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1/5th Scale Denny Improved Ericcson

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Jasonb:
With some  :pinkelephant: and  :cartwheel: having taken place this weekend it must mean it's time to start another build thread.

Most people seem to opt for building the Rider Ericsson Engine with it's four legged "table and furnace slung below but I have always liked the look of the Denny Improved version. There is the Eisner kit available for one in 1/4 Scale but I have read of issues with the design and castings. I did get a look at the drawings for this and could see some obvious issues of fit and when I did a basic layout of it in CAD there were other things I did not feel looked right.

So I decided to go back to basics and scanned in a patent drawing so that I could "trace" it in Alibre CAD and pull the sizes directly off of that. This shows one of 5 sets of dimensions that were taken from the patent once it had been scaled to my chosen size which is a 40mm bore making the model approx 1/5th scale, this also kept the flywheel within the XY envelope of my CNC so I could cut that from a slice of cast iron bar.



I initially just drew the various rods and linkages as simple flat bars with holes at the pivot points and did a trial assembly to check how everything moved and once happy with that set about detailing the various parts that would all be fabricated or cut from solid. I found that setting them to 50% transparency and then assembling over the Patent drawing also made checking the proportions easy, sectioning the parts also made sure nothing was going to clash internally



A quick check of what materials I had in stock and what needed to be ordered and this lot arrived a couple of days later from M-machine, the main items are some flat black bar for the base plate, slice of CI for flywheel, Brass tube for displacer (did not use it) and some thick wall steel tube that will become both Furnace and Cylinder Jacket and a piece of 70mm square for the furnace base.



After marinading in brick cleaning acid to remove the mill scale the piece of flat black bar for the base was cut a little oversize and then various holes drilled and tapped.



I then made use of the tapped holes to mount the base to a machining plate and used the CNC to bring it to the correct overall size with rounded corners and also reduce the thickness where the furnace sits. I roughed this out with an adaptive path using a 6mm flat-ended cutter then finished with another 6mm cutter but this time with a 1mm radius corner which left a small fillet where the angled edge to the raised section meets the flat. and using a 0.2mm scallop between passes the angled slope will need little in the way of hand finishing to get it paint ready.


crueby:
Off to a great start!  Am pulling up a comfy chair to watch along...   :popcorn: :popcorn: :popcorn:

Dave Otto:
Cool another one  ;).

Dave

gerritv:
One of the great features of CAD, drawing over a photo/canvas etc. (feature name depending on the software). Then iterating to get the assembly you need.

Patents are such a great source of information as well. The language is rather obtuse and specific, it takes a while to get used to reading them..

gerrit

crueby:

--- Quote from: gerritv on February 19, 2024, 02:07:59 AM ---One of the great features of CAD, drawing over a photo/canvas etc. (feature name depending on the software). Then iterating to get the assembly you need.

Patents are such a great source of information as well. The language is rather obtuse and specific, it takes a while to get used to reading them..

gerrit

--- End quote ---
100% agree on both the drawings and the patents!  And patents from way back are available online  from many countries, though each has their own  style search engine that can take a while to learn.


 :ThumbsUp: :popcorn: :popcorn:

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