Luna-Tic improvments

[R9000]

They will go in without, but I find it's better to drill a small pilot hole.

[cjsowry]

looking at the xt90-s its expensive. but might be worth a go too.

yh, defiantly drill pilot hole on bigger screws. I use small self tapping screws to hold small things it place. they go in okay without a pilot hole!

[cjsowry]

Not the dumbest of dumb questions I've asked. BUT....... these linear actuators. the mount holes hold the ram with the motor above it. This caused problems with space inside the bot. SO. could I drill new holes sideways into the existing ones so I could possibly mount it with the motor to the side of the ram itself.?!?

Just brain storming a back up plan!! Always have a plan B!!

[R9000]

I expect you could, but I wouldn't vouch for its strength once you've drilled the hole. You could make an adaptor that bolts on and has another hole at 90 degrees - just a thought. Might give you more strength, but it is more effort and would need a little more space.

[overkill]

Agreed; there will not be much metal left in the pivot once you have drilled a new hole. Making a new pivot bracket will definitely be stronger. You'd think that for the tiny extra cost, the manufacturers would make the pivot a separate part that can be rotated 90 degrees.

[cjsowry]

Anybody reading this for learning or reference, don't try number 3 on the list of improvements. I've tried to extend the axel the hex nut screws too. And secure it into the side panel with some bearings. Doesn't work. The wheel and drill work them selves loose very quickly. You need the reverse thread screw to hold it all in place. Might sound obvious to a veteran but to a newbie it'll save you half a days work and £10.

Right, where's my m5 reverse thread screws got to.!?!?!

[Tim The Plumber]

Not the dumbest of dumb questions I've asked. BUT....... these linear actuators. the mount holes hold the ram with the motor above it. This caused problems with space inside the bot. SO. could I drill new holes sideways into the existing ones so I could possibly mount it with the motor to the side of the ram itself.?!?

Just brain storming a back up plan!! Always have a plan B!!

If you have 2 small plates either side of the origonla hole with a bolt through and then weld a couple of bolts with their heads cut off sticking out sideways from the ends of the plates, between them, you will be able to have a universal joint and not need much more space.

[cjsowry]

took me a few minutes to figure it out, but yes. good idea...

[cjsowry]

Here we go again. Question time. I've been noticing people's drive train more recently, alot have one motor each side. Linked by chain or gearbox directly to one wheel. And this is then chained to a second or third. I went 2motors to drive two wheels each side on Luna-tic, because I didn't know any better and easy. Are there advantages to having two motors directly mounted to two wheels per side or save weight and cost by linking the two wheels by chain or belt.???

[R9000]

Here are the things I can think of in favour of the four-motor setup:

-If one wheel jams, it won't jam up the other one on the same side.
-No resistance created by having a chain or belt in your drive system.
-You don't have to have a section of your bot dedicated to pulleys and belts, making the drivetrain smaller and less vulnerable (fewer failure modes).
-Just plain more pushing power.

[cjsowry]

I may have forgotten a bit of physics here. I thought about the extra pushing power, but wouldn't the secondary/slave wheel for use of a better word. Be producing the same force as if it was directly attached to a motor?!

[Tim The Plumber]

2 wheels with 1 motor have the power of that motor and the force of that motor divided by 2.

2 wheels with 2 motors have double the force untill you are on just the back wheels when you are being pushed about and lifted at the front. Then you are back to the same as the above.... just when you need the force...

[cjsowry]

Good, thank you. Must have been a Blonde moment!! Seen a few new builds with one motor, driving two or more wheels, thought I may have been missing a trick or something. More motors equals more pushing power. Sorted. I'd imagine there comes a point where the benefit is outweighed by other factors. Otherwise why no 10 wheeled push bots with 5motors each side!!?

[Tim The Plumber]

Well the point of more motors is lost when the amount of force is determined by the friction x the weight of the bot. More motors just makes more of your precious weight taken by stuff that does not damage the other guy.

I suppose you would get better acceleration and higher possible top speed but keeping control of the things seems to be more of an issue than speed.

Again the challenge of maintaining force whilst the bugger lifts you you and thus gets all of his drive down and you slide backwards is significant.