SloMo Wobbler

[Dave'H]

A small ocsilating engine in slow motion



SlomowobblerE2.mov - YouTube


Just as a bit of info. It is running at about 700rpm, about 12 revs/second.


The real time length of the video clip is about 0.9 sec, if you count the revolutions it should be about 10 or 11.


Now wasn't that bluudy exciting :D:D:D
:)
DaveH

[pipeclay]

Not really but whatever rocks your boat.

[Avery]

What does it do? Why?

[Stustoys]

Hi Dave'H
Well I like it.
One of these days when I can see some floor in my shed I'm going to make me one.
Whens it going to run on steam?

Stuart

[Dave'H]

It really doesn't do any thing, except go around and the clyinder rocks.

Just some thing I made thats all, normally they run quite fast so it is hard to see what is happening. So I thought I would show it in slow motion.

:U
Dave'H

[kwijibo99]

Nice bit of work there Dave, she seems to run very smoothly.
Is the flywheel fabricated or fully machined?
Cheers,
Greg.

[matthew_g]

I think you are right, wasn't worth posting.

It really doesn't do any thing, except go around and the clyinder rocks.

Just some thing I made thats all, normally they run quite fast so it is hard to see what is happening. So I thought I would show it in slow motion.

:U
Dave'H

Well I think it was worth posting, As it shows all of us your machining skills.
Good work there mate..:2tsup:

[Dave J]

Wow, tough crowd today, you make something in your shop and post it up, only to be knocked down when you post it.

I think you did a good job on that Dave, I like it.:2tsup: I would be interested to know a bit more about it as well, and as Greg said is the flywheel cast or from solid?
Engines are something I want to get into in a few years time, they wont do anything but will look good on the mantle piece, but you get the enjoyment from building it.

Dave

[Dave'H]

Nice bit of work there Dave, she seems to run very smoothly.
Is the flywheel fabricated or fully machined?
Cheers,
Greg.
Thank you Greg, fully machined on a small Sherline mill. Made from a 30mm dia piece of brass.

Dave'H

[Ueee]

Nice work:2tsup:
I love gizmo's that don't really have any function but to exist.
Love that flywheel

Ewan

[pjt]

Yeh nice bit of work, something about motion that facinates me, when I was a mere youngun I had a small steam powered stationary engine, used to watch it for hours:B,
What is actually powering it?


Pete

[Dave'H]

Thank you Pete, Ewan, Dave, Matt, Stuart, for you nice words:U

Running on air about 1.8 psi - any lower it doesn't run.

:)
Dave'H

[Steamwhisperer]

Outstanding Dave
There is a serious amount of satisfaction in getting inert lumps of metal and machining them to exacting sizes, fitting them all together and making an operating machine.
Well done

Phil

[pjt]

Having another look at this and I reckon there's more going on than we can see, some sort of valving/porting to get the air in then the same to get the exhaust air out, plus a rotary seal of some sort between cylinder and housing plus sealing on the cylinder rod or a very close fine finish, however it's done it's a good job, perhaps Dave might expand a bit more on the inner workings:)


Pete

[Pete F]

Wow, tough crowd today, you make something in your shop and post it up, only to be knocked down when you post it.

I think you did a good job on that Dave, I like it.:2tsup: I would be interested to know a bit more about it as well, and as Greg said is the flywheel cast or from solid?
Engines are something I want to get into in a few years time, they wont do anything but will look good on the mantle piece, but you get the enjoyment from building it.

Dave

Amen to that. I'm personally not much into modelling, too busy making life sized parts. Having said that I have 3 low temperature Stirling engines about half finished I hope to one day get complete and give them away to friends. One thing I will say to those who seem to do nothing but come up on this forum and look down their noses at other members, is that there is a remarkable amount of machining in these little engines. Things like accurately laying out the flywheel spokes and then machining them isn't as easy as it looks until it it's time to do it. In my case I also have some flat plate that I'm still somewhat scratching my head as to how I'm going to secure it for the machining operations needed.

Good on you Dave (H) for putting this up and Dave (J) if you do decide to do some engines yourself, these are the ones I'm doing. I may reserve my recommendation for when they're actually running though :D Jan is a really nice guy though and if you email him he'll send any plans. The low temperature versions are especially intolerant of any friction, so any machining needs to be spot on.

hand_stirling (http://ridders.nu/Webpaginas/pagina_stirling_hand/handstirling_frameset.htm)

Low Temperature Stirlings - YouTube

Pete

[Dave'H]

Having another look at this and I reckon there's more going on than we can see, some sort of valving/porting to get the air in then the same to get the exhaust air out, plus a rotary seal of some sort between cylinder and housing plus sealing on the cylinder rod or a very close fine finish, however it's done it's a good job, perhaps Dave might expand a bit more on the inner workings:)
Pete

I just have undo the little screw and it falls to pieces, I'll take some for photo's to show the ports (holes)

A couple of photo's to show the size

http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8199-dscn0689.jpg

http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8200-dscn0692.jpg
:)
Dave'H

[Acco]

Do you have clip showing it running at normal speed?

[Dave'H]

Thank you Pete F
:)
Dave'H

[Dave'H]

Do you have clip showing it running at normal speed?

Hi DJ

I'll find it and post it.
:)
Dave'H

[Acco]

Hi DJ

I find it and post it.
:)
Dave'H

:2tsup:

[Dave'H]

Normal running speed - doesn't look so good
DSCN0693.avi - YouTube

I'll get there soon! ........got there............ looks much nicer going slow
Dave'H

[Pete F]

Dave I just noticed you're in South Africa. I used to go over there a lot for work, and one thing some members here may not be aware of is that it's sometimes difficult to get hold of things that even in Australia we may take for granted. It can make projects much harder from what I understand speaking to those over there.

The best thing about South Africa (well apart from the women), is being able to go to a game park, look at all the cute little animals ... and then go back to your lodge to eat them :D For those less, err, "game", when you eat beautifully aged SA beef it makes you appreciate just how crap the meat sold domestically in Oz really is!!

Pete

[Dave'H]

Hi Pete,

It was very difficult to get stuff and expensive as well, it is a lot easier now with ebay and the likes.
I still have to "import" a lot of stuff mainly because the hobby machinist/model engineer just isn't catered for, just not enough of us.

The meat is good and South Africans are reducing their intake, because it is so cheap we ate too much of it, so we all die of heart disease. In the 70's and early 80's heart disease was the highest in the world. Having half a (fried) rump steak for breakfast every day doesn't really do one any good.

I wasn't born here I was born in England, (Leicester) came here in 1980 - on a three year contract,(with a view to stay), never left - I'm beginning to like it here:D:D:D

I think the weather and the life style were the main reasons for staying.

And as long as we beat you at cricket I'm happy :D:D:D

Dave

[Dave'H]

Pete,

I meant to ask what work did you do here?

Dave

[drsed]

And as long as we beat you at cricket I'm happy :D:D:D

Dave

I'd keep depending on the climate and the beef, if I were you Dave! :)

I like your machine, by the way. :2tsup:

[Dave'H]

Thanks drsed,

Wishful thinking:D

Dave

[Pete F]

Pete,

I meant to ask what work did you do here?

Dave

I was hauling plane loads of people between Australia and SA. We'd go quite a ways south on that sector, it was quite normal to see icebergs. Coming back was at night and it was also not at all unusual to see the Aurora Australis. I will never forget one night it was particularly strong, one of the freakiest things I've ever seen. The aurora was from horizon to horizon, and it looked like it was actually going through the aircraft (naturally it's not, it's right on the edge of outer space, but that was the optical illusion). For a number of hours we were immersed in the aurora 360 degrees around us, each wave was like a pulse. Very much like a cheap sci-fi movie really. Quite spectacular anyway.

Yes Capetown is one of my favourite cities, it's all just a bit of a shame about the crime over there.

Pete

[jhovel]

Dave,
Very nice work!
Do you have a drawing for this wobbler?
I've downloaded a few, but this is by far the most elegant.
It would make a great first project to do with my grandkids!
Cheers,
Joe,

[Dave'H]

Having another look at this and I reckon there's more going on than we can see, some sort of valving/porting to get the air in then the same to get the exhaust air out, plus a rotary seal of some sort between cylinder and housing plus sealing on the cylinder rod or a very close fine finish, however it's done it's a good job, perhaps Dave might expand a bit more on the inner workings:)

Pete

A few photo's showing the ports (holes)
http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8202-img-0819.jpg



http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8204-img-0821.jpg

There isn't an awful lot to it.

Dave'H

[arose62]

Hi Dave'H,

when I read your post, it appeared to be a random posting of something you'd found on the net - nowhere did it say that you had made it. If I hadn't started to attempt to begin to have a go at a wobbler, I wouldn't have bothered to read further, and halfway down the page notice that it's your own craftmanship on display.

I think that if you had opened with "Look at what I made", then the responses would have been much different, and probably more positive.

I like it, I agree that the flywheel's elegant, I wonder about the grooves on the piston, and I wonder do you know anything about Cape Town's Town Hall (which my grandfather is supposed to have been involved in building).

Cheers,
Andrew

[Dave'H]

Hello Andrew,

My first impression was that I had posted something that was not supposed to be posted, I nearly deleted it.

I agree I should have said that "I had made it", and next time I will. It is my understanding it would have been better received, no real harm done. I could have gone back and edited it and put the words in, however I thought that was not the right thing to do, as some members had already posted a reply.

Just one of those things that's all.

The grooves tend to hold a bit of oil, or not. They do something because they do get 'dirty'.

Just a fun little engine, more fun to make than run:U

I live in Johannesburg, so I don't know a lot about CT's Town Hall, I have seen it, even been inside to meet the Mayor couple of times, but that's about my lot.

Thank you for your kind comments, and I will get the proper words in next time:U

Regards
Dave

[Dave J]

Hi Dave'H,

when I read your post, it appeared to be a random posting of something you'd found on the net - nowhere did it say that you had made it. If I hadn't started to attempt to begin to have a go at a wobbler, I wouldn't have bothered to read further, and halfway down the page notice that it's your own craftmanship on display.

I think that if you had opened with "Look at what I made", then the responses would have been much different, and probably more positive.

I like it, I agree that the flywheel's elegant, I wonder about the grooves on the piston, and I wonder do you know anything about Cape Town's Town Hall (which my grandfather is supposed to have been involved in building).

Cheers,
Andrew


Another local guy Andrew, Col lives down your way, he started a thread on the first page about CNC end mills.

Dave

[jack620]

Hi Dave,
Lovely work and welcome to the forum. I hope you'll find the majority of us Aussies are friendly and helpful. :wink:

I wish I had the skill and patience to make something like that. I'd have to replace a lot of window glass before I managed to complete something like that. Out of interest, how many hours do you reckon you spent making it?

Regards,
Chris

[Grahame Collins]

Thank you Pete, Ewan, Dave, Matt, Stuart, for you nice words:U

Running on air about 1.8 psi - any lower it doesn't run.

:)
Dave'H

That would indicate a bloody nice fitup.

Years back I had a class make an air powered reciprocating engine as a vehicle to encourage student precision lathe work. The kids that got them running had a contest.

Part 1 outright revs
Part 2 the lowest air pressure it would run on.

The regulator on our compressor only went down to around 10 psi and most would not run on that.

1.8 Psi is a really good outcome.
congratulations

Grahame

[Dave'H]

Hi Dave,
Lovely work and welcome to the forum. I hope you'll find the majority of us Aussies are friendly and helpful. :wink:

I wish I had the skill and patience to make something like that. I'd have to replace a lot of window glass before I managed to complete something like that. Out of interest, how many hours do you reckon you spent making it?

Regards,
Chris

Hi Chris,

Thanks for your kind words and the welcome:U
Everyone is friendly. Just a silly misunderstanding that's all.


Oh dear this is embarrassing, http://www.metalworkingfun.com/images/smilies/blush.gif Well it took me about 3 months, on and off designing it. Then when I started to make it I thought I would make it upside down (so to speak) just for the heck of it.

To make it about 15 hours spread over about 2 weeks. I kept on changing my mind, and the design. That 15 hours doesn't include all the whoops!, bits I made didn't like and made them differently.

If one includes everything I would say 30 hours.

Bear in mind, I'm normally quite slow when I do things like this, I stop have a fag, cup of tea, biscuit, talk to the dog, watch the cricket. Especially when we are beating the Aussies:D

No rush for me http://www.metalworkingfun.com/images/smilies/biggrin.gifhttp://www.metalworkingfun.com/images/smilies/biggrin.gifhttp://www.metalworkingfun.com/images/smilies/biggrin.gif

Dave'H

[Dave'H]

Hi,

One of the ideas behind this engine was to make it run on breath power.

My son and a few others can, I can't - I just go dizzy and fall over:D:D:D

Dave'H

[Dave J]

Hi,

One of the ideas behind this engine was to make it run on breath power.

My son and a few others can, I can't - I just go dizzy and fall over:D:D:D

Dave'H


LOL, I do my projects in a similar time frame with many stops for the same reasons, after all it's hobby so we are in the shed to enjoy our time, not to rush to the end.
I also often get side tracked on other jobs on the way through, and after woods wonder how I came to be working on what ever it is.

Thanks for the explanation on the engine and the extra photos.:2tsup: This may look like a really simple engine to build, but the skill in the fitting and machining would show in the end with the amount of psi needed to run it as you have done. Great work.

Dave

[pjt]

A few photo's showing the ports (holes)
http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8202-img-0819.jpg



http://www.woodworkforums.com/members/76606-dave-h/albums/dave-h-album/8204-img-0821.jpg

There isn't an awful lot to it.

Dave'H
Thanks for posting the pics of the inner workings Dave :2tsup:
I can't see any seal between the cylinder body and the main housing, I would be guessing that there isn't other than the two mating surfaces coming together well enough to prevent/slow down any air leaks, maybe just a smear of oil is all it needs? also does it require a push start to get it going if the inlet port isn't lined up when it last stopped.
Once again good job


Pete

[Dave'H]

Pete,

Like you say it relies on the two mating surfaces and a smear of light oil.
Therein lies most of the problems, it is always a trade off between getting a seal and the friction between the two surfaces.The spring on the screw provides the holding force.
There is a round recess that reduces the surface area which helps to reduce the fiction.

It always need a flick of the fly wheel to get it going at about 2.5 psi, after 30 seconds of running I can turn the psi down. There is no power at the flywheel, there is just enough energy to over come all the fiction and lift the piston against gravity.

I can over come the effect of gravity on the piston by turning the engine upside down, and a slight increase in speed can be noted, it will run on a slightly lower psi when run upside down.

So long as it goes round the grand kids luv it:U:U:U

I would like to say they are a lot easier to make than it appears.
If the seal isn't too good use some more oil, increase the spring pressure and turn up the air pressure - it will whiz round:U I'm always of the opinion "if one uses enough force it will move":D


Dave'H

[Dave'H]

Dave,

You are right, for most of us it is a hobby, something we enjoy doing and yes "showing off" what we have done.

When (if) I grow up I might make something useful:D:D:D:D:D
:U
Dave'H

[pjt]

I'm with the grand kids just watching it go round:D



Pete