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richb77
17-10-2008, 03:53 PM
Afternoon all,

As the title states i am a noob at this with what i guess is one of the most common Noob questions going :)

Some background first.

I am a Mech E/Designer with a good engineering background in everything from Military antenna to consumer electronics. Most of my time is on 3D CAE but i often escape back to the Bridgeport and colchester manual machines.

I am looking to build something for home projects and would like open source plans or similar as i cant afford the huge time resource needed to develop the kit from scratch.

I have the plan set for JoeCNC 2006 found on CNCzone but its too grand for what i want.

What i am after is the ability to machine aluminium on a bed no larger than 300 x 300 (12" X 12")

Anyone know of a set of plans that would suit?

I want to build from scratch as A) buying a Denford style mill is more expensive and B) half the fun is building something.

Budget restrictions at the moment (i say at the moment as i know once i start it will go out of the window) is approx 500 working, i have a laptop (mobile workstation capable of thrashing Solidworks). I am pretty good at scrounging so i would think the dearest parts will be the controller and motors (maybe servo and not stepper?)

First things first is the chassis/bed/framework.

Any help is grately appreciated ;)

irving2008
17-10-2008, 09:18 PM
Rich,

Welcome to the forum.

I too looked for a set of plans for a similar machine and came up with a blank. So I decided to build a small 250 x 250 machine using MDF to my own design for PCB milling and as a learning solution. I am working on a bigger design for machining ali, but I am still debating using aluminium extrusions or a welded steel frame.

I, as would many on this forum, would be interested in your thoughts, as a Mech E/D, on, and tools for, how to do structural analysis to avoid wasted build effort.

Irving...

richb77
17-10-2008, 10:43 PM
Hi Irving,

Looks like i have either a long development schedule ahead or build a monster :)

As for FAE tools.

I dont know much about any possible open source software but i use Cosmos in Solidowrks quite regularly.

Its pretty good for tension, stress, deformation and heat dispersion but to expect anything less than 80% accuracy would be optimistic.

The other issue is th epower needed to run such software. A simple heat transfer model on a heatsink will take a machine with 2GHz processor and 4Gb RAm approx 5 minutes. Doesnt sound much but add a few other parts and it raises that time quite a bit.

As for my dilema. I may scale the JoeCNC to suit what i need frame wise. I dont like the idea of an MDF frame for anything other than maybe a small scale wood router. Aluminium or at a push HDPE or similar frame will do for what i am after.

richb77
17-10-2008, 10:57 PM
Hi Rich, Welcome to the forum.

500 all up and running....Might be possible!
Have you anything in the way of linear slides or bearings?....Your indication of a time factor is worrying....Everything takes too long to do :D

Hey Kip,

I am totally free from any hardware at the moment. I am pretty handy with most things so its a case of if i cant build it i will buy it ;)

Lee Roberts
17-10-2008, 11:31 PM
Hi Rich welcome to the forums mate !

Take a look at www.slidesandballscrews.com i can offer the same stock for the same prices, let me know if i can help :).

irving2008
17-10-2008, 11:45 PM
Hi Irving,

Looks like i have either a long development schedule ahead or build a monster :)

As for FAE tools.

I dont know much about any possible open source software but i use Cosmos in Solidowrks quite regularly.

Its pretty good for tension, stress, deformation and heat dispersion but to expect anything less than 80% accuracy would be optimistic.

The other issue is th epower needed to run such software. A simple heat transfer model on a heatsink will take a machine with 2GHz processor and 4Gb RAm approx 5 minutes. Doesnt sound much but add a few other parts and it raises that time quite a bit.

As for my dilema. I may scale the JoeCNC to suit what i need frame wise. I dont like the idea of an MDF frame for anything other than maybe a small scale wood router. Aluminium or at a push HDPE or similar frame will do for what i am after.I've been using Framework (http://members.ziggo.nl/wolsink/) which is freeware but has some limitations. Runs fine on a 2GHz laptop and gives a good idea about deformation under load of a gantry for instance...

I'm interested in your suggestion of HDPE... there was a recent discussion here about PVC v Ali for construction and a bit of research suggested that PVC was about as rigid as MDF but stronger in tension. When I looked at other plastics, including HDPE, I wasn't impressed by much of them as compared to thin-wall Aluminium box section which, weight for weight is more rigid and stronger. Can you shed any more light on this? PVC was much more expensive as well....

richb77
18-10-2008, 01:04 PM
i was thinking HDPE simply for cost. I would need quite a bit more volume of plastic compared to aluminium and to be frank i have more experience with aluminium and weight to strength it makes perfect sense.

Corrosion shouldnt be an issue even though aluminium is extremely reactive it takes a long time ot corrode seriosuly.

Although it may also mean i start a home anodising bath :)

I shoudl add, I am still looking for a suitable plan set ;)