[modeleng] Re: Back to it

"...pretzel-ize rthe crankshaft forging...?  You too?  Sure does things to the 
psyche when that happens, doesn't it??  I had better luck in turning one from 
the solid out of C1141 Alloy----for a Stuart V-10.

Al


--- On Sun, 1/25/09, Harry Wade <hww@xxxxxxxx> wrote:

> From: Harry Wade <hww@xxxxxxxx>
> Subject: [modeleng] Back to it
> To: modeleng@xxxxxxxxxxxxx
> Date: Sunday, January 25, 2009, 4:59 PM
> I've gotten back into the workshop this week after being
> away for a while and rather than start in on my main project
> (the 2X Tich) I've decided to shake the rust off by
> taking a short detour and do a Stuart D-10.  The castings
> have have been under the workbench for some time and are
> from early Jones & Bradburn (the current owners)
> production and this is my first Stuart engine which has NOT
> been out of the old Stuarts in Henley.
> 
> My first discovery was the prolonged
> "normalizing" process has apparently done nothing
> to improve the main castings.  These are rough and brittle
> and there is an occasional dead white hard spot.  Even with
> gentle machining chips of metal break off any square edge
> which will need to be filled before painting.  I continue to
> find dimensional errors on the drawings which requires that
> I now check through all the dimensions.  If I wanted this
> kind of experience I could have bought some old Clarksons
> castings, nevertheless, it won't build itself so I will
> soldier on.
> 
> The first job was the crankshaft which in this kit is to be
> built up of mild steel flat and rod.  I actually prefer this
> method anyway, using Loctite & pinned assembly, and the
> crankshaft has come out perfectly.  I must admit that I was
> never ever able to finish off one of the old drop-forged #10
> engine crankshafts without pretzelizing it and I
> wouldn't bother with one now.  I have another Stuart kit
> (a "Launch" engine) which is from the old Stuarts
> but which includes a pre-brazed crankshaft, essentially a
> built-up version of the forged crankshafts.  I will probably
> go to a Loctited & pinned crankshaft on this one also.
> 
> I'm presently shaping the bearings and in this version
> the drawing calls for the middle bearing to be split, which
> of course is a necessity.  Something I don't care for
> however is they call for the middle bearing cap, which is on
> the under-side of the shaft, to be loose and simply rest in
> the bearing slot and rely upon being held captive in close
> quarters to hold the cap in place.  Since I don't have a
> ball-nosed milling cutter of the size needed to make the
> slot as-designed I'll probably substitute a squarish
> split block in a squarish slot.
> 
> I plan to spiff the engine up a bit, extra detail in a few
> places, to make it look a little less
> "Stuart-like", but not to go overboard.  There was
> a chap some years ago, "Anthony" IIRC, who spiffed
> up a Stuart #4 or #5 and #9 with much more prototypical
> detail and they made beautiful engines and each was featured
> on an ME cover at least once.
> 
> The Stuart 10's are thought of as beginner's
> engines but none are a piece of cake, they force you to use
> almost the entire range of basic model engineering skills. 
> In 1982 Tom Walshaw began a series on ME entitled
> "Handmaiden" which described the building of a
> Stuart H10 using only hand tools.  He claimed it took him
> very little longer than building with machine tools.  One
> assumes he had better castings.
> Regards,
> Harry
> 
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