Web based micro-industries (CNC machines)?

[D.C.]

If you are willing to spend a little bit of cash experimenting on this I have an idea.

Most builds tend to be out of aluminium (weak) or steel (need welding skills) even though it has been known for a rather long time that big lumps of cast iron or granite do the job better and modern epoxy granite is much better still.

If you want to carve out a niche instead of offering a full cnc machine offer a standard gantry design that makes a brick shithouse look like it's a straw bale, but comes in user defined lengths.

You will probably be able to put food on the table doing this because buying small quantities of epoxy costs an insane amount, if you can invest a few grand up front to buy the epoxy can get a lot more for your money. By contrast the bulk cost of steel/alu vs the retail is not that great.

Make sure that you can mount either supported round rail or hiwins, have a seperate foot plate so that people can choose their own block spacing and you have pushed the hobby market up a notch.

PS: If you are after some cheap but rusty steel up your way I found these guys the other day:

Steel Beams and Columns, Gates Fencing and Railings items in AinscoughMetals store on eBay!

[GEOFFREY]

D.C. An interesting idea ( from previous posts I realize that you may be "biased" towards epoxy granite) would a granite gantry be very heavy?

I suspect a granite gantry would be far better suited to a fixed rather than moving design (fixed being my "bias"), but the preference on this forum seems to be for moving gantry, mainly I suspect due to space limitations.

I have a good friend who has a fibreglass factory who has an injection/vacuum unit and whilst I have not asked about granite I feel sure that it would be no problem for him to make it the various gantry components complete with any correctly positioned captive fixings that may be required. Just a thought.

Fivetide, if you really want to get this off the ground and none of the real experts want to get involved, I would be prepared to act as leader/coordinator although I would still be looking for help/constructive comments from those experts. G.

[D.C.]

D.C. An interesting idea ( from previous posts I realize that you may be "biased" towards epoxy granite) would a granite gantry be very heavy?

I suspect a granite gantry would be far better suited to a fixed rather than moving design (fixed being my "bias")

I'm not really biased I don't think, the reason I keep banging on about trying this approach is that if you look at what the "I have more than god to spend and a team of PhD's working for me sort of places" Things like epoxy granite and carbon fibre are the materials of choice (and trusses are the arrangement of choice).

Cast iron is 250 year old tech for machines and we are using alu and steel because we can't afford to get custom lumps of cast iron done for us and it isn't really feasible to start a smelting foundry in your garden just to make a cnc machine.

But homebrew epoxy granite is feasible. If you use some thin walled steel box section, source a carboard tube for the centre, devise a reasonable mix and do a few experiments to find a good setup that is superior to the empty steel box or alu extrusion/alu plate designs people are using now there is no reason why you can't make a moving gantry with the stuff. Don't forget if you are relying on the epoxy granite for stiffness you can cut down a lot of weight in metal.

A few things to read:

http://www.mycncuk.com/forums/diy-cn...l-casting.html
CNCCookbook: Epoxy Granite Fill

You can actually save weight and get better performance using EG:
http://annals.fih.upt.ro/pdf-full/20...-2012-2-13.pdf
If you design a beam from EG to have the same deflection for a given force it will actually weigh half what the steel does and have superior dampening charcteristics to boot.

PS If you are wondering about the cardboard tube, it is there to turn the energy in the vibration passing through your beam into heat (the energy has to go somewhere and if you want to dampen a vibation you need to suck the energy out of it and turn it into a different form energy or it will just keep on vibrating your beam or be passed into the rest of your machine) The cardboard tube is proven to work in cnc machine beams and also in things like automotive shafts.

[blackburn mark]

modern epoxy granite is much better still.

that's right up your street that fivetide!
you probably know as much as anybody here about epoxy
the advantages of a solid machine may make it stand out against the competition

if you can crack the epoxy granite conundrum you may be onto something interesting

[GEOFFREY]

that's right up your street that fivetide!
you probably know as much as anybody here about epoxy
the advantages of a solid machine may make it stand out against the competition

if you can crack the epoxy granite conundrum you may be onto something interesting

What exactly is the conumdrum? It doesn't look like rocket science to me. -Waiting for lots of comments to the contrary. G

[blackburn mark]

to be honest I don't think there is a "conundrum" but as it is, nobody seems to go for it and actually make one

there is a thread on the cnczone that goes on and on about mix ratios and filler type and it seems to just drift past logic into an endless pissing contest

I'm sure some care and though is needed for a choice mix but like you say "It doesn't look like rocket science" and the real nack to the job in my opinion is managing to commit and deciding to crack on with making it happen (like anything else)