TOYO
Forum Replies Created
-
AuthorPosts
-
Ah yes,.. as the sun sets on yet another day of track side entertainment, the PT cools off and I endevour to enlighten all about the project thus far…in order to improve endurance the Tomy motors(green end)were replaced with the low resistance but short lived xtrek original (unsupported comutator)type and much removal of excess weight from what ever I could(only 1 gram.. down to 25). A severe vibration was evident with the starboard gearbox and the crown wheel inner support shaft was found to be eccentric so a complete new crown wheel was more carefully made, however some vibration is still there and probably caused by the 6 tooth motor pinion, it must have had some effect though,as the power balance adjustment is just left of neutral. The pcb was moved forward 1.5 mm and more clearance made around the motor wiring to reduce binding of the front suspension strip. I am begining to have some doubt about the trailing arms torsional strength as high speed cornering is not ideal, even though c of g is as low as possible the rear tyres lose grip easily and me thinks the loading on the outside tyre is high enough to bend the arm until a point is reached that it flicks back causing the tyre to break away….hmmmm. New tyres made from blue “absorbathane” were fitted, (closest thing to gindable glue I’ve found) batteries charged and track dusted down. I decided to go for only single charge attempts in view of motor issues’ and the turning circle was set for minimum move ment, the new tyres made an impact and average speed steadily increased from 3.4km/h to 4.6km/h with 43-47-49-48-48 laps recorded (didn’t break the magic 50..doh!) speed is well down on the Enertecs 5-5.5km/h but the Chrysler rarely made contact with the wall. The minimum speed jumped from 1km/h to 1.9km/h and top speed went up to 9.6km/h measured over a 2 metre section with 1.5 metre run up, wheel dia is 13.5mm and 4400 rpm on full power with the motors churning over 35000rpm, there was less than 200 rpm difference between the wheel speeds on full power. Strangely, I prefer to drive the car very slowly around the course with a goal of not making contact and managed 15 laps at an average of 3.2 km/h. Where to now with the outstanding xtrek?
Unacustomed as I am to blowin’ me’ own trumpet, check out “When an engineer blah blah blah” as for the xtrek …Hmmmm..as usual these days unapproachable electronics but poorly concieved automotive aspects. I couldn’t for the life of me get the GODdamn thing to follow any command within a mile.(It’s supposed to run on a track like a hot wheels) Why it’s rear wheel drive I have no idea, better bet to reverse the motor feeds and have fwd and a single castor wheel central at rear. The transmitter is a work of art and I wonder if it was intended for something a bit (no pun intended) more sophisticated, it’s proportional smoothness and repeatablity is outstanding, when the batt’s are going flat just dial in more thottle to compensate, the steering response is directly related to wheel speed and therefore isn’t affected by battery power, unlike a micro’.A motor syncronising adjuster that actually works, 3 seperate power curve adjustments ( low -scarey-sideways) which all give the same top speed and 3 channels that will allow 6 cars to race at once, the only let down is the poor range of 1.5 metres (Enertec’s go for more than 5!) So EBJ if you get one and decide to rid yourself of it quickly I’ll gladly take it off your hand’s for nicks’.
Much appreciated Betty, GOD will surely turn you into a sunbeam, anyways’ have finished some serious testing on the race track…..BRILLIANT, there appears to be nothing this chassis can’t be applied to,it took some practice getting used to being able to reduce the power coming into a corner to avoid a broadside (too much weight over rear wheels)and using little or large amounts of steering when required, half of the track was in the rain but it made no difference to the PT as even in a slight four wheel drift and the front tyres breaking traction steering was as precise as in the dry. I fitted an adjustable turning circle limiter to the steering link and modded the transmitter to stop reverse motion being activated on what ever wheel is on the inside of the circle and this immediately gave the car high speed predictability, it did however spoil it’s spectacular ability to be driven accurately in reverse and curtailed it’s prowess with snail pace obstacle courses on the kitchen table…damn,damn,damn. It is however blighted with poor endurance, on a double charge only 60 laps were completed, but considering what the circuitry must be doing to allow such wide variations of performance it is, I feel an acceptable limitation. Have said that, I will consider building another with both motors turning in the same direction. How does’ it compare? The Enertecs are serious little cars with oustanding endurance/speed and are highly suited to a long slow curve circuit, what the Xtreck lacks is far outweighed by its’ ability to tackle anything, fast, slow, tight, broad, wet or dry and importantly, the fun factor.
Build em’? narrr…same old story, too expensive too fragile too GOD damn fussy about their environment….get a mini-z.
Can’t wait to see a proportional BCG!!! but as for modding, will it require a complete rework? I’m certainly interested.Whoa’ hold the bus there buddy, this ain’t no 4wd(yet) purely front wheel drive only, this little gem will need an epicyclic drive between the front crown wheels which will give 100% drive to the rear axle only when both motors are at the same speed, as one slows down so does’ the epicyclic output, this will cause the steering to over react rapidly compared to the amount of turn that was initially signalled from the controller, however a roller clutch in the drive would overcome this but give no drive to rear axle in reverse. Phew! don’t worry…Ive already taken this chassis to extremes on the cad.
Whoops ,in my excitement I forgot to mention some new pics of this little screamer in the gallery.
Whilst trying to nut out seemingly impossible steering problems with the awd project, I came across an “X-TRECK-2” reading the info’on the box seemed to good to be true…alas it was more orrible’ than anything you could imagine, you can understand why they need a track to run on, but why so sophisticated the transmitter ???..curious thing the “X-TRECK”.
But arf’a mo’-push aside the awd and nut this one out…much cad work followed but in the back of my mind (just like the Roman Philosopher SENICA told us)I was prepared for failure. But it didn’t and it does’.Jesus wept how good can micro racing get when you have PROGRESSIVE THOTTLE and VARIABLE STEERING that allows you to steer around any obstacle course you desire at a speed of 1km/h or scare yourself stupid on a race track with a top whack of 9 km/h, not only that, drive in reverse with almost equal control and have the same turning commands (in forward motion left turn is left in reverse left turn is still left!!!) From a standing start give it full power and watch those front wheels spin like crazy but don’t panic for you have complete steering control and 9 minutes of absolute bliss ahead of you.
I guess you want to know it works, simple really, image a normal front wheel drive/front wheel steered chassis but have a separate variable speed motor driving each wheel…and thats all there is to it! Under a hideous PT Chrysler shell I managed to squeeze in twin motors and 8 to 1 crown wheel type gearboxes, the shaft of the alloy crown wheel drives a cv joint with a ball dia of 1.6 mm onto a stub axle of the front wheels, the gearboxes are adjustable from 0 degrees to 7 degrees trail and the usual toe in/out eccentrics on the steering link, a centering spring is fitted with an alignment cam as well.This unit is suspended from the top with a PVC stip that also allows changes in wheel base length. A centre section carries the shell mounts/pcb/batteries/front suspension strip and rear suspension mounts. The rear wheels are mounted on trailing arms either side of the batteries and are sprung by a .4mm piano wire sring. All up weight is a crazy low 26 grams.What I thought would be an insurmountable problem related to the fact that one motor spins forward whilst the other spins in reverse and no two motors have the same characteristics in this situation, however the good folk at xtreck fitted a power balance adjustment to the transmitter and so no problem exists, it also boasts 3 power curve settings, GADZOOKS what more can these things do?Very good point Merc-blue, but I am just a simple nuts and bolts man and some basic tests have shown that 2.4 volts go in and near enough 2.4 volts powers the motors which I use (they are not recommended for voltages higher than 2.6v), the endurance car is on it’s third motor now so obviously pcb mods aren’t going to increase motor life.So these are the limitations that I work within, another factor is that I have had no pcb failures in more than 2 years ( I have several cnc machines that like to cause days of misery trying to find which capacitor on the smb has blown).Betty is correct,you talented bunch perform miracle’s with pcb’s that I just don’t understand and I have the automotive systems but the results will be the same…a fast micro that is uncontrolable with premature motor failure. If speed is king then ultimately you will end up with a slot car, as interesting as that sport is it can, in no way compare with the brains and talent required in r/c.
The front springs are made of delrin using a type of thread cutting attachment on the lathe with .75mm pitch,needed something that wouldn’t attract magnet, they are also more supple that metal.Yes Jamie,I have no doubt that modifications to the electrics will produce a rocket ship, many years ago I raced an 860 Ducati and speed was absolute priority, bugger handling and efficency, but I’m an old man now and get no joy from straight line performance, the car must be controlable, reliable and offer near perfect repeatability within a defined environment so it becomes a matter more of skill than good luck.I hope to take them to Japan in near future and possibly hook up with some geeza’s for an assesment of cars/tracks and maybe a shoot-out hence the awd project, just to see if this is a solution to limitations of rwd only.
When I was a wee lad it was always the same,put your toys away and go to school/bed/work, not any more…the machine shop is swamped with micro’s and I don’t have to put them away anymore. But alas troops, as said many times before I’m one of the lucky ones and micro’s just seem to fall into the sphere of my work and have no limitations as to what can be achieved,(just wait a while and the awd should be ready)I have managed to streamline production of cars but don’t expect change from A$500…If it is a must have item remember that they probably aren’t as robust as a Tomy and cannot be modified unless you specify what you want before ordering…..oh and black Subaru reached 10.6 km/h over 3 metres but have lost interest while working on new car.
Thanks again Betty.K, must say your offroader project has been the most interesting saga about micro’s I’ve ever read/seen, your imagination and determination to see something through to the end is to be commended, even more astounding is the ability to produce a workable product with only basic tools!.. I would however like to give you some advice….beg, borrow or steal a modelmakers lathe/mill combo (stay away from watchmaker machines they are too specialized)
Emco/unimat/are ideal, cheap too,(Ive got one)I have no doubt that with some machinery and your skill, crazy things are gonna’ happen. Enough of all the guff..new car survived 50 laps@ 6.4 min on single charge but only averaged 4.5 km/h due to continually having to power off to avoid serious accident- will get better though.. many new pictures in gallery.Crikey! thanks for putting the pic’s up Betty(how did you do that?..yet another Goddamn thing to learn)Have managed to squeeze in one more pic. Am trying to get weight down and have knocked out side and rear windows-down to 25.5 grams, 2 less than endurance car. Motor draws so much current that steering was slow to react, have brought toe out down to almost zero and this restored situation. Managed some laps on track after above mods’ and is now controlable but slams into wall pretty hard if you don’t line up corner and miss turning point…ooo nasty! Gee I don’t think I’m up to prawning around with mosfets just yet..sounds a bit scarey to me, I managed to get just under 5 minutes today so will continue weight loss program.
Oh.. so thats how they work, there can be no doubt that backlash would be almost eliminated, axial thrust during a corner would be evenly distributed, very cost effective to produce and highly suited to this size car, but what about loading on the balls during a corner?, they are rotating in one direction and the thrust of the drive gear is at 90 degrees, they also need static preload to keep them all in contact and reduce slippage. I guess one could be made but the geared ones I am using are only 4.4mm dia as there is no more room, probably be done with 1mm dia balls, I can get stainless balls that small-but not sure about hard ones…hmmmm not sure the benefits are worth it, gears don’t slip, no peload, can be physically smaller, less parts, lighter,no maintenance, limited slip ability by thicker lubrication and I guess in my case-having a machine that’s sole purpose in life is to produce small gears makes it easy to lean in their direction. Anyway,a few pics of new micro racer have been uploaded.
TTTThirty kilometre’s per hourrrr! Jesus wept!When-were-how-by whom? I am but a mere amateur and shall now take poison, but before that, this ball differential that is spoken of in hushed tones..I have built compound turbine engines, epicyclic steering gear for tanks, constant mesh g/boxes and nipple clamps but haven’t yet come across ball differentials, roller & cam “differentials” that don’t allow reverse(gas cars) I am familiar with. I work on a theory that if it isn’t used in full size practice then it’s not worth miniaturising, however in my business it always pays to seek out the unusual and these devices I would like to know about.
As much as I try the TYCO’s gentle 13km/h and total reliability doesn’t capture the imagination like the micro’s and this question of just how fast can one go was too much temptation.Hmmmm… so it was to be expected that yet another Enertec was sliced up and reconfigured. This time a jig was made first and the chassis digitaly machined/drilled whilst held in place to ensure absolute alignment between front and rear axle’s. Although identical to the endurance racer great care was taken to lighten each part and lower the ride height by 1.5mm, a different tooth profile for the half shafts has produced a diff’ as smooth as silk, stainless steel kingpins(non-magnetic) to eliminate magnetic conflict, but the big difference is the reduction from 11-1 to 8-1 still using the 160 dp gear profile which appears to be quite suited to these cars. After getting all the rewiring right first time(!)it was applied to the race track…GADZOOKS..although somewhat slow off the mark it accelerated at a rate that I couldn’t keep up with, back to the calculator…no load wheel speed of the endurance car is 2600/3100 giving an on road speed of 7.2 km/h measured over a 2 metre section( the prototypes have similar no load speeds but only crack 6.5km/h due to higher weight and low efficency g/box)however this latest device produced 4200/5000!! giving theoretical speeds of 11.36/13.37 but don’t panic, measured over 2 metres it pulled 10.33 km/h with the motor churning out 40000 rpm all this on a single charge!! Phew..this is all a bit scarey for me, the motor used is not a green end cap (as fitted to all the other cars)and which appear to be a bit of a plonker, but has a yellow end and gets quite warm as the others are as cool as cucumbers. I may be forced to rid myself of this screamer and fit a docile greeny as the car is almost uncontrolable and goes flat in 4 minutes, to be fair though this was only it’s first run and it may need some fine honing.
Thank you, Talldude, hmmmm.. a video, I could do that..and send to Ausmicro?..leave it with me for a while.
SUCCESS! Had to put project aside for a few days, however first serious attempts made today, one lap travelled centrally around circuit is 9.1metres, so 110 laps is just over 1000 metres,a calculator was rewired from “=” button to a very light mechanical switch which is activated by the passing cars antenna.A stop watch operated by daughter.Eight attempts were made with a double charge only, 100 laps-12.01 min,106-12.47min,109-13.48min and at last 111-14min@ 4.32km/h but then..118-13.58min,140-16.39min@4.59km/h,130-15.27min and 130-14.49min@4.79km/h!!During the outstanding 140 the Subaru spunout on lap 82 but reverse was only a crawl?? anyway straightened up and completed the rest, by days end reverse was just a memory, one set of brushes had worn out and broken off only just contacting in forward, which is understandable as the motor had by now covered an amazing 16km over 3 different testing periods!Three 10 lap sprints produced average speeds of 5.2-5.45 and 5.55 km/h, boost was never engaged throughout,5 single charge runs were also completed.Steering remained totally consistant throughout the days total distance of 12km.Calculated that each steering command costs 2metres! so perfect timing and duration of the command was essential. Have couple of images for gallery.Anyway have achieved the goals and will put micro racers away for time being and attempt similar endurance test with TYCO Crossfire,sure been lotsa’ fun.
Excellent information troops,(obviously yet another goddamn thing to learn on top of “end of year” accounts which I’m up to my neck in) will ditch original charger and rewire car to flashy looking computer controlled charger,however will only resort to different batteries if unable to crack 1000 metres.
Crickey! you guy’s ain’t just good lookin’..smart too! Removed batteries and tested cells individually. Tis’ true that a single charge isn’t enough however they did come up to 60%-70% and the second charge 90%-100% at 1.37 volts apiece. I did this three times with approximately the same result. A third charge was tried but no measurable difference was found, they did however become warm. Last year charged a “c” cell made in France, but only came up to 75% so repeated charge, after a while could hear hissing sound then several loud pop’s, negative end cap had bubbled out and battery was red hot, been a bit shakey about this repeated charge business ever since.
From an efficiency point of view there are at least 4 aspects of a Mini-Z that I would dearly love to reconfigure, one is so irritating that I throw my hands up in disbelief,(send lot’s of money and I will give answers)Anyway I do believe this forum is about micro’s and so….managed some laps on circuit, flywheel and flaired guards showed their worth, car no longer jack-knifes if you power off while turning, and if you side-swipe wall car merely glides along so you can steer away without fuss. After double charge(naughty!)new Subaru completed 80 laps at average speed of 4.1 km/h and covered 728 metres!
So tantalizingly close is the magic 1000 metres that this is what I shall aim for.Have managed to get weight down from prototypes 33 grams to 27.5,tran’s housing with bearings but no diff’ is 2.5 grams.Yes,I know that another battery taped to roof will ensure victory but that doesn’t prove (oh no,it’s that word again)efficiency of design.Will do serious attempt soon.Have uploaded more images in member gallery,I can’t find an easy way to tell price all of this,as much as I would like to build micro’s all day, Japanese business comrade(wife) won’t let one out the workshop for under A$550 + GST.Jesus wept,personally I think the money better spent on 2 Mini-Z, I hear they are unbeatable. Interesting thing about proportional cars-bought first one after 8 non prop’types(Tamiya FF02 Celica)wife said it would be faultless Japanese quality, we were both disappointed,now has alloy front chassis, single reduction right angle drive, variable brush gear timing, splined drive coupling,teflon sealed suspension, zero tolerance ball joints etc,etc.Runs for 22-26 minutes and easy 28-30 km/h.But needs enormous area to operate and too much manual dexterity to drive smoothly,at moment prefer simple twitching thumb control.
The enertec’s have proven 100% reliable electrically for over two years,motors however are very efficient-output shaft bearing only phone’ vibrators,the commutator end is unsupported and suffers poor contact after about 3 hours use. New type car was briefly tested today and is knock out compared to prototypes, has lotsa’ major changes,sprung and sealed delrin trans’ housing,motor drives alloy diff’directly thru’ single 11-1 reduction,flywheel equiped motor to smooth out horrible 6 tooth pinion vibration (turning 35000rpm on boost)front fluff resistors and axle boxes made from one piece,all steering bushes are alloy, centre-ing spring pivot removed from above magnet and mounted in top plate, double sided cam screwed to steering link to allow adjustment of spring end gap,adjustable turning radius cams, toe in/out eccentrics and original alignment eccentric,Ackermann offset is .25mm(this makes inside tyre turn tighter radius than outside reducing scuffing).Car is 8 grams lighter on rear axle but only 2 grams lighter on front, original 5mm wide tyres reduced to 4mm and front wheel dia increased from 13mm to 13.5mm rears are 14mm(Wheel spin is concerning).Curious fault of prototypes was inside rear wheel momentarily spinning backwards while cornering,to overcome this delrin(nylon-non magnetic)4 turn helical spings 4.8mm long made and fitted with brass thrust washer mounted on kingpin shafts,original seesaw device removed and as mentioned rear floating axle,differential packed with light grease. Have been unable to asses this as yet but car tracks near perfect on cement driveway compared to prototypes bouncing all over the place,can’t wait to test on track and hopefully crack 55 lap-7.8minute endurance set by prototypes.My apologies if this subject bores crap out of everyone.
Thanks for help troops, have uploaded with success (I think)images in member gallery.Would also like to thank good folk at AUSMICRO Greatly appreciate this opportunity to show pics, “arigato gozimas”.
Am wrestling with conscience about this question of making transmissions, as stated before it is not economic, diff’ will take 3 hours,housing about same and then chassis must be modded to suit, to reap benifits of trans steering must be o/hauled as well, have just finished new car that has no layshaft(motor pinion drives diff’ directly, motor pinion is 1.26mm dia with 6 teeth-need eyeglass to see it!)with rear suspension.Have drawn on cad and could be 4 axis machined on cnc,still gonna be $$$$.
AM TRYING TO UPLOAD IMAGES IN MEMBERS GALLERY, BUT KEEP GETTING TIMED OUT ERROR ASP 0113, OBVIOUSLY SOMETHING ELSE TO BE LEARNT, WHAT AM I DOING WRONG??
SORRY ABOUT REPEATING REPLY ABOVE,I’M A BIT DIM ON THIS INTERNET STUFF, AM TRYING TO SEND PHOTO’S–BUT THE CARS AND PIECES LOOK SO SMALL, DON’T KNOW IF YOU HAVE CAPABILITY TO ZOOM.
-
AuthorPosts
