Airfix 1/12 Bentley Blower

[Bugatti Fan]

Impressive progress Francois!

Going back to the body covering dilemma. Maybe the ladies glove leather might be worth another look. Perhaps trying a bit stretched over and glued to a piece of plastic card and spraying it afterwards might give a better rendition of the rexine in scale. Worth an experiment maybe?

[François]

Here's a recap of the sub assemblies completed (or close to)

Frame

fuel tank

Front axel (with working brakes)

Rear axel (with working brakes)

Bulkhead and steering column (steerable)

Transmission 

I should start assembling some of them together shortly 

[Bugatti Fan]

What an improvement on all those kit parts by being replaced.

Cannot see Airfix ever completely re tooling that elderly kit, so you and Nick have a nice little niche market for making replacement upgraded parts for the modeller who want to improve it.

Edited September 25, 2023 by Bugatti Fan

[Pierre Rivard]

Very, very, very impressive work. With your research, design expertise and 3D printing you have basically redesigned the whole kit.

You could market this as a trans kit... or a complete kit as I doubt very few original parts are left.

[Bugatti Fan]

Pierre, I think that Francois is already looking at marketing some of his upgrade parts.

Look at the buying and selling section over on Britmodeller.

Also, Nick Edwards is developing a number of Bentley kit upgrades. Look up his Unobtainium website. He does a nice set of replacement wire wheels for the Bentley.

Edited September 25, 2023 by Bugatti Fan

[François]

A few more sub assemblies completed.

The final drive shaft

The pedal cluster assy. Here's what I was aiming for

And what I came up with

 Test pedal on the left and final result on the right. Mounted on the  pivot shaft are the clutch fork followed by the clutch pedal and the brake pedal to the right. The accelarator pedal will be located between the clutch and the brake but doesn't pivot on the same shaft. Notice the Bentley pedal pads.

The rear brake tierods

And here are a few pictures of some subs in place.

[François]

I woke up this morning asking myself, when is enough detail enough.  Didn't take long to find the answer, never. Frankly, if I can do a specific detail,  why not.

I'm saying this because today I decided to look at the clutch since it needs to fit properly with the clutch fork I made. 

Now since it looks like I will have a brake pedal that actually activates the brake when depressed, why not have a clutch pedal that also does something.  My idea is to modify the clutch housing by removing the moulded center spigot and replacing it with a spring loaded spigot that is in contact with the clutch actuating fork.  Depressing the clutch pedal would push on the spigot and make it move. Sorry but that's where the mouvement stops, I don't plan on doing an actual clutch. I know it's alot of work for a very little mouvement but like I said at the start of this post, if I can do it, why not.

I forgot to take a picture of the clutch before I started to cut it up but fortunately,  it was 3d modeled.  So here's what the kit clutch looks like. 

 

And the real thing

Here's what l'll be doing,  replacing the moulded center spigot with a brass outter flanged sleeve and an inner spring loaded spigot. Since it's the clutch,  via the square hole on the center moulded spigot, that drives the transmission shaft, I need to lock the new spring loaded spigot so it can still drive the trans while moving in and out freely. I made a small slot thru the spigot and will drive a pin thru it.

All the parts are done and ready for finish. 

 

Here's a little video of the clutch fork activating the spigot. 

 

Another crazy idea a have is to install a micro gear motor where the starter would be and to hook it up to the ring gear.  This would rotate the crank and pistons all the way down to the rear wheels.

I did a bit of research on micro gear motors but everything is to big.  I would need something no bigger than 10mm dia x 25mm long. Does anyone know a source for small motors?

 

[Bugatti Fan]

Fascinating developments. modelling

This is going into the realms of super modelling. By far more than I would attempt for a static model.

[absmiami]

Holy cow

Francois - have you tried Zero  Paint’s textured paint?  Might work for the body shell … 

[François]

Absmiami, the plan is to cover the body structure with a 4 way stretch fabric so I would like to avoid painting the skin if possible.

So the clutch is done and the spring loaded spigot works.

 As for my gear motor idea, I found a vefy small planetery gear motor. I bought two different ratios, 136:1 and 700:1. They measure 6mm dia which is perfect. I'll mount it in an excentric housing so I can fine tune the center distance between the pinion and ring gear and play with different pinion/ring gear ratios.

Motor without housing 

Motor with housing 

 

[Bugatti Fan]

After all this you might also like to use Nick Edwards' catch phrase   'May Contain Airfix!'   lol.

[François]

The rear brake linkage is done, and it works. Here are a few pictures and videos.

 Started on the front brake and handbrake linkage 

The transmission is in. Everything rotates from the clutch to the rear wheels 

 And last for today, trial fitting of the gear motor (mounted in the starter bracket 

 

[Pierre Rivard]

Speechless...

[François]

Merci Pierre !!⁸

 

[François]

In order to complete the front brakes assembly,  I need to fabricate the  perrot shafts which are these things

 

And here is where they are mounted on the car.

 

I wondered why they would name this part after a bird. It turns out it's actually named after it's inventor, Henry Perrot. Besides,  the bird is a pArrot. Live and learn.  Quite ingenous guy. This shaft transfers the rotation mouvement from the inboard linkage driven by the brake pedal to the shoe cam that activates the brake shoes. The reason it needs to be double jointed is to allow suspension and steering mouvement while braking.

 

Another fun fact. With a double universal jointed shaft, it's important for both joint to be rotationnaly aligned. This will reduce the speed variation from input to output. I did the mistake of rotating 2 joint by 90deg in one of the very first machine I designed back in 87... didn't work so good. I'm not sure it would matter all that much in this case since the perrot shaft does a max rotation of 15/20 deg only.

 

I'll be using 3/32 dia aluminium tubing to fabricate my perrot shafts.  Normaly,  they are hidden under a gator. Depending on how nice they turn out, I might cover only one and leave other visible. 

[François]

 

Today I fabricated the 2 perrot shafts. Really hard to do but I'm quite pleased with the result for 2 reasons, first I think they look pretty good and second, they work as they should. They transfert the rotary motion from the brake linkage to the brake shoes even when the wheel is steered. Here are some pictures and videos of the process.

The prototype 

All parts cut

I used a small styrene rod to make the yoke and a .01 dia nickel rod for the pivot

All done 

In action

   I tried to make a gator to cover 1 of the 2 shafts by rolling a piece of nitrile rubber but the results are not very promissing so far. Unless I find a small (about 3/16 dia) and very thin tubing, I might leave both shafts visible. Edited October 3, 2023 by François

[François]

I finally went with a balloon for the gaiter, the kind you make balloon animals with.  I now that latex will eventualy degrade but when it happens, I'll have 2 visible perrot shafts instead of 1. So, aside from the hand brake plus à few parts to paint,  the brake are done.

 while I'm waiting for a few printed parts for the handbrake,  I started to tinker with the engine.  Won't be easy to get everything aligned and working but I try my best.  So far, I've got the 2 upper bevel gears test fitted. Plus alot of sanding and tweaking done.

 

 

[François]

Did more engine prep today. In order to better show case the internal engine components once the model is completed,  I made a side window on the engine block where an aluminium sheet would normaly be. Not sure yet just how I'll finish it up but I'll think of something.  I made the opening on the exhaust side (passanger) seeing it's less crowded on that side. Another view point will be from under. So I added some small magnets to the oil pan so it can be easily removed. I honed the 4 cylinder bore using a honemade honing tool. Not very sophisticated but it works.

Some progress shots

With pistons randomly inserted

Honing tool 

Magnets on oil pan

 

[absmiami]

Great 

[François]

Still working on the engine and alot has been done in the past few days.

Here's what been done.

1- Removed the exhaust manifold mounting plates to make painting easier as the bloc will be painted aluminium (bottom) black (center) and chrome ( top and vertical drive shaft housing). New 3d printed plates will be installed later on.

2- removed the 'want to be' engine core to lower casing mounting stud and will replace with real nuts 

The real thing

The same will be done on the intake manifold side.

3- speaking of the intake manifold, I 3d modeled it and will replace the moulded one. I also added alot of details to this section like correct timken style lock nuts and tach drive housing.

The moulded manifold

The 3d modeled one

The tach drive housing

The real housing

4- when I first designed the internal engine components, I added the cam shaft drive gears thinking it would be fun if they actually worked but really thinking that they would not. Well it turns out that they do work. From the gear mounted on the crank all the way up to the bevel gear mounted on the cam shaft. Except the the cam shaft is not really a shaft but just a plastic cylinder that was printed with the head.

printed cam shaft

So, I decided to crank it up a notch and add a proper rotating cam shaft that goes thru the head from front to back. That way, I'll also drive the dynamo coupling.

Here how I did it. I had to drill a 3/32 dia hole thru the head. To do so, I printed a drill jig to properly hold the head and drill thru.

Head drilled and with a 3/32 dia aluminium tubing that acts as a bushing for the cam shaft.

All internal parts

And voila, a rotating cam shaft (and dyno coupling)

 First test fitting on frame 

[David G.]

I'm still following along and I'm still amazed.

David G.

[LaughingIndian]

still here too … speechless … thanks for all this!

[NOBLNG]

I don’t know what to say except…WOW!?

[François]

Thank you all for the positive feed back. 

I continued on the engine today, fabricated the engine block side and end plate out of polished aluminium sheet.  Normaly,  both side plates would be full but I made a special one with openings so that the pistons can be seen in motion. This feature wasn't present on the Alfa romeo. On that model, the moving parts can only be seen from underneath.

Also did some weathering on the internal engine parts and assembled it.

After a bit of tweaking,  the pistons move up and down

I inserted the cylinder core assembly in the engine housing and did a trial run with the slower of the 2 gearmotors I ordered, 700:1, 46 rpm. I'm hoping that the 136:1 will be strong enough. Please keep in mind it's just a test fitting.  Once complet, the gearmotor will look like the starter. You'll notice that the power source is the actual car battery,  I inserted 2 button batteries inside it.

So, like the infamous Dr. Frankenstein once said,  "IT'S ALIVE!!"

   

 

 

 

[Bugatti Fan]

Will this model eventually be mounted on a special display base to enable the working parts to be seen in motion? Or is all this being done purely as an engineering challenge?

The detailing work is absolutely superb, and way above what the majority of us would aspire to be  doing with that old Bentley kit. A very interesting thread to follow none the less, that would encourage many to make some of the improvements that Francois has done on their models too.

Edited October 10, 2023 by Bugatti Fan