Radio Control 6

Ok, so I was wrong, my dad said it looked too long and thin, searched web, the drawing I was using for the dimensions was wrong, whole front end was wrong. so I redesigned, it's different and fully useable :-)

Design from a long time ago, engine mounted cross wise, 3 stage gearbox, rear battery pack containing 5 off AAA batteries, front axle wrongly positioned. OpenSCAD exported image.

New design, engine mounted where it would be on a VW Beetle, 10:1 small worm drive gearbox, Li-Po batteries built into clip on command module, front axle correctly positioned, all wheels correctly placed. OpenSCAD exported image.

The actual model, mostly in coffee coloured PLA, original car chassis was painted in similar tan colour. wheels in white colour PLA and sprayed silver. Dimensions are correct, speed is scale 70 mph like original, I also just printed the a second set of parts and made the PCB for my controller, with luck have that assembled tomorrow.

I have body designed, have to print in 2 parts, working upon support to get the weird shape to print, NOT looking too good yet:

Radio Control 5

Rolling chassis is only perfect, but will have to do:

Wheels are perfect in functionality and look (they look just like original buggy), front wheels and steering are nice and loose with no wobble, motor and gearbox are spot on, full speed range from very low to reasonable (but not stupidly fast) top range, steering range is as good as real thing, motor stays cool. I am pretty chuffed.

On with body, maybe after I turn it into monster truck with big pneumatic tyres, or a standard VW beetle, maybe publish with a number of choices :-)

I have coffee, silver and yellow filament coming next week, so I'll create a couple in correct colours, keep 1 as above and fit my controller to the other, then I can test my controller properly :-)

Radio Control 4

It works!!!!!!

Ok, it's just a rolling chassis, had to fit slightly more powerful motor, motor needs better mounting, steering is not particularly good, wheels are not good, but it's getting there, I can drive it around, speed range is nice.

Radio Control 3

This is all way harder than I originally imagined.
I have working. neat little RC controller module based upon ESP8266. To further understand, skip back to my April 2016 post.
I want to test it in actual models, I had 2 types in mind:
Trix: a 70 year old sailing boat.
Buggy: a mini remote control car.

Trix: Kind of fallen in a heap, nothing to do with controller RC or electronics. It was originally built by my grand father as a toy for his son (my father), back then it was all mechanical self steering. Roll on a few years until around the 90s when my kids were not yet teenagers, I fitted it with crystal RC, 1 servo for rudder, a 2nd servo with long arm to pull in the main sail. The rudder worked so well that it didn't matter that the arm was useless. We spent a week end sailing it around the lake at Wellington Country Park, kids played solid. Then my Dad turned up and was quite distressed that the wooden hull was totally soaked. He took it away and I didn't see it again until recently.
I got it back, it has been coated inside and out with a thick coat of resin. I rubbed it all down, under coated and painted white all over (original colour, white main, red base). I was just going to put a line around it and paint the base red. But my Dad tells me that is not correct, with sail boats the line MUST be the water line. So, I fitted all the deck fittings, rigged it all up and floated in the bath, marked the water line, then painted the base red up to the water line. My Dad was not available for any of this. Ok, all done (I thought), than my Dad comes around, the water line is much too high!!! It won't sail properly!!! So basically, scrap everything I've done, rub it all down to remove the paint and some of the excess resin, then float it and adjust the keel weight by drilling out the lead and filling with filler, then I can re-do it all over again. I've put it back in it's box, I'm not in any rush to re-do months of work.

Buggy: This is way more difficult than I ever imagined, build a toy car, how difficult can that be?
See fully in June 'Radio Control 2' post, but basically "Put receiver into Buggy, not so good, it works perfectly off load (lifted off floor). It won't drive for long even on a flat smooth level floor. The cogs bind, probably too much play. I'll probably redesign to use worm gear drive. Again, once I get it working with standard transmitter / receiver then I can play, get to know it then switch over to my controller. Cut out all the variables."
I've moved to a standard FlySky receiver, I've created a whole involute gear library so I can create a worm drive gearbox, it still does not work:

The motor is a standard MR2, this may not be up to the job.It's now got a 10:1 worm drive gear box. I powered it with a 2 Amp bench supply. Going from still to motor moving is hard, I should have thought, but a motor is basically an electro-magnet which is basically an inductor, it's going to need a large current to get it started then it will settle down to a lower current, takes up to 1.5 Amps to get it moving, any alignment issues with motor to worm or worm to axle and it just won't start. But it works very well on bench supply! anywhere between 2 to 6 volts, it's a current issue. Switch to my battery box (in background) with 5 off AAA batteries and motor won't start, I thought I had issues with contacts making to battery, switched to standard 4 battery holder, still doesn't work. It may work with a large capacitor in the circuit to supply the large start up current. But if the motor is on load, at higher speeds, it pulls down the voltage enough the interfere with the steering servo.
I have some 3.7V lipo 5-10# batteries, will give them a go.
I thought this would be so easy!!! Half thinking about buying an off-the-shelf RC Car kit to test my receiver, but I'm not ready to give up quite yet. Writing this has helped me get it straight in my mind.

Breaking news:

Lash up, 2 lipo 3.7v batteries in series (7.4v) and it works :-)
Re-design to do it properly, watch this space......

InvGears2

New version, see here:
http://www.thingiverse.com/thing:1654911

I no longer like the bevel gears in the lib, will deal with them later.
Now got worm drive, created manual examples, 2 sizes, both work much nicer than I expected, next I'll try in ABS with a 500 rpm motor, see if it works or melts!

The worm algorithm is quite 'sexy'.
set:
iShowC = 1;     // 1=Show all calculation circles
iShowT = 1;     // 1=Show all calculation tangents
iDemo = 1;      // include demo code

In InvGears.scad, you now see just the points that make up the worm:

It's even nicer in OpenSCAD where you can view it from different angles.

Now set iShowC to 0 and re-build and you see worm surfaces:

See how ends are flattened so it keeps to correct length? That is accomplished using 'conditional', see OpenSCAD manual.

InvGears.scad

I had trouble with my RC car design, needed to get the gearbox working much better.
So, I created InvGears.scad.
See
http://www.thingiverse.com/thing:1643825
All files NEED OpenSCAD version 2015,03-02 or later they will NOT work with previous versions.
InvGears.scad is meant to be used as a library for use in other scad files.
Everything is still very much work in progress.

Example.scad demonstrates it's real use.
This contains a parametric 2 stage, 3 axle gearbox.
Variables near top of file control the parameters of the gear box:
Pitch sets gear tooth size and therefore ultimately controls size of gearbox. On my printer 0.7 is about as low as I would go, 0.8 for higher print quality.
The rest of the variables are documented in the file.
Un-comment gAssy() to see just the gears, use OpenSCAD View|Animate menu to see the teeth movement for adjusting Pressure.
Typical gAssy() view:

Comment out gAssy() and un-comment Assy() to see full assembly.
Typical Assy() view:

Comment out Assy() and un-comment print1() to get printer plate of housings (parts shown in white above).

Comment out print1() and un-comment print2() to get printer plate of gears (parts shown in red above).

In both printer plates there are extra cubes.

I created my printer in 2013, it's a RepRap metric Prusa with home made hot end:

Your printer probably creates better quality prints, to be honest I have no idea how the quality compares. You will see that my printer has NO fans, I find that adding cubes to my prints allows the plastic to cool down between layers so that it doesn't go wrong, the cubes are my alternative to fans.

I did say that the files are work in progress, the Example supports Spur, Helical and Herringbone gear types only.

InvGears.scad:

The file can be used on it's own to see how it all works.

There are 3 variables near the top of file:

iDemo = 0;

Set this to 1 and the you will see output.

Variables similar to those found in Examples.scad are further down in file, these control what is shown in demo.

iShowC = 0;

Set this to 1 and you will see the 4 circles of interest for the gears.

Please refer to http://www.cartertools.com/involute.html by Nick Carter to fully explain.

The 4 circles show Outside, Pitch, Base and Root as explained by Nick Carter and shown in his first drawing.

It also shows the 2 radii that define each side of main tooth.

iShowT = 0;

Set this to 1 and you will see the involute point calculations, radii and tangents.

These show up best with Rim, Adj and Typ all set to 0.

This is explained best by Nick Carter in the rest of his drawings and explanations.

Once you get to this stage you can alter the other variables and see the difference they make clearly.

Don't forget to set iDemo, iShowC and iShowT back to 0 before using the lib in your files or Example.scad.

InvGears.scad also includes bevel and cycloid gears, but I have not yet created an example for those.

Mini Drawers

In my last post I wrote:
"Whilst awaiting, I now have lots of very small parts, M1.6 washers and nuts, M2 washers and nuts etc. I have no place to keep such tiny components, so I'm creating a modular clip together drawer set.
Clip together is not an easy concept to make work in 3D printing."
It's now obvious to me that I know little of what people want!
I published as http://www.thingiverse.com/thing:1621667
231 views, 60 downloads, 40 likes, 48 collects, 1 make!!!!
Published last night at 12:33, this is stats from less than 24 hours!
The world is nuts!