Len Mason's "Mastiff" - chewed from the solid

Hi All,
This is the start of a build log of my attempt at Len Mason's Mastiff, a 4-cylinder horizontally opposed engine of about 25 cc. I've chosen to do without castings, partly because of cost but mostly because I like carving metal. I also wanted to know how much extra work there really is doing it this way compared with making jigs and setting up castings.

As a start I redrew the whole engine in 3D using Geomagic Design and made necessary changes to the crankcase and other parts, also changed all threads to metric. Here is the external appearance of the engine as modified:



and some sections:



Kirk Burwell at Hemingway Kits kindly put together an anything-but-the-castings kit of parts which will save a lot of time sourcing bits and pieces:





The picture also shows two kits each for a pair of home-made spark plugs, I have no experience with these, so I have my fingers crossed.

The Al blocks came from the local suppliers' odds-and-ends shelves:



The crankcase was already completed before I found this forum, but I put this in the picture for completeness. The jpegs exported by Geomagic Design are rubbbish so I've attached the same pictures as pdf files.

I'll show progress on the crankcase in the next post.

DT

Looking forward to seeing the building of this  engine.  Wishing you a successful outcome for all your efforts.

Frank

Thanks Frank, I really appreciate the good wishes!
DT

A very ambitious project - best of luck and success with it. 

Cheers,
Phil

Looking forward to following along with your build.

Dave

I hope you can make the drawings available. I have the book, but the print quality of the drawings makes them unreadable. It looks like they took original pencil drawings and reduced them to fit the book and the  line width is so tiny the drawings are useless. I wanted to build this years ago, I bought the book when I attended an ME show, about 1994 I think.

This looks to be an interesting project, I wish you every success     

Actually I make all my engines from solid. From the solid modeling you posted it doesn't look like there is a lot of complex details (fillets, bosses etc) to contend with so it shouldn't really be too big of a job.
The only thing I can advise is to do all the hole drilling (major holes) and internal cavities first. The reason being is once the outside has metal removed and there aren't many square surfaces left it's hard to clamp or fixture the part to do the internals.
Good luck on your project. I will be following along to watch the progress.
gbritnell

Hi DT
I have the book as well and intend to build it at some stage.
Will be following along for sure!
Pete

Great project DT. I will be following along as well.

Bill

For reference: This is the alternative the set of castings for the Mastif.

I don't have the skew gears for the oil pump

DT I see you mentioned a "kit" for two sparkplugs. I did not see those on the Hemmingway website. Is it something that Kirt sells separately with drawings?

Jo

Jo,
I've just looked again at the Hemingway website and the plug kits have disappeared! They were next after the Rimfire and NGK plugs with a part number HEA 1000. This must be a very recent change as Kirk sent me a replacement insulator (to replace one that was broken in transit) that arrived only a few days ago. Best contact Kirk directly if you are interested.

Thanks for the picture of the castings, by the colour these look to be in CI? The skew gears drive the oil pump and contact breaker, the pump needs two small pinions as well.

RonGinger asks about making my drawings available, what do other people think about this? I don't want to tread on any toes etc. Ron's comment about the quality of the drawings in the book is correct, this was another reason for the re-drafting in GD.

gbritnell says:

Quote from: gbritnellActually I make all my engines from solid. From the solid modeling you posted it doesn't look like there is a lot of complex details (fillets, bosses etc) to contend with so it shouldn't really be too big of a job.
The only thing I can advise is to do all the hole drilling (major holes) and internal cavities first. The reason being is once the outside has metal removed and there aren't many square surfaces left it's hard to clamp or fixture the part to do the internals.
Good luck on your project. I will be following along to watch the progress.
gbritnell

During the redesign I made a point of removing, if possible, anything that was awkward to make. Thanks for the advice re keeping the outside of the billet intact as long as possible - this is how I intend to work.

Can anyone tell me the range of RPM to expect from Mastiff?

DT

Those are all Ali castings. I suspect that the Skew gears are the ones that used to fit to car/motorcycle speedo drives 

Drawings  MAP used to do drawings in the 1980s as PE.32, they don't any more  Kirt sells 9 pages of A2 imperious ones with 122 pages of notes to aid the builder, so he is not making anything on their sales and my guess is that you showing this build is likely to increase sales of his casting sets which is where he makes his money. And as you say you have done a redesign so you own the copyright of that redesign so it is up to you if you would like to make them available to the members  .

Jo

Actually, PE32 is still there, although mis-spelt:

http://www.myhobbystore.co.uk/product/22178/matiff-set-plan-pe32

Beware, Len Mason's son is very protective of his father's legacy.


Skew gears?  Make your own .  If I can...

Rod

Why is it under the model boats.

Jo