1930 Bentley Blower by Aifix 1/12 build log

[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
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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.

 

[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.
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[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

 

[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 by 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)
View attachment 20231007_214148.mp4

First test fitting on frame

 

[François]

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
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I inserted the cylinder core assembly in the motor 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!!"
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[Uwek]

WOW - great efforts on these moving parts - very good work and details

 

[François]

I've been working on the water pump. The kit's pump is no good dince it only has 1 legs. The real pump has 2 legs, one that is plugged (passanger side) and one connected to the block.
Here's the kit's pump


The real one

My 3d modeled pump

And my 3d printed pump.
Still need to install the bolts on the front flange and the rubber hoses with clips


I also 3d modeled the cooling fans.


View attachment 20231014_215137.mp4

And finished the handbrake linkage. Just need to chrome the lever.

 

[François]

Up date time, I've been busy on many fronts at the same time.

1- Due to "peer pressure", I remodeled the water pump and from cover to better reflect the picture posted by nick. I had it resin printed instead of trying to print it myself. The result should be alot better.

The real thing

The 3d model


The new pump (still drying)


And the cover plate (also still drying)


2- I started to assemble the brake ajuster but I'm still missing a few aluminium parts that I need to fabricate.


3- I modified the steering wheel. The one on my ref car has plastic covering on the 4 spider branches. In order to do this, I removed the center portion on the wheel, printed a new one, inserted 4 heat shrink tubes, glueds the 4 branches to the wheel and shrunk the tubes. Looks ok to me. I also started assembly of the stator control that mounts on the steering wheel.

My ref car steering wheel


The kit's wheel (sorry for the poor picture)


Heat shrink test


All the parts ready to assemble


The finished wheel


and with stator control


4- received the fans. I had to make a sanding jig to sand the mounting surface of the fan housing. They look very nice and they spin!

Jig and parts before sanding


Housing in jig


Fan assembled




Back from paint


5- started to instead the gazilion bolts on the engine block aluminium cover plates. 1 done. 2 more to go.


6- the engine block is all painted, lower portion aluminium. Core black and top chrome.

7- finalized the handbrake release lever

 

[dockattner]

As I mentioned on another of your build reports 'cars aren't my thing.' But like a sick voyeur I simply can't look away from your work. Stunning.

 

[Corsair]

Your work is stunning and your dedication to accuracy is nothing short of astounding ! I'm always amazed and impressed beyond belief when I review your posts !

 

[François]

Thank you all for your positive comments, it means a lot to know that my (over the top?) efforts are appreciated.

 

[pugwash]

Truly astonishing.
One minor gripe....the shrink wrap on the steering wheel spokes look a bit 'bulky' compared to the real thing.
Only my opinion, but it would look better painted?

 

[François]

Yeah, I know. I tried to find a thinner heat shrink but I already have the thinnest kind. I'll try reprinting the wheel center with narrower arms and retry the shrink

 

[pugwash]

Mmm...if you are printing the spokes of the wheel, can't you indicate on that 'print' the slightly thicker area (which you are trying to depict with shrink wrap)....and then paint it?

 

[François]

I could try but I don't think my printer if precise enough. I'll give it a try and see.

 

[François]

Not much done today.

Fan assembly done.



And water pump face plate mounted.


It was noted (thank you Pugwash) that the steering wheel arms are maybe a bit big and I have to agree. I'll reprint the center portion and see it I can heat shrink on a narrower arm and maybe compensate bit on the print for the too thick heat shrink.

 

[François]

I'm rethinking the steering wheel. I really don't like my first try, the heat shrink is too bulky and out of scale. I even tried heat shrinking over a smaller section arm but that didn't work either, the heat melted the plastic. So I'm scraping the shrink idea altogether. I'm going to try using super thin rice paper tape (about .002" think) to simulate the plastic cover used over the spider arms.

So let me remind you of my goal.


My first try with the head shrink.


my first rice paper test (not as bulky as the heat shrink)


the rice paper and newly printed wheel center


l'm also slowly advancing with the engine dress up, I've got the second aluminium cover plate installed and drilled. Still have to put the bolts on.

 

[pugwash]

Wheel is now much more convincing. Well done.

 

[Dave @W]

I just caught up with this fantastic model. I'm surprised that Airfix didn't do better with their rendition but you for sure made the fixes needed and a lot more.
Nice that you caught U-joint proper phasing. Any out of phase double U-joint application is a very real cause of component failures. Even good machine shops and garages have made these $$ mistakes as I've found out.

Just an observation but I do question the use of a single 12V battery in the 2020 and Birkin's car. I understand that this is what you are basing your build on but for sure it's not 1930 period perfect. 6V batteries were the "standard" of the period. You would need a different and 12V version of virtually every electrical component.

 

[François]

Thank you Dave. While researching for the battery info, I did find a period electrical drawing showing 6v batteries but they used 2 in series this the 12v. This period photo seems to show only 1 large battery as in the continuation cars.


I assembled the brake adjuster today, I would need a strongher return spring to properly stretch the cable but my parts would not take the stress. But it still fonction as it should. The cable can be tensionned by turning the adjuster knob, this would have compensated for brake pad wear.
Here are some progress and finished pictures and a video of the working mecanism.

View attachment 20231022_210140~3.mp4

Also redid the steering wheel using the rice tape described in my previous post.