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

[ozzie46]

I used JB Weld on my Mastiff and it has held up extremely well. In fact the whole crank case is held together with JB Weld and screws.

Ron

[deltatango]

Thanks Ron, that sounds like a big vote for JB Weld.
DT

[deltatango]

The cylinder blocks now need the cylinders boring into them and these need to be precisely positioned so that when the liners are fitted they can act as spigots to locate the blocks onto the crankcase. In an earlier reply to a post another member reminded me of the use of "buttons" for precise location of holes (that was for the spacing of the crank- and camshafts) and I read up on this now. I didn't know it at the time but one button had been made already as a gauge for the holes in the crankcase sides so a second one was turned from MS bar. I'm a convert to tangential tooling and for close-tolerance work this is hard to beat for the quality of finish and the ability to remove very small amounts of metal:



Both faces of the blocks were blued and the bore centres scribed in. The blocks were then located on the crankcase by two edges and a circle scribed through from the inside to show where the hole would emerge. The blocks were set up in the four-jaw chuck with one centre running true. The roughly scribed circle on the other face was used to check that drills and boring tools would miss the chuck jaws as they came through:




The first bore was drilled:



Bored to size, checked with the gauge made much earlier:




and the water space and recess for the liner flange turned in with a home-made internal grooving tool:



Now for the tricky bit, mess this up and you start over...

A pilot hole was drilled for the second bore using the scribed center:



one button located in the existing bore (I'd drilled this for a screw and nut but the fit was good (!)) and the second button loosely fixed with a screw into a threaded hole in the button. The assembly was then offered up to the block and the fixed button inserted, the loose one being wiggled until it also entered its matching hole. The fixing screw was tightened and this button should now provide a precise reference for the boring:



With the block back in the four-jaw, the button was set to run true with a DTI:



and the second bore completed. The trial fits using the buttons as spigots were very satisfying:



Phew...

DT

[deltatango]

A lot of the cylinder block metal has to be turned into chips to find the final exterior shape. Most of this is straight-forward carving with a 12 mm slot drill:



and



leaving us with:



and the corners of the recesses have to be cleared to give the securing studs and nuts somewhere to go:



The three stud holes were drilled in the flanges of the blocks and three "transfer punches" turned up (not hardened) to fit the 5 mm clearance holes:



the punches were used in combination with the existing buttons to make centre pops for drilling the holes for the studs:



The studs were turned to length in an M5 threaded mandrel ready for the final assembly (which is still some way off...):



DT

[Admiral_dk]

Looking good so far 

Best wishes

Per

[90LX_Notch]

Still following along David.  Some very nice setups.

-Bob

[deltatango]

Thanks Per and thanks for the comment on the set-ups Bob,

One thing that this build has definitely taught me is the truth of the advice that "time spent making tooling and jigs is never wasted". A lot of the learning has  come from reading MEM blogs.  In the past I've been too keen to get on and make "bits", now I've learned to slow down, think more, and make tooling.

David

[kuhncw]

David,

Nice work on the Mastiff and thanks for the time and effort you are putting into your build log.  There is a lot of good information in it.

You are absolutely right about jigs and fixtures.  That's the way to go.  Figuring out the fixturing is part of the fun, in my opinion.

Regards,

Chuck

[Roger B]

Good progress    I like your use of alignment buttons   

[deltatango]

Thanks Roger,
It was a reply to this blog by "steamer" (Dave) that pointed me to using toolmakers buttons for aligning holes. One up for MEM.
David

[deltatango]

Just looked at the date on my last entry in this blog, it was six weeks ago. In the time I've had for the workshop I spent most of those weeks turning the cylinder head blanks into scrap. One is probably usable but much less than perfect, the other became a definite scrapper when a cutter worked its way out of the ER25 chuck and cut a neat hole from the water space through into the combustion chamber. That is the first time that has happened to me, I'll try to make sure it's the last! Two new blanks are now being cut.

The only useful work on Mastiff was to drill and ream the holes for the inserted valve seats and guides. I made a transfer punch to locate one hole on the block, marked off the other three to drawing then checked these with the punch:



Located the centres using a needle:



Then spotted, drilled and reamed 8 mm:



The blocks are nearly finished, mustn't stuff up from here on!



The combined valve seats and guides are needed before I can drill the ports, after that some tapped holes for securing the water inlets are all that's needed. The final shaping of the outside will have to wait for the heads to be finished which is where I'm headed now to start over...

DT

[Ye-Ole Steam Dude]

G' day DT,

Some progress is better than no progress. This is a beautiful project and I am enjoying following along.

Have a great day,
Thomas

[Jo]

You are doing well David 

Just off to fondle  my Mastiff castings your good work is helping me understand what will be needed when I get round to making my one.

Jo

[deltatango]

Thank you Thomas and Jo for the encouraging words! When you've just had to accept that a lot of hours of work have gone in the bin then the boost is very welcome.

I just looked back at Jo's picture of the castings from early in the build log. In these the water spaces are cast in to the heads which would save a lot of the machining that I messed up. I might become a casting fondler yet... Hope the blog helps with other Mastiff builds, particularly Jo's.


DT

[Roger B]

I tend to call the first attempts that don't quite work 'trial pieces' , it sounds better than scrap 

The second attempt usually goes smoothly as you have already found all (most of  ) the pitfalls