Im new, am a 3D designer. Need a New cnc machine and need advice and guidance

[njhussey]

I Have been researching builds for little under a month so far...thats why i now registered with the forum so that i can start :) I never fully intended building one, but it would be a fun project and would make quadcopter building a fair bit easier..ecspecially cutting wing ribs haha.

Didn't know quads had wing ribs??!! ;)

The builds i have looked at so far were to get an understanding and somevideos are quite enteraining...My CAD abilities will hopefully help me along and to make sure the design is solid before I make the first purchase and cut. Ill post the design on here aswell to see what you fine people think of it :)

That's the best way to do it...

A general question... What sort of accuracy can be achieved by an average well built,accurately assembled machine? Can they top some of the commerical machines?

Only if you make them ridgid enough and use the correct equipment....but then would you expect to make your own car in your garage and expect it to be better that a production car?

The thing Im finding hardest in terms of research is the general jargon that goes with CNC, after thinking of the dimensions of the machine I would like 900mm rails and 600mm rails. Able to point me in the right direction?

Thanks again

If you have a look through build threads like http://www.mycncuk.com/forums/gantry...eady-eddy.html this one or http://www.mycncuk.com/forums/gantry...rst-build.html, http://www.mycncuk.com/forums/gantry...-building.html, http://www.mycncuk.com/forums/gantry...g-machine.html then you'll get the drift of what needs doing and roughly in what order. Look through all the build logs and then with your 3D design expertise put a couple of drawings up of the frame for people to critique and you'll be on the way. Once you've got your basic design then AND ONLY THEN can you think of ordering things like ballscrews and rails etc. Once you've got your frame, ballscrews and rails sorted then you can think about the electrics you will need.

[FlyHighRC]

Thanks, Wasnt expecing his forum to be so saturated with experts at this level on a UK site, Its very nice to see :)

In terms of my design, A plane is designed around engine and passangers, the same for a car in a nutshell. Well To make the design process easier I want to chosse all the size gear Ill need to get it off the ground. So I have found these rails...Are they good enough? If so I can take the dimensions and add them to solidworks so that the design is built around these giving me the size. Also motor mount dimension would be handy...Stepper motors to me seem to have the same mounting and bolt patterns and are just longer with power...Is this correct?

If so then again, the design process will be easier :)

Im also considering these rails also quite allot bigger but Im only 20 and am a student so funds are tight so I dont want to outgrow a machine right away... CNC 3D wings would be nice :D

What are your thoughts on going bigger?

[george uk]

Hi

few tips for you to think about.

Well To make the design process easier I want to chosse all the size gear Ill need to get it off the ground.

Design and build first. for 2 reasons 1. Getting the correct ones. 2 Saving on postage by ordering everything at once

In terms of my design, A plane is designed around engine and passangers, the same for a car in a nutshell.

CnC machine is the other way round. Biuld the frame as solid as you can... the rails, motors and sized around the frame, that why you should do it first

What are your thoughts on going bigger?

It goes up in complexity and costs, it a lot harder to get a big frame properly square, its easyer to get a medium size one accurate. Keep to a reasonable size.

[FlyHighRC]

I think I will still have to design around the rails, its the way I have been taught and may sound odd but without a reference it becomes difficult to scale the machine,for me anyways.

Are these chinese CNC parts decent quality or are they to stay away from?

A reasonable size sounds reasonable haha. I think I will just do that...I can expand once i get my head around everything and have sufficient finances in the future :)

[njhussey]

I think I will still have to design around the rails, its the way I have been taught and may sound odd but without a reference it becomes difficult to scale the machine,for me anyways.

Are these chinese CNC parts decent quality or are they to stay away from?

A reasonable size sounds reasonable haha. I think I will just do that...I can expand once i get my head around everything and have sufficient finances in the future :)

What is the max size you want to machine?

As a designer you'll know that first you need to identify the requirement before you can come up with a design/solution. Set out what you want the machine for, then you'll know what size you need to design. Then you can draw your rails and email Chai at linearmotionbearings2008 (ebay store, though don't go through eBay as you get better prices) to get a quote for the rails and balls crews all in one go, the more you order the cheaper prices he'll give you.

What you're saying is a bit like "I've got a 1000kv 24A out runner. ..I'll design my RC plane round that...which although can be done it's better to say I'll design a 1000mm span plane and then after estimating the Wright of it select the motor, ESC etc...

Sent from my Galaxy S5

[FlyHighRC]

true, Its just the way I have designed before, And the irony is a good designed plane is always designed around the propellor... Oh, I do have some big motors. 1600W to run on 22V, it is lying around and never came up with a use for it...And I have seen people use brushless motors as spindles... any success?

The machine I would Ideally have by the end of this is as:

roughly 800x600mm though that can give or take a bit...though preferably a little bigger than smaller.
Be able to machine carbon/glass fibers, plastics, woods and be able to do some aluminium work without feeling restricted
Be simple,cheap and easy to use.


They are my basic requirements :)

[njhussey]

If you want 800 x 600 cutting area then your overall size will be approx 1200 x 900 which is just about desktop. My machine is going to have a cutting area of 1000 x 500 so I can cut whole sheets of balsa for ribs etc. Have a look through my build (so far) and you'll get an idea of the size of it, it's larger than you think in the flesh. My frame us from 50 x 50 x 4 mm steel and weighs 70 just for the bare frame...

Sent from my Galaxy S5

[FlyHighRC]

Putting a plan together for now :) Just to make sure i meet current and possible future targets...making it as future proof as possible...also simple assembly for maintenance and possible upgrades. With ball screws and rails being the parts that judge the machines length what do you think of these? though these are quite a bit larger,would expect the machine tp be in the region of 1600x1200 which is pretty big but i got the room :)

[JAZZCNC]

With ball screws and rails being the parts that judge the machines length what do you think of these? though these are quite a bit larger,would expect the machine tp be in the region of 1600x1200 which is pretty big but i got the room :)

Your heading into trouble already and doing the classic mistake new builders make by thinking it can't much more difficult to go larger.? Well your wrong it's whole differant ballgame. First and foremost your Budget is blown to bits.!!
Long and wide machines need larger ballscrews and more of them.! Strength needs to increase to keep ridgidty this adds weight This means larger motors, drives, PSU and more of them.! Longer cable chains more wire runs and the list goes on and the cost goes up fast.
Then you have the build it's self with rail alignment and getting on same plane which over longer wider distance requires careful prep and some knowledge which for a first time builder to take on is a risk and not something to do if your on a budget.

My suggestion is take a step back.! Build to your imidate needs not the future as they will 99% change when you actualy start using the CNC machine. You won't upgrade this machine too much from original you will 99% want to build another machine with all your new found needs.
If you build this machine correctly and use decent quality components and electronics you will most likely recover all your initial outlay and possible more. Cut corners and you'll regret it later and will make selling on harder.

Regards the rails then Stay away from round type rails all together because even the supported ones are not so great. Chai as started selling profiled linear rails and they are cheap enough to warrent not using round rail and they make world of differance to the machine and it's sell abilty. They make the diffrance between just average DIY and Great DIY/Professional. They will will certainly add more than there value to the selling price and make sell abilty far higher.

[FlyHighRC]

Do you have a link to these linear rails?

I dont know much about CNC but i know how to incorprate strength into a design. If there is one thing Im good at its designing...dont get me wrong...i have seen builds on this forum which to me seem fine but people who have been there and done that have pointed out aspcts of designs that didnt show up to me...but all their critisims and expertise has been written down on my Pukkapad to bear in mind when designing my machine, which will be posted so others can tell me what needs improvong and whats ok etc etc.

Really appreciate the help :)