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Muso31

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Everything posted by Muso31

  1. Thanks for the kind comments but I'm just using trade skills for RC as it's a hobby Yes. The diff housings and the diff both have a 5.10mm diameter to house the cups which then mesh with either the large planetery gear when using the custom diff, or stock fixing when using the new alloy diff housings. Here's a video of an early version of the diff with the gears in action on the 3D print. This is driven from turning the drive cup, excuse the yellow fingers I just ate an orange ... It could be fine but I'd rather use the diff with a spur gear that can slip - that will be the next thing to design
  2. Sadly they're not the cheapest things on earth. Mine was £800. There's some Ankermake M5's knocking about on eBay though that were kickstarter projects for around £500. I'll use it for a lot of other things so it's worthwhile having one, depends what you need it for! I'll get more parts anodised in future, should be able to reduce the costs of these too once the first batch of stock is shifted.
  3. Hi @BuggyDad - I've taken the Avante/Super astute planetary gears and housed them in a newly designed Madcap diff... It's still in testing before being released to prod, although that wont be too long. Full info is on the thread here -
  4. It's actually just the little raised parts near the 4x sunken oval shaped holes. These little raises have to be exact or it doesn't fit in the profile in the chassis. I've got a decent 3D printer now so I can check parts much faster and get them to production. Maybe the photos over exaggerate it as it's similar to the original, the counter sunk profiles are the correct metrics for the type of screw and yes the alloy is pretty strong in this area on the part. In other news, someone anodised one of the gearbox plates, looks very nice...
  5. Red madcap went to my brother from Santa as it was his originally! I'm still waiting to run mine properly as it has a Brushless in. Once the newly designed diff is in production I'll be taking her for a spin! I'll be upgrading the A2 diff cover, popping in the new diff, and then looking into designing a new counter gear and spur that can slip and handle more punishment than the stock option. I also upgraded to the racing A wing Hop Up which is quite nice: Once the gear box parts are in I think that will be it.... unless alloy C hubs etc are desirable
  6. Update time, getting closer to some prod parts. First off the A2 bracket has proven a bit more of a headache than parts usually are, in that there's some small bevelled rises that have to fit exactly in the right place in the chassis of the cover won't sit as it aught to. Here's the latest part but I've made some tweaks to this revision which will need to be milled: The planetary diff rev 1 is printed and all is looking great, quite pleased to see everything fitting together without any tweaks needed: Here it is next to the SA version: After I have a 3D print of the final rev, it'll be milled from Delrin and released publicly. Very happy with the diff as it's already working perfectly. As for the diff housings, they're near release and should be available in Feb. Not too long now...
  7. Ah thanks @bavee much appreciated! You should have said, I'd have thrown in some treats
  8. Thought an update is due on this.... First off Delrin (acetal) doesn't absorb moisture like nylon does, so it can be designed to be more precise as it is a lot more stable in its properties. So the diff will be machined in Acetal, I've had to redesign it to make it suitable for machining as injection moulding costs thousands for the templates (for mass production), and it doesn't offer any benefits over a milled component. So here's the new diff ready for testing before it goes into production: I'll be testing the diff with 3D prints first. As for the diff housing... I've been working on the best tolerances for the shaft to fit inside the bearing. These are looking good, 3D printed for testing before being milled from a strong alloy: Little bit of work to do but things aren't too far off release. Bear with!
  9. I think you could be right... This link https://khkgears.net/new/gear_knowledge/gear_technical_reference/design-of-plastic-gears.html says: On the other hand, these plastics are subject to greater dimensional instabilities, due to their larger coefficient of thermal expansion and moisture absorption. These should be taken into consideration when plastic parts are designed. Therefore the design engineer should be familiar with the limitations of plastic gears. It is usual that plastic gears are brought into use after a practical test. It is similar for the other gears, but it should be handled by both something called backlash, and the pitch diameter. The backlash is effectively the play between teeth, I've set that on the diff gear to 0.10mm so there is a tiny bit of play. For example, when moving from reverse to forward, the diff will need to rotate the teeth 0.10mm before making contact with the idle gear and moving forwards. But also, it's the pitch diameter that forms the mesh and not the outer diameter, so joining a pinion gear without the relevant gap would mean upsetting where the teeth should meet (at the pitch diameter). I'll set the outer diameter to 26.15mm, may as well keep it the same if it's good enough for Tamiya..... ...edit actually I'll edit the design to be the correct size once I know exactly which material will be used
  10. Cheers both, the thing I don't understand here is for the diff to be 0.8 module it has to be 26.40mm. Either I'm missing something, or Tamiya just don't work to fine tolerances with these components. I think I'll stick to an accurate metric tolerance rather than shrink the new diff design by 0.25mm to match the Tamiya one. This would allow a perfect mesh to be formed with the idle gear if a new one of those is to be designed. I'm wondering if these minor differences in tolerance are contributors into the reliability of the gearbox, but I'm inclined to say they must know more than I do! Still a bit of a head scratch though - I'd be interested to see if the more expensive components have a finer tolerance, as an exact/precision mesh is less likely to fail under load. The more I work on this, the more I suspect Tamiya simply viewed these as toys
  11. ...Quick favour to ask from all kingcab/Madcap users. Could you please get a set of calipers on the diff and tell me the outer diameter, ideally to 2 decimal places? Mine is 26.15mm but I want to see if there's much fluctuation due to wear etc. I'm making some tweaks to the diff to make the tolerance tighter than whats acceptable at Tamiya, there's quite a bit of end play on the inner gears. Weirdly, the center planetary gear is 0.59 module and the outer are 0.6. Not sure why they didn't make the inner gear 0.15mm bigger to equal 0.6, or make the outer gears 0.59 module also for consistency - although it's close enough and I suppose it isn't as important in a diff as the internal gears don't spin at any great rate. It's probably these little details though that make them a cheaper manufacturer/product than others. I assume more expensive RC kits are precision engineered, though this is only an assumption
  12. Gotcha, it's the first step towards handling more modern motors, maybe some other options on the way in future. I imagine most people will stick to the original ball diff and use the updated housings, but it's nice to have options. So with the gear diff and ball diff housing complete it's time to finally tackle the spur. @kontemax any chance you could do some rough sketches regarding your thoughts below? I think I understand what you're suggesting, but for confirmation it could be best to see it on paper. All options are on the table here, personally I'd like to try and keep the stock gearbox housing. It could be good to come up with a design that requires the Asute housing, and a compromise/hybrid that can work in the current setup?
  13. Same I wasn't even aware you were using it - Agreed that it'll cause wear in the long run, at least we'll have some other options in the near future. You'll be getting a free set for your input
  14. I suspect so. So a solution will be needed for the spur. It'd be nice to come up with something that doesn't require a new gearbox cover, failing that theres always the SA cover option. We might need to think about either a none adjustable slipper spur, or something else. This part will need a bit of thought soon. New diff is done (apart from the cover). Here we have it... Sadly Tamiya parts are injection moulded rather than CNC so I'll need to speak to some contacts about manufacturing options, this one isn't as straightforward as the machined alloy components (such as the new diff housing)
  15. Yep can keep the questions here, just didn't want to spam people with technical info, but good with me if there's an interest in that anyway. Thanks for the photos these are perfect. I'm able to overlay them as a guide so I'll get the gear holes/seating added in the right places. It's good to be weighing up options regarding the spur design as I'll move on to that once this diff is done (won't be too long). It could be good to have a spur that matches the current vintage set ups, then create one that uses a different/better configuration. Swappable or configurable parts is an option also. The pitch diameter and teeth etc are different, but I'm making an assumption that the planetary gears utilise the same distances/spacing as it's the same gears so they'll need the same mesh. It could be good if someone posts the drawing from an Avante so I can triple check this. Obviously I'll be making these gears fit nicely into a .08 module madcap diff, hopefully there's no surprises here and the planetary gear setup is consistent across all models. Just to get sidetracked - I'm a little surprised that people have used the Avante diff in the likes of the kingcab/madcap as it's 1mm smaller in diameter and one less tooth which must make the mesh horrendous. It's being sold as a solution to the ball diff but this is going to cause obvious issues. Anybody who's done this should probably remove it, and I can see from the forums a few people have. Anyway - yes this spur is going to need some sort of slipper function as I'm assuming the planetary gear diff cannot slip, unless I'm mistaken? So I'd have thought planetary gears must always be used in conjunction with a clutch on the spur
  16. Yep great stuff thanks. I'll make the metal insert a skeleton gear to shed some mass. The spur is on the backburner at the moment whilst I finish the diff, after that I'll have some questions, do you want me to post those here or DM? Just a quick update on the diff and a quick question for all. So far we're looking good... But I now need a drawing to make sure that the seating for the planetary gears is an exact match to the super astute/avante diff. I downloaded an SA user manual so I could screen grab the drawing but as you can see the resolution is poor: Can anybody send me a high res version of this or a scan from a manual? Ideally the diff drawing and the diff cap drawing. I need to overlay this drawing in the software to make sure the holes are in the exact same position. RC community to the rescue?! Team effort haha. Thanks all ...edit the housings are all modelled now, will get those milled and released in a few weeks time
  17. This is all superb info thanks. I've started toying about with your first suggestion: Here's my thoughts so far. This is a very rough design and isn't exact yet, but I was more concerned with the functionality at the moment. I've drawn up a 70T spur with a bevel for an insert: The second part will be to create a steel insert that screws to the posts I've created, obviously these posts in their current state will collide with the idle gear bracket so I'll address this in a full design. For the insert I've drafted the following: This will need counter sunk holes to clear the cover but again, that's a small formality for the final design. One of the positives of this design is that the same inner piece could be used on a spur with more teeth, a 70T version (as above) and a 77T for example. Once the two are screwed together it'll produce a Delrin outer spur with a steel inner: Hopefully something along these lines is going to be a significant improvement, although ultimately I'd have thought a slipper clutch design is required. @kontemax is this in line with what you were thinking?
  18. Thanks for the input Max, that's pretty useful. People have already completely redesigned these gearboxes and good on them for doing so. I have a lot of time for anybody attempting to solve a problem, and I won't be doing a new gearbox as it's been done already. Will happily give them a plug and pat on the back though if needed. The list of problems you've presented to me validates the sentiment that theres a lot of opportunity for improvement, and it's therefore better to have upgraded parts as we're presently in the worst case scenario. We've also overlooked that these were produced in the 80's/90's and technology and materials have moved on since then. So we either have no options to address these problems, or we have some improvements available using modern tech. Personally I'm in the camp that it's better to attempt to improve upon the current issues rather than the worst outcome - which is to do nothing at all. And the way I see it, with input from the likes of yourself, improvements will be absolutely possible. A 100% perfect solution will never exist (mine certainly won't be that) and wear and tear sadly is a natural part of existence - The mortar on my house is subject to wear, my body is (unfortunately!), as is the parts on these vehicles. All's I see here is the opportunity to come up with solutions to problems, which is what I'd like to attempt to do (the worst that will happen is it costs a bit of time and money): Check! Check! Check!... Sorta, I'm on it right now. I'm assuming that not every single RC vehicle breaks the teeth of its gears? Otherwise the hobby wouldn't be possible. So it should be possible to replicate gears from the more robust models, or reproduce the current gears using another more modern/suitable material. Will keep an eye on this one Diff cups are easily replaced or reworked, again, will keep an eye on this point and find a reliable model (which is were I'll need some input/direction). I don't plan to make a sealed unit but what I can say is, after over 30 years of owning two madcaps the only dust that collected was extremely easily removed from the diff cups of one of the vehicles, and the other one had no problems with any dust or dirt. Maybe I'm not using them enough, or in harsh enough environments, but hopefully this is an edge case that doesn't need to be addressed. Hope that's useful
  19. Kind offer thanks! I can dismantle one of mine though so I'll crack on with that over Christmas. Pin version - https://www.ebay.co.uk/itm/225230838638 M3 screw version - https://www.ebay.co.uk/itm/225270660602 Motor mount - https://www.ebay.co.uk/itm/225130030935 I should hopefully be able to reduce the costs of these longer term. They could be anodized also, would be interested to see if anybody attempts this
  20. Excellent cheers, I can see here (ALEXKYRIAK's madcap post) that theres an M2 thread on the housing: I'll opt for the same so the same screws can be used. That's all I need to know for these thanks, will get these produced over the next couple of months also. Haha this is no problem, I've added more detail to mine to make it a replica of the original part (not that detail is required on an internal part) and it's nice to have options. In a few weeks time I'll post for some testers if anybody wants to try the new parts. Thanks for the input everyone, and I hope Father Christmas brings you some nice RC treats
  21. I'm inclined to say let's give it a go, different versions can always be worked on in future. I'll start with the Tamiya gear bag 9405431 but it shouldn't be too difficult to release this part also if wear is a problem. I've calculated the pitch diameter, pressure angle etc and a the outer workings of the new diff gear are complete: As a rough test, I've overlayed this on a Madcap diff and it's looking good, the minor discrepancies are grease on the diff and the fact the photo wasn't taken directly on top: All that's left to do now is to design the inner workings of this to house the planetary gears. I'll be taking those measurements from the Avante diff which I'm waiting to arrive in the post, sadly Royal Mail strikes are making sure that's not any time soon. I think you're right. It could be a simple fix to manufacture this in a strong aluminium, so I'll get these release over the next couple of months, only question is regarding the best fixing/union methods... The manual seems to suggest that an M2 thread is used to join the MP5 and MP6 housing? If an M2 screw is being used as a self tapper I think we may have found a big point of weakness as that would never form a strong enough hold. Or is there a thread on the female part? I think if this can be improved upon it could resolve a lot of issues with the original ball diff
  22. On it. So the planetary design is actually preferred to bevelled gears? Does anybody know about the durability of the planetary gears? As I've seen comments about them wearing quickly. I've already machined and released these parts on eBay with feedback from @Kol__. There's two versions of the A1 support bracket, one uses a pin like the original, the other gives the option of using a screw instead of the pin. I'll also release a metal diff cover soon also, the CAD design for this is done... One of the factors regarding the noise of a gearbox is the pressure angle of the teeth, the madcap must have a low pressure angle which means less noise, but less horsepower. I need to measure a diff from one of my vehicles to confirm this, I'll take a look at it today. I think this should be achievable fairly quickly. Are there any thoughts on materials? So far I've used Standard 6082 spec aluminium for the brackets which is plenty strong for their purpose. Aluminium is light but I'd have thought would be prone to wear in a gearbox? I assume the current nylon isn't strong enough. Is there a reason stainless steel isn't used? Is this due to weight or another factor? Also, does anybody have the part number for the weak housing? I'd like to take a look at these Cheers all, great info ..edit, another quick question sorry. Is there any worth in a Counter gear produced in another material? I could replicate the current counter gear in CAD in a few hours so it'd be a quick part to produce. But is there a value regarding the reliability of these gearboxes, and if so, which material would be most suitable?
  23. Hi all, as an engineer who recently reignited my RC passion having found two dusty madcaps in the loft, I've decided to attempt to solve some RC problems through modern engineering. I already sell some parts on eBay which were mostly created as I personally wanted them for the madcaps. I do this for the love/hobby and the challenge of filling some gaps with missing parts in the RC community. The next project I'm embarking upon is to resolve the common issues with the diff in these vehicles. I know people have created complete custom gearboxes but I'd like to make parts that are already compatible with the vintage vehicles and don't require such a large overhaul (also more cost effective/accessible to all). I'm also aware that some have used planetary gears and diff housing from the Avante, but this diff is 30 tooth so for me, the pitch diameter couldn't be completely accurate even though it may appear to work. I'd like to produce a high quality bespoke solution rather than attempting to 'shoe horn' something else in from other parts. I've began to build a new diff in CAD and I'm waiting for an Avante diff to arrive so I can measure the gear housings which will be replicated to fit inside the 31 tooth diff housing - but I wanted to conduct some user research and get some vital feedback which would be very welcome that via this post. So the first thing I'll manufacture will be a 31 tooth version of the planetary diff. So far, I can see the the diff itself is 08 module (divide the pitch diameter by the number of teeth) and I'm working on an exact pressure angle and root fillet radius before testing the planetary option. Does anybody have any comments regarding materials for the diff? Metal requires lubrication and will most likely wear before nylon does? Do many other vehicles use metal? What about the most reliable/bomb proof diffs? Following this initial project, I'd then like to look into the possibility of engineering a bevelled gear 31 tooth diff. I've ordered a TA06 diff case to look at how it's put together. The things I'd like to know in general, are what is it that people would like to see in these components? Is there any feedback having ran the vintage diff units regarding improvements you'd like to see? I plan to use nylon but it's possible to make any parts in metal, as it's also possible to release a redesigned counter gear etc to compliment the new component. To me, the design and manufacture of these components is relatively straightforward, but the experience gained from running these RC vehicles isn't! Would even a metal bevelled gear diff, and counter gear, be enough to hold a modern brushless motor and/or address the weaknesses in these components? Or would a slipper clutch be required in addition? All thoughts and feedback would be very welcome
  24. I'm pretty sure the SA diff is a lot more than 31T but the avante/Vanquish is 30T as mentioned above and appears to use the same gears as the SA. Tempted to drop a 30T geared avante diff into a Madcap running a 17.5T brushless to see how it goes as the pitch is apparently the same. I'd have thought the magic formula though would be a 31T diff redesign with TA06 internals
  25. I wonder if they're aluminium. I've ordered one to take a look at it. Does anybody have a TA06 steel gear diff unit to measure the dimensions? I'm wondering if the bevel gears could be housed inside a 31 tooth diff, with some redesigning of the unit.
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