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MadInventor

Super Heavy King Tiger

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I can't wait to see this move under it's own steam, I love the hammer dinks, although I did wince when the steel tank rear-ended the tow tank, ouch! Any damage?

No damage fortunately, I think if it hadn't hit the tow tank it would probably have gone straight through the fence with the downhill slope. :P I'm just pleased the silver cans had plenty of power to pull a slightly overweight vintage tiger as well as 9Kgs of dead weight up a slight incline. I think with further gearing down and dual brushless motors, the steel tiger is going to be a bit of an animal, escpecially if I go for an 10.8V battery instead of a 8.4V :angry:

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Martin, you have been busy. I like the newly revised version of the camoflage, the previous version sure had a lot of polka dots.

Though I think they even look nice when they are just tan coloured.

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No damage fortunately, I think if it hadn't hit the tow tank it would probably have gone straight through the fence with the downhill slope. :angry: I'm just pleased the silver cans had plenty of power to pull a slightly overweight vintage tiger as well as 9Kgs of dead weight up a slight incline. I think with further gearing down and dual brushless motors, the steel tiger is going to be a bit of an animal, escpecially if I go for an 10.8V battery instead of a 8.4V :lol:

I think brushless and LiPo with some gearing down will get you some half decent run times too.. otherwise it's going to munch it down like a big 'un.

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For some reason, I prefer tanks with single color. The desert yellow is nice just by itself with anti magnetic paste added.

On a more serious note. You are charge under section III (a) of military proceedures using one tank to tow another tank. Is an absolute NO, NO what you did. Unless is to prevent enemy capturing the Tiger. Your full report on my desk at 0800 hrs else to the Russian front without winter gears.

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That is simply awesome!

It's the sort of thing you dream about building,but very few have the skills :)

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What did you use for the welding?

A good friend of mine TIG welded it together for me :(.

Another progress repor't to follow this weekend, I've got the plate for mounting the gearbox to fitted, and the detail work manufactured for one side of the hull. Won't be long now before the gearbox is fitted.

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A good friend of mine TIG welded it together for me :(.

Another progress repor't to follow this weekend, I've got the plate for mounting the gearbox to fitted, and the detail work manufactured for one side of the hull. Won't be long now before the gearbox is fitted.

Subscribed!

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Hi all, here's the latest on the tank:

Last weekend I added the final detail to the left side of the tank. Look closely at the photo, the cleaning rods are made from steel, as are the clamps holding them and the tow rope, and the tow rope itself is metal, slotted into the ends of the standard tamiya part, which I drilled out to slide the wire rope into. I also superglued on the spade, pry bar, and winding handle.

img33435_08052011190222_1.jpg

I have also fitted an aluminium plate in the front of the tank to mount the front gearbox onto. This is mounted on 4 aluminium 8mm rods with a 3mm hole drilled through, and the plate has m3 threads tapped into it. There's a few too many holes in it as i had some alignment issues.... ;) You can also see clearly the plastic collars I made to prevent the suspension arms from working their way out of the chassis.

img33435_08052011190222_2.jpg

Today has not been as productive as I would have liked. I spent most of the morning doing trig to get the holes in the right place for making the 4 vertical plates I am going to use as the basis for the gearbox. The afternoon was then spent making a jig to attach each plate to so that it is held precisely whilst I drill and size it accurately. Alignment is crucial when building gearboxes from scratch and an error of 0.05mm can be enough to junk a part.

To give some idea of the work involved, here's the back of a cornflake packet with a diagram for laying out the holes for the jig:

img33435_08052011190222_5.jpg

From this a large block of metal was mounted in the tilt vice, clocking the vice to ensure it is both flat and square. I've used the tilt vice as later I will need to cut the plates at an angle to ensure they fit in the front of the tank ok.

img33435_08052011190222_3.jpg

This was then drilled and tapped for M3 threads to hold the gearbox plate solidly in place, as well as drilling holes to leave clearances for the shafts and bearings that will be fitted to the g/b plates.

img33435_08052011190222_4.jpg

I also started work on the first plate. This will be vertical when fitted in the tank, and I have recessed the allen head screws so that I can get the plate as close to the hull as possible to give maximum support to the front sprocket axles. The 2 additional holes are for the main sprocket axle, and the idler/bevel gear.

img33435_08052011190222_6.jpg

Getting 4 of these made and mounted to the flat plate in the hull is going to keep me busy for some while, after the 4 plates are made I've got at least 8 horizontal supports to make on the lathe, as well and the centre block for the transmission. When I have some more progress I will post pics.

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This is the progress on the gearboxes in the last week. The frames have been profiled to fit tightly into the front of the hull. (Don't forget the upper is welded in place and cannot be removed like on a normal tamiya king tiger. I have revised my design so there will now no longer be a central block supporting the drive shafts and bevel gear gear bearings, but 2 smaller blocks fitted inside the main supports. Unfortunately I've got to move all the frames inboard 0.5mm as the screws holding them on won't go down in the hull. The gearbox side plates are a precision fit and I forgot the screw heads were wider than the 5mm thick ally I used for the frames. Still, shouldn't take too long to rectify. Whilst I'm waiting for the boring head to turn up I can also plod on with machining the flats on the drive shafts where the grub screws are going to wind in to hold the pinion gears in place. When I finish this it's going to be nice to build a kit without having to make three quarters of it myself !

img33435_15052011190058_1.jpg

img33435_15052011190058_2.jpg

img33435_15052011190058_3.jpg

23/05/2011, edit:

More progress since last weekend. The 1st stage of the gearbox is now complete, it was an absolute pig to build with the 90 degree drive and tight fit, I had to remove the front lower glacis plate in order to fit the main drive shaft pinions (Pinions from modelsport with 5mm dia hole for brushless motors.)

Here's a rather blurry pic of one of the 2 home made input shafts I made:

img33435_23052011071419_1.jpg

Fitted with Jugg2 UJs ready to accept input from a reduction box and motors at the rear of the tank.

img33435_23052011071419_2.jpg

Home made drive shafts for the final sprocket drives:

img33435_23052011071419_3.jpg

img33435_23052011071419_4.jpg

View of the assembled gearbox before fitting in the tank.

img33435_23052011071419_5.jpg

img33435_23052011071419_6.jpg

Small vid of me testing the transmission for smoothness before fitting in the tank.

http://www.tamiyaclubmovies.com/movies/33435/m9UR8142Z91.AVI

Gearbox fitted in tank. The tight fit of everything is clearly evident. Note the thickness of the upper frontal armour plate ;)

img33435_23052011071758_1.jpg

Internal view of the gearbox fit. Jugg UJs are ready to accept input from whatever reduction gear / motor combo I decide to go with. The next bit should be relatively easy after the 90degree drives :D

img33435_23052011071758_2.jpg

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This must be one of the maddest projects I have seen, and I though I was good mixing meccano to make a cantilever suspension set up.

More more more please.

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That thing should be able to withstand handgun fire (atleast thaks to the angle)

Beautiful work!

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This must be one of the maddest projects I have seen, and I though I was good mixing meccano to make a cantilever suspension set up.

More more more please.

Sorry guys, no more progress on the tank at the moment, I've been working on this:

http://www.tamiyaclub.com/forum/index.php?showtopic=62511

instead. I might get back to the tank when this current project is rolling, I'm hoping it shouldn't take too long......

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Progess Report !!!! :)

After much deliberation I have decided to build my own final drive for the tank. i was very tempted by MFAs reduction gearbox motors and the yare excellent value, but in the end decided that I didn't think they would be able to handle the torque. So I've gone with using 2 TXT-1 gear sets, with the addition of a hornet spur gear to the top end of the transmission to give me additional gearing down. With 10tooth pinions, this will give a final drive ratio of 44:1. Here's todays progress on the build of the gearbox. This is the second attempt at the aluminium plate as I ddidn't get the holes quite right in the first one. two more plates, a few spacers, and the drive shafts for the final drive gears, and I'm in business.

img33435_16072011180106_1.jpg

img33435_16072011180106_2.jpg

img33435_16072011180106_3.jpg

img33435_16072011180106_4.jpg

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Hi all,

I had a bit of a setback with the gearbox build, I got 2/3 of the way through it to find that the lid wouldn't fit on. Arrggghhhh. As Wile Coyote used to say, back to the old drawing board....

So after a bit of head scratching, I redesigned the gearbox so that it was 6 mm lower.

img33435_10082011233006_1.jpg

img33435_10082011233006_2.jpg

I have spent most evenings for the last 2 weeks building the gearbox, so this evening I was able to fit the mounting plate for the gearbox into the tank.

img33435_10082011233006_5.jpg

The gearbox is nearly completed, this is what it looks like in the tank

img33435_10082011233006_6.jpg

img33435_10082011233006_4.jpg

img33435_10082011233006_3.jpg

Thats 2 txt-1 centre transmissions squeezed in there, along with a hornet spur gear added to the high end of the transmission to give an additional gear reduction. The final ratio should be in the region of 44:1, and I have fitted 2 ansmann 80turn rock crawler motors for minimum RPM and max torque.

I've still got to make a bracket to secure the gearbox, machine the flats in the right place on the final drive shafts (within the gearbox) for the hexes to screw down onto that the final drive gear fits on, then 4 spacers later and 2 drive shafts, and mechanically it's ready to run. Just bung in some RC gear and solder the wires on the motors and it's good to go. And I'm rather looking forward to that day. ;)

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You don't do things the easly way do you. Great stuff, wish I have 1/10 of the skills you have.

Just realized you also built the Jadpanzer. :lol: No wonder the King progress seems to have stopped. You are forgiven for the delay.... ;)

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Thanks guys,

Managed to get in a quick test drive round the lounge last night, quite a bit slower than a tamiya tank but I think a good scale speed. 10.2Kg including all the radio gear and batteries. Hopefully off out this afternoon to take some video, so watch this space for a YouTube video link :)

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It's a great scratch build mate! How long does the battery last pushing such a large weight?

Watched the video too. It really does have that 'heavy' effect over terrain that a real tank would have.

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It's a great scratch build mate! How long does the battery last pushing such a large weight?

Watched the video too. It really does have that 'heavy' effect over terrain that a real tank would have.

Thanks for the positive comments Mark.

I suspect the run time would be similar to a normal tank, as it moves at about 1/4 the speed of a normal tank for about 5 times the weight.

Unfortunately it shredded the 90 drives after about 6 minutes run time, so haven't had a chance to flatten a battery. (That's all the clicking you can hear at the end of the video).

As I've put such a maximum effort in to get it this far I'm going to step back from it now for a while. I proved it would run and could move under it's own power, but the plastic gears in the 90degree drives just aren't strong enough for the torque the initial reduction gearbox produces.

The 90 degree drives have a 4:3 gear up, as I could only fit 15tooth gears on the final sprocket drives, and these were driven by 20 tooth thundershot bevel gears. The TXT-1 / hornet combo gearbox at the back has a reduction ratio of 60:1, so with the torque of the 80 turn motors the inputs to the 90 degree drives have enough torque to twist/shred pretty much anything. They took the teeth off the plastic gear that drives the final 15 tooth pinion on the right hand 90degree drive, and twisted the flat out of the inside of the bevel gear on the input shaft on the left hand side. The problem is the massive amount of traction that the weight provides with the wide tracks. The tank is fine going in a straight line and up and down hills, but when turning you can really hear the motors straining.I now have several choices:

1. Try and get someone to replicate the thundershot gears in hardened steel and hope they will take the abuse.

2. Completely redesign the 90 degree drives to remove the 4:3 gear up and use heavy duty gears (No idea where to get these from though, but whatever I use will have to be hardened steel thoughout, I can see it just chewing up even TXT-1 gears, which are made from brass.)

3. Redesign the front transmission to use no bevel gears and mount the motors and reduction gear up the front, as is done with tamiya tanks. The problem with doing this is that all the weight goes up the front end and the springs won't cope. It already sits a couple of mm lower at the front end than a standard king tiger, with just the weight from the 90 degree drives. Also this would mean binning the reduction gearbox at the rear of the tank, and this would be a shame as it works very well.

Right now I'm just going to sit back for while from this project. it's taken a massive effort to get it this far, and the failure of the 90 degree drives is a bit of a blow, as a lot of time and effort went into building them. Having turned over the transmission by hand at the motor pinion, I can feel the amount of force that goes into turning the tank, and I wouldn't be surprised if the UJs failed if a heavy duty 90degree drive system is fitted.

On the plus side though the tank handles completely differently with the massive weight. As you can see from the video, the hull is very stable over rough ground, with the suspension doing all the work, unlike with a lighter tank. It also ploughed through the weeds like they weren't even there, when the camera tank tried it the front end was lifted slightly by the plants. I also noticed when turning the tank sharply that the tracks chew up the ground very effectively (As well as my bevel gears :) ).

I do hope to get this going reliably at some point, but at the moment I can't face another major amount of engineering on this project. The next job on my machining list is to make a mahogony jack block for my Jagdpanther, nothing too technical or tolerance critical B).

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These guys do steel bevel gears in 32DP, you'd have to use another separate gear next to it as it wont come with one - a big long flat on the shaft methinks :)

http://www.hpcgears.com/newpdf/bevel_gears_8.0_48.0dp.pdf

http://www.hpcgears.com/newpdf/spurgears_32dp.pdf

don't let this dull your enthusiasm for the project, its fantastic, cant wait to see it flattening hedges :lol:

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These guys do steel bevel gears in 32DP, you'd have to use another separate gear next to it as it wont come with one - a big long flat on the shaft methinks :)

http://www.hpcgears.com/newpdf/bevel_gears_8.0_48.0dp.pdf

http://www.hpcgears.com/newpdf/spurgears_32dp.pdf

don't let this dull your enthusiasm for the project, its fantastic, cant wait to see it flattening hedges :lol:

Hi Bugjammer,

Thanks for taking to post these links up for me. I appreciate it's taken time for you to find the appropriate data for me. Looking at the bevel gear lists I'd probably have to go for 24DP (I don't think 32DP is going to be strong enough, I'd ideally like the 16DP as they can take way more torque, but the smallest diameter bevel gear is 35mm which won't fit in the tank !) I'd then be looking at about £80 for 4 bevel gears, which is too steep for my taste at the moment. I seem to remember RW racing offering a service to custom build gears, so I may contact them to see if they can do anything for me. First I've got to figure out if I'm going down the bevel gear route though, or whether to completely redesign the transmission to fit in a similar fashion to the way tamiya have designed them. As soon as I have some more news, I will of course keep everyone informed.

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Have a look at this site:

http://www.rccommand.com/Tank%20Upgrade%20Parts.php

Scroll down to precision engineered high torque gearboxes from Tamiya.

Designed for tanks built to scale weight in 1/16th scale(a scale weight KT in 1/16th needs to be 30-35 lbs/15-20kgs).

RC Command also make custom tank gearboxes to your requirements.

Yours is behaving entirely prototypically.

Tiger 1's and KT's were well know for eating gearboxes,Tiger 1's were nearly 53 tons all up,KT's were nearly 60.

Their 'boxes were designed for tanks 10-15 tons lighter

Mark

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