We used the NPC T-64'S with the same puncture proof wheels in Carbide, using 2 x optipower 4s 5000's in series, and we never ran short of capacity.
If your budget will allow- id stick with the optipowers.
I think I'll end up going for the optipower because of the discount scheme. Can you reccomend a charger?
How many batteries did you use for your etek?
Also the wheels came in and seem slippy.
Did you have any traction problems? I tried degreaser and it didnt help. Sanding them helped a bit.
Lots of progress on the design.
Attachment 6271
We have struggled with the locking mechanism for the electric arm.
The resultant forces from the hydraulic cylinder arm are at a ratio of about 3:1, so 24 tonnes of force to resist!
With a shot bolt or ratchet set up, the material would just deform, or needed to be very bulky. the failure mode is also pretty catastrophic.
We have decided to go with a band brake driven by a 32bore hydraulic cylinder.
http://www.tribology-abc.com/calculators/e3_5d.htm
It is a lighter set up, it has a much kinder failure, in that the drum will just slip, and it should still give us enough holding force to give us our 8 tonnes at the tip.
All of these mechanisms have took their toll on our weight budget. Everything in the photo is 97kg currently, and we still have to add hydraulic oil, hoses and Armour ( which will probably be mostly 15mm PE)
The remaining design work will mainly be taking weight out of the existing components to free up weight for armour. We hope the design will be finished within a week!
Most of the components are laser or water cut, so we are hoping the rest will go together pretty smoothly...
Lots of progress on the design.
PROGRESS, 2016-10-04.JPG
We have struggled with the locking mechanism for the electric arm.
The resultant forces from the hydraulic cylinder arm are at a ratio of about 3:1, so 24 tonnes of force to resist!
With a shot bolt or ratchet set up, the material would just deform, or needed to be very bulky. the failure mode is also pretty catastrophic.
We have decided to go with a band brake driven by a 32bore hydraulic cylinder.
http://www.tribology-abc.com/calculators/e3_5d.htm
It is a lighter set up, it has a much kinder failure, in that the drum will just slip, and it should still give us enough holding force to give us our 8 tonnes at the tip.
All of these mechanisms have took their toll on our weight budget. Everything in the photo is 97kg currently, and we still have to add hydraulic oil, hoses and Armour ( which will probably be mostly 15mm PE)
The remaining design work will mainly be taking weight out of the existing components to free up weight for armour. We hope the design will be finished within a week!
Most of the components are laser or water cut, so we are hoping the rest will go together pretty smoothly...
Last edited by Andron4000; 5th October 2016 at 10:41.
The angle that the hydrualic nipper sits at looks as though it would just skip along the top of an opponent once clamped, as opposed to puncture it.
Seems like you could lose a lot of weight from the drive train, unless you want to be a pusher as well. With so many spinners it might be better to go for armour so as to be able to be upright and moving to deliver the weapon?
The spike is just a place holder part at the moment to gauge the size/ weight. I think it will have to be more tooth like to follow the arc of the arm.
The top arm is waterjet 15mm aluminium, and we've managed to cut quite a bit of the weight out by adding the spine strip and gussets
arm assy.JPG
The drive chain is pretty simple now. We had to get rid of the chains and sprockets for weight, and now it consists of the wheel, an adaptor plate to the t64 motor gearbox, and a mount bracket.
drive assy.JPG
The weigh is down to 90, with about 5kg to add in the front right armour, and about 10kg in the plastic armour on the rear
The central weldment that hold the arm and band brake drum will act as the baseplate. I think it will need to be redeisgned to be bolted together and modular. This will speed up manufacture and make repairs possible
drum assy.JPG
Looking to get design finished by next week and lasers/ waterjet on order!
Looking very good...
a question about the ram here. You said it was setup 3:1 to give you 8tonne at the tip. But it doesn't look like that on the pic. It looks more like 1:1. Or am I getting lost somewhere here lol.
Its a 2 stage weapon.
The hydraulic set up is 1:1. The whole assembly above moves powered by an electric motor, like an axe.
Once we want to start the hydraulic crushing, we need to lock off the electric movement which is the 3:1
Hello
Almost done!!
I have spent all weekend designing, and just have a few things left to cut holes in for weight saving.
2016-10-10 1.JPG
As you can see, it is pretty naked at the moment. I have abandoned all armour to figure out how light I can get the main weapon arm and other essentials before trying to protect them.
I have left the 2 arms at the front steel. If nothing else them might be able to take a beating..
2016-10-10 02.JPG
This is the two stage crusher/ piercer. the big disk thing on this side is the drum for the band brake and the little hydraulic cylinder operates it
2016-10-10 03.JPG
The electric motor will operate the arm like an axe.
2016-10-08 03.JPG
The hydraulics will then extend. Both the large and small cylinder extend and retract together, and because of the size difference, the smaller will react faster. this will lock the band brake onto the drum.
The large cylinder is shown at end of stroke here. We are relying on it pushing stuff in towards the main shaft so that all the reactant force arnt going through the band.
The failure mode of the band is hopefully just slippage, rather than snapping the band or shearing the drum flange bolts...
2016-10-10 04.JPG
We have been forced to use the T64 for the axe motor, as we cannot find the weight for a separate circuit to run the 48v ampflow. I'm hoping that at about 1:12 ratio it should have enough power to self right us, and also be a half decent hammer...
This gearing may have to be with a waterjet steel spur gear, again, weight...
2016-10-10 05.JPG
I added these steel bands to give us something for the 'armour' to attach to.
We have a big sheet of 15mm PE1000 in the workshop which weighs 9.5kg. I think this will be the way to go, as you do seem to get quite a lot for the weight.
I'm hoping that if its angled right it might deflect, and the bands will act quite elastic...
2016-10-10 06.JPG
oh yeah, and the arm was clashing with the body so I cut a massive hole in the floor so that we can retract far enough to self right!
I have said hope a lot in this post.
All in all, its looking pretty good. Everything on screen is about 97kg.
Waterjets and lasers should be on order this weekend and we will start sticking it all together next week!
I think we are settled on batteries now and are going for 6 of these
OPTIPOWER LITHIUM CELL 5000 4S
5000mAh 4S lithium cell complete with 12agw plain silicon wires and JST-XH banace connector. 30C rating (true) with 80C burst.
To run 2 in series and 3 parallel (6 total) for 15000mAh capacity, 150 regular output and 400A burst.
-Can I run a single 400amp fuse (like below) just after the batteries, and can this double as my removable link?
http://www.ebay.co.uk/itm/MEGA-fuse-...3D380474772302
With the lipos, I was hoping to use the FRA discount scheme. I did send an email out on friday to 'grant@robochallenge.co.uk' and 'ros@processmeasurement.uk.com' asking for advice on a charger for the batteries but have not yet got a response. Is there anyone else I can contact, or perhaps another way to get a hold of them?
Last edited by Andron4000; 10th October 2016 at 22:56.
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