V4 Oscillator Motor

[ACHiPo]

ACHiPo, a few pics of the disassembled piston, I believe contact with any type of oil will turn it into a messy sticky black goo,


View attachment 121344View attachment 121345View attachment 121346View attachment 121347View attachment 121348That makes sense. Thanks.

 

[Steamchick]

ACHiPo, a few pics of the disassembled piston, I believe contact with any type of oil will turn it into a messy sticky black goo,


View attachment 121344View attachment 121345View attachment 121346View attachment 121347View attachment 121348

Excellent work! Please can you tell us the clearances between bore and piston OD that you use? What is the tooling like? What speeds and feeds to use? - and where we can get suitable grades of Graphite? How is the piston affixed to the Delrin inner? - if an interference fit, what are the relative sizes of part? (to avoid bursting the piston?).
Thanks,
K2

 

[holmes_ca]

K2, I am no expert on graphite material, the piece I had was of unknown identity, hot air engines need low friction and as far as I'm aware very accurate dims are not a must, and any kind of contact of moving parts will reduce power and it will even refuse to run,

to machine Graphite I think can be dangerous to your health it floats in the air as a cloud of dust and will leave a film everywhere so my advice is to be careful and definitely use a vacuum close to the work, the piston is 0.700 dia and a sliding fit I turn it to .0005 oversize and then push it into the cylinder what takes place as I do this is the graphite surface is compressed that 0.0005 and sizes the piston, I use hss tooling, the Delrin is just a slide fit and does not interfere with the inside of piston,

Fizgig is a very simple engine to build and more complicated engines such as Vickie from Jerry Howell would I feel sure require more accuracy regards dimensioning,

Edmund...........Alberta

 

[vederstein]

Yeah, anything with a substantial amount of copper in it is stupid expensive.

360 brass is my favorite material to work with, but that makes an engine very pricey.

...Ved.

 

[Steamchick]

THANKS Edmund. Very interesting!
K2

 

[Ken I]

I would not recommend graphite - just simply unnecessary for the application.

Graphite is great for flame lickers and Sterlings (external combustion engines) which require as little friction as possible and generally won't even tolerate piston lubrication.

Steam or compressed air power much less of a problem.

Regards, Ken

 

[Steamchick]

Thanks Ken, I'll save it for commutator brushes and compressor applications. I just thought maybe Mr. Holmes had a good idea for small air motors like your oscillators. (Like A compressor running backwards?).
I have learned about machining carbon though.
K2

 

[Richard Hed]

ACHiPo, a few pics of the disassembled piston, I believe contact with any type of oil will turn it into a messy sticky black goo,


View attachment 121344View attachment 121345View attachment 121346View attachment 121347View attachment 121348

How much pressure will tht take? Will it break under too much stress? Do you use some kind of strengthing material inside?

 

[holmes_ca]

How much pressure will tht take? Will it break under too much stress? Do you use some kind of strengthing material inside?

I haven't a clue, it is brittle material it seems to be just compressed granules even rubbing the surface of the piston with a piece of paper will erase the surface until I slide it into the cylinder bore that's when it becomes compressed to a hard and slippery fit,

The Delrin insert is just a slide fit in the bore and there is no strengthening agent or material other than the Delrin

Edmund............Alberta

 

[Steamchick]

Clever - Making something that works well without understanding the material properties, etc. must have taken a bit of trial and error to get right. Well done! - And thanks for sharing your experience!
K2

 

[fcheslop]

Noggin end sell graphite in the UK
P.O.M is also hydroscopic and if you should happen to get it too hot it gives of formaldehyde gas. Delrin is a brand name as is Hostaform and a few others I forget.
One of the benefits using graphite for hot air engines is its low rate of expansion and self lubricating
https://www.nogginend.com/product/Graphite-Round-Bar-graphite-rod

 

[holmes_ca]

Clever - Making something that works well without understanding the material properties, etc. must have taken a bit of trial and error to get right. Well done! - And thanks for sharing your experience!
K2

K2, I cannot take credit because there was information previous to building my first Fizgig, (this is my 2nd fizgig), that was in 2000, Mick Collins the originator of Fizgig suggested two types of piston, both aluminium, one solid and one hollow, all I did was to use graphite instead, indeed, Jerry Howell's Vickie kit has a slug of graphite included so it seems to be common practice,

Ken1, in this thread also confirmed that practice

 

[Steamchick]

Like Watt, Eddison and many others, the cleverest ideas are "borrowed"... but take some credit for considering the application to air motors - like this oscillator. A huge number of ideas end up being used for a "new application" that the originators never imagined. e.g. non-stick frying pan coating....
K2

 

[johnmcc69]

Attached are assembly drawings of Ken's V4 engine(s) with BOM. Detail numbers coincide with Kens original detail drawings. Design all by Ken.

"KAD approved"-"Ken Approved Drawings"

John

 

[Ken I]

Thanks to the 3D wizardry and compliments to Johnmcc69 - an animation of the motor :-

Animated / Partial Wireframe

Regards & Thanks To John