Weighting Tamiya M03 Mini for LiPo Cells
There are now several LiPo packs available that are shaped like a stick pack, so they will fit the Mini M-Chassis.
But! They are a LOT lighter than a pack of NiMhs. So much so, that most clubs that race minis now specify a minimum weight for all minis. It’s usually around 1350g.
This isn’t such a bad thing, as a LiPo mini without extra weight doesn’t handle very well anyway!
So, you need to add extra weight, usually in the order of around 200g. There are a few of ways of doing this.
1. Stick weights all over the place – ugly, but you can put them where you want to get the best handling. It’s up to you where you stick em.
2. Carefully put lead around the battery, and in front and rear bumpers – tidy, more concentrated weight where you want it. If you open up the chassis you’ll see a gap above the battery, you can put a strip of lead in there. It you take the bumpers off you’ll see they are hollow, you can fold some lead into those too. It’s very tempting to put lead in the large void at the back of the chassis, but that’s not really where you want to put it, the handling will be effected a lot.
3. Create lead packing strips to fit above and below LiPo – accurately imitates a NiMh pack, so handling isn’t changed whatever battery you use – and you can use either a NiMh or LiPo pack. Above the LiPo is usually a hollow, create a lead strip to fit into that hollow. Underneath the battery you can use a double thickness strip, it should hold in by friction. If you wrap the lead in tape it looks nicer, and can help you get the right thickness so the strip holds itself in. You can stick it to the LiPo if you wish, but then that LiPo can only be used in that car. The main advantage of this is the main extra weight is below the Lipo, and it actually ends up with a lower centre of gravity than with a NiMh.
The performance difference between NiMh and LiPo in an M03 is minimal, the voltage curve of a LiPo is a little better, so may be a bit stronger in the latter part of a race in comparison with NiMh.
Written by simon.
How To Add a 40mm Cooling Fan to Tamiya M03 Mini
Small fans are often used on Radio Controlled Cars, for cooling speed controls, or motors.
I was running a 30mm 3 Racing fan on my Tamiya M03 Mini, and I recently ’stuck my finger through it’. This is common occurence, where a misplaced finger causes the fan to break.
I had repaired it with superglue and it had been okay for a meeting or two.
In one run though, I felt I was down on power, and I reckon it’s cos the fan broke again, and end up looking like this…
Broken 3-Racing 30mm Fan
I think that was enough to jam it, and cause an increased power drain on the batteries, and hence a reduction in power to the motor, slowing the car.
Time to replace it, I wondered if there was a way of fitting a larger, 40mm fan in a similar place.
After some measuring, a failed attempt at a mounting bracket, I came up with a small bracket that mounts a 40mm fan above the motor.
40mm Fan and Bracket
The bracket is a simple piece of aluminium angle, with two M3 bolts securing it to the fan, and one M3 bolt securing it to the chassis.
Simple and neat. A 40mm fan is more effective and stronger than a 30mm fan.
Written by simon.
Poor Man’s Dyno or Motor Checker
http://www.vimeo.com/3160587Poor Man’s Dyno or Motor Checker Video
I wanted to compare some motors, and wanted a simple way of reading RPM. So I needed an RPM counter of some sort. I thought about making one, but I quickly came across some on ebay.
I ordered one up, and it’s quite a bit bigger than I expected it to be, but that’s not a big deal.
It works very simply, you stick some reflective tape to whatever is rotating, and shine the laser on it. The reflective part needs to be less area than the non-reflective part. It then just counts the reflections and displays the RPM.
Brilliantly simple. Sure, it doesn’t check anything else, no torque measurements, or current measurements etc, but for a quick and dirty comparison it’s great.
It is of course important when checking motors to ensure that the voltage is similar on all of them. So use a fully charged race pack, and test them all at the same time, one after another.
I could even go so far as to test them under load, such as fitting them into a car and using the drivetrain as a load, as long as it’s the same conditions for each motor then it should be consistent and useful.
Written by simon.
Tamiya M03 Mini Tyres
I struggled with tyres last night on my Tamiya M03 Mini, I was using S-grips on the front and M-grips on the back. Both were very well worn, and had been repeatedly glued, so the sidewalls were pretty coated in superglue.
Supergluing the sidewalls is a great technique to reduce the bite of a tyres, but when they start wearing, you don’t get enough grip from them at all!
I then tried a new set of Express tyres on the front, and they were TOO grippy, loads of turn in sure, but also grip roll, which isn’t really necessary.
I think it’s time for some new Tamiya Tyres… I’ll get a couple of pairs of each, and play around. The common forumala for indoors is M grips on the rear, and either ‘kits’ or S-grip on the front. Though, getting S-grips to work can be problematic – they can be too grippy. Hard foam inserts are fine, especially on the front. And perhaps they’ll make the M’s on the back wear more evenly?
Here’s the part numbers etc.
53254 M-CHASSIS 60D SUPER GRIP RADIAL TYRES(1 PAIR)
50683 M-CHASSIS 60D RADIAL TIRES(1 PAIR) **’kits’
50684 M-CHASSIS 60D M-GRIP RADIAL TIRES(1 PAIR)
53255 M-CHASSIS 60D INNER SPONGE HARD(4PCS.)
Written by simon.
Connectors for Fans etc. on Radio Controlled Cars
I picked up some of the small 2mm ‘Corally’ type banana connectors, off of ebay [search for: 2mm gold connector], these are ideal for use connecting fans, UBECs, LiPo cut-offs, etc.
http://www.vimeo.com/2991381In my e-savage I had two fans and a UBEC I wanted to connect direct to the battery voltage. I connect two wires, one to each of the +ve and -ve on the Deans battery connectors, and run them to where I want the sockets of for the accessories.
Then, I soldered three of the 2mm sockets in a small triangle, and onto one of the power wires. So 6 2mm sockets in total, 3 +ve, 3 -ve. Heatshrink around each triangle of three, gives a nice neat 3-way socket.
On each fan/ubec I have a 2mm plug on the power wires, heatshrink them again and plug them into the socket.
It’s important that there is no bare connector showing, especially as the +ve and -ve are often positioned next to each other.
