Author Topic: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine  (Read 27498 times)

Offline sshire

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Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« on: September 02, 2015, 02:09:53 AM »
Lady Godiva Rides Again - Episode 1
Roy Ozouf’s Coventry Engine


“Lady Godiva, was an 11th-century Anglo-Saxon noblewoman who, according to a legend dating back at least to the 13th century, rode naked – only covered in her long hair – through the streets of Coventry in order to gain a remission of the oppressive taxation imposed by her husband on his tenants.”


At NAMES, Kvom and I were looking at a Roy Ozouf designed oscillating engine, the Coventry. I apologize for not knowing who built this excellent example.





While building the 1/4 horse, I had been studying the plans in Roy's book and devising some sort of machining plan for the side frames.
The drawings in the book are very well done, as is the text.

The Side Plates

Starting with the side plates, two pieces of .5" aluminum plate were sized to 6”x8” and squared up. This absolutely looks like a job for CNC. Since the Bridgeport can't even spell "CNC", the rotary table and DRO will suffice.




The first operation was to spot drill all 16 pivot holes and put each into the DRO memory. Since both sides of both plates will need to be laid out, this will save a bit if time.



Next, a Dykem bath, scribes, odd leg calipers and dividers to do the layout on both sides. 



All 16 holes were drilled and reamed 3/16"





The horizontal and vertical cuts were done in the vise. The part then moves to the rotary table. 




I wanted radiused corners on the inside recess as Roy suggests. ¼" corner radius carbide end mill (.0625 radius)



With the rotary table centered under the spindle and a 3/16" locating pin, the part was milled to .125 depth. Each set of holes has a turning radius.




The center completed on both sides. 



Back in the vise, decorative elements were milled.



Next the outside was milled with a .25” carbide center cutting end mill.
 






I was concerned about the cutoff jamming while clamped in the vise.
After indicating the part, the final cut, which broke the part free, was done clamped to the mill table.



Cutoffs



Some initial cleanup with Oliver. I’m waiting for some small Cratex wheels and points for the Foredom handpiece for final cleanup and polishing of the recess.



Including layout, each side took about 7 hours. If this was a profit-making venture, I could think about CNC. Since it's definitely not, I'm only spending my time. And, George Britnell has gained even more respect ( if that's possible ) after doing this plate. 



Now, the whole process gets repeated for the other plate. 
Then, the plates will be aligned with dowel pins to through bore the 7/8" hole for the cylinder pivot. 


Both frames will be sent to Cletus at the Close Enuf Machine Shop's Metrology Division in beeeeutiful Springbucket, TN for a QC check.

Stay tuned for the next thrilling episode. 











Best,
Stan

Offline Don1966

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #1 on: September 02, 2015, 02:21:56 AM »
Stan that's some amazing work your turning out. I am glad to see you pushing your limits because we never know them till we try just what we can and cannot do. Excellent work buddy and I'm sure Cletus will agree with his QC Deptartment.

Don

Online b.lindsey

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #2 on: September 02, 2015, 02:24:54 AM »
Very impressive start Stan. Can't wait for the next installment!!

Bill

Offline sshire

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #3 on: September 02, 2015, 02:29:56 AM »
Thanks. That was proof of concept to see if I could do it in metal. Plan B was to do the CAD drawing and 3D print. Then, send that to Cattail Foundry as a pattern to be cast in aluminum. No need as I'm happy with the part I made.
Best,
Stan

Offline Dave Otto

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #4 on: September 02, 2015, 02:44:16 AM »
Very nice work Stan!

Don't you just love those 3 flute carbide end mills?

Fun to see you on to a new venture.

Best regards,
Dave

Offline sshire

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #5 on: September 02, 2015, 04:07:19 AM »
Dave
I'd never used them before. I'm very happy with the finish and they go through the 6061 like butter. After doing a speed calculation for the ¼" ones and cranking the Bridgeport to its max speed...wow. I kept them pretty wet with coolant and had the air nozzle getting chips out of the path. I'm sold.
Best,
Stan

Offline Jasonb

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #6 on: September 02, 2015, 07:47:15 AM »
Looking good Stan, I'll be following along.

J

Online Jo

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #7 on: September 02, 2015, 08:09:00 AM »
Stan to complete the legend: Godiva required the townsmen to remain indoors at the time of her ride but one man looked at her out of his window and was struck blind...from that point on we find the English were using the term "Peeping Tom".

Its a pretty little thing but is based on a real engine? or one of those Victorian toys? (Like my  :old: AGE)

Jo
Usus est optimum magister

Offline Steamer5

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #8 on: September 02, 2015, 09:03:52 AM »
Stan,
 Looking good.......giving Jason a run on the fabrication front!

 :popcorn: :DrinkPint: on standby!

Cheers Kerrin
Get excited and make something!

Offline Roger B

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #9 on: September 02, 2015, 10:08:54 AM »
That's a good looking engine and a good start on your version  :praise2: I will be following along  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline sshire

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #10 on: September 02, 2015, 12:48:04 PM »
Thanks for the interest in this build.

Jo
As KVOM posted earlier, the name of the engine is from Don Coventry, an Englishman, who found a similar engine in a surplus store and published a picture in Model Engineer. It's unusual for having the pivot at the bottom of the cylinder rather the at the center, as is the case with the McOnie.
There is no mention of whether the engine that was found was a model or a full-size engine. If anyone knows, I'd love to find out.
There is also some confusion as to whether Peeping Tom was struck blind or dropped dead. The legend continues.
Best,
Stan

Online Jo

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #11 on: September 02, 2015, 01:09:56 PM »
There is also some confusion as to whether Peeping Tom was struck blind or dropped dead. The legend continues.

If he was caught looking at my casting sets I know what would have happened to him  ;)

Jo
Usus est optimum magister

Offline kvom

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #12 on: September 02, 2015, 01:14:52 PM »
After NAMES I was surprised you did the quarter horse before this one, but now it's well under way.  Other than making the SW model I've done nothing as I pledged myself to finish the paddle engine before starting anything else. 

I did investigate using Shapeways to make the 4 frame separators, and ordered an example in "metallic plastic".  Probably won't go that way, and the same parts in metal are two expensive.  For me those parts appear difficult to make as drawn;  I have no CNC lathe and the shapes look hard to duplicate exactly. 

I plan to make the side frames from steel, as I have a quantity of 1/2" plate lying about, and no aluminum.  Given the speed with which you work, I'm sure you'll have resolved any problems and be finished before I even start.  So I'll be following along.

Here's the video I took at the show:


Offline Jasonb

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #13 on: September 02, 2015, 02:19:11 PM »
So as you have a bigger ME archive than me Jo how about looking out the article?

Vol 148, No 3677, pg 370 and Vol 166, No 3849 also page 370 look the most likely.

The spacers should not be too hard to turn, just turn to length, centre drill each end, turn & thread the spigots and the rest is between ctrs work - cut the tapers with a round nose tool to leave the raised middle then use a form tool to round it over.
« Last Edit: September 02, 2015, 02:22:14 PM by Jasonb »

Online Jo

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Re: Lady Godiva Rides Again - Roy Ozouf's Coventry Engine
« Reply #14 on: September 02, 2015, 02:49:56 PM »
As requested.

Jo
Usus est optimum magister