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Author Topic: Wrestling with Robbo........  (Read 29814 times)

Offline Stilldrillin

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Wrestling with Robbo........
« on: June 06, 2012, 02:11:22 PM »
The original posting of this year's initial rebuilds, got a little lost, among the offers of auction lots.
So, I've reconstituted the Robbo postings.........


Time to start on Robbo......

You've all seen the story, up to pres.......... 
                       
                                                          http://madmodder.net/index.php?topic=6110.0

First off. I don't like relatively thick wall, brass hot caps........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020382.jpgWrestling with Robbo........


Too much heat can pass to the cool end.
So, I sawed it off, to replace with a piece of steel vacuum cleaner pipe......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020388.jpgWrestling with Robbo........


I noticed the original end cap was concave copper, and painted black, to absorb the heat.
A rub with emery highlighted the hammer marks........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020402.jpgWrestling with Robbo........


I radiused a piece of delrin, and gave it a tap, or two........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020400.jpgWrestling with Robbo........


Looks good now........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020403.jpgWrestling with Robbo........


Carefully parted off, just behind the cap........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020405.jpgWrestling with Robbo........


Bored the cool end 1/8" deep to take the chrome pipe, and cap.
Looks ok, I think.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020406.jpgWrestling with Robbo........


I emeried away the chrome, and silver soldered the cylinder in place........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020407.jpgWrestling with Robbo........


Then after a clean up, replaced the original copper cap......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020410.jpgWrestling with Robbo........


Another clean, and a quick assemble. I think they look made for each other......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020411.jpgWrestling with Robbo........


Not a bad day's work.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020412.jpgWrestling with Robbo........


Need to sort out how to make a lightweight displacer now, cos I don't like the wasted volume of the regenerator.

It's nice to be back to it again!  :D

David D
« Last Edit: June 28, 2012, 12:40:11 PM by Stilldrillin »
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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #1 on: June 06, 2012, 02:14:49 PM »
Having now had the time to examine what I'd achieved with the hot cap. I was feeling very pleased with meself.  :D

I had only ever silver soldered two small joints before.
It just goes to show, if enough notice is taken of techniques shown on here, the beginner can produce some very satisfactory work.  :thumbup:

Displacer time!
The cap bore is 1.4". I cut some steel sheet .020" thick, and wrapped it around a 32mm ali bar.
Ground the inner overlap to a feather edge, and strapped it tight.

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020413.jpgWrestling with Robbo........


Then turned the outer feather edge. Moving the pipe clip section by section.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020416.jpgWrestling with Robbo........


Swapped the clip for some stout wire, and fluxed........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020418.jpgWrestling with Robbo........


Then silver soldered........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020419.jpgWrestling with Robbo........


Just a nice line showing in the bore........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020422.jpgWrestling with Robbo........


Cleaned up nicely.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020424.jpgWrestling with Robbo........


I think that will do nicely........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020426.jpgWrestling with Robbo........


A busy few days ahead, including Harrogate. End caps next. As, and when.......

Thanks for watching!  :)

David D
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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline DaveH

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Re: Wrestling with Robbo........
« Reply #2 on: June 06, 2012, 02:30:55 PM »
David,

Well that has turned out very nice  :bow:

Great job  :thumbup: :clap:
 :beer:
DaveH
 
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Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #3 on: June 06, 2012, 02:54:27 PM »
Thanks Dave.

My first proper session of metal forming, and silver soldering, went very well.......  :D

David D
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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #4 on: June 06, 2012, 03:50:24 PM »
Time for the displacer end caps.

I used the original piece of delrin to dish a piece of steel sheet.

Then used it with a piece of emery cloth, as friction drive to turn to a sliding fit in the displacer tube.....

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020438.jpgWrestling with Robbo........


And silver soldered it into place........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020441.jpgWrestling with Robbo........


Quick clean up.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020443.jpgWrestling with Robbo........


I turned an ali top cap. A push fit x 10mm thick.

Just for those who love to see swarf.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020498.jpgWrestling with Robbo........


I milled away some of the weight. Leaving a bridge, for an M3 grubscrew, to lock onto the screwed shaft......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020499.jpgWrestling with Robbo........


The original displacer shaft bush was made of two opposing gland nuts, with an O ring in between. Didn't like that idea.
Locktited the glands in place. Drilled out and re bushed at 4mm dia.

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020502.jpgWrestling with Robbo........


Then milled away the hex head under the deck, for even less dead space.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020501.jpgWrestling with Robbo........


Next job was to temporarily re-assemble and give it a try. Dunno why the little end is so noisy.......



Hmmmm........  :bang:

Time for another think, I think.

David D

« Last Edit: August 15, 2016, 03:19:18 PM by Stilldrillin »
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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #5 on: June 07, 2012, 08:12:15 AM »
Well..... I've done all I can to improve the existing parts.
It is so close to running! And very much improved, over the lifeless lump I first tried.

I've had a good think, and a measure round........
I read, somewhere, the displacer volume needs to be around 1.6 times, (or more), the power piston volume.

The displacer measures 1.32" dia x .45" stroke. The power piston measures 1.018" dia x .73" stroke. Giving a ratio of only 1.037.... Hmmm....

If I reduce the power piston dia. to .8"...... This will give a ratio of 1.68....... If my sums are correct.

Anyone got a comment? Or two pennorth?

David D




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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline sbwhart

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Re: Wrestling with Robbo........
« Reply #6 on: June 07, 2012, 10:40:51 AM »
Just checked the calc through using my long winded way and I get .796 so .8 is the man to go.

 :D :D

Stew
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Offline OldMetaller

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Re: Wrestling with Robbo........
« Reply #7 on: June 10, 2012, 04:05:33 AM »
Nice work David!  I could see some Old Machinist's tricks being wheeled out there!  I especially like the Delrin dodge!

Regards,

John.
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Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #8 on: June 12, 2012, 01:27:21 PM »
Thanks for your comments Chaps!

I found the advised ratio is 1.5....... So, I made the steel cylinder with a bore, around .843".

Stuck it into the original cylinder, using high temp slide lock. Then honed it, using a piece of delrin, and fine grinding paste........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020509.jpgWrestling with Robbo........


All done.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020510.jpgWrestling with Robbo........


Turned the piston to +10 thou' , and parted off.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020512.jpgWrestling with Robbo........


Screwed onto an M5 threaded mandrel, and finish turned.

Removing the last thou' or so with fine emery, backed by a 6" rule, a la Cedge.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020513.jpgWrestling with Robbo........


Looks ok, I think.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020517.jpgWrestling with Robbo........


Lit the burner......
So sorry for the amateur dramatics! But....... You know how it is..........



It's been a good day!   :D :) :D :)

David D
« Last Edit: June 15, 2012, 01:30:38 AM by Stilldrillin »
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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Rob.Wilson

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Re: Wrestling with Robbo........
« Reply #9 on: June 12, 2012, 01:38:07 PM »
 :clap: :clap: :clap:  :clap: :clap:  She goes like the clappers David   :clap: :clap: :clap:  :clap:

I always fined your "bring em back to life" threads a great read ,,,,,,,,,,, well done  :thumbup:



Rob
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Offline Bluechip

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Re: Wrestling with Robbo........
« Reply #10 on: June 12, 2012, 03:13:21 PM »
As the Venerable Foggy would say ...

WELL DONE, THAT MAN

 :thumbup:

BC
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Offline krv3000

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Re: Wrestling with Robbo........
« Reply #11 on: June 12, 2012, 03:24:27 PM »
well dun from me to
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Offline sbwhart

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Re: Wrestling with Robbo........
« Reply #12 on: June 12, 2012, 03:38:17 PM »
That will certainly do 

:nrocks: :nrocks: :nrocks: :nrocks: :nrocks: :nrocks:


 :clap: :clap: :clap: :clap: :clap: :clap: :clap:

Well done Dave I knew you'd tame it  :whip:

Stew
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Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #13 on: June 12, 2012, 03:59:30 PM »
Thanks for your kind replies Chaps!  :thumbup:

Only cobbled together, to prove, or not!
Now needing proper assembly, with gaskets, and the big & little end bearing fits sorting out.

Innit a great feeling, when an engine finally comes to life!!  :D  :D

Stillgrinnin.  :)
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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline millwright

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Re: Wrestling with Robbo........
« Reply #14 on: June 12, 2012, 04:41:27 PM »
Well done David,
 another one ressurected and running well :beer:
John
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Offline AussieJimG

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Re: Wrestling with Robbo........
« Reply #15 on: June 14, 2012, 01:33:08 AM »
Looking good, sounding good and running well. Congratulations David, on another job well done.  :nrocks:
Jim
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Offline stirling lad

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Re: Wrestling with Robbo........
« Reply #16 on: June 14, 2012, 08:54:24 PM »
brilliant !! blooming brilliant,you clever ole fox... :smart: :clap:

...Mike...
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Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #17 on: June 29, 2012, 02:28:21 AM »
Thanks for all your support, Lads!  :thumbup:
It's much appreciated, when the hobby seems to be wading through treacle, and life is getting in the way..........  :(


This engine appears to have had two builders, before me. The first has done a really good job of details.

The linkage system fit and finish, is first class.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020453.jpgWrestling with Robbo........


The second builder has botched a few points.

The cross pins measure up at around .106"/ 2.7mm.......  :scratch:

The original displacer shaft has an 1/8" hole........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020450.jpgWrestling with Robbo........


The gudgeon pin was an 8BA screw, only locating in it's threaded hole. Not touching the other bearing areas.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020535.jpgWrestling with Robbo........


So, I drilled through at 2.7mm........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020536.jpgWrestling with Robbo........


And made a 1/8" headed pin, to suit.......

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020539.jpgWrestling with Robbo........


I hate to see wobbobly flywheels. This one had most of it's sections eccentric too!

I trued both bosses, and the inner rim. Opened up the bore, plugged and re-drilled to 6mm.

The eccentric spokes area, I left as is. A balancing feature..........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020537.jpgWrestling with Robbo........


The wick end of the burner locates in a central hole. Under the hot cap. Leaving the tank end to pendulum from side to side.

So, I fitted a 10 x 2mm magnet in it's base........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020541.jpgWrestling with Robbo........


And one in the oak base........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020540.jpgWrestling with Robbo........


Underneath the brass base. Made a new knurled filler cap too.........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020544.jpgWrestling with Robbo........


Put on your sunglasses............



After a some time. The revs had climbed much too high for me. I like to see the wheels go around.

So, I trimmed the wick back as far as it would go. It runs around 150rpm now........

http://i110.photobucket.com/albums/n95/Dayjo/After%202012/P1020555.jpgWrestling with Robbo........


HAPPY!!!  :)

Defor.




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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline stirling lad

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Re: Wrestling with Robbo........
« Reply #18 on: June 29, 2012, 09:39:43 AM »
another excellent rescue David, and its looking really smart after a wee polish too.
thanks for another ecucational thread.. :thumbup:

  ...Mike...
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Offline NickG

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Re: Wrestling with Robbo........
« Reply #19 on: July 21, 2012, 01:34:04 PM »
It's a beauty now! Nice 1 David!  :thumbup:
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Offline Stilldrillin

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Re: Wrestling with Robbo........
« Reply #20 on: July 21, 2012, 04:02:58 PM »
Mike, Nick.
Thank you!  :thumbup:

It's now had a couple of hours running happily, around 20mins at a time.

When it stops, the residual heat creeps into the cylinder, nipping the brass piston in the steel bore.
I think that could be called an accurate fit...... I'm astounded!  :bugeye:

And pleased!  :)

David D
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David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Rob.Wilson

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Re: Wrestling with Robbo........
« Reply #21 on: July 21, 2012, 05:15:02 PM »
I think "jobs a good un " too David  :bow: :bow: :bow: :bow: :bow:

Sure is a smooth runner , a testament to your ability as a machinist  :clap: :clap: :clap:


Rob 
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Offline Dean W

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Re: Wrestling with Robbo........
« Reply #22 on: July 21, 2012, 05:36:03 PM »
Could have sworn I had commented on this before.  Guess I'm going crazy, again..
Well, it surly is a "goodun", David.  It's absolutely beautiful in all respects, and runs
like an American watch!  (We made really good watches!)  : )
Thanks for the excellent video!
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Offline saw

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Re: Wrestling with Robbo........
« Reply #23 on: July 21, 2012, 05:37:27 PM »
Nice work  :thumbup: :thumbup: :thumbup:
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Offline doubleboost

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Re: Wrestling with Robbo........
« Reply #24 on: July 21, 2012, 05:39:53 PM »
Hi
David
Just read this post
Cracking job you have made of it :clap: :clap: :clap:
Like you said some bits were very well made , others not so good :Doh: :Doh:
It will be around for a long time now :) :)
John
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