Gadgeter/DIY corner (car n non-car)

[KARTer]

(1) How to diy a 'tool' for cleaning small spaces/spots of rims which have 'hard-to-reach' design?

 

(2) How to 'measure' grip provided by different surface material?

 

Let me explain: my DIY race track (for radio control racing at home, MiniZ class) is almost finalised. Now need to simulate the grip provided by commercial track in the shops:- they use 'special' (but costly) rubber mats, I am trying to use handyman sand paper to save money. I need to 'measure' the special rubber mat's friction/grip and get the correct grade of sand paper to match it.

 

Maybe i put the miniZ car on the mat and try to measure what side-force is needed to push it side-way while stationary? (ie simulating sideway-Gforce in a fast corner), but how to measure the side-force (cant rely on 'feels' if i use my fingers to push it)?

 

Many thanks

[Adrianli]

(1) How to diy a 'tool' for cleaning small spaces/spots of rims which have 'hard-to-reach' design?

 

(2) How to 'measure' grip provided by different surface material?

 

 

Many thanks

 

1) Use a toothbrush.

 

2) Use a digital hook weighing scale and pull the r/c car along the surface. More drag = higher force needed = higher scale reading.

 

[Yeobh]

This simple off the shelves cleaning brush will do the work - no need to re-invent the wheel

[Stratovarius]

1) Cotton bubs?

2) Try using a block of wood/metal and slide across the surface of the material. If distance travelled is the same, frictional force should be similar. You can use a compression spring to push the subject across. This will ensure force exterted is constant (more or less).

 

Just my thoughts.

[SimonTan]

Tie a string over the car. ( you will need to experiment with the car to get the CG location, and tie at that point.p

Hang the string over the table, attach some weight at the other end of the string.

Rest the car on your sand paper.

Keep Adding weight(washers or nuts) untill the car slide from the sand paper.

 

Weigh the weight of material added.

You will need a sensitive weighing scale, those used to measure cooking flour or cocaine in small grams intervals.

 

I have done it during my secondary days to investigate frictional material.

 

[KARTer]

Tie a string over the car. ( you will need to experiment with the car to get the CG location, and tie at that point.p

Hang the string over the table, attach some weight at the other end of the string.

Rest the car on your sand paper.

Keep Adding weight(washers or nuts) untill the car slide from the sand paper.

 

Weigh the weight of material added.

You will need a sensitive weighing scale, those used to measure cooking flour or cocaine in small grams intervals.

 

I have done it during my secondary days to investigate frictional material.

Thanks, thanks..... now school days' lessons (physics) start coming back in my mind liao...

[SimonTan]

Clean the wheels of remote control car without removing the wheels?

Quite difficult. The best best is to use air jet to clean it.

Get can a small air compressor.

 

Edited December 30, 2011 by SimonTan

[KARTer]

1) Cotton bubs?

2) Try using a block of wood/metal and slide across the surface of the material. If distance travelled is the same, frictional force should be similar. You can use a compression spring to push the subject across. This will ensure force exterted is constant (more or less).

 

Just my thoughts.

Other than bro Simon's tips, use of compression spring sounds good, one question though: you think if I sandwich a sprint between two small pieces of say cardboard, one piece in contact with the car, one with my hand, and compare the compression needed to move the car on different types of surfaces, will this give me good indications of side-force hence grip?

 

Now I have two methods Bro Simon / yours to double-check

Edited December 30, 2011 by KARTer

[KARTer]

the gadget you showed looks good, but also expensive looking, no?... where you think I can get one (or at least ask for the price)?

[Adrianli]

the gadget you showed looks good, but also expensive looking, no?... where you think I can get one (or at least ask for the price)?

 

MUSTAFA Centre level 4, next to car accessories. Less than S$10 if I remember correctly.

 

I have one to check if karang guni cheat me of used newspaper money, weigh my r/c models from 800g to 10kg and weigh my luggage before check-in.

 

 

Not sure if S$10 is too expensive to u, but to me is a cheap n useful gadget.

Edited December 30, 2011 by Adrianli

[KARTer]

MUSTAFA Centre level 4, next to car accessories. Less than S$10 if I remember correctly.

 

I have one to check if karang guni cheat me of used newspaper money, weigh my r/c models from 800g to 10kg and weigh my luggage before check-in.

 

 

Not sure if S$10 is too expensive to u, but to me is a cheap n useful gadget.

I was at mustafa yesterday morning, should have bought one...$10 is very reasonable..

[Stratovarius]

Other than bro Simon's tips, use of compression spring sounds good, one question though: you think if I sandwich a sprint between two small pieces of say cardboard, one piece in contact with the car, one with my hand, and compare the compression needed to move the car on different types of surfaces, will this give me good indications of side-force hence grip?

 

Now I have two methods Bro Simon / yours to double-check

side force as in pushing sideways? G-force depends alot on the object's angular acceleration. So it's quite impossible to judge this using static experiment. Best is to trial and error. What you suggest is still to judge to COF as there is not additional angular force acting on the car. So i will say this method will not be a good indication.

COF is a constant while G-force depends on angular velocity. I don't think it is possible to link them up.

[KARTer]

side force as in pushing sideways? G-force depends alot on the object's angular acceleration. So it's quite impossible to judge this using static experiment. Best is to trial and error. What you suggest is still to judge to COF as there is not additional angular force acting on the car. So i will say this method will not be a good indication.

COF is a constant while G-force depends on angular velocity. I don't think it is possible to link them up.

Yes, I know dymanic G-force (in corner) and static side-force are not the same..... now i have to decide on either dyn or stat method (both as rough guide to which grade of sandpaper to pave the corners).

 

I can go all out to build a few fast corners using different grades of sandpaper and do an on-road test (ie actually running the car thru the corners) and see the results.

 

Or

 

I do static tests just to decide which sandpaper gives the highest friction (ie preventing the car to move side way when i apply side-force at the stationary car)...

 

I feel the static method is maybe good enough for the purpose? (it's much much less lehcheh than the dynamic on-road tests)