Benson engine

I have ordered both of Anthony Mount's books, but they're being shipped from the UK and will likely take 2 weeks to arrive.  And then I'm travelling for 2.5 weeks thereafter.  In contemplation of the Benson, are there any plans available either online or from contributors here that I can get without violating any copyrights?

Legally no.

Jo

I'll wait then.  Might decide to do one of the others in the books anyway.

Having received the documentation, I have proceeded to model the engine in Solidworks.  Fabrication looks to be a challenge because of the numerous small parts.  I am thinking it may make sense to build the governor first to test my ability with finicky assemblies.  In any case, the attached image is where I've gotten with the model.

What size are you going for? and what are you using for the "red"base casting?

J

Undecided on size.  I read your 1.5x build log, and it's tempting to go that way just to be able to work with larger stock on the tricky parts.  OTOH I just bought a very nice 7" flywheel at Cabin Fever that would work well with the regular size. 

The base is red only because I was playing around in SW.  My thinking is to mill it out of aluminum and form the edge with a router bit.  I have a friend with a powder coat setup that I can use rather than paint.  I'm going to experiment on some colors to see how it would look on an engine like this.  It would certainly be more durable than paint.

SW gives the mass data on parts, and I priced out having the cylinder cast at Shapeways.  Brass would cost over $200, but aluminum would be half that.

I'm leaving on Tuesday for a 2 week trip to Antarctica via Buenos Aires, so I won't have to make any decisions until then.

That seems very expensive for a cylinder of that size are you thinking of cutting from the solid?

I have just done a cylinder that is 24mm bore, 36mm across the flanges and 57mm long from a mix of brass and bronze. I only had to buy the bronze for the main cylinder this was a 4" length of 1.25OD x 0.75ID hollow bronze cost £5 DBP, flanges were cut from some 1.5 x 0.25 flat bar I had laying about but likely cost less than £5GBP and same sort of cost for the bit of bronze block for the valve port block.

Dry assembled



Soldered and finish machined

Thanks for that example.  If one attaches the flanges then the decorative ribs and be turned on the cylinder without needing to bend them around the OD as with your Benson model.

Yes and you don't need such a large bit of metal.

I discovered why I had been having some issues mating a few parts in SolidWorks.  I had made an error in positioning the center point for the cylinder on the base by a couple of thou.  When I redrew the base and saved it I got a lot of other errors in mating parts that seemingly had nothing to do with the correction.  It's very likely a more experienced SW user could have fixed them simply, but I decided to break the engine into some smaller sub assemblies.  That will isolate mating issues in one from correction to the others to some extent.

Adventure in astragals on the menu today. 

as·tra·gal

noun

ARCHITECTURE:  a small semicircular molding around the top or bottom of a column.

Leave it to Jason to know the name for these decorations.  Since the Benson engine has 2 of these on the column and 1 on the cylinder, I think it behooves me to know how to turn one before diving in for a fabrication (on casting set they're already on the castings).

The obvious solution is a form tool, and other than a couple of rough grinds I haven't made any.  I did buy one for forming the rims on the wheels of my locomotive.  So I took as my example the Clickspring youtube video where oil quenching tool steel is machined and hardened.  I don't currently have any O1/O2 steel in bar form, but do have some 3/8" diameter O1 drill rod, so that was my material today.

The first order of business was to mill the rod flat to half its diameter.  A shallower flat cut was also made to help alignment in the lathe tool holder.



Next, a 10-degree angle bar positioned the piece for cutting the relief angle.



Then the form for the 3/16" astragal was milled using the same size endmill.  For a more complicated shape I'd use the CNC mill.  I could also have drilled a 3/16" hole before milling the relief angle.



I heated it to bright red with a Mapp gas torch and quenched in lubricating oil.  The result was a blackened surface, but seemed pretty hard when I attempted to file it.  Then I tempered it with the torch, all rather a guessing game at the correct color, but the result was such that I could sharpen the edges with grinding wheel (oilstone would be more precise).

Testing on a piece of 3/4" brass went well.  No chatter to speak of and a decent finish.



Came in to the house to find a free shipping offer from MSC, so ordered some oil hardening bar and some larger O1 drill rod.

I'll be away from home for the next two weeks as I visit Antarctica.  Probably no models to visit there, but there is a steam train excursion that runs from Ushuaia and back.

Nice tutorial on the form tool!

Say Hi to the penguins for us. Maybe you can entice some to come back and get jobs as shop elves... They smell fishy, but they dress well!


Just looked up that train at Ushuaia - cute little engine, would make a nice running model.

So what is the temp in balmy Antarctica this time of year, it's their summer time. Send food piccys from Buenos Aires 

Cletus

BA is excellent for steaks (and leather goods made from the leftovers from steak production).  I was there in 2007 for a week,  but can't remember what else I are there other than beef.

I have a 3-season packing list.  4 days in BA with daytime temps in the 80s. 4 days in Ushuaia with daytime temps in the upper 40s.

The temps at the coast where I can find them on weather.com seem to be in the 30s during the day and 20s at night.  We are supplied a parka and boots for going ashore in the Zodiac inflatables.  I have my waterproof offshore sailing bib and long johns for lower body insulation, and a fleece jacket for upper.  Likely to be too warm with the parka.

Enjoy your trip!

Thanks for showing the form tool. Something to remember.