Author Topic: Roy Ozouf's Coventry  (Read 17775 times)

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #15 on: October 24, 2016, 10:32:56 PM »
After a few days work, something more to show.

I bought the flywheel casting a year ago, so decided to work on it.  The rim as cast was quite round, so I was able to chuck it using my large 3-jaw with the reversed jaws, and get it to run pretty true.  Then faced the hub and drilled and reamed the center .501".  I was also able to face the rim being careful to avoid the protruding chuck jaws.  With some 1/2" drill rod loctited, I could then turn the rim.  Took .100" off; nominal size to start was 5.25" diameter.



Most of today was spent on the pivot shaft.  This is where the cylinder rocks back and forth via the main bearings and through which the air is supplied and exhausted.  I took a lot of care with this part to try to insure everything is parallel.  Material was a 12" piece of 13/16" diameter 4140 stressproof steel rod.  First chucked in the 6-jaw to face, drill and tap one end, and then turned that end down to .626" diameter.  Then sawed off a bit more than needed and faced the sawed end and center drilled it.  Now with the other end in the collet chuck I could turn the entire length to .751", one thou over the target diameter.  This shaft mounts to a pivot block, and I want to avoid any leaks between it and the air supply holes, so a good tight (non-press) fit is my goal.  I own a .75" reamer and will wait to see if I need to shave it after the block is made.  At this point I have this:



Now I could use the collet chuck on the main shaft.  I faced the unfinished end to length, drilled and tapped it, and turned it down to .626" as well.

Next I needed to drill a 1/8" hole crosswise through the center.  This hole is used to locate its position in the block.  In addition, I needed to drill and tap two 2-56 holes the secure the shaft to the block with screws.  Here's the setup for this:



Finally, I need two holes at a 45 degree angle to the others and which connect with the air passages in the bore.  A spindex would have made this pretty easy, but lacking that I set the angle on the surface plate:



And moved the V-block to the mill for drilling:



Done!



And for completeness, here's the parts from this weekend:




Offline philjoe5

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Re: Roy Ozouf's Coventry
« Reply #16 on: October 25, 2016, 02:01:03 AM »
Good progress kvom, and I like the workaround for not having a spindex.

Cheers,
Phil
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #17 on: October 25, 2016, 10:40:50 PM »
Today was cylinder day.  It's 2" diameter, and I had a choice of 4 materials on hand in order of increasing cost:  steel, cast iron, brass, and bronze.  Tried turning some 2" HRS and the finish was awful, so went with grey CI.  My stock piece was 2.5", do needed to turn a section down:



After reversing the piece and facing to length, I step drilled the bore using S&D drills to 15/16, then bored to a target of 1".  Overshot so ended up 1.007", but measurement shows the same on both ends.  So hopefully no taper.



Next on the mill for a preliminary slot to provide a datum for aligning the holes in each end.



With a parallel in the slot and against the face of the vise, I found the center of the bore in order to drill the air passages.  I also spot drilled the cover mounting screws but didn't drill/tap them.  Plans call for 4-40 screws of which I have none, but I had lots of 5-40s.  I'll wait until I make the covers to see if 5-50 will work just as well.



Next I needed to finish milling the slots for the port block, so needed to set the initial slot parallel again.



Cylinder finished except for threaded holes for covers and threaded holes to secure the port block.


Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #18 on: October 27, 2016, 12:50:23 AM »
Shorter shop session today, but I managed to get the piston and its rod made today.  Piston started as 1.5" bronze rod.  I cut off a piece, faced both sides to 1/2" long, and drilled/reamed to .254".  After threading one end of the rod 10-32, I pressed the other end of the 1/4" drill rod into the piston.  This took a fair amount of effort using my bench vise as the press.  I doubt it will come loose.

Then with the rod mounted in the lathe's collet chuck, I turned the piston diameter down to a close fit with the cylinder.  The fit seems excellent throughout the length of the cylinder with no light showing around it.  Seems to confirm lack of taper in the bore.



Ouzof shows a groove in the center of the piston.  He used a pin to secure it to the rod, but I'm not sure if it's needed to reduce friction as well.  It will be easy to add if needed.

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #19 on: October 27, 2016, 10:06:25 PM »
Finished the crosshead that I made a start on yesterday.  It was from a bronze cutoff from a prior project, so I won't post the steps I went through to carve it out.  Some 1" round as a start would have been more straightforward.

Here's the finished (except for an oil cup TBD) piece attached to the piston rod and crank pin.


Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #20 on: October 28, 2016, 08:46:15 PM »
Today's project is the top cylinder cover and its gland.  First, cut off some 2" brass rod, chuck it, and turn a 3/4"x1/2" spigot:



Reverse, face to length, and cut a tight fitting spigot to match the cylinder bore.



Over to the mill to drill the clearance holes for the mounting screws.



Mount the cover to the cylinder, chuck on the lathe, and drill-ream the center .251".



Test that there's no binding between the cover, piston, and piston rod.  Happy dance follows.



Use a 7/16" endmill to form pocket for the gland



After turning the gland to a good sliding fit to the cover pocket, use the mill to drill clearance holes for 2-56 mounting screws.



Drill and tap matching holes on the cover.



There are still a couple of operations to do on the cover and gland, but I need some short 2-56 screws to continue.




Offline philjoe5

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Re: Roy Ozouf's Coventry
« Reply #21 on: October 28, 2016, 09:10:38 PM »
Looking good kvom; life is good when it all fits together :ThumbsUp:

Cheers,
Phil
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #22 on: October 30, 2016, 01:45:20 AM »
Today's target is the bottom cylinder cover and the pivot block.  Chuck a piece of 2" round brass and turn a 1" spigot that's a close fit to the cylinder bore.



Over to the mill to drill all the necessary holes.



Back to the lathe to face and adjust length.  I left it a little thick for wiggle room on next ops.



For the pivot block I failed to take many pics, but the initial job was to cut off a piece of 1.75" square brass bar, square it, and drill many holes.  The .75" through hole for the pivot shaft was not going to be a success using drills, so I spiral milled it on the CNC mill.  My first pass resulted in a hole that could have been a press fit.  I tried opening it up with successive passes adding .001" to the diameter, but that just resulted in rubbing instead of cutting.  Finally put the shaft back on the mill and shaved a few thou.  Result is a sliding fit, but not as close as I'd hoped.



Finally to drill the air passages, the block is set at a 45 degree angle, and the X-axis is centered on the pivot shaft.  Then the passages are drilled after the hole is started with an endmill.



Test to see that all the holes in 4 pieces line up and another happy dance.


Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #23 on: October 30, 2016, 08:24:57 PM »
I made a start today on the port block, which mates to the slot in the cylinder.  This  needs to be a tight fit to the slot to prevent air leaks.  I started with a 1" cutoff of some 1.875" hexagonal brass bar that I faced on both sides on the lathe.  Then on the CNC mill machined the outer profile.  The cylinder slot is dimensioned 1.25" wide, and a 1-1/4 parallel fits it with a loose sliding fit, so likely several thou wider.  Therefore I set a .005" roughing clearance on the profile and used a new HSS .375" endmill.



After moving to the manual mill and machining off the bottom, I measured the width of the block as 1.257".  It would not enter the slot, so followed a series of applications of 200 grit paper on the surface plate until the block started to want to wedge into the slot.  Then some final fitting using 600 grit until I have a tight sliding fit.



The block is still too thick.  I am going to diverge from the plans and sandwich a some .125" ground plate between this block and the steam chest.   By doing so I avoid needing to machine 3/32" port openings through thick material, and the ground plate will provide a good surface for the slide valve.  The total of the two needs to equal the plan dimension of 7/16" thick, so the block will have a finished thickness of 5/16".

Next shop session will involve drilling the air passages and mounting holes in the block.
 

Online Tennessee Whiskey

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Re: Roy Ozouf's Coventry
« Reply #24 on: October 30, 2016, 10:25:44 PM »
I've been quietly following along with interest.  I am waiting for the next step.  I think I know where you're headed,  but,  not sure.  Surface finishes look great BTW.

Cletus

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #25 on: October 31, 2016, 07:29:21 PM »
Lots of holes needed in the port block.

First, the two holes that connect the end of the piston to the steam ports.  Ouzof drew them such that the bottom of the hole is tangent to the bottom of the slot, but as made there is approximately 30 thou above the slot.  In any case I don't want the drill to break through the bottom so it's drilled 1/8" above.  Then I faced the bottom unless the holes looked aligned with the cylinder.



Then the two holes are drilled from the top to meet these passages.  There are the only two holes that are not through the block.  The holes for the air supply and exhaust are also drilled.



Next, reverse the block and mill passages to connect the supply and exhaust holes in the cylinder.  1/8" wide and 1/16" deep.



Spot and drill 10 mounting holes through the block.  I'm not crazy about how Ouzof dimensions from the edges while I'm referencing the center point.



Face mill to reduce thickness to 5/16".



Tap 4 holes 2-56 and countersink 4 others.



Finished!


Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #26 on: November 05, 2016, 09:14:07 PM »
Todays' effort is the "link".  It slides up and down on two guide bars attached to the right frame, and is driven by the eccentric.

Squared some brass bar ~ 2.5x1x.6", and then machined this shelf 5/8" above the bottom and 1/4" in/



Then drilled and reamed the holes for the slide bars (3/32").



Some more shaping on the manual mill.



Now ready for final profiling on the CNC mill.



Per the plans, the guide bars would pass through separate pieces soldered to the link.  This method avoids the soldering, and ensures that the holes for the bars are parallel.

In operation, a small die block in the slot provides motion to the valve linkage.

Offline sshire

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Re: Roy Ozouf's Coventry
« Reply #27 on: November 06, 2016, 02:03:21 PM »
Kirk
Nice way to make the block. Without a CNC mill, I had to do mine the old-fashioned way. I drilled the two guide rod holes after soldering the blocks to the oval piece so that they'd be parallel. Seemed to work with no binding.
Best,
Stan

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #28 on: November 07, 2016, 10:08:03 PM »
Today's bit was the two "cheeks" for the crankshaft.  Having squared two bits of 1.5x.5" HRS, I used the CNC mill to produce this:



The holes were spiral milled with a 1/4" 2-flute endmill, and then reamed.  Then I used the same outer profile to mill a matching pocket in some soft jaws.  After a bit of hacksaw work to remove most of the sides, I could hold the parts in the vise jaws in order to reduce the thickness.



After some deburring, a test fit with the rest of the crankshaft pieces.



Then noticed I'd mis-remembered the plans, so the cheeks are currently 7/16 thick instead of 5/16.  I'll correct that next time.

Offline kvom

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Re: Roy Ozouf's Coventry
« Reply #29 on: November 10, 2016, 07:54:23 PM »
I loctited the cheeks to the separator, so they're ready to be pinned.  I still need to mill a key slot in one of the shafts and then make a gib key to fit the shaft and the flywheel.

I had intended to work on the eccentric strap today, but with only a little time in the shop elected to work on the valve.  I discovered that while the 3-48 die I'd just bought is 13/16 diameter, I don't have a die holder that size.  So threading the valve rod will have to wait too.  The valve itself was milled from a larger bronze cutoff from another project, and the majority ended up as chips.  Once down to a correct size oblong, I milled the bottom pocket using a 1/8" endmill.  Then for the cross slots, I used this setup.



Finished: