Author Topic: Maiwald Makeover........  (Read 27634 times)

Offline Stilldrillin

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Maiwald Makeover........
« on: July 23, 2012, 10:43:14 AM »
This rebuild is not finished, yet. Though, I started it almost a month ago.

I thought I'd post the first instalments here, until I catch up.

----------------------------

Maiwald Hot Air Engine, rebuild.........



Well, here's the start of another of my rebuilds!  :)

Yet another frail orphan, from my toy cupboard.

This is a James Maiwald hot air engine. It came to me at the end of 2009.




It isn't well! The main bearings are too far apart, and the flimsy crank is flexing.  >:(




This is the best it has ever run.......

<a href="http://www.youtube.com/watch?v=1jYypC74hik" target="_blank">http://www.youtube.com/watch?v=1jYypC74hik</a>


My thoughts are to fit an extra pair of bearings, held closer in to the crank throw.

Also, I thought it's flywheel looked better on my Maiwald flame licker. So, it was cannibalised.


Removing the bearings from the steel frames proved a struggle.
The frames are laser cut, and the bearings were just rammed in, much too tight.....










A pair of inriggers. The excess material will be removed later.......




A bit of a shock, finding swarf in the displacer pot! Impacted onto the brass bush. Very poor workmanship..........




This was the state of play, at knock off........




More to come, as and when.   ;D

David D



David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline lazylathe

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Re: Maiwald Makeover........
« Reply #1 on: July 23, 2012, 11:26:06 AM »
Hi David,

I have seen a few of those engines for sale and always wondered about them...
Now i know better! ;)

I managed to acquire a Maiwald about a year ago and it runs very well.
At the moment i do not have any pictures but will be adding it to my engine collection thread soon.
The swarf in the end cap worries me a bit, will have to look into that sometime.

Consider me following along with you!

Andrew
A new place to hide my swarf!

Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #2 on: July 23, 2012, 09:01:03 PM »
Hi Andrew!

Not too sure where this will go to, or what delights lie in store. But, it's great to have you along with me.....  :))

Lets just say, this engine could/ should be much better engineered than it is........   ::)

-----------------------


After giving this thing a good coat of looking at, I decided it was much too wide.......

So, I reduced the alloy spacer by 10mm per side, to 48mm.




Extended the thread on the beam pivot shaft. Then screwed on two nuts, and faced to make 48mm spacer rod.




The frame relied on the wooden base, to hold it all square.

Drilled the frames for an extra 48mm spacer shaft, to triangulate and make it self supporting.......




The beam pivot bearing had also seized. Turned an alloy bush, with a slight positioning step........




To hold it central........




The alloy big end/ crank assembly is much too flimsy. But, I'll give it one more chance......

Rebuilt it, using my favourite sleeve lock, at each end of the crankpin.......




Progressing, steadily!   ;)

David D
David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline Dean W

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Re: Maiwald Makeover........
« Reply #3 on: July 23, 2012, 10:45:18 PM »
Hi again, David!  I'm watching along again.  I always keep my eye on you.  'Fraid I might miss something spectacular!  :)
Dean
In beautiful N. Idaho, U.S.A.

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Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #4 on: July 23, 2012, 10:59:11 PM »
Hi again, David!  I'm watching along again.  I always keep my eye on you.  'Fraid I might miss something spectacular!  :)


Hi Dean.
Really nice to see you're coming along too.   :cheers:

I'm not too sure about spectacular....... But, I do try to provide an interesting climax!  :whoohoo:

------------------

Very slow progress, I'm afraid........

I assembled the crank frame with it's three spacers.
It's now rigid/ self supporting enough, to file the underside flat, to my surface plate.......




Finished the inrigger bearing holders........




Glued into place. Aligned with a length of 4mm silver steel. Positioned outward, by a piece of foam........




Perfectly aligned.........




Rebuilt the crank assembly. Installed a temporary flywheel.

Oiled round...... And fired up..........




And........








It still wouldn't run!   :wallbang:  :wallbang:

Hmmmm..........      :help:

David D



David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline dsquire

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Re: Maiwald Makeover........
« Reply #5 on: July 23, 2012, 11:53:16 PM »
David D

Quote
I'm not too sure about spectacular....... But, I do try to provide an interesting climax!  :whoohoo:


That should be interesting!  Might is be :censored:

Back on topic here. It is looking good David. I have been watching silently in the background. It will be a nice one when it is finished.

Cheers  :cheers:

Don

Good, better, best.
Never let it rest,
'til your good is better,
and your better best

Offline lazylathe

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Re: Maiwald Makeover........
« Reply #6 on: July 24, 2012, 01:52:37 AM »
Hi David,

Looks good so far!

Does it have a leak by any chance?
That swarf you found might have wore out the displacer bushing?
I have been known at times to use a slightly thicker oil on the displacer rod to ensure a good seal. :censored:

If i know you at all the next time i log in it will be chugging away... :D

Love all the upgrades you have done!!

Andrew
A new place to hide my swarf!

Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #7 on: July 24, 2012, 07:25:12 AM »
Hi Don.
Ok. No more might be's...... Mebbe!  :thinking: Thanks for your confidence in my rebuilding.  :cheers:

Hi Andrew.
Thanks. Steady as we go.......

Leaks? Well........
I've covered up the power piston bore, and sucked on the displacer bearing, attaching it to my tongue, for as long as I could manage. Nowt wrong there!  :ThumbsUp:

The displacer shaft is a really good sliding fit in it's bush. Feel, I'm missing something, somewhere.....  :shrug:



------------------------------


Well, here we go again........




After the fail, it was water tested.     

No dramatic bubbles, but, some water inside, on stripdown.   :thinking:

Calculated the ratio..... That's ok at around 6 to 1.

I really don't like the pifflin', (out of square?), crank throws. So, I started to make another assembly.........




Then the tiny big end bearings arrived.   :)

Turned two, 4mm thick discs, 16mm dia. drilled through 7mm, and mounted on a mandrel in r/ table.......




Application of 4mm endmill........




Drill and tap M3.......




Two new big ends, ready for loctiting........




Tiny, fiddly bits n pieces, that won't stay in me fingers. Or on the bench, once they've escaped..... Grumble.........    >:(

David D

David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline lazylathe

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Re: Maiwald Makeover........
« Reply #8 on: July 24, 2012, 02:15:19 PM »
Curiouser and curiouser.... :thinking:

Great update and nice work on those small, fiddly bits!

Maybe a bit of a  :thewhip: to get it in line is in order?

Andrew
A new place to hide my swarf!

Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #9 on: July 24, 2012, 09:58:21 PM »
Thanks Andrew.
A whip may just come in handy. I've tried almost everything else!  ::)


Well..... Here we go, again!

I drilled the crankpin holes.......




Luckily the assembly stayed temporarily pressed together, to allow a test run.

Assembled, with a pair of spare Mamod flywheels........




Fitted a new "wonderwick".


Fired up.




And it still wouldn't run. Again!   :wallbang:


What's wrong with the thing???   :wallbang: :wallbang:


Everything's been checked/ re done!! Hasn't it??  :shrug:


Took off the hot cap. Sucked...... Hard...... It stuck to me tongue....... Nothing wrong with it!!!




Until, I poked a finger inside........




The wall thickness is around 9thou'. The end cap is 4thou', "tin"...........




I guess it was acting as a one way valve!   :wallbang: :wallbang: :wallbang:

Sheesh!!

Sigh........

Nothing else to do, but make another, more robust cap. :(

Couldn't find any 1"od tube in the bits tub.

Mrs Drillin's exercise bike, now has a 2" shorter saddle stem. (From inside the frame tube). Hope nobody tells her......   :paranoia:

Topped to 24mm+. Bored to 23mm.........




Friction turned an end cap........




Couple of thou' under bore size.........




Silver soldered together........




Cleaned up, quite nicely........




I'm starting to worry about me. I don't get upset any more. I just expect things to go wrong........

And they do. Regularly!   :wallbang: :wallbang: :wallbang: :wallbang:

Machining a new, thicker flange, tomorrow. Probably!   ;)

David D

David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline lazylathe

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Re: Maiwald Makeover........
« Reply #10 on: July 25, 2012, 11:59:41 AM »
Good find David!!! :ThumbsUp:

One way valves in Stirlings do not work, especially on the hot cap... :rant:
Hopefully this will be the start of a good thing!
I have a good feeling about this one this time!
 :pinkelephant:
Andrew
A new place to hide my swarf!

Offline Dean W

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Re: Maiwald Makeover........
« Reply #11 on: July 25, 2012, 08:03:15 PM »
"I just expect things to go wrong... And they do."
Well David, that should keep the disappointment factor low.   ;D
You're doing great there.  You really have a knack for sorting out unseen problems in all these orphans.
Dean
In beautiful N. Idaho, U.S.A.

Shop Projects:
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Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #12 on: July 27, 2012, 09:33:36 PM »
Andrew, Dean.
Thanks for your confidence in me!

I actually have had a few misgivings, this time........  :-\




Found one of my penny washers was the right o/d, for a 50% thicker flange.

Bored it to just slip over the original........




Marked the 12 oclock position, for orientation. I could then spot, and drill through, 'cos the holes were not in any sort of pcd.

Turned a step on the cylinder to support the flange in position.........




Silver soldered together.......




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




Fired up, using a different burner

We got a very hesitant runner!!




It reminded me of my little grandaughter, when she runs. All arms and legs, and stopping every few seconds!

Very hesitant!

So, I lubed the piston, with slide oil, and it just took off........

<a href="http://www.youtube.com/watch?v=U6t5qWivWH0" target="_blank">http://www.youtube.com/watch?v=U6t5qWivWH0</a>


That will do for now!   :pinkelephant:   :ROFL:


But!
Steel piston. Loose fit, in an alloy cylinder. Don't like that idea!



Do I make an alloy piston?

Or brass?

Do I open it out, and sleeve with steel, and brass piston?

What does the Team think?

David D
David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Offline Dean W

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Re: Maiwald Makeover........
« Reply #13 on: July 27, 2012, 09:58:54 PM »
It does run quite well now, David.  All knees an' elbows is a fun way to put it.  ;)
Are you worried about the piston for some reason, David?  It seems to be doing okay in it's position in life.
If you want to change it, I would go for a brass one in the aluminum bore.  That combo has work well for
me in a few engines of the past.  Free machining leaded brass has some good self lubricating qualities.

BTW, the new hot cap looks really nice!
Dean
In beautiful N. Idaho, U.S.A.

Shop Projects:
http://www.deansphotographica.com/machining/projects/projects.html

Offline Stilldrillin

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Re: Maiwald Makeover........
« Reply #14 on: July 28, 2012, 07:27:18 AM »
Dean.
Thanks for your kind comments.

The steel piston has been machined under 10mm nominal. (Don't remember how much, at the mo.).
A 10mm endmill shank, wobbles in the bore.
The engine will only run for the 1 minute or so, it takes the slide oil to "melt" into the bottom of the cylinder. It then stops, while puffing smoke!

I would prefer to give it the customary, 1 drop of 5W-30. As I do to my other engines!

A new brass piston sounds good to me!  :ThumbsUp:

David D

« Last Edit: July 28, 2012, 01:19:47 PM by Stilldrillin »
David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!