Cherubim

I don't think that you should abandon a project as good as Cherub! Maybe if you tried revamping it or something similar.

I have decided to do some work on it over the Christmas break.
New lifting arms,
new Wotty,
different radio
And a few other mods to try and make it a bit more reliable,
It still won't win much but should last the fight.
Hope to keep you posted :D :D

Awesome! i love cherub! :D

Yeah, I like Cherubim because it sort of reminds me of Dreadnaught. Not all powerful but still good looking with those lifting forks.

Have been working on the new lifting forks hope to get pictures up soon,
looks like i will have to change the 30mm shaft too!

One of the new lifting arms they are made of 10mm Hardox type steel I could not drill them!!!
They have been bent to a similar profile to the old ones note the large lug on the top of the
new design this is to help the robot move when flipped upside down as they will keep the front higher
so the wheels at the back can touch the ground. :D :D




http://i569.photobucket.com/albums/s...g?t=1293038641

Sorry to hijack your thread Craig, but I thought you'd like to see this but you don't read the antweight section:


I call it 'Saint Jimmy'

http://www.youtube.com/watch?v=ZPzOyGw9CMw

Looking very nice Dave :D :D :D
Looking forward to seeing it go at one of the shows.
welcome to the world of not knowing which way is
Forward :uhoh: :uhoh: :uhoh:

Fitted new shaft and the new lifting arms, sorted out the welding to fix the armour.
the relays that control the lifter are going to be changed for a speed controller, I just like the idea!!
If all goes well should be ready for testing at Barnsley :D :D

Pictures 1 and 2 showing the new shaft 30mm and the new lifting arms 10mm Hardox type steel.
Also the Wotty 180 that was in Saint is now powering the Cherub with a BR6000 receiver, The Saint now has a Wotty 360.
Picture 3 shows the armour for behind the wheels 6mm Hardox Just for Kan Opener :D :D :D


http://i569.photobucket.com/albums/s...g?t=1296035244
http://i569.photobucket.com/albums/s...g?t=1296035244
http://i569.photobucket.com/albums/s...g?t=1296035244

Just fitted the speed controller for the lifter all works OK.
I am waiting for the solid state relay to sort out the motor break but if that dose not come in time then I will just disconnect that for the moment.
The Wotty 180 is working well on the drive so all looks OK for A Barnsley test.

Dose anyone read this?

Yes Craig i do and all is looking very good
hope the hardox lifters last longer than the steel ones did last time ...

:rofl: :rofl: :rofl: :rofl: :rofl: :rofl: :rofl:

Quote:

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Originally Posted by craig_colliass

Dose anyone read this?

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I do :) just don't comment often as heavyweights aren't my field...it does look fantastic and I am very much looking forward to seeing it in the flesh at Barnsley.

Yes the flanges were cast steel they were a temporary fix for RIAT the new ones are 10mm Hardox type steel that I could not drill and the foundry could not bend with out heat!!!!

http://i569.photobucket.com/albums/s...g?t=1296899101
All done ready for Barnsley WARNING this robot could damage other robots handle with care!!

:uhoh: :uhoh: :uhoh: :uhoh: :uhoh: :uhoh: :uhoh: :uhoh:

http://www.youtube.com/watch?v=AxUCCWX2G34

After the Barnsley Event, some work and modifications to Cherub was needed.
On the whole the robot worked OK. Only a chain link broke in one fight,

I have screwed the battery box to the under tray of the robot as it got bits of Jonno's arena stuck between, this pushed
the tray even lower and fouled the floor slowing down the robot.
Also I am trying some wheels on the lift arms so when I have Beast on board again I can drive over to the pit and
dispose of it there! :D :D

I hope to get some tyres from Oxford soon and inner tubes for the drive wheels and then see how it dose
in the next event. :uhoh:

I had decided to either scrap Cherub or rebuild it. After some thinking I decided to rebuild but it was close. :uhoh:

The good bits
The basic principle seems to work OK.
The drive motors with gearboxes and wheels work well.
The shape and armour seems to take the Thor test OK

The bad bits
The lifting system is unreliable (chain snaps too often)
The lifting system is far too slow.
Batteries don't seem to last the fight.
Inner frame is far too week this gets bent up every time.

The Work I am hoping to do on the robot.
Make a torque limiter to reduce the likelihood of chain breakage.
Change the lift motor and gear ratio so the lifter will operate much quicker 1/4 turn in 1/2 second!
Lithium-ion batteries.
The Inner structure of the robot will be completely re-done no more 25mm box section rubbish this time it will be 5mm armour bulkheads, Thor proof hopefully :mrgreen: :mrgreen: :mrgreen:

When I asked I was told that you weren't allowed lithium ion batteries

Lithium-Ion are A123 batteries, I think these are allowed
The batteries you are thinking of are Lithium-polymer batteries these are not permitted in heavies at the moment.
Though I believe LiPo batteries are being tested on the heavy weight robot Big Nipper so soon they may be :D

Correct A123's (LiPofe4?) are allowed, but lithium polymer aren't. Big Nipper are currently testing Lipos in heavies at our events (not sure if RR are letting them at theres), but it'll be a year or so before we come to a decision on them, if they are allowed, their will be very strict rules in place. Most people won't have an issue running A123s, theres a few poeple already one them; Storm 2, Behemoth, Toxic, Thz and a few more.

Just to clarify; Lithium-ion or Li-ion are the sort of batteries you find in laptops and phones.

Lithium-Iron-Phosphate (Sometimes called Lithium-Iron, hence the confusion) or LiFePO4 are A123 cells.

To further confused matters Phosphate's chemical symbol is PO, so you have Li and Po in the chemical name of Lithium-Iron-Phosphate which sounds like Li-Po which is Lithium-Polymer, the banned battery in heavies!

Argh!!!!!!! :shock:

Well I'm glad thats sorted :crazy:

Thread Unlocked

Many thanks Kane

After a little break in the work on the Cherub rebuild, things are moving along quite well, I hope to use 24v A123 packs for the power rather than the SLA 24v system used before this has released some weight that has been spent on increasing the base armor from 3.2mm aluminum too 5mm steel armor the same as on the top!

Also the motor for the lifting mechanism is being changed for a 250w drive similar to the motors in Pilgrim and Spiderbot. the ratio is being changed from 300+:1 to about 100:1 this will increase the lift speed by a factor of at least three. also I hope to use some sort of friction drive to reduce the chain damage I have experienced in the past.

The speed controllers will probably stay the same for the moment. but the idea of running the robot at 36volts is something I would like to do in the future.

The inner structure and motor mounting brackets are being completely redesigned to withstand the hammers and crushers that are about at the moment.

The idea is to get it ready for 2013 and give Saint a rest. :mrgreen:

Start to the winter build Is going well I had to get another drill for the project as the batteries on the old one were getting past it and the drill was not too far behind. :shock:
At the moment I'm getting the motors repositioned in the robot, done the drive motors now for the lifter motor.

The battery box is made and the link bracket I have decided to completely rewire it as the old routes for the cables have been changed too much, A lot of failures in the arena are due to small errors with the electrics, for me it's usually a link popping out.

Hope to get pics up soon :)

this has probably been detialed before but struggling to find it, what motor do you use on cherubim's lifter?

cheers alex

This is a good question :D

The first motor used on the lifter on Cherub was a mobility scooter motor with a gearbox 30+:1 ratio it then had to go through a 2 stage chain drive to get any power to it and as a result it was far too slow.

The motor I am hoping to change it for is similar to the ones in Pilgrim and Spiderbot, these are EMD 24v 12.5A 300w motors gearbox output speed is 140rpm at that voltage I will be running the motors at slightly higher voltages as I'm using A123 batteries in it. this will go through a single stage chain drive 3.75:1 so will spin at around 37-40rpm I am not confident this will be powerful enough and am trying to contact Mike Hamilton-Macy to see if he has any bigger motors to fit these gearboxes.

thanks :proud:

Did some tests with the new lifting motor everything went really well till smoke came out. :shock:
Now looking to see if I can squeeze in a Bosch 750w on to the gearbox. :?:
I can't believe I would need this much power just to lift another robot up!
With the Bosch the arms should be good to lift about 250kg That's 1/4 of a tonne that's if the gearbox can take it. :uhoh:

Wow, what size gears are you using to take the force? They must be pretty tough!