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

[Neale]

Many thanks for the comments. I'm still building the frame for my new machine, and haven't reached the stage where I have to worry about single or double motors. It brings up a bunch of related issues, so I'll stop hijacking this thread and start another one.

One last vaguely relevant-to-the-thread point, though - I started out a couple of years ago with my MDF JGRO machine in order to make an engraved presentation plaque (immediate need) and the thought that I would be able to cut things like wing ribs, fuselage sides, etc. Haven't done any of the latter yet, but found lots of other uses for the machine that push the (admittedly very modest) limits of what I have. Spent the last couple of days profile-cutting 6mm and 9mm ply components for a slot-together architectural model, and watching the wheels go rounds at a mind-blowing max cutting speed of 700mm/min was tedious. The moral of the story is that if you are happy to cut modest amounts of material at slow speeds, you can get away with a real junk machine. But if you want to be able to do a good job at proper speeds, do it properly first time!

[FlyHighRC]

Well for me right from the outset I wanted a mchine that is future proof for me (Hence why these guys are pushing so hard ;) ) so that way i can cut plastics,woods and do so ali work in the future and have a machine capable for it all. I was first introduced into CNC at school and was quickly dissapointed with the machines they had... werent very good. Then I got to start using a Roland MDX-540 as part of a young engineers thing.. that machine was better and could chew through plastics...struggled with carbon fiber and did aluminium at 400mm/min, not sure if it could go quicker or the company didnt want to push it but it was annoying to watch frankly.

[FlyHighRC]

Would this be a better frame? Following a design more towards what other people are making...

[FlyHighRC]

Oh building a machine to now combat resonance..meaning pulleys..those pulleys will need a special mount t fix onto the ballscrew right? This is now sounding more and more expensive... Please try to remember my budget :D

[JAZZCNC]

Oh building a machine to now combat resonance..meaning pulleys..those pulleys will need a special mount t fix onto the ballscrew right? This is now sounding more and more expensive... Please try to remember my budget :D

Nothing special needed for using pulleys and the only extra expense are the pulleys & belts roughly £15 per axis. Which isn't much more than direct mounting by time you have bought correct couplings.

[FlyHighRC]

ahh yeah, just looked at this site, not too bad at all 31T10/25-2 | Ondrives

Im revamping my old design, the frame im happy with...i cant see there being much wrong with it after i strengthen it which was the main critique with it. So I have stiffened that up now. Also the gantry is sitffened up which I will show later, mian change is 2 pieces of 6mm plate welded onto the box section and did away with angle Iron(Which I call L Bar) where the Lbar was is now replaced with 6mm steel welded onto the boxsection

Green is 6mm plate, Note, I will need to extend the bottom 6mmplate awayslightly to make room for the bolts close to the vetical 6mm piece

[Clive S]

As a matter of interest have you thought about how you will fix the ball nut and bracket to drive the Y axis it seems you are running the screw through the uprights in the gantry. Also there are cheaper places to buy belts and pulleys. ..Clive

[FlyHighRC]

Yeah I realised that haha, Did it at half 7, Ill put it to the mrning haha, those uprights in the gantry will be behind the horizontal box sections

[JAZZCNC]

ahh yeah, just looked at this site, not too bad at all [url=http://www.ondrives.com/p/9519/31t1025-2]31T10/25-2 | Ondrives[/url

Nah too expensive try these people or go to your local bearing supplier as they are often cheaper and will sell without Vat for cash.
http://www.beltingonline.com/timing-pulleys-bars-272/

Your gantry is looking slightly better but still needs work. Also by the looks of it you haven't given much thought to how the ballscrew end bearings will mount and how the motor will connect.? Has it stands now it can't be done without special machining and using FF/FK bearing blocks.

10mm plate would be better for the bearing plate 6mm is still a bit flimsy.! Can't afford any flex or resonance here.

[Robin Hewitt]

Most machines will scratch Aluminiun away but to cut it correctly and accurately requires rigidity and NONE of these have enough to cut aluminium to any decent standard and survive.

I must be misreading this, I thought that Jazz and me would see eye to eye about routing aluminium, I did go to Specsavers so it can't be that.

Did I see that the proposed mill only requires 10mm in the Z axis? Was that a typo? People usually allow 6-12 inches on the Z axis just in case they need it in the future thus destroying the machine for what they actually do. I think 2" or 3" in the Z is optimal if you want 10mm.

If you are going to rout aluminium I further suggest you copy the milling machine. On a milling machine the long bed is only supported in the middle because that is where the cutting happens. No point supporting it where the cutting doesn't happen, let it overhang, no problems.

To make your router strong, bolt Hiwin carriage blocks upside down to something solid such as a concrete joist.

Next bolt your gantry to the same joist so the table can slide through underneath it.

Why not make the gantry out of a second concrete joist? You don't have to move it so go wild on the dead weight.

If you don't like this idea, the usual excuse for not going down this route is, "It takes up twice as much space in the X axis and I haven't got room".

If you want to cut aluminium, design in a flood coolant return from the start, anything else is a ghastly fudge.