[TC11] Wimbledoom

[Erik Leppen]

I guess it's time to share my works for TC11. To be honest, I started building almost on day 1, so this means I tried out a lot of things that didn't work, and that I won't show all. Anyhow.

 

So, my first plan didn't work because it didn't fit the box (remember the diagonal question? It was a long thin design.) Secondly, I didn't want to do a spinner. A spinner seemed boring to me. I wanted to do something bit more technical. A lifter? A slammer?

 

I built a lot of (non-functional) battlebots back in the studded age, when I was still a nerdy teen, but I don't have those photos anymore (which is a shame). A few bots I do still remember, so I chose a design from those that I always liked. The concept is this:

So, it's a "horizontal dual hammer" bot. I think there are very few horizontal slammers, and I think it's cool. The original was named "Wimbledoom" because it had a flat top with some sort of a stadium with two figs and a tennis net (white fence) and some minifig audience. So let's use that as a working title for now (even though the tennis theme won't return) The idea is that there will be some sort of force built up and then released to slam the hammers forward into an enemy that's in between. The high speeds and sharp ends of the hammer will damage the enemy. Then, a slow return mechanism should bring the hammers back in their original positions. So, how to build up force? The frist thing I thought was "wprings are too weak, I want something better" and I was thinking about a flywheel approach, where a motor tries to let a wheel spin really fast and then somehow make a sudden connection with the weapon. This idea got quite far:

The idea was that the orange axles move the gear racks so the green gears mesh with the red gears. If slid back, it meshes with the blue gears, which would be the return mechanism.

 

It didn't work. It had far from enough force, and most energy was lost to the drive train anyway. I tried mechanisms with fewer gears (and using tires as gears) but they all didn't work. So I went back to the idea I originally rejected:

Springs. These are all long springs I have except for some black ones from a motorbike set. As if it was meant, the dark-gray ones are half as strong as the other ones, which are about equal. Which means this is the perfect spring:

As energy is distance times force, this spring, with a distance of 6 studs and a force of two 8466 springs, should store quite some energy (remember, this is the suspension from three large sets added together).

 

So, now the hammer itself.

Of course, this is a mock-up. It needs to be strengthened with plates and tiles, because, well...

one particular piece didn't survive a test version... (it was already slightly damaged)

OK, so I needed a mechanism to rotate the hammer about 180 degrees (preferably slightly more), and a frame to hold it. For the frame, I learned: if it needs to be strong, make it triangular.

This is not exactly Pythagoras correct, because the straight sides are 7^2 + 24^2 = 625, where the diagonal is 25^2 + 1^2 = 626 (due to the 2x2 corner plates at the pointy end), but this difference is so small that noone will notice.

 

To rotate the hammer more than 180 degrees, you can't just attach the spring to the hammer directly - you need a system of beams to amplify the motion in some way. This was a long puzzle and I eventually came up with


(the red axle is where the spring will attach)

The idea is that this is one half of the bot. It will eventually look like so:

which gives plenty of space in the center for PF material and a drive system for some wheels.

Doubling the frame gives

which, as you can see, stays in place without me having to hold it, so it has an automatic locking mechanism due to the geometry of the beams (it locks over center). Moving the yellow part a little makes it blast away with quite some force. I'm happy!

 

Dimensions of this unit so far:
Width 17 (which is half, so width will be 35 or so)
Depth 34
Height 8

Well within the limits.

 

Next challenges are: fitting some drive mechanism, finding a way to trigger the mechanism, and maybe most importantly, building the return mechanism (which is where the 40t gears come in).

Edited April 17, 2017 by Erik Leppen

[Leonardo da Bricki]

This is a cool idea, and looks really dangerous, sort of a thing that I would be afraid of hitting myself with.

[msk6003]

So many spring. How much strong?

[roppie11]

that is a very cool weapon. I also thought of a horizontal hammer with the help of rubber band. But i couldnt figure out a way to make it work so i went with a vertical hammer. Good luck it looks very promising.

[Erik Leppen]

I moved one side of the trisngle out of the way to make space for a wheel.

I wanted a fairly big wheel, but I don't have motorcycle wheels. The biggest wheel that fits is the good old truck wheel from 42043 and many other sets.

Doubling the whole thing, and adding a simple drive system in between. The wheels are just far enough apart to have enough force for rotation and drive.

I added a batter bos and receiver module in the back. This was more work than I expected because the original design didn't have room for the connectors for the receivers. So I had to change the whole shape of the BB holder. I'm not entirely happy with the bump in the back, which makes it 3 studs longer, but I wanted an easy-access on-off switch.

Here's a bottom view. Also as you can see, I decided on a color scheme: lime with yellow, and the rest in greys. The BB module is easily removed by pulling the 8L stop axles. Also the drive motors (will be M motors) go on the brown 3L axles

Edited April 8, 2017 by Erik Leppen

[Ramacco]

Lovely robot. Also an interesting technique to use studded parts to connect the Technic beams to each other. Any reason why you do this?

[Erik Leppen]

Strength and compactness.

The connections have zero play ad are much stronger than pinned connections, because pins are hollow and studs are solid. The two 13L beams conndeted by 1x4 plates acts like a single 26L beam. As a consequence, the whole triangular frame acts as a single large piece. As long as theforce is perpemdicular to the direction of the studs, there's no problem. If it was connected by pinned beams, there would be more bending. Also, the large springs are slightly larger than 1 stud in diameter  (which is why I normally never use them), so I needed a solution that was less than a stud wide in order to keep the whole unit as flat as possible. A fully studless solution would likely have become 9 studs high instead of 7 now (or 7.8 including the plates).

[PKW]

I really love this build and how compact it is, but I see that drive is really compact, even with 1.6:1 gearing the bot will be quite difficult to drive and have low power on turning (trust me also because the battery box is on the back) do you have L motors to use? And maybe a way to move the CoM more on the front of the bot?

[Erik Leppen]

Progress!

I added a gear system to drive the hammers. The idea will be that the clutch will be coupled, the hammers will return backwards, then at the right moment the clutch will be decoupled and the hammers slam forward.

This vertical axle will be used as a trigger. I'm so happy it just fits in between all the rest! Turning it slightly will push the blue 1x2 beams against the hammers just enough for force to build up. Unfortunately, right now they are very close from turning over center, so without friction, the hammers will always release. The clutch chould prevent that.


The idea is that the clutch will be connected to the trigger, so that at the exact time of decoupling, the hammers are also pushed outwards.

The backdrive mechanism will be driven by a third M motor that will fit right there (again, on the brown axle).
The gearing is 12/20 * 12/20 * 12/20 * 12/16 * 8/40 = 81/2500, which is about 0.032

This is the complete image, in starting mode, and after release. The normal mode right now is 44 x 37 x 13 studs.

The ends of the hammers are very thin because this makes the hammers lighter, and they will require much less momentum to accelerate, so they become much faster.

even with 1.6:1 gearing the bot will be quite difficult to drive and have low power on turning (trust me also because the battery box is on the back) do you have L motors to use? And maybe a way to move the CoM more on the front of the bot?

I don't have L motors, unfortunately.

When, in the end, there's space left between the motors and the battery, I can move it forward a bit. But there will be some more weight in the front for the switch mechanism (which will be quite large), so I think the center of mass will end up pretty close to the wheels.

But yes, 2 M motors is a bit light for this size. It will have to do - XL won't fit and I don't have L.

[agrof]

This is a very original idea, and technically one of the most sofisticated, amazing. 

I see flying bricks though (which are just attached by studs) from the arms, and also it looks quite flexible, so I am not sure if the energy wouldn't be lost in flex, instead of the impact.

[Erik Leppen]

There's a little problem. I was gonna post about the switcher module that would tie everything together. The problem is: it doesn't work. Apparently, the M motor can't flip the two clutches reliably, at least not when the springs are "loaded" (compressed). I tried 12:20, 12:36 and worm:8, but for some reason, even with a worm it doesn't work. So something might be locking the mechanism somewhere, and I haven't found out what. Anyhow, here's the module itself.

I know it's hard to see with all the black, but this is the 12:36 geared version. The two changeover catches are connected with the long axles with the blue 1x2 beams you saw in earlier posts. So this module will go on top of the bot.

These will be all the pictures for today, because I ran out of daylight ;)

Anyhow, as PKW suggested I moved the battery box two studs forward (and half a stud down), and found another way to mount it. The on-off switch is gone, and the bump on the back with the two green panels is also gone, so it's 3 studs shorter now. But now there's a small empty space in the back. I might put a guide wheel there, but I might also leave it empty.

 

 

 

[agrof]

Have You tried to move it manually with a crank? It can give a good feedback if more force is needed (XL motor, gearing even more down?).

[PKW]

54 minutes ago, Erik Leppen said:

There's a little problem. I was gonna post about the switcher module that would tie everything together. The problem is: it doesn't work. Apparently, the M motor can't flip the two clutches reliably, at least not when the springs are "loaded" (compressed).

I've never tried the new clutches bur I know that the old one offers a lot less resistance, have you tried them? Also with smooth 2M connectors, not grippy ones, that would may solve the problem

[Erik Leppen]

Using the old ones sounds like a good plan. I didn't think of that. The problem with this is that the whole things moves a half stud, but maybe this can work out. Thanks for the suggestion, will try tomorrow!

[PKW]

1 hour ago, Erik Leppen said:

Using the old ones sounds like a good plan. I didn't think of that. The problem with this is that the whole things moves a half stud, but maybe this can work out. Thanks for the suggestion, will try tomorrow!

I found that if you are only requiring to use gear on one side of the clutch then the half stud is not necessary, take a look at this file to understand what I mean: Example (LDD file of a moc)

Edited April 12, 2017 by PKW

[Erik Leppen]

Good news! It was not the clutch that was the problem. The problem was that the hammers were too far back, so the spring worked in the opposite direction, and therefore the motor couldn't push them out. So the issue has been solved without having to rebuild the switcher module.

Bad news: it turned out that a few parts were under quite some stress because of the release mechanism, and the axlehole of a yellow 2x4 beam didn't survive the force of the weapon. As you can see in previous pictures, the link near the 40t gears consisting of two yellow 7 beams and one 2x4 L beam suffered too much bending force. So I rebuilt that link and reinforced it with plates, and used only beams with round holes.

But the best news is that I have videos to show!

Here you see only the weapon. So this finally answers the question by msk6003 early on. It also shows the weapon is unfortunately quite slow, and the M motor struggles, but I'm so glad everything seems to work. It's a bit hard to operate though :)

On ‎7‎-‎4‎-‎2017 at 3:13 PM, msk6003 said:

So many spring. How much strong?

This also shows the drive. I think the concerns by PKW about the center of gravity turn out to be irrelevant: the center of mass is almost exactly at the wheels when the hammers are extended. In normal mode, when the hammers are folded, the center of gravity is slightly behind the wheels (no more than 2 studs), which is good, because I have space in the back for a dummy wheel (which is much better than sliding over the floor). Also, the speed is decent. It's not super fast, but it can turn quite fast and for two M motors I'm more than happy.

So, I think the techniques are almost done. I also added a bit more lime. The body will be very sparse, because I don't want to add too much weight. So I will probably only cover the 5x11 frames and the back with some plates and tiles. And of course, add the hammer's ends.

[Kelkschiz]

Very cool inspirational mechanism. Good luck in the competition! 

[agrof]

Despite the relative slow loading, I am deeply impressed. Another serious entry. 

Edited April 13, 2017 by agrof

[Erik Leppen]

I did some work on the body. I think it turned out quite cool.
It's now almost finished. I think I will be changing the ends of the hammers a bit, and I want to add a dummy wheel in the back. That's it.

[PKW]

Love that aesthetics and green color! Also really happy that you have no issues with th CoM  (i thing the whole mechanism weight move it to the front enough to the front) also for what concerns steering speed/torque I checked my old mechanism and I was using 1:1 M motors instead of 1,6:1 so that helped too

 

For the dummy wheels yes do that but some real bots or even some of my legs ones were trapped in the pit/edge of the area due to a caster wheel that fell off and prevent the bot to free itself! Ahahah never forget that robotics combat is also a matter of luck

[Erik Leppen]

I just posted my entry in the entry topic.

Here're the latest images, and the entry video.

The final bottom shot shows that I added a dummy wheel in the back, which works like a charm (the bot looks perfectly horizontal, and runs very smooth)

 

Also I decided to just keep the name, I liked it, even thought it has doesn't mean anything at all anymore.

 

[heyitsdisty]

I really like this entry! Reminds me of the Robot Wars contestant Splinter (but without the scoop). Those hammers/pincers look pretty powerful, and the armour design is very eyecatching - you managed to make bare Technic beams actually look really good. Nice work!