SAW-US, A Build Diary

[razerdave]

Having looked at the robot in an actual picture, there are several things you can do (if you are willing) that would save you 23g straight off the bat without hampering its performance in any way:

Heatsink plate from the sabretooth: 5g - not required at this weight level
Terminal Blocks: 3g each, 4 for the big one at the back (13g total) - solder straight to the tabs on the board, they're a good size, nothing too delicate
Battery connectors: 2g or so, only need 2 connector rather than 2 if you solder the 2 cells into one permanent pack
Receiver: 1g - take all the pins off (this is not essential, only do it if you are comfortable)
Wiring: you can lose about 2g worth of copper out of that lot

Also, those batteries are WAY too small to be powering a HPXF and motors too.

[Sportball]

Having looked at the robot in an actual picture, there are several things you can do (if you are willing) that would save you 23g straight off the bat without hampering its performance in any way:

Heatsink plate from the sabretooth: 5g - not required at this weight level
Terminal Blocks: 3g each, 4 for the big one at the back (13g total) - solder straight to the tabs on the board, they're a good size, nothing too delicate
Battery connectors: 2g or so, only need 2 connector rather than 2 if you solder the 2 cells into one permanent pack
Receiver: 1g - take all the pins off (this is not essential, only do it if you are comfortable)
Wiring: you can lose about 2g worth of copper out of that lot

Also, those batteries are WAY too small to be powering a HPXF and motors too.

Hi Dave,thanks for the feedback.
The photos you see are my second prototype only, I am in the process of designing the unit in polycarbonate.
Heatsink, thanks for the tip I will prise this off at a later date.
Terminal Blocks: You mean the ones on the Sabertooth, I don't really want to damage this as I cannot afford to replace it and want to use it again and again.
Battery connectors: I thought of this but decided to try this first as it means batteries can be plugged in to the JSTs off the shelf making replacement easier, although i do see your point.
Receiver: I think i will lose the case first before i take the pins off
Wiring: Yes the wire was something i got from work and is way over spec and difficult to solder.

The batteries are too small?? You mean the 120mAh is not enough or the discharge rate? I bought them as recommended on this site somewhere due to the weight, they do last 15-20mins or so...I liked the idea of 2 single cells so i have the option of separating them if i have size restraints on future projects.

[joey_picus]

Discharge rate is probably the issue - I run most of my robots on 120mah 25C batteries (actually the ones Gary linked!) and have usually been okay for a few fights without charging, so you're fine for capacity.

[razerdave]

The problem I have had is the battery was not man enough to supply both flipper and drive with sufficient current. This can be down to the battery discharge rate or how much your servo pulls (the HPXF is a bit power hungry). From experience, 160mA should be your minimum for that, and 20-30C should be perfectly adequate.

[Sportball]

Looks like a need to spend some more money then..

[haz]

http://www.ebay.co.uk/itm/6-X-Turnigy-1 ... 4d072d0ead

If you are dead set on separate cells. I've used these before, although I soldered them into packs.

If you are coming to the AWS on Saturday I can lend you a pack.

[Sportball]

Thanks Haz' much appreciated.

We (my son and I) couldn't make the event today as we live in East Anglia. We are looking out to attend our first event if something more local comes up in the new year.

I have decided to lose the flipper for now and this makes my batteries more suitable. After watching a few more events on You-Tube my theory is that most people lose by falling off the edge so I am going to concentrate on a rambot and practise my driving technique.

Have there ever been any events closer to home?

[BeligerAnt]

I don't think we've ever ventured into the wilds of east Anglia
That's not to say we wouldn't if someone decided to run an event. Since the majority of builders are based in an area roughly between London and Birmingham that's where most of the events are. We have had events in Yorkshire, Wales, Sussex and even Ireland and Holland. Generally the further the event is for most people to travel the lower the turnout.
I suppose it depends whereabouts you are in east Anglia. Chelmsford or Cambridge would probably be OK for most people, Norwich or Lowestoft less so.

[Sportball]

I am 15 mins from Cambridge which would be a great place for an event. You wouldn't want to go near Norwich, it's hard controlling a robot with 6 fingers and a pitch fork...LOL.

I believe the one in Nuneaton is less than 2hrs away so I may venture over in the new year.

[BeligerAnt]

What we need is a nice company on the Science Park to give us a venue 8)
In addition to teaching kids (and adults) about engineering, this hobby also teaches parents about the motorway network