Getting rid of the gears in the Optima Mid

alcyon · #1 08-08-2016

It's been a long time since I was on Oople. Just to let you all know, I am working on a twin belt optima mid at the moment.
It will be a system similar to the Schumacher Mi1, in which a short belt is driven from the layshaft which connects to the rear diff pulley, which is basically a double diff pulley.The layshaft pulley will be a 14T or 15T S3M same as the Lazer size. Right now my second revision is using 14T over the 13T of the first revision. One side will be using Lazer ZX diff pulley and the other side my custom designed Optima Mid Diff pulley, only available in gear diff at this time. The gearbox must be drilled to insert new 3D printed shaft inserts , the center gear shaft and bearings will be used back.
For the first prototype I had issue of the new short belt slipping. Once I upped the pulley size to 14T and tightened the belt tension a bit, there is no more slipping of the short belt, but now I have a problem with my XL mid belt pulley somehow not having correct tooth cutting dimension causing the original long belt to slip the pulleys on high loads. I had this same issue for a ball diff pulley I made for first revision.
I am working with my supplies to resolve this issue, I believe its just a CNC radius issue, as the original kyosho pulleys are sharped edged on the inside, but my machine pulleys have some radius ,causing the belt to want to come off the pulleys.
I will keep you all updated, but some of you already on facebook have seen my prototype pics.
Right now Standard Mid gearbox ratio is 2.6, with this new system it will be 2.21, if I decide to up the pulley to 15T it will be 2.06.
The advantage of this system is you do not need to grease your gears anymore and even if some sand get in it wont cause damage. This will greatly reduce maintenance time. The only wear and tear item are the new short belt, and top pulley, in order of higher wear.

KRob · #2 08-08-2016

That sounds cool.
Only raced my Mid once since I rebuilt it and it sounded like the gears were skipping under hard braking (even though it's got Thorp gears in it), but not been bothered to look in it yet.
So will be interested to see how this goes. Good luck with it.

Whilst you're here

Any good shops in KL worth visiting? I should be there later in the year and can't seem to leave my hobby behind...

alcyon · #3 09-08-2016

Quote:

Originally Posted by KRob

That sounds cool.
Only raced my Mid once since I rebuilt it and it sounded like the gears were skipping under hard braking (even though it's got Thorp gears in it), but not been bothered to look in it yet.
So will be interested to see how this goes. Good luck with it.

Whilst you're here

Any good shops in KL worth visiting? I should be there later in the year and can't seem to leave my hobby behind...

Yes Tamiya in 1U damansara. Why not have a gathering here with the vintage guys ? Which is only about 2 guys right now lol !

alcyon · #4 09-08-2016

Modified 3racing 14T pulley with 3D printed sleeve.

Drilled gearbox using a 3d printed jig, with a 3D printed sleeve to move the center gear shaft position.

Center gear shaft and 2 bearings re used coupled to a 3D printed belt flange. Also note the lazer ZX pulley combined with my new Mid half. Notice the scuff marks on the Mid Half diff pulley, this is caused by the incorrect inner radius on the machined pulley, pushing the belt of the pulley and causing it to slip.

How it looks like assembled.

HKS_TRD · #5 09-08-2016

Hi Alcyon
This looks really interesting.
Maybe if you go this far may as well use a Lazer rear gearbox?
I imagine it could be adapted to the mid chassis or look into a open gearbox for the Mid similar to what James did for the ZX-R
How can I find you on Facebook

alcyon · #6 09-08-2016

Quote:

Originally Posted by HKS_TRD

Hi Alcyon
This looks really interesting.
Maybe if you go this far may as well use a Lazer rear gearbox?
I imagine it could be adapted to the mid chassis or look into a open gearbox for the Mid similar to what James did for the ZX-R
How can I find you on Facebook

Hi Dan, been a long time. There are just too many things to change if I were to go for a lazer gearbox, the motor plate..chassis, it wouldn't be an Optima Mid anymore, the goal is to convert the Mid with minimal cost and max reusability of existing parts. And open type plate gearbox will again incur more costs. I basically have a machining problem and the accuracy of my 3D printer is deplorable to make the pulleys, I will be sending out STL files to a 3D print specialist and lets see if he can print the pulleys accurately.Look for my name RamaChandran on facebook, you will see a pic of me with glasses and a black T shirt lying down, with my wife with sunglasses taking the pic.
Just see the location to confirm, I am pretty sure you'll get me !