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Creating the The Lotus 72C in 1:12 Scale
Page 2  (Page 1, Page 3)

The diary continues.  I have decided to show some of the process and parts rather than all, because of the time it takes to produce the drawings, then prototype parts to make sure they can be produced easily.  That said it will still be more than any other company will show you. :)

June 25th.     It has been a while since I posted any progress, although there has been quite a lot.

However, today I did some work in my machine shop and produced some experimental parts (for other projects) as well as the Stub axles for the front and rear wheels on the car.  I am very happy with the result.

I started with some 1/2" diameter brass bar and machined the stub axles as per my drawing, which also enable them to fit the lotus 72D kit as part of the trans-kit.

Looks a little rough, but that is more the digital picture.  The aluminum part is the wheel nut without the hex machined on it.

Very fine thread 4mm x 0.35 pitch.  The part is a bit dirty as you can see.  The length of the part is approximately 0.75".

Just so you see the nut does actually fit perfectly, the way I wanted it to.  When the wheel hub is in place, it should be clamped by the nut and have a half thread showing out the end of the nut.  We shall see! :)

The back side has a shoulder to give enough space for the pins and nuts that locate the wheel.  It is hard to see in this picture.  The rest of it is the correct diameter to fit the suspension hubs, front and rear, supplied in the Tamiya kit.  I'm thinking of putting nylon bushes in the hubs on my kit.

To keep everything spinning, the inner part will be a push fit, no glue needed.  Tight tolerance on such small items.

I don't think I will supply the parts like this, as you will want to do some work.  These axles are not supposed to be brass.  Well low and behold with a little magic, look what can be done almost looks like it should.  Now you can really see the shoulder on the back side.

Damn! that stuffs good!

That is a few seconds submerged in some "Blacken-it", then removed and let dry, then washed in hot soapy water.  Because of the effect, I think I'm going to make more parts in brass for the kit, that should be metal.  (Umm!  Methinks I need to stock some of this?!?)

That's all for this day, although the front sub-frame has been redone, the rear wing end plates are completed and an aluminum prototype of the tub and drivers seat was done, but I found some mistakes and an easier way to produce it. 

Do you want to put the tub together with rivets, or would you prefer it to just look like rivets?  That's kind of rhetorical, more like Henry Ford saying "You can have any color you like as long as it's Black" :)  So guess what it's going to be. :)

June 26th.      Back in the "model factory", my machine shop, I have fabricated the Universal joint hubs that will go inside the wheels and at the disc brakes.  They looked huge on the drawings, but in my stubby little fingers, the parts are almost lost!  (1/4" OD.) I have a little more to do on them, hence no picture today.  But due to the complex fabrication of these parts, I have decided to cast them in white metal.  The result will be, half shafts that actually drive the parts they are supposed to when the axle is turned.  In other words; at the front you spin the wheel and the disc brake will spin, even when you move the suspension.  At the rear, no matter which wheel you turn the disc brakes will turn and at the same time the wheel and disc brake on the other side will turn.................that is as long as YOU assemble it correctly. :)

So far the only parts that are going to be white metal....the brake and clutch cylinders on the front, the hub universal joint housings, pinion housing for the rack an pinion steering, upper and lower suspension "wishbones" and parts of the engine, Oh! and the wheel centers.  It is the best way to get the cast look on them.




July 3rd.      I have been having fun in my machine shop again, and after fabricating the first stub axle, I have decided on a different method of assembly to make it easier.  Instead of push/transition fit, the universal joint will be a slide fit with a screw to hold it in place.

So here is the new stub axle and assembly. I have not shaped the mounting boss to a square as you can see, but it will be on the finished item.  If you look carefully inside the UJ housing you can see a round "key", which is what will supply drive through the half-shaft.

The small brass piece next to the UJ housing is the parts that will be inserted in each end of the half-shafts and you can see the notch in it, which will engage the key inside the housing.  That is a prototype half-shaft in the picture I have used just to show some indication of what it will look like.  The other aluminum part is the cap to the Universal joint.  You will notice the "bellmouth" opening on it to allow more motion from the half-shaft.  The screw is a 1/4" long flat-head 00-90, which is inserted in the end of the stub axle and screws into the back of the UJ housing.

Here all the parts have been assembled inside the rear suspension support from the Tamiya 72D kit.  You can see how the half-shaft has movement when assembled.  And yes that is a re-machined wheel that you have not seen.

Today I also worked on the wheel center, which currently is a blank, with the profile of the rear of it machined in, including the axle hole.

And there you have it...........the assembly mounted in the wheel, to test clearance and position.  All seems well! :)

Nov. 25th 2007: As most of you know, it's been a while since there was anything new posted here. That was because a great deal of the work I had done was wrong. Although I had drawings from Lotus, they had gone through an evolution just as the car, so I was building a 72E and not a 72C. :(

That was a little disheartening after all the work I had put in, however, most of the information has been straightened out with the aide of a gentleman called Erich Walitsch in Austria. Thank you Erich!

However, the basics are the same, so I have left most of the text and pictures of this project pretty much the same.

Also the website business really increased and took all my spare time I had to work on the project. I am re-dedicated now, so you should see more on the progress soon.

There is a change on the front sub-frame, a minor change to the axles, also a slight change on the drive shafts, but as these were all test pieces it's not so bad.

I have also found a machine shop locally that can compete with the quality and price of Japan, which is great! Especially if something needs changing. I can just drive there and explain it. :)

I have just about finished the body sides and the "buck" to enable the windshield to be vacuum formed.

Next weekend I will try to post some pictures of the new "correct" progress.

If you want to see just the pictures click here.

March 16th. 2008. I have made some great progress with the tub, bodywork and started on the engine.

The floor will be aluminum and the tub is going to be made out of very thin photo etched sheet aluminum and you will have to fold it into shape.
Some of you may not like this, but I am going to supply every kit with miniature rivets for the tub. You will be able to assemble the parts without them, but you will want to install them. The holes will be there for them.

I have completed all the work on the left side bodywork and side pod. I have to give them a final coat and sand them both down for smooth finish, to reproduce the best item when it comes to molding them. I will post some pictures after I have that done. The side pods have the proper aero shape inside them as well. I am really happy with them.

The engine is still in process, it is taking a while because of the amount of parts. You will get the resin block, cylinder heads, inlet manifold and Cam heads as separate pieces, with white metal cam covers. There will also be end plates. The whole thing should go together pretty much like the regular engine. There are a lot of pieces to make for it. As soon as I have the engine done I will be able to work on the Air intake box.

The nose is almost completed as well, just some more minor adjustments and it will be ready, probably 2 more weeks before I actually get to finish that though.

To be continued.........................Page 3