Playing with the Axial

I had a quick trip out with the AX10 today, being as this has been the first day it hasn't been wet and rainy for about a week now.

Latest mods are the side panels, bonnet and roof, made from a cut-up paper folder and the lid of a tupperware container. Overall cost - less than a quid. I've got my HPI Rock Grabber tyres and black coloured Rock-8 wheels fitted now, these were really intended for the current Clod project (see below) but never mind, needs must. I've used the old Axial aluminium beadlock rings on the outside of the wheels just for effect, and have used the much heavier stainless steel HPI ones on the insides. The ESC is now a Nosram Tomahawk Reverse, this has a much better instant reverse function when compared with the previous Mtronics RV-20 Sniper, so I'm experiencing a lot less rolling over backwards when I overdo the steep uphill bits.

Other mods? A section of old silver watch chain wrapped around the front axle, this gives me about an extra ounce and a half of weight on the front end, this helps the front wheel traction slightly when the whole thing is pointing up at the sky. And I'm also now using a Futaba T3-PDF transmitter. This gives me switchable rear wheel steering, rather than the mixed setup of the old (actually newer type) 3PM-FM. I've now got mixed feelings rather than mixed steering, I've lost the proportionality of the original TX but I've gained the addition of pure RWS when I need it, and besides which it is far less clunky when going from 2WS to 4WS.

Currently on order (coming from the USA) is a new STCR aluminium motor mount/skid plate. This will allow me to move the lower links inboard of the chassis side plates, I don't actually need any extra articulation due to the tyre/cage clearance, but this will allow for less side hangups which occur surprisingly often. The link screws and the matching rod ends now bear considerable witness to the fact that this happens as much as it does!

Not much movement!

I haven't got any further with the plates - I've not had much spare time lately mainly due to to the Kala and Sean being on school holidays and I've otherwise being playing with the Axial. I've been thinking a lot about chassis design - do I really want to do something a bit different or try something more original this time? I'm still not sure which way to go.

Anyway, in the meantime I've been collecting all the basic electricals I'm going to need to at least get this project properly running, these include:

A pair of S/H Gmade 60 turn motors, complete with 9t pinions and adjustable motor mounts @ £35 + £4.50 P+P

A new cheap chinese 300A dual motor output crawler ESC @ £15.00 inc postage (came with a free mini torch keyring!)

A S/H Futaba T3PDF 3-channel transmitter and receiver set, complete with rechargeable battery pack @ £16.50 + £7.50 P+P

I'm going to need a pair of servos next, probably cheap MG995/996Rs, and I still need to get the rest of the alloy axle parts from the US.

Total spent so far is about £140 - some of this was initially as spares for the 'Zilla - and since buying the Wheely King kit mainly for the tyres and beadlocks for this project as well as for the gearbox for the black TL crawler truck I've sold on the rest of it in three lots, differential lockers, 17mm wheel adaptors and wheelbase extension kit which has pulled back (£2.99 + £1.99 + £11.99) £16.97, which is getting on towards half of the initial £38 purchase cost.

Clod twin vertical axle/gearbox plates

These took a fair bit of thinking about and some very careful drilling and filing to produce - here we have the first stage of my twin verticle plate axle/gearbox mounts for my second Clodbuster-based crawler project.

They were cut out of a length of 1/8" wall 2" x 1" aluminium rectangular box section. I've drilled the mounting holes for the axle tube screws, and now have to either drill or hand cut the centre holes for the axle tube spigots. This size is bigger than the capacity of my pillar drill (and I don't otherwise have a drill bit of this size) so I would need outside help if I choose to drill them.

The right hand plate has been slotted and also recessed at one point to accomodate the moulded ribs on this side of the gearbox assenbly, and has been carefully hand-trimmed to fit the counter-gear area of the box. There's enough clearance to allow for a couple of coats of paint if I later decide to do the whole thing in black, which is my usual style of finishing things.

The original diagonal strut mounting positions have been reproduced through the plates for added anti-rotation security, and there is a bit of trimming still to do in order to allow the original gearbox half clamping hardware to be accessable, or else the tube mounting hardware will have to be modded to allow for assembly of the tubes after the two gearbox halves have been completely assembled. I'm not sure which is the best way to go with this as yet - I've still got to consider servo mounting and this may affect matters.

The tops of the plates are probably higher than they will end up, but this will depend on my eventual choice of centre-chassis design. The lower front corners will later be radiused, although I intend to fit a 'ramming bar' here to prevent damage to the plastic gearbox itself.

More work to do as time allows...

Second thoughts...

...on using a twin vertical plate (TVP) method for mounting the Clodbuster gearboxes onto the chassis:

The two plates would stand about 50 mm apart and be equidistant from the centreline of the truck. The left-hand one as demonstrated here will also act as the inner servo mount. I haven't trimmed the top bit yet as there is a wide range of choice when it comes to determining optimal shock and link positioning, the best locations won't become apparent until the whole build is further advanced.

The lower edges of the plates will act both as skids and as protection plates for the gearbox casings, and also mount a lower heavy-duty crossmember to act as a primary bumper, which may itself incorporate some kind of skidplate.

As made in cardboard here, the plate has had a hole cut in it to match the outer diameter of the inner end of the axle housing. Another option would be to actually sandwich the plate between the gearbox assembly and the housing. This would necessitate widening the differential to ensure drive is fully maintained, but would also widen the truck by the corresponding amount. (I intended the final width of the truck to be 12.5 inches in keeping with 2.2 class competition regulations, it is this size already, so doing this would require further modification beyond what I already envisage if I wish to maintain this standard.)

I'm now awaiting delivery of the first pair of aftermarket aluminium (Hot Racing) axle tubes, which are coming from the USA. I have material to make the plates from, but will need the new parts to determine exact dimensions prior to engaging in actual production.

First thoughts...

...on servo locations. Having looked at practically everyone else's take on this matter, and taking behind-the-axle steering into consideration, I've figured that this is probably the best place to put them. As you see it here the servo is balanced on an allen key and a plastic servo plate, supported by an out-of-sight body post. I really want it lower, I can't do this with out either cutting plastic (which is a waste of potential 'Zilla spares) or using the aluminium axle tubes which I haven't ordered yet. Oh well. Next...


... and on a chassis design:


Just a bit of scribbling really, but something like this might work. Is that cereal packet empty yet?

Box Project Two

The produce box that previously held the parts for the Black TL01 build is seeing some more use and now contains the start of another project:


Since I built the 'Zilla I've been occasionally buying a few spares for it as and when they came up cheaply on t'bay. I've now collected (just about) enough parts to build another pair of Clodbuster axles. First thoughts were to build them up stronger and with better steering and then fit them to the Z, but then again it is what it is already and I also fancied building a 2.2-class sized crawler (albeit with 4WS) with a width and wheelbase of 12.5 inches.

This will have to be another budget build, and I'm going to be careful with money. It was to this end that I originally bought the heavily-discounted HPI Wheely King Crawler conversion set, obviously for the beadlock Rock-8 wheels and the large diameter Rock Grabber 2.2 tyres it contained, amongst the other pretty things also found within.

Having already used the gearbox in the TL, some of the body mounts on something else and with the other unwanted bits back on the dock of t'bay this set of round things should end up costing me the worth of about £20. So far I've stuck four ounces of lead (which is all that I had left after putting some inside the TL's tyres) in each of the wheels and have now painted the (nice and heavy) beadlock rings matt black.

The (new but s/h) Losi Competition Crawler (LCC) shell came with its masks and stickers from a guy named Carl who frequents the UKRCRC (United Kingdom Radio Controlled Rock Crawler) website forum for a tenner posted, all I can say is thank you very much!

Also to this ultimate fiscal end the Z and this one (name???) will have to share my Novak Rooster Crawler speed controller, and probably the Z's batteries too. An initial thought is to modularize these components for easier swapability in the future.

One of the axle tubes/C-hubs is already broken so I'm going to have to replace this, aluminium ones are a natural choice here for strength whilst being not too expensive, these (at least some varieties) are importable from the USA in pairs without attracting any customs duty.

Beyond that I'm not quite sure how I'm going to go about the chassis construction.

Brain-storms ahead!

Watch this web-space...

So you want moving pictures?

The last set of pics were actually 'stills' in more ways than one, the camera automatically generates a single image file each time you begin shooting a video (for easier later identification of the clips in a folder perhaps?), and the Arachnid was waiting for the camerawoman (Heather) to say 'go' each time we started filming one. So nothing was moving in each of the pictures that I've already posted further below.

This next set of images are (IMO) the best individual frames extracted from the (moving) video footage we shot:

Arachnid caught on film!

Two quick clips of the Gmade Spider-axled Arachnid:

Scorpion Spider gets out!

I had a trip to the rocks at Weston sea-front today with the Scorpion Spider. Actually it isn't exactly that, scorpions are not spiders and spiders aren't scorpions. Both are arachnids though, that's what it'll have to be. Andy's Arachnid.

First Savöx

The winter fuel bills are paid, spring is here, and I finally had enough money to get the first Savöx SC-1256 TG servo for the Spider/Scorpion. That's 'TG' for 'Titanium Geared'. It's rated at 20Kg/cm @ 6.0v, which is somewhat better than the last attempt with 17Kg Power HD HD-1501MGs. These ones have orange centre cases and labels as well, which all fits in very nicely with the overall colour scheme!


I've also put the 'Zilla's wheels and Giant Trac tyres on it, I think the slightly excessive width of the Gmade Ultracs had something to do with the premature failure of all its earlier steering servos, although to be honest the Pro-lines aren't much slimmer. Rumour has it that fitting the Gmades to Maxx-sized offset wheels narrows them by as much as an inch, so maybe that's something to think about later on.


I'm still in two-wheeled steering mode though. I still have one spare HD-1501 here, but I suspect that if I put it on it won't last very long, which is a bit of a waste of a perfectly good servo that will be fine in a less demanding truck. I'm going to try a couple of runs out like this and think about possibly getting a bit of weight into the wheels before I go any further. In the meantime I'll have to save up another £53.99, or even more if I want to go to the heights of something like a Hitec HS-7950TH (35kg @ £100+).


Hopefully I'll get some outdoor photos done very soon!

Up the rock-path!

First test run. Let's see how well it can climb a pile of rocks.


I haven't yet fitted any wheelweights and I didn't trim the foam inserts in the tyres to allow them to flex a bit more. I had intended to use the 35t Integy motor that was bought for Army Truck but when I came to fit it to the new gearbox it turned out that the motor shaft was a bit too long, and consequently it fouled on the countergear. Rather than trim it down, which I feel I might end up regretting being as I do a lot of swapping of parts between trucks, I decided to fit a normal silver can RS540SH motor instead.



I don't think it did too badly. Please excuse the gaps where I fetch the truck from the top each time - there's no room to turn around up there right now and I didn't want to drive it back down the slope because the tyre cleats just get filled up with moist dirt and this then costs me grip going back up the rocks next time around.

Direct link to vid:

http://youtu.be/6rjXPmK3aFA

Introducing TL-01 'Black Truck'

I now have another running (or should I say - crawling) TL-01 truck:




The HPI Wheely King gearbox conversion works fine, although there turned out to be one complication I hadn't foreseen. The mounting holes on the gearbox are not diametrically opposite relative to the output shaft. This means that, as it turns out in practice, the motor shaft is closer to the spur gear by the equivalant of four teeth on the drive pinion.

The effect of this is that with gearbox fitted to the 23 tooth mounting holes on the chassis, the drive meshes perfectly with a 19 tooth pinion fitted to the combined motor and gearbox assembly. This is in fact very good for this particular conversion because it gears the truck down even further.

I did the build with the 'speed tuned' gear set incorporated into the rear gearbox, this combination now gives me very good wheel-speed for the low speed driving that the truck is intended for. This set-up also means that I still have the option of swapping out the speed-tuned set for the standard items if I want to gear it down further again.

The bodyshell comes from a Nikko 'Street Beast' (see picture in sidebar), as found at a car boot sale minus its controller for £1.50. I'm going to need to reinforce the truckbed where the bodyposts come through it because the material is a bit thin here, but otherwise it's a pretty good fit. The wheelbase of the chassis is a bit longer than that of the shell, which possibly spoils the aesthetics slightly, but at least this keeps the whole thing as short as possible to reduce hangups caused by the rear of the body grounding out etc.

I'm also going to need to do something in the front bumper area. The original item locates and retains the 'U' shaped bar which holds the front arms on (on TL-01B Baja's only - narrow track touring car TL-01's have screws here - just like on the back ends of all of them). As it stands the bar is free to completely pull out in a forwards direction if it gets caught up on something whilst driving in reverse. I did though have a pair of Baja chassis end plates kicking about, so these are now mounted on both ends.

(If you haven't come across these bits before (maybe because you've only seen TL-01 cars and they don't have them) they look a bit carbon fibre-ish and they clamp the major chassis/gearbox halves together on the rear of the buggies - they fit the fronts of any TL-01 just the same - if you trawl down the page a bit you can see one in the photo below the one of the cracks - it's lying in the box in front of the chassis.)

Another TL-01 then...

I did think about converting one of the other TL-01 trucks to become the downgeared version, but on the other hand I really like them as they are and don't particularly want to change any of them. My spare parts box is/was pretty full though, so I think it is probably best to use all of this stuff up and build a fourth truck. I bought a couple of spare chassis along the way, one was empty of mechanical parts and the other was a fairly rare lightweight (grey plastic) touring car chassis, which I sold on minus its nicely hopped-up internals for more than I paid for it.

Anyway, here's my kit of spare parts:


The first spare chassis got used to replace the one on Blue truck after it got cracked when it collided with the triangular base bar of a park picnic table which was hidden in long grass (the bar not the table!). The chassis I've used to try out this modification is the only spare I've now got and is unfortunately the cracked one. I've tried to repair it once already with chemical (epoxy) metal but this proved not to be strong enough. I'm now going to have to make some sort of metal shoe to reinforce this area, which is where the front arms attach. I've highlighted the cracks, which are in different places on each side, with a red CD writing pen. The ink from these tends to draw itself into the cracks making them easier to see:


An evening's work has got me this far. I've locked the differentials with hot glue, and have used bronze bushings to replace the plastic originals throughout the gearboxes and driveline. I couldn't really see the point of going for expensive bearings here, being as this truck won't need any advantages that these can give. Besides which it's likely to get pretty wet and muddy at some point, which would probably wreck them anyway.


I've used black screws everywhere they are visible just to keep things as tidy as possible. The pinion gear isn't here yet so I can't yet fit the new gearbox - the next stage will now be to get all the electrics fitted.

Gearing down a TL-01 (Part 3)

The only other thing I'm actually going to need to buy for this conversion is a 23 tooth motor pinion gear. I already have a 'speed tuned' gear set here, which came with a complete chassis I bought some time ago for a tenner.

Obtaining a 23t pinion gear is not difficult if I wanted to use standard Tamiya parts, but there are a couple of downsides to this choice. The first of these is the fact that Tamiya 'AV' pinions are made of a very soft aluminium, and this means that they wear out quite quickly. I've used up several in my three TL-01 trucks over the past few years, they last reasonably well with standard 'silver can' motors but cannot really take the power of a tuned motor. They tend to wear their teeth to sharp points, and make increasing amounts of noise as they do so (also noticeable if you manually push the car backwards). They also leave grey alumimium oxide residue, which is itself abrasive, on the other (plastic) gears in the rear gearbox.

The second downside is that you have to purchase them in pairs with a one-tooth difference between them, and one out of each pair does not fit a TL-01. Therefore you have to pay extra for something you are not ever going to use.


Here are the part numbers for each of the sets that contain one gear that will fit a TL-01 (options - 19, 21 and 23t):

Tamiya 50355, 18T & 19T AV Pinion Gear Set
Tamiya 50356, 20T & 21T AV Pinion Gear Set
Tamiya 50357, 22T & 23T AV Pinion Gear Set

It must be noted that Tamiya refer to the pitch of these gears as METRIC 48 pitch, which is not the same as a regular IMPERIAL 48dp (diametric pitch) gear.

This 'AV' size was used in Manta Ray, Group C, TL01, TB01, Wild Dagger, Detonator, Vanquish, Avante2001 etc.

In reality these Tamiya gears are metric 0.6 module pitch, which do NOT mesh correctly with normal 48dp pitch gears. My understanding, having read a fair number of RC forum posts, is that 0.6 mod equates to 42 pitch, and that GPM aluminium spur gears for a TL-01 are advertised as being this size.

(For reference 48dp - imperial diametric pitch = 48 teeth on a 1-inch diameter gear, 64 pitch = 64 teeth etc.)

I cannot find any reference to Tamiya clarifying this issue - their official answer is to "only buy Tamiya pinions"!

Now to the Tamiya TL01 Speed-Tuned Gear Set (#53342 or OP-342):


These are moulded in black plastic, to easily discern them from the standard (off-white coloured) version.

Also for reference, here are the Final Drive Ratios (FDRs) for each fitable size pinion, and again for each size when used with the Speed Tuned gearset.

Pinion Gear..... Normal Ratio...... Speed-tuned Ratio
19T ................. 7.96 ................. 5.95
21T ................. 7.20 ................. 5.39
23T ................. 6.57 ................. 4.92

This is the pinion gear I've chosen to use. It is intended for use in a Maverick Strada TC/MT/XT/XB series car/truck/truggy/buggy. Its part number and description are MV22081 MOTOR GEAR 23T 0.6 MODULE:


£3.53 + £0.89 postage & packaging.

UPDATE:

You can forget all I wrote at the start of this post about needing to buy a 23t pinion. I didn't. As I realised when I came to put the gearbox into the truck the mounting holes on the gearbox (to the truck) are not diametically opposite in relation to the output shaft.

This means that a 23t pinion will not fit, even though the gearbox is fitted to the truck on the 23t mounting holes. Actually, the difference in the offset is almost exactly equivalent to four teeth on the motor pinion. So a 19 tooth pinion DOES fit here instead. And being as I already had at least one spare 19t here anyway I had no need to buy anything new (beyond the gearbox itself) at all.

Anyway I hope the following makes things a bit clearer. If you use a rule on the gearbox lining up the mounting holes (this only works on one side!) it also just touches the output shaft as a near-perfect tangent, whereas the imaginary correct line should have passed centrally hole to shaft to hole.

Gearing down a TL-01 (Part 2)

OK. Starting at the end point. The first picture shows the HPI 87634 gearbox mounted into the Tamiya Tl-01 chassis, as fitted with the longer Baja King/Champ suspension arms and a 1.9" wheel and tyre, along with an attached Integy 35 turn lathe motor.


In order to obtain the best possible wheel torque for crawling and climbing
ability, the object of the exercise is to try to achieve an approximately 3.0/3.5 MPH (or good walking pace) top speed for the truck.

The gearbox is positioned to use the 23 tooth pinion option (and the chassis motor mounting holes to match) because the ratio of the gearbox is a rather large
7.4 to 1, and this would give excessive overall reduction with any of the smaller available (19t, 21t) pinion sizes. To achieve the best possible wheel speed for crawling and climbing use it is likely that a 'SPEED TUNED' internal gear set will also be required to additionally compensate for the gearbox's large reduction ratio.

This pinion choice has the distinct advantage of mounting the gearbox as far forwards as possible. This positioning means that it is necessary to remove a lesser amount of plastic material from the rear (left-side and smallest) part of the main chassis in order to fit the new additional gearbox. This rear (left) part is one-half of the rear main gearbox compartment, and it is far easier to re-make and reseal this area to prevent otherwise damaging foreign object ingress when less material is initially removed.

There is plenty of tyre/motor clearance, in fact more than is found on any TL-01 fitted with standard touring car suspension arms, these including the Stadium Raider and Ford Lightning trucks. The next three pictures show different views with the gearbox and motor fitted (N.B. the suspension arm has been reversed - this gives the longest possible wheelbase when using only standard parts):






The next three photos show inverted views. The gearbox smoothly protrudes below the bottom of the chassis by about 6mm (1/4").






An additional advantage of this mod is that a motor guard/heatsink will now fit around the completely exposed motor. Previously, when the motor was buried in the chassis, a full size heatsink would not fit.


Three more views, showing the gearbox alone in the chassis. In the last one daylight can just be seen past the box. In reality the box is quite a tight fit in there, and becomes in part a longitudinal structural member.






The chassis only requires cutting of the left hand side, which is ordinarily constructed in two parts, whereas the right hand side is a single piece and does not need any re-working. These next two pictures show the material removed from the lower part(s) of the motor area. The lower of the two little 'fins' above the motor protector mount has been trimmed back slightly just to avoid contact with the motor itself:





These last two pictures mainly show the amount of material removed from the front (left) chassis section. The rearmost upper and lower screw locations remain unaffected: