Bentley 4 1/2 litre Blower in 1/12th scale - may contain Airfix.

[nick]

Hi all, been doing some pesky day-job work last week, hence no updates, should be back on the Bentley soon. I've got some CNC bits I want to tackle next, so I'm just trying to learn 'sheet metal mode' in fusion 360 - something I haven't played with before, but looks very interesting.

 

You tell it the shape you want to make, what type of sheet you want to use - steel, brass. ali etc and thickness, then it goes away and does all the hard sums for you , bend radii, cut outs, what a flattened out curved sheet needs to look like etc, etc. That's the theory anyway, right now I have no idea how to do any of that stuff, so off to plug myself into Linked-In for a bit.

 

In an ideal world, I'd like to do this while I'm sleeping and wake up knowing how to do it  I'm sure Musk is working on that too.

 

Nick

[Noel Smith]

I used to do CNC programming for Sheet Metal Working Punching and Nibbling Machines. 

Basically it is working out stuff in the flat using bend allowances depending on the angle being bent or radius being formed that calculate how much the metal will stretch on each bend. Much easier now that 3D cad can do it for you!

On very thin materials it will be extremely minimal in practice.

 

Edited July 3, 2023 by Noel Smith

[nick]

Back now, slight diversion installing a new utility room for my dear wife, which in turn led me to using the old cabinets in the workshop, which in turn caused me to carry out a complete re-fit. Anyway all done now.

 

So here's a completely new engine made with the new CNC water panels,

 

 

I'm pretty pleased with this to be honest, it's still 1/12th not 1/8th and I think the precision of the panels has really sharpened it up, plus it's the second one I've built now so I learnt about some of the finishes etc from the first one.

 

 

Quite pleased with the tacho cable, I made it by winding a strip of ali tape around a wire using a geared affair I made for making rigging on my HMS victory

 

 

Basically it turns both croc clips at the same time, it's amazing how useful it is sometimes!

 

Thanks for sticking with what's turning into the worlds' longest build it seems!

 

Nick

 

[Dancona]

Dear Nick,

 

Nailed it, absolutely spot on !

 

Congratulations

 

David

[CrazyCrank]

I'm speechless !

[nick]

3 hours ago, Dancona said:

Dear Nick,

 

Nailed it, absolutely spot on !

 

Congratulations

 

David

Wow, thanks David, that’s good enough for me. 👍

[nick]

I’m liking the new, super-tidy (for now!) workshop too

 

 

mostly cast offs from the old utility room plus a few excellent hobby zone flat pack mini drawers and tool holders

 

 

 

[nick]

I’m currently contemplating the chassis - stay tuned for the next exciting instalment!

[nick]

I’ve only today got copies of Gerald Wingroves the Complete car Modeller vols 1 & 2. He tackles the Bentley in vol 1, fascinating stuff. It’s very much of its time, but well worth reading.
his workshop and tools are amazing, not to mention the old school lengths he goes to getting stuff done. Real dedication and expertise. 
I did smile when he was talking about new fangled nibblers for brass cutting that consume about 1/8” in the cut, which he considered a terrible waste ‘with the price of brass these days’ it was probably about 4 farthings a yard then. 
 

he appears to be making use of something called ‘extreme skill’ instead of technology. Weird. I shall be sticking to fat fingers and a big computer I think. 
 

 

[Noel Smith]

The late Gerald Wingrove's Complete Car Modeller books 1 and 2 have been a  great source of inspiration to me over the years.

Very much books of their time before the advent of a lot of the modern technology we take for granted today, but none the less still very good books for any aspiring scratch built car modeller to get hold of.

I had the great pleasure of visiting Gerald at his very first workshop when he lived in High Wycombe where he showed me what he was working on at the time. Blower Bentleys as it happens and his drafts of CCM1.

His CCM No1 book was published back in the decade when the Airfix 1/12th scale Bentley Blower was first issued. Besides the two techniques books there were two others that were feature books about his work. The Model Cars of Gerald Wingrove and a later book that was named The Art Of The Automobile In Miniature by Gerald and Phyllis Wingrove. Both books feature  completed models and are fantastic eye candy. Gerald wrote a book about ship modelling before embarking on the car models. A fine example of his work is the large diorama that is on display at Bucklers Hard in Hsmpshire. It depicts Bucklers Hard back in the days when wooden warships were built there. He also wrote a book about projects that can be made on the Emco Unimst Miniature Lathe. I made a four way toolpost using the plans in the book for my little Unimat. Saves me loads of time when using the machine as I don't have to keep setting up a single tool post every time I need to use a different tool.

 

Edited July 16, 2023 by Noel Smith

[nick]

I realised I hadn't drawn the exhaust manifold. I know why now. I've just spent two days on this damn thing, it looks deceptively simple in these renders. it wasn't!

 

 

Anyway done now.

 

I've made some good progress on drawing the chassis as well.

 

Surprise, surprise the airfix shape is wrong.

SO I could either produce my own body with the correct rear chassis shape - I'm trying to avoid this is as it's just about the only part I plan to use from the kit, or follow the incorrect airfix shape with my otherwise correct new chassis. I've gone for the latter. The curves are wrong on the rear section and it's hard to see unless you lay the rails on the drawing, so I've decided to live it. for now anyway. The walls of the kit chassis are around 4 or 5 times thicker than scale, not super obvious on the finished model but I want to see if I can make these out out CNC Brass sheet anyway. Haven't got to that bit yet either. I have a few ideas for how I'm going to do that.

 

I may even draw a correct version while I'm at it, as it won't take much effort, and I will fairly inevitably end up junking the airfix body along with everything else when I start looking at it properly no doubt. 

 

I'm also avoiding all the fiendishly complex looking advance retard levers and cranks going to the Magnetos that I will have to tackle at some point. I think it's because I haven't figured out how the hell they work yet!

[nick]

Update. 

 

I've never seen this modelled anywhere, but I think the chassis has a doubler or sleeve fitted on the centre section, you can see the front Vee shape here

 

 

And also this stealth grab of the Bentley Evolution CAD process shows it too

 

 

This may or may not be correct, but to be honest it suits my purposes and lets me break the chassis into three, smaller manageable components. With this in my mind, I have created tooling to make male and female dies that I can CNC machine out of something, probably just hardwood, and I'm going to have a go at pressing some annealed brass sheet into this form.

 

I really don't know if this will work, but I'm going to give it a try. Watch this space!

 

 

[Colin W]

This is very impressive and getting better with each update. 

[Noel Smith]

Really progressing well this project. It will be interesting to see when Nick's various Bentley bits go on the market.

 

Would be fascinated to know about how to obtain the engineering drawing the chassis members are being overlaid on.

Is it one that can be downloaded directly from the internet, as it looks like an archive drawing showing all the details.

[PROPELLER]

5 hours ago, nick said:

I really don't know if this will work

 

Good luck!

Stamping is really a challenge! Be careful with the gap between te male part and female one...

It will be necessary larger than the thickness of metal sheet.

And you have to find a large and strong press! I have never can do a piece over annealed brass more than 0.3mm...

 

Dan.

[nick]

57 minutes ago, PROPELLER said:

 

Good luck!

Stamping is really a challenge! Be careful with the gap between te male part and female one...

It will be necessary larger than the thickness of metal sheet.

And you have to find a large and strong press! I have never can do a piece over annealed brass more than 0.3mm...

 

Dan.

Oh.

OK I suspected as much.

I wanted to go for 0.4mm for scale, the fold is only about 8mm deep so I had hoped to get away it!
 

I’ll give it a go anyway now I’ve gone this far.
 

Plan B is to CNC Cut a hardwood jig, cut out 3 separate pieces, top, side and bottom, form in jig and silver solder. 

 

stand by!

[nick]

7 hours ago, Noel Smith said:

Really progressing well this project. It will be interesting to see when Nick's various Bentley bits go on the market.

 

Would be fascinated to know about how to obtain the engineering drawing the chassis members are being overlaid on.

Is it one that can be downloaded directly from the internet, as it looks like an archive drawing showing all the details.

I found this online **SOMEWHERE** unfortunately I’ve been collecting images for over a year for this project so couldn’t tell you where I found it. It differs from the one in the Haynes manual too. Drop me a pm and I’ll see what I can do. 

[nick]

Well it didn’t NOT work. It’s not right either though. I’ve seen enough to think it can be made to work.

 

I ended up 3D printing the dies and as long as they have a lot of infill density, they do see to work. I might switch to hardwood if they don’t survive. 

 

im trying to be clever and CNC drill the frames as well as cutting them out fully before forming. This means locating the blank in the dies is critical and that’s the bit that’s letting me down in version 1. 

 

 

so learning from that, I’ve come up with this design for version 2. 

 

 

the logic is that the square peg at the rear positively locates the blank in both x and y and the tongue and slot at the front keep it centered in y but allow for stretch/contraction in x as the piece is formed. 
 

once again no idea if this will work, so welcome to the ‘suck it and see’ school of engineering

 

[nick]

I’m close to giving up now on this idea now. As expected, the stretch isn’t linear so the idea of pre cutting the final shape just isn’t going to work.

And despite being tethered front and back I think it’s just ‘rolling off’ the curved part when pressed. Well I gave it a go. 
 

 

I’m going to have to fabricate these now I think by cutting out separate top, bottom and sides and soldering. Stand by for the next round of failures. 

 

[PROPELLER]

3 hours ago, nick said:

I think by cutting out separate top, bottom and sides and soldering

 

he best way, for sure! As the sides of the fuel tank...

Dan.

[albergman]

Why  not just 3D print them Nick?   Too soft maybe for what they need to support?   If so maybe a brass "brace" glued out of sight? 

 

Beautiful progress anyway.

 

Frank

[nick]

2 hours ago, albergman said:

Why  not just 3D print them Nick?   Too soft maybe for what they need to support?   If so maybe a brass "brace" glued out of sight? 

 

Beautiful progress anyway.

 

Frank

Hi Frank, I know it will just sag at anything like scale thickness. I tried printing the box section engine stand for my F40 motor and that sagged, so I made that from brass. I’ll get there in the end!

[nick]

14 hours ago, albergman said:

Why  not just 3D print them Nick?   Too soft maybe for what they need to support?   If so maybe a brass "brace" glued out of sight? 

Frank, you got me thinking there, A brass plate running the entire length inside the C section would be invisible and also provide the stiffness needed, it will also allow me to get the nice, curved external fold edges (as they would be printed) that would always be a problem to achieve with a soldered joint, so I think that may be the answer. Especially If I made the doubler plate from brass as well, which is easy as it's just folded, not pressed. I'll give that a go next I think. Thanks for the inspiration!

 

Nick

[nick]

This is all your fault Frank! I've nearly finished drawing the hybrid design now, so the grey bits will be printed  and the yellow bits CNC cut from brass sheet, hopefully this will solve everything!

 

 

You can see what's going on a little better here with the printed parts removed from  one side

 

 

Nick

[albergman]

 Glad I could assist on this marvelous project.   An invoice is on its way. 

 

Nice that you can actually print the recess to take the fitted brass support.   Will it be a flush fit or be recessed?