ET Westbury Side Paddle Engine

[kvom]

I started my build of this model engine the past few days.  This will likely be a very long term project, but you have to start somewhere.  This is the same engine "JimmiBondi" built in an earlier thread that has unfortunately lost its photos.

I have gotten my new CNC mill mostly straightened out and myself through the early learning process.  The first two useable parts produced with the mill are the outer frame plates.  There are two earlier attempts in the scrap heap.



I also made a start on the inner frames by preparing the stock blanks (5"x10"x3/8") and drilling the many holes:



The frame plates are 6061 aluminum rather than the steel used in the original.  By milling the hornblocks integral with the frame the issue of attaching them is eliminated.

I also made a "trial" cylinder in aluminum before doing the actual ones in cast iron.

[granath]

Very nice! i have had my eyes on this build at HMEM but great that you are posting you're build here! i will definitely follow this, what type of mill are you using? any pictures ?

hope for more updates SOON!

Regards// Victor

[derekwarner_decoy]

kvom.......& welcome to PD's.......I think many members will  & watch your posings    with great interest ..... Derek 

[kno3]

Good luck with your build, it should be a very nice engine.

[kvom]

I machined the first inner frame yesterday.  No real problems and the trial cylinder fits nicely into the through slot.

 



Unfortunately I didn't have as much luck today on the second.  The work raised up from the fixture plate cutting the outline and unfortunately the endmill was in a critical areal where I couldn't save it.      This will have to wait as I have no more suitable aluminum stock.

Guess I'll just work on finishing the CI cylinders next.

[R.G.Y.]

I built this engine from castings supplied by Reeves. I only had a unimat 3 lathe at the time I have yet to fit it into a boat. One thing I found, on my plan the bolts holding the cylinder, frame and steam chest coincide with the cylinder end plate bolts. R.G.Y

[kvom]

Thanks for the heads-up.  There is quite a bit of material around the bore, so it might be possible to alter the bolt circle or the start angle to avoid the interference.  I'll check when I draw up the back of the cylinder.  I am thinking to use 8 bolts on the rear cover for appearances rather than the 6 shown in the plan.

- update -

I redid my drawing of the cylinder face incorporating the clearances for the mounting studs.  Indeed a 6 hole bolt circle gives only a 1/16" clearance  between the two lower face holes and the front/rear studs.  If I use a 8-hole bolt circle, only the bottom face hole has a problem.  And on the front cover that hole is countersunk to provide for the guide bars.  So I plan to use the 8-hole pattern omitting the bottom hole on the front cover and using a dummy bolt on the rear.

[kvom]

Today I decided to skip any CNC work and actually turn the cranks for a change.  I decided to make the valve slides as I had some suitable material.  It is a lump of the mystery brass I used previous in Bogs' engine.  It's a lot harder than 360 and needs smaller cuts too.

So the first task was to square two blocks and then reduce to size:  7/8 x 13/16 x 5/8.



Next I machined out the 1/16" deep valve pocket, which is 5/8" square.  I used a centercutting .25" endmill to plunge to depth in the center, then moved along the perimeter.



Next I cut the 3/8" slot.  As I broke my last remaining 3/8" endmill I used a 5/16 to cut to depth, then widened it with the side flutes.  Then with the same endmill I made the cheek cuts.



Last is the 1/8" slot to hold the eccentric rod.  I used a 1/8" endmill to cut to depth, then a ball-endmill to round the bottom of the slot.

[R.G.Y.]

Yes I moved the covers around one six of a turn, on the blank end. Had to fill one set of holes in the rod end cover, the one where I found the mistake. As of course can't turn that end. R.G.Y

[kvom]

My CNC mill decided to go on the fritz (limit switches not registering properly), so I started looking at materials needed for future parts as well as parts to make on the lathe in the interim.  While I did do have brass stock for the cylinder covers, it is a bit larger than required, and I hate to have to machine away 25% or more.  I found some 1-5/8" round 260 brass online and ordered a foot, so that will need to wait.

I do not have any brass  or CI suitable for the steam chest other than some 2" round, which means losing most of it to swarf.  I do have CRS and aluminum barstock that would work.  Is there any reason not to use steel or aluminum for the steam chest?

[kvom]

Rather than machining, I spent a good deal of time yesterday reading over the magazine articles again and doing some planning.  I also drew up some of the parts in CAD.

The part that's giving me a problem is the lifting link shown on page 476 of the 22 March 56 issue.  The scanned drawing is very hard to decipher.  Does anyone have the original plans and can scan that page?

[Eddy Matthews]

The plans for the engine are in our Downloads section....

http://www.paddleducks.co.uk/smf/index.php?action=downloads;sa=view;down=197

Regards
Eddy

[kvom]

Thanks Eddy.  Your scanned copies are much clearer than the site from which I downloaded the plans.

Having decided to make the steam chests from 6061 because of material availability, I started on the first one by squaring a suitable block and milling it oversize in all 3 dimensions.  Then I center drilled both ends to hopefully end up with a straight line for the valve rod.  Next I chucked in the 4-jaw and used a live center in the tailstock to align the block with the center holes.  It was not really necessary to be extra precise as I will be drilling and reaming the holes on the mill later.  The objective here is just to turn the round boss that will later hold the packing gland.  The face of the boss will serve as the datum for further machining.



Here's the blank ready for milling, along with the blank cover plate that will also be milled to fit.



The mill has some issues with the limit switches, so I'm waiting for the vendor to come up with a fix.  So using the manual mill and lathe in the interim.  The block of aluminum I have for the other chest is a bit bigger, so I decided to put it off for another afternoon.

[kvom]

I worked on the cylinders the past two afternoon; after fubaring one I had to restart that one with a new strategy.  I used the manual mill to reduce the round bar to size on 5 sides, then milled the round top on the CNC mill.  It was slow going squaring the sides as CI needs slow SFM (400 rpm, 5/8 endmill), slow feed (4 IPM), and a modest DOC (.100 shook the mill a little too much for comfort, but .075 seemed OK).  Here's the result of those ops:



Then I did the bases.  I'd already run the CNC program with the aluminum trial cylinder, so this part went smoothly:



The holes were drilled .101 to be tapped for 5-40 studs.  The next job will be to drill the bore and the cover mounting holes (also 5-40).

[kvom]

Some more work on the cylinders after watching the Masters golf:

First I used the CNC mill to center drill all the holes in one face each cylinder, then a #38 drikll 1/4" deep for the cover mounting studs.  Next I moved to the manual mill to drill the bore 11/32 and then ream .376".  I preferred to drill manually for feel.  The bore holes now had a sliding fit with a piece of 3/8" drill rod.



Now I used the drill rod in the lathe tailstock to position the cylinder body in the 4-jaw chuck:



Then I used a 23/32" drill with a MT2 shank that I borrowed from school to drill the bore.  400 RPM and a slow hand feed with frequent pecking.



Then reaming to 3/4" with the reamer held in a chuck in the tailstock:



Now they're ready to drill the steam input and exhaust holes.



The plans show 6 studs for the cover plates, but as drawn the two bottom holes interfere with mounting holes in the base.  So I went with an 8-hole pattern omitting the bottom hole, which would interfere with the steam inlets.

Spent a few hours more working on the cylinders this afternoon.  This time it was drilling the inlet and exhaust holes.  The inlet holes on each side are drilled from the lower "lip" of the borem on each side to intersect with the pockets milled in the base.  Westbury thankfully drew the plans so that the angle of the inlet holes is 30 degrees relative to the bore.  This means that the cylinder can be positioned in the milling vise with a simple 30-60-90 angle bar.



I first needed to mill a flat at the bottom of the bore, then center drill the three holes separated by 3/32".  Then a 3/32" drill for the inlet holes.  Repeat on each end of each cylinder.



The exhaust hole connects one side of each cylinder to the central pocket, and once again a 30-60-90 angle bar serves to set the cylinder in the vise.  the exhaust passage is 3/8" diameter, and intersects with one of the stud holes.  However, there is enough material left to thread for a stud.