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Just need work out you're going to mount the big Fresnel lens so the project will qualify for a "green" grant.

As luck would have it this has just arrived. A good look over confirms everything is as it should be, it was advertised as used twice, appears to have been well looked after and came from an engineering company nicely coated in oil.

Hi,

never seen geneva cross before, googled and seen now, why would you want to complicate the annealing machine further
as a twin torch set up and reduction gear motor drive woukld suffice. (just curious)

regards

nick

Good question. I guess this is a shedist thing, I look on it as an oportunity for some engineering. Initially I will build a roller only Geneva drive and once the operation is confirmed I will add the cam that locks it.

a true shed 'pest' at his best

keep us posted with the pic's on production :-)

Thought about making one of those myself. I'd probably use the CNC router at work to make the 'wheel' and a car window electric motor. Ideal as they will already have a reduction gear.

Show us your stages in manufacture in pics please.

Anything CNC would be nice right now...I still have to machine back by another 2mm on the radius after this stage is finished.

It takes a lot of work to get this far on a small milling machine, I need to get the table to 300 diameter so a few more cuts yet, last few while be fine and tedious to get a reasonable finish. This is only 12mm thick, the platen is 20mm so will be a very solid days work allowing for cups of tea and giving the machine a rest.

So not a lot done but an update.

Looks good so far. Is that a 4" rotary table?

What type of motor are you planning and will the geneva drive be imersed in an oil bath?

6" Rotary table, second hand off eBlag. If it was an internal Geneva drive I would have considered an oil/grease bath but as it is external I am thinking about letting in some steel inserts and then machine them to suit the cam which will be a 10mm OD bearing or maybe a couple stacked. I have not looked for the bearings yet and as it is such a low duty cycle I could always use PB.

Drive and gearbox, well certainly for the case rotating station one of these

http://www.ebay.co.uk/itm/220765749811? ... 1423.l2649



Voltage: 24V DC
RPM: 25RPM
Diameter: 37mm
Shaft length: 21mm
Length (excl. shaft): 90mm
Shaft diameter: 6mm
Weight: 324g

As the platen is suspended on bearings I do wonder if one of these is powerful enough to act as a main drive as well. Fine control of the speed will be electronic and I have a good 7A 24vDC PSU already.