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Been following your project for a while. I don't mean to derail the thread but these repro WWII pieces you are referring to, is there somewhere they can be seen? Say on some other thread somewhere? Just curious. The Yoke is very cool.

rraeford wrote: ↑Fri Oct 04, 2019 7:05 pm Been following your project for a while. I don't mean to derail the thread but these repro WWII pieces you are referring to, is there somewhere they can be seen? Say on some other thread somewhere? Just curious. The Yoke is very cool.

WWW.WW2AIRSOFT.ORG.UK
Look under ww2 airsoft weapons , I'm Dadio there as well , you could do a search for mk5 sten , Owen gun , Bren and again and again or hatching a flock of sterlings ,there's a fair few going Back 10 years or so .

He Dadio, a little late but I just read your post about the gear being too small.
So, I'm wondering how you made the gear just a slight bit bigger? I mean the only way I see it possible is by changing the teeth size. Which would mean it' isn't the exact same pitch any longer. And mating 2 gears with slightly different pitches will wear out both gears fast... Another option would be an extra tooth, but then your gear diameter goes up a lot in comparison, so that's probably not feasible.
I think what you had to do was; lightly shift the gear position... by that's just my opinion based on the little bit I read: so please correct me and help me understand.

Mr. ED wrote: ↑Sat Oct 05, 2019 7:36 am He Dadio, a little late but I just read your post about the gear being too small.
So, I'm wondering how you made the gear just a slight bit bigger? I mean the only way I see it possible is by changing the teeth size. Which would mean it' isn't the exact same pitch any longer. And mating 2 gears with slightly different pitches will wear out both gears fast... Another option would be an extra tooth, but then your gear diameter goes up a lot in comparison, so that's probably not feasible.
I think what you had to do was; lightly shift the gear position... by that's just my opinion based on the little bit I read: so please correct me and help me understand.

In Fusion 360 the CAD programme I use there is the facility to scale up or down the size of the part , it only needed 1.7% increase in size ,the tooth profile remains the same only a tiny bit larger , in fact the stock Yokomo gears are a little under size compared to properly made .8 mod gears so I'd already had to scale down my gears to make them reverse compatible , I'd just cocked up the math on the diff gear , if I went with accurate .8 mod gears then the gearbox would need to be modified and genuine Yokomo gears would not be compatible .
My guess is that the moulds that Yokomo used are correct size but the gears are made from nylon that shrinks slightly as it cools ,as all the great shrink in a relative scale mesh was not affected but the gearbox would have been designed to fit them .

Started work on a parts set to use a Kyosho Scorpion 2014 diff , hard to explain but its a sort of ring gear with internal and external teeth that you insert a Scorpion diff into , I've been unable to use the Team C diff in the new gearbox because of the minor design change I had to make earlier so I'm hoping a Scorpion re re diff will be a suitable replacement , its not a ball diff but its a sealed unit and with modern diff oils you can still adjust its tightness .

This will probably need a tweak to the gearbox to make it fit , possibly a dedicated gearbox that's adapted around the bearing supports , for those who don't recognize it it's a Scorpion diff with a 3D printed interlocking ring gear that matches the 834b gearbox

The genuine yokomo diff is hard to find , this should mean completing the gearbox is a lot easier and cheaper .

I've made some modifications to the gearbox and the Kyosho Scorpion modded diff will now fit and it will still accept the stock diff , just out of curiosity I tried to fit the Scorpion diff in a genuine gearbox and it very nearly fits ! With a little material removed from the bearing support on one side it would fit , the bearing support is just 0.5 mm too tall .The other up side is that finding dog bones should be easier as well because both ends will be the same size and its a very common size .

Dadio wrote: ↑Tue Oct 08, 2019 2:06 pm I've made some modifications to the gearbox and the Kyosho Scorpion modded diff will now fit and it will still accept the stock diff , just out of curiosity I tried to fit the Scorpion diff in a genuine gearbox and it very nearly fits ! With a little material removed from the bearing support on one side it would fit , the bearing support is just 0.5 mm too tall .The other up side is that finding dog bones should be easier as well because both ends will be the same size and its a very common size .

Ingenious! One of the coolest things I've ever seen. Not kidding. One of those solutions that once you see it, it seems obvious but I never would have thought of"up-sizing" a diff gear. So many problems solved!

When I first though of it I massively overcomplicated it by trying to make it incorporate the plastic side of the Kyosho diff housing , I was just trying to work out the position of the 4 screws relative to the gear teeth when I realised that if it just had a lip on one side and a few screws on the other to stop it walking then the job was done , I'm still tempted to make a ring to go round the side and use countersunk screws as it might be neater to look at .

Diff fitted

This shows the bearing adapter and how its fitted


Whole diff fitted

This is all untested , I'm printing a revised gearbox that will be hopefully the final production version compatible with both Diffs and then I'll put that gearbox into testing .... never ending test drives , to be forced to constantly drive rc cars , I'm really sacrificing here guys !
Also drew up plans for a jig to drill the holes in the gear 2 axle for the drive pin and set screw for the chain sprocket .

yeah, that is a really trick idea. It lends itself to 3d printing, vs machining. man it would take forever to cut that gear and expect it to be perfectly true.

Holy ball races Batman!
And I thought my CATs used large bearings.
The stock Yoke diff bearing must be ENORMOUS!!
Anyway, nice work on the adapted main gear.

The diff bearings are 24 mm outer 12 mm inner diameter , huge , no idea why , the other 6 bearings are pretty standard size 5x10x4 flanged , its just the diff , I'd guess they made the diff with 12 mm out drives and they just looked for an off the shelf size bearing and found not too many choices ....
I'm most of the way through building up a complete new gearbox to run the new diff setup to swap into my modded runner Dog , I'm also looking into just making adapter sleeves to use Kyosho metal Sprockets for running hotter motors .

I just finished a complete new gearbox with the Kyosho diff in it but its compatible with both diffs , I found that 61 mm dog bones fit well and are easy to find cheaply on eBay , tomorrow if the weather gets better I'll start testing the new setup ,I'm starting it with a brushed motor , see if it holds up then I'll move to a brushless and see if I can break it

I think I'm really close to being able to provide sources for all the parts I can't make , the Scorpion diff ,scorpion axles all round (even with one way's) and now I think the front central drive axle might be possible with minimal modification .
Looking at the Tamiya Wild One rear axle it looks promising to be able to make most of it by modifying one and I've found a diff out drive for a BSD car that might be a direct fit for the other end , the Tamiya axle will need shortening ,cross drilling and tapping and a flat cut on the end of the shaft , I'm designing a 3d printed jig to drill the cross hole ,measure the correct length and position the flat on the end , with the jig all you'd need to modify the part yourself would be a 2.5 mm drill bit , an M3 tapp , a hack saw and a file , fingers crossed this could be the last parts of the puzzle to being able to build up a complete functional replica without any original parts !