making discs from flat sheet

[Twinsquirrel]

Hi all

Wondering if anyone could help me, I need to cut 2x 160mm diameter discs form a sheet of 5mm aluminium sheet I then need to cut a groove 2mm deep x 2mm wide 5mm from the edge. I don't have a mill and have been told in no uncertain terms that I wont be getting one for at least a couple of months so I have a feeling I am up against it here.

Any ideas gratefully accepted.

Cheers

David

 

[Tin Falcon]

David:
If I was doing this on my mini lathe here is what would happen. punch mark the center of the disk then mark out the 150mm D circle with a compass holding a fine line felt tip marker. Then cut out the circle on a band saw.
Clean the 6" face plate and mount on the mini lathe. dig out the double sided tape and stick several pieces on the face plate put the live center in the tail stock and move it so it is about a 1/2 inch from the face plate. align the center mark in the center and push the center and plate against the face plate .Place the handle of your tail stock at 1 o'clock. Set up a tool to clean up your edge. Machine diameter to size. Grind a grooving tool 2mm wide to make your groove.
Actually I would set this up on my 9" south bend but I know you have a mini . Work safe.
BTW are you starting a LTD Stirling ? A bold starter project if that is the case.
Tin

 

[Twinsquirrel]

Hey thanks for the fast response Tin, I will definitely give that a try tonight, I have plenty of material to play with (picked up a sheet 1000mm x 500mm x5mm for £1.50 (about $3) at a local steam fair at the weekend BARGAIN!!!).

Yes, gonna give a LTD a try, I did manage limited success a few years ago on an LTD built only with hand tools but I don't really hold out much hope of a reliable running engine on my first proper try this time but as long as I learn something in the process I will be more than happy.

Will try to dig out a video of the "hand tool" LTD engine I built.

Cheers

David

 

[mklotz]

Another option is a (woodworking) router with a 1/4" straight bit and a jury-rigged pivot point.

Make sure everything is nailed down well and you have good ear protection.

 

[Twinsquirrel]

Sounds vicious!!! but I am sure that would work. I have plenty of time and material so I will probably give both suggestions a try

Cheers

David

 

[Bogstandard]

David,

Here are two ways I did it, very similar to the way Tin did it.
If you don't want the centre holes or dimples, just use a bit of barstock, flat on one side and a centre in the other, and trap it between the tailstock centre and your discs.

http://www.homemodelenginemachinist.com/index.php?topic=1809.0
http://www.homemodelenginemachinist.com/index.php?topic=1510.0

For the recesses you could use a little tool like this one.

http://www.homemodelenginemachinist.com/index.php?topic=844.0

John

 

[Twinsquirrel]

Brilliant, managed to cut the discs last night using a combination of the above suggestions... Thanks guys it would have taken ages for me to work that out for myself.

BTW here is a video of the "ugly" LTD stirling I built a couple of years agos, excuse the state of the garden and house we had just moved in!!![youtube=425,350]<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/oFojv0nYHXU&hl=en"></param><embed src="http://www.youtube.com/v/oFojv0nYHXU&hl=en" type="application/x-shockwave-flash" width="425" height="344"></embed></object>[/youtube]

 

[mklotz]

David,

IMO, no engine that actually runs can be called "ugly". The essence of the mechanical art is in performance, not appearance. The turned brass finials and pin-striping on Victorian engines, while very attractive, did nothing to improve performance.

Taking on a Stirling, and an LTD at that, as a first or early project is a mechanically gutsy thing to do. The fact that you did *and* got it to work speaks admirably about your skills and perseverance. Don't sell yourself short. I've built a number of heat engines over the years and I would never have even considered taking one on as a first project.

I see you're running it on hot water. For exhibitions, you might want to try something a little different. Set the engine on one of those ice packs one freezes (e.g., for use in a picnic cooler) and set the engine in the sun (they do have sunshine in the UK, don't they?). The engine should/may run in the opposite direction. I do this at our outdoor exhibitions and the onlookers are fascinated (and utterly confounded). With no heat source in evidence, they're forced to completely rethink their ideas of what an "engine" is.

 

[rake60]

Nice running stirling David!

Rick

 

[CrewCab]

Thanks for sharing David, good job ........ and ....... nice use of a CD btw ;D

CC