Where to mount speedo's?

Hi all,

After having my speedos arive in the post the other day ive sized them up to my heavyweight and am looking for a sensible place to mount them. Seing as my heavy is very compact there isnt many places to drop them in. The best place i can see from a space point of view is above the motors (bosch 750s on 36v)
The first problem i thought of would be over heating....but i can stop this bye slidding a sheet of ali inbetween the motor and the speedo.
The main problem i can think of is interfearance...with a motor 2cms from a speed controller will the magnets in the bosch create electromagnetic interfearence? Thanks for your comments.

regards
Dave moulds
Team Turbine

in the middle, out of the way of anything. further in, the better protected. Try to keep them as near to the motors as possible to keep cable length as short as possible.

Our DogXBollox controllers sit next to one of the motors (but were running at 24v). Make sure theyre easy to get at in case of problems.

If you put them above the motors, the cables from the interface will have to be run across any way.

The sheet of aluminium should provide a good electromagnetic shield. Bear in mind that you have two very good aerials - the motor leads - going straight into your controller, so mounting them further from the motor will be of limited benefit. The controller should be able to deal with the interference.

My advice would be to mount them wherever you get best protection from physical attacks and worry about EMC later.

Ok, ill bear all this in mind, also are 4qds sensitive to vibration?

regards
Dave moulds
Team Turbine

It depends which 4QDs you have. Mute used to use NCC-70 which blew up (MOSFETs went bang) if we hit something hard... or self righted a bit too high :) We used to get about 5-6 events out of them before they had to be returned for repair. Mute is a high vibration environment though :)

Ive heard that the Pro-120 are much more resistant, but I havent actually used them myself.

I wouldnt count on the 120s. I think were up to 4 events without losing one but thats a record. Interestingly enough one is mounted with limited anti-vibration mounts (never gone wrong yet) the other two are bolted to the chasis where we get the most problems but these two are for the drive and the current limit altered to 70Amps.

You will have more problems dealing with 4QD when (not if) things go wrong and when all our spares are done for we will try a Robotech. Weve been charged twice now for repairs when the boards still dont work after they came back fully tested.

What if i slide some rubber underneath the board and its mounting plate...as abit of a shock obsorber?..or some polystyreene.

Regards
Dave moulds
Team Turbine

p.s. there the ncc70 36vs

Im not very familiar with the construction of the 4QDs but the mounting plate is likely to be its heatsink and it will get hot. Rubber and polystyrene could burn. Also, air needs to be able to circulate around the heatsink - putting any filler material around it could cause it to overheat.

Dave,

I know that 4QD make aluminium box housings for the controllers that you are using (the NCC60/70 series). I used one for each controller and found them excellent - both as heat sinks and as protection. They dont weigh much either.

Jeremy

Oh? Ive tryed looking on the 4qd website for them but i think ive missed it somewere, got a link to were i can buy 2?

regards
Dave moulds
Team Turbine/PLF

http://www.4qd.co.uk/accs/boxes.htmlhttp://www.4qd.co.uk/accs/boxes.html

We have used NCC70s without too much problem - but they themselves are noisy and you will need to protect your receiver from them. They have a fair sized chunk of ali in the middle which is the main heat sink - this should be bolted to something metal and heavy if you are going to work them hard. We used the sink as the main mount with the corner holes linking through stand offs to prevent board bending - that worked OK. Then we installed the boards only on the corner holes through stand-offs, and used a finned heat sink mounted to the existing one - result - mounts sheared very easily. So - I would use the heat sink as the main mount but also use the corners too.

I dont know about the 4QD boxes - are they design for robot shock loads? I doubt it.....

Dave, we mounted HANNIBALS pro 120s on a 1/16 ali plate by the pcb heat sink. The heat sink bolt holes were drilled and tapped up a size and the original brass screws were replaced with s/steel bolts. The ali plate was then mounted onto the chassis with 4 rubber/stud mounts. Never had any problems with the Pro 120s but never really been tested accept at the RW7 qualifiers when Disco Inferno went to town on us.

Tel