Author Topic: Jowitt MkII Popett Valve Steam Engine  (Read 27105 times)

Offline bruedney

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #15 on: February 12, 2016, 07:34:16 PM »

Bruce thats not the link to the finished engine, just the duplicate copy of this thread on ME ;)

J

Whoops wrong one - sorry guys - but I knew I had seen a thread somewhere - must have been a thread from my wife's sewing  :-[
‘Results! Why man, I have gotten a lot of results. I know several thousand things that won’t work.’ — Thomas Alva Edison

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #16 on: February 18, 2016, 05:33:38 PM »
Frame Ends

Start by machining two pieces of aluminium to 32 x 26 x 12mm



Locate the far edge and right hand end then move in 5mm and drill and tap M3, move along 22mm and do the other hole. If you use a vice stop then the other three pairs of holes can be done without having to locate the edges each time



With the vice fixed jaw and stop still clocked in the bottom slot is easily located and using a 12mm dia cutter taken to 8mm deep followed by drilling & tapping for the M5 thread.



Next set the ends to 3.6degrees and flycut or mill the slop on the outside face to complete



Feet

Machine two bits of Aluminium to 12 x 8mm and at least 24mm long, locate an edge and end then drill the two 5mm holes countersinking one to take the head of an M5 CSK socket screw.



Pop a 5mm pin into the hole and set a milling cutter 8.5mm above the vive jaws and then take a series of tangental cuts which will leave a facetted face as seen on the one in the vice. This can quickly be cleaned up with a file to leave a nice smooth curve as in the foreground.



A few M3 and M5 screws can be used to see how it all goes together, don't drill out the M3 threads in the side plate to clearance yet.



Drawing to Download

J
« Last Edit: February 18, 2016, 05:37:51 PM by Jasonb »

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #17 on: February 23, 2016, 08:27:39 PM »
Bearing Caps

Start by machining two pieces of aluminuim to 10 x 10 x 28 and then hold in the vice and locate a side and end. Drill the two 3mm holes then the 1.5mm oil hole right through followed by a 6mm 2 or 3 flute cutter plung 4mm deep to cut the socket for the bush.



Changing to an 8mm cutter plung 6mm deep to form the counterbore to the 3mm hole and then the flat area 4.3mm in from the end.



The two side frames can now be screwed back together and the caps screwed into place. Locate the centre of the crankshaft hole, spot drill then open up with 6mm and 10mm drills and finally use a 12mm milling cutter to take the hole to size.



With the frames stood upright the 1.5mm holes for the bearing retaining pins can be drilled using the matching hole in the cap as a guide. Mark the caps before removing so you can assemble them in the right position in the future.



Using the same method as for the feet the tops of the caps can be rounded over to 10mm radius



Oiler Bush

These are simple turning jobs from 6mm rod. Face the end, drill 3.5mm and tap M4 x 0.5 metric fine then part off two 5mm lengths. If you don't have metric fine then 5/32 x 40 ME or M4 x 0.7 will do. These bushes can be fixed into the bearing caps with Loctite or JBWeld

Main Bearings

Turn down enough material for two bearings and parting off allowance to 15mm. Face off and drill in stages to 9mm, bore out to 9.8mm and then ream to 10mm.



Use a parting tool to cut the 12mm dia waist groove 10mm wide and then part off, repeat for the second bearing.



And a quick try out to see how these parts go together.



Drawing to download

Offline Jim Nic

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #18 on: February 23, 2016, 09:18:37 PM »
Following the masterclass along here Jason.  It looks like an interestingly different engine that I can easily see in my future.  Thank you for posting this build log.
I don't know about completing it in under a month, but that's a different matter.   :old:
Jim
The person who never made a mistake never made anything.

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #19 on: March 01, 2016, 07:15:43 PM »
Thanks Jim, it was a fun little project and I'm sure you will enjoy it too.

Cylinder

Probably the most involved part on the engine, if you don't feel upto it then the curved top and sides could be left square so you have a + shaped cylinder or even just leave it as a rectangular block.

I used and have shown Metric Fine threads on the drawings but ME 40tpi or even standard Metric Coarse could be used if you don't have the fine series taps & dies

The cylinder can just be got out of a piece of 40x80 cast iron bar as it comes out a little over these nominal sizes. I started by sawing off a lump with enough allowance to clean up to the required 64mm length.



Next the top and bottom surfaces were cleaned up on the lathe taking similar amounts off each to reach the 36mm finished thickness.



Then over to the mill to take a light cut off one edge



Then rotate the work 90 degrees in the vice and using a square make sure the first edge is true, a light behind helps to see any gaps. Once set the second edge can have a light skim. followed by the other two to bring the block down to size.



Mark the position of the bore in the middle of one end and punch.





Back to the lathe and set the punch mark to run true in the 4-jaw using a sprung centre and dti



Using a standard right hand tool the spigot was roughed out



Then completed with a round nose tool to give the 1.5mm internal radius, the punch hole saw also enlarged with a spotting drill.



And then starting with a 6mm bit progressively opened up to 22mm with a range of drill bits.



This allowed room for a sturdy boring bar to fit and take the bore out to the 24mm diameter finished size.



Then lightly chamfer the corner so the O rings don't get damaged when fitting the piston.



To be continued

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #20 on: March 01, 2016, 08:07:19 PM »
Cylinder continued

With the main bore in place next we can start to put some shape into the block. Starting with a newly purchased roughing mill from ARC the majority of the waste was removed 7.5mm tall and 3mm per pass.



<a href="https://www.youtube.com/watch?v=DKdBznM3ni8" target="_blank">http://www.youtube.com/watch?v=DKdBznM3ni8</a>

And then with a 3-flute cutter finished to the required 8mm depth and 46mm width



Without disturbing the work the four M4 clearance holes for the hold down studs were added



Now working from the top the two waste areas can be milled away as before and the holes for the oilers added. I counterbored the cylinder hold down holes but unless you are using large washers that is not actually needed.



The three tapped holes can then be counterbored 1mm deep for bosses like the bearing caps.



Next the back end of the cylinder can have the six cover holes drilled & tapped M2.5, note I have altered their position on the drawing which avoids a clash with the steam passages.



The inlet side is drilled 9mm x 16mm deep and tapped M10x1 followed by drilling and reaming 4mm the rest of the way through, a standard 4mm drill should just reach.



The exhaust side is again tapped M10x1 by 16mm deep then drilled 6mm for a further 16mm before reducing down to a reamed 4mm hole the rest of the way through, finally use a 8mm CSk bit to form the valve seating at the bottom of the M10 hole.



The two steam passages can be drilled 3.3mm into the cylinder bore and the outer part tapped M4 for plugs.



The last hole is the M6x0.75 exhaust port which is drille dup until it breaks into the 6mm hole and then counterbored 8mm x 1mm deep



You could stop at this stage



To be continued

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #21 on: March 01, 2016, 08:25:26 PM »
Cylinder continued

To round over the top of the cylinder I turned up a temporary plug so one end could be supported by the Rotary table tailstock and gripped the other end with the jaws expanded inside the bore. It was then just a case of taking a cut rotating 4 degrees (one turn of the handle) and then taking another pass.





The sides were done in a similar way, the tailstock in the 4mm hole and to hold the other end I made up a locknut so the M10x1 tap could be used as an arbor.



A bit of work with a file will soon blemd in the facetted cuts into a nice curve.



Finally the dummy bosses can b estck in with a dab of loctite



Drawing to download

J

Offline Don1966

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #22 on: March 01, 2016, 09:23:21 PM »
Nice bit of documentation and procedures Jason. Following along is made easy and the results are simply stunning. Still following your progress and enjoying the class......... :ThumbsUp:

 :popcorn:
Don

Offline zeeprogrammer

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #23 on: March 01, 2016, 10:20:08 PM »
Very nice. And like Don said...good documentation.

We should start a popcorn franchise  :popcorn:
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Offline crueby

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #24 on: March 01, 2016, 10:29:30 PM »
Very well done, watching along here too...   :popcornsmall:

Offline Dave Otto

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #25 on: March 02, 2016, 01:23:42 AM »
Beautiful work Jason!

Thanks for the update.

Dave

Online Kim

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #26 on: March 02, 2016, 06:32:29 AM »
Following along and learning!  :popcorn:
Thanks Jason!
Kim

Offline Jasonb

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #27 on: March 13, 2016, 08:10:57 PM »
Thanks for all the comments chaps.

Cylinder End Cover

This is quite a simple piece after the cylinder, I used a stub end of cast iron bar but steel would do. Turn down to 30mm dia and then turn the 24mm dia x 3mm long spigot and part/saw off



Now holding by the spigot face off to 3mm thick and decorate as desired, I went for a simple 20mm dia recess with a rounded edge. The original CME engine carried the CME logo here.



Now over to the mill to drill the six M2.5 clearance holes on a 30mmPCD and thats the cover finished.




Eccentrics

I turned down a piece of 1" bar to 24mm long enough for two eccentrics, parting cuts and a little to clean up afterwards then set the bar in the mill vice, indicate the middle then move 1mm to the back and drill and ream out to 10mm dia. It could also be done in teh 4-jaw but I could not be bothered to change it over.



You can then part off two slices and finish to 6mm thick, drill and tap for a M3 grub screw in each.

Drawing to Download

Drawing to download

J
« Last Edit: March 14, 2016, 08:28:01 PM by Jasonb »

Offline Don1966

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #28 on: March 13, 2016, 08:34:48 PM »
Cool Jason, still with you mate....... :ThumbsUp:

 8)
Don

Offline zeeprogrammer

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Re: Jowitt MkII Popett Valve Steam Engine
« Reply #29 on: March 13, 2016, 09:00:53 PM »
Informative and enjoyable.
Very nice.
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