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Making Inserts

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I have to start by giving credit to Kennedy-rd, not only for the method, but for convincing me - after a few attempts, that I could do it.


I don't recall seeing anyone do a thread on this in recent times, so for all the other 10-thumbed here on forum, here is what I just learned to do.


The "project" was a Lotus Exige. I'd given it the twice over, but as a plastic machine it was never going to be good enough to get track time, so I decided I'd turn the wheels down to inserts, pro-race equip it, and document the insert job.


Here's the stock setup, dickens of a job getting the tyres of the hubs, as I'd glued them on.



They're a pretty big wheel, so before I started, I checked the O.D. of the shoulders, to see if I actually HAD any wheels that were large enough inside diameter that I could turn down the hubs to get inside. 14.99mm, and about 1mm thick, I need about 0.4 or 0.5mm of "meat" left, so I'd need an inside measurement for an alloy rim at least 14mm



Found one. The Ninco 18" EVO Prorace wide is 14.15mm

Now note, the inside of that rim is "stepped" 14.15mm is the size of the narrow section that goes most of the wheel depth, but the 1mm of it nearest the outside edge of the wheel is a little larger diameter measurement. So turning the plastic hub down evenly, would leave an ugly gap of about 0.5mm all around the rim, between the outside edge of the plastic insert, and the alloy of the rim - some cunning will be required.



Plastic hub is now fitted to my tyre truing lathe. I simply super-glued it onto the Ninco 2.48mm single wheel fitment. I can "crack" that glue bond later - hint, use poor quality super-glue..........it'll do for what we want, but won't break the hub when you come to remove it from the shaft.

Note also the carbide cutting tool fitted to the "super-Cheap" dremel clone. Rough tool, but does all I want.



Normally I'd be holding the "dremel" carefully with both hands, bracing against the benchtop and the tyre lathe, but I only have 2 hands and one is holding the camera. held square onto the wheel, so I grind front and back evenly. I have it running as fast as possible. Ninco plastic shaves, it is a much harder one than Scaley wheels I've turned down previously. Flakes all over the bench and me.



Test fitting the wheel - do this regularly, it is easy to go too far and end up with a loose insert. At this point the wheel JUST slips inside the wider outer lip area of the alloy wheel, so the front edge is turned down enough.



Between the last shot and this one, I worked from the right side instead of the left, and turned down the plastic hub EXCEPT about 0.5mm of it's depth at the front. The "lip" I have created is clearly visible. I checked the width using the digital calipers. Slighty over-did this part to 13.95m, so it in theory will be a little loose in behind the front lip, but that's okay. They are seldom 100% round, even using this method, and as I find later, in practice, it slides in fine, and is touching at several points around it's circumference. Just right.



Now I get a sharp blade, and with the lathe turning, and hands braced, I score the wheel just behind where I estimate the brake rotor sits in the hub. Keep pushing until it cuts right through the outside rim.



The eye-ometer was working tonight, my cut was a fraction of a mm behind the brake rotor, just as I wanted.

Then I score part way through the boss of the plastic hub flush with the rear of the disc rotor, just enough so that I can grind it off with a clean outside edge shortly.



Remains of the plastic hub pulled off the shaft of the truer. Sorry, a bit of a blurry shot.



Now the boss has been ground off flush with the back of the brake rotor, and yes, it fits nicely into the alloy at left.



Finished article.



Repeat until you have a pair. The finished inserts are pretty much flush with the front edge of the alloy rim, and a nice snug fit.

I could probably get away with just push fitting them, they'd be as secure as say a Slot.it insert, but I'll probably smear a little silicon glue/gap filler on the edge before final fit to the car later so they don't pop out during a race.


Recovering Slot Addict :ph34r:  *  Custodian of many used screws (mostly loose :rolleyes:)  *  Total kidder  *  Companion of other delusional slot addicts :lol:  

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Nice job mate. Im sure that will help those that want to upgrade there plastic wheels. Just to add to the above I dont have one of those fancy truers. So when I turn down my wheels to make inserts I take one of the 2 wheels of the axle & stick the axle with one wheel attached into the dremel. I then grind the wheel down on a file. When that wheel is done I then glue the wheel I took off back on & use the same process. Same principal different tools.




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I am impressed - I don't think my darling wife would let me play with toys like that - I have enough trouble keeping all my skin intact with a stanley knife :huh:

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Can you imagine MTWD allowing me near so many sharp objects at once Mark?? No - I thought not! :huh:

Captain's log: We are enroute to some planet whose name I cannot pronounce to do something really complicated that I don't understand.

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Nice job Mark.

The eye-ometer was working tonight

.... er.. thats eyechrometer in munter speak.


John Warren

Slotcars are my preferred reality

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