Sterling speed-build.

[Peter.]

Hey all.

Today I'm attempting to build a working LTD sterling in a few hours - this will also be my first engine. Just using scrap I have lying around in my workshop I hope to get it done inside of 5 hrs with a break for New Year's dinner.

I started at just after 4pm, got the displacer cylinder cut and now working on the power cylinder. No plans, not even bothered doing any calcs, just going to wing-it and see what happens.

I'm taking timestamped photos so you know I ain't cheating - wish me luck!

 

[lazylathe]

Good Luck!!!! Thm:

Looking forward to seeing this one play out!!!

Andrew

 

[kcmillin]

This is very ambitious Peter. I will be following along for sure.

Good Luck!

Kel

 

[Tin Falcon]

when I got started in this hobby and was on some what of a roll I started and finished a couple engines starting on a Saterday and finishing the following one. I personalty have not had success trying to blitz build. looking forward to seeing your results.
Tin

 

[Peter.]

WellI'm a bit annoyed because I just removed the memory card from my camera without waiting for it to power off properly and lost about a dozen photos on a corrupted card

Anyway, so far I have the power piston and cylinder made, power pushrod, displacer cylinder parts cut. Just going to work on the dilacer rod and piston, then start bulding the post.

 

[Tin Falcon]

Breathe peter: looks good so far
Tin

 

[Peter.]

Flywheel is a cd disc and bearing from an old HDD on a delrin hub

 

[Peter.]

Displacer parts. I know delrin doesn't glue very well but I'm counting on it holding given the very low loads on it.

 

[Peter.]

The moment of truth isn't far away now guys

I wasted an hour and a half trying to get an ally piston to work in an ally cylinder - that's a non-starter I found so I re-made the cylinder in delrin and now it glides nice and smooth.

 

[Blogwitch]

Peter,

Talking about speed builds, in the early days of this site, we organized one for making a finger engine, and it was very popular. It was done in a very light hearted way, unlike nowadays where things tend to get a bit heavy.

The post has got a bit fragmented over time, but there are still a few engine videos to be seen, including the eventual winner, the spaghetti tin can.

http://www.homemodelenginemachinist.com/index.php?topic=2063.0

I don't know where my video went, but the engine is still in my shop, working as well as the day it was made.

Maybe a few more of these very few rules, all join in, blitz engines should be done. but none should take more than a few hours to build.


John

 

[Peter.]

Aye, perhaps I should have made ne of those

Well it's done - but it won't run on a cup of hot water. Pretty sure my displacer is too small in diameter and it also curved up a bit and touches the bottom.

Still, it was a good way to spend an evening

 

[Jeremy_BP]

Wow, well that sure was fast. I'm astounded.
It won't run on a cup of hot water? Will it run on something hotter?
Do we get a nice finished picture?

 

[Peter.]

Well here it is in all it's non-working glory.

 

[mklotz]

Try running it on something a bit hotter than a cup of water. A tea/votive candle is a possibility.

Two cranks out of phase by 90 degrees? (Can't tell for sure from photos)

How is displacer chamber sealed? As a test run a fillet of Vaseline around both joints. If it still doesn't work, Vaseline can be easily removed without damage to engine.

Did that HDD bearing have any lubrication in it, eg. grease or oil. These are flea-powered engines and conventional lubricants can cause too much friction. Run them dry or use only the tiniest smidge of graphite powder.

Keep fiddling. It can't hold out forever. Good luck.

 

[Peter.]

Cheers Marv

Cranks were set for 90-degrees off-set.

I've made a few inprovements, followed your advice and blasted solvent through the bearing. I also added another CD to double the flywheel mass. THe flywheel now free-wheels 25 turns with a flick where before it would only make a handful of turns.

I've pulled the bottom plate off, and removed the displacer which had warped. Making a new displacer at half the thickness and less clearance on the outside, and I'm going to use a longer throw on that too, trying to improve the movement of air in the displacer.
Is it necessary for the displacer to come close to touching the top plate or can I leave a few mm of gap?

 

[doc1955]

I've found from building the ones I have there is a fine line on the piston to cylinder fit. That is what gave me the most trouble. The piston needs to just drop through the cylinder with both ends open to the atmosphere but drop slow or not at all with one end closed.
They are a pain to get to run but once they do as long as you keep everything clean they are consistent runners.


I personally don't go out to my shop for speed builds I like taking my ever lovin sweet time if I want to be rushed I'd just go to work where all kinds of dead line exist. (just my opinion) after all I started building models to unwind.


But never the less to each their own your work does look good.

 

[Peter.]

Aye it was definately an impulse decision on a bored Sunday afternoon.

Anyway - guess what? With the new changes she runs on a cup of hot water with a little ice on the top!

http://peterrimmer.myby.co.uk/vids/ltdrunning.wmv

 

[maverick]

Glad it runs now, they are a bit fiddly as is noted here. Mine held out for months before the secret was found, a tiny high spot
on the crosshead touched the guide every revolution. A stroke of the file fixed it but not before trying a dozen other things first.

Regards,
Mike

 

[mklotz]

I'm glad the fiddling worked.

 

[Peter.]

Yep I'm well-satisfied now. Not with the finish of course - this is an unashamed lash-up - and as such I'll not be doing any more work on it now that I've made it run.

I'm don't really have the skill for high quality work but now I've sorted the mechanics I'm going to set my sights on building one that will run on a warm cup of tea, then if that works well, I'll try a hand-powered one.