconsistency that the
electronic modules were all indicated as 24 volts but the motor wasn't. I cast carefulness to the wind and went for it...

While the motor ran well enough one track would get hung up somewhere on the idler momentarily but would usually 'power' its way past this.
The idler and sprocket cages on both side showed scrubbing but actually mostly just paint. I will however work towards softening the effects of the roller chain pins and master links even further. When I assembled the tracks this time I cleaned up the master links pins further but more is needed.

I measured the clearance between sides of the idler at 21mm and the sprocket cages at 20.5mm - both of these should be more than sufficient to pass the roller chain with no problem. I did notice that both the idler and the sprocket center lines are offset by 1-1.5 mm with respect to the bogie center line. Not a lot when running the dynamics might make a difference.

My greatest issue at present is adhesion for the rubber loops. my first attempt using CA intended for RC car tires and the like didn't end well. The tracks were so stiff it made installation even harder, after a few attempts at running the hard CA was turned into black dust which ultimately failed.

After re-cleaning the chains (as described above) and loops my second attempt was to use GE (General Electric) silicon 'glue'. This was chosen as I felt, if it stayed put at all, it would remain flexible unlike the aforementioned CA. The tracks were reassembled and allowed to cure. The second attempt began much more promising as the assembled tracks were much less rigid. This was also the first use of 24 volts. I think I ran the chassis for about 20-25 seconds; my longest run, raised on blocks. After this time passed the right hand loop, partially, spontaneously detached from the roller chain whereupon I terminated the test. All 4 loops showed signs that they were ready to exit stage left... I was disappointed that the silicone glue didn't pass muster. Somehow I felt I should have known better as even marketed as an adhesive the product remained 'silicone slippery'. I will need to take extra care removing any silicone residue as it will no doubt influence subsequent bonding efforts..

I have a whole battery of other adhesives I want to try including Lexel, and even Loctite 480- however I believe this is essentially the same as my first used RC tire black CA. Beyond this I'll be searching for other adhesives.

This is such a neat little model; I really want to get it running. In the interest of shortening the research if any of you who have built this model have proven techniques please let me know. good rubber adhesives are of particular interest....I don't see any other hurdles I can't meet but the adhesive is a major one.

Jerry
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