View Full Version : NEW MEMBER: ello

16-05-2010, 10:20 PM

I'm a sheet metal worker by trade looking to get into CNC. I've used manual bridge ports and lathes in my time and have had an interest in the CNC side of things. I was made redundant last year and have spent my spare time teaching myself solidworks CAD. I have designed a few projects, which comprises of Perspex components and PCB circuit boards and now need a way of making them in Quantity. I am looking to build my own CNC mill so I thought it would be a good idea to join a club and get some advice before I start.

I am a complete beginner so any advice or suggestions on plans, materials and parts to build a CNC mill would be great.


John S
16-05-2010, 10:30 PM
Welcome Zed, why don't you add a name and location, there is often local knowlege from members wiling to share if we know where you are based.


16-05-2010, 10:37 PM
ok John will do

17-05-2010, 09:36 PM
Is anyone there?

17-05-2010, 09:37 PM
is anybody willing to help?

John S
17-05-2010, 09:59 PM
Wot with ??

Gizza clue what you want to do / cut / make etc.

Are you looking for a router or a cnc mill ?

18-05-2010, 06:39 AM
Wot with ??

Gizza clue what you want to do / cut / make etc.

Are you looking for a router or a cnc mill ?

There are a few clues in my first post to what i wanted to cut like 'Perspex' ever heard of it? A bit like glass but not. And 'PCB circuit boards' speaks for its self dont it?

Also i was asking about plans you know as in 'construction plans' i.e DIY, build it yourself, home built, dont buy one make one that sort of thing.

Am i looking for a router of a cnc mill? I dont know i'd thought i'd ask you guys!!

I was just looking for some advice on plans that are avalible on the internet or ebay or whereever so i can build a low cost cnc to cut out Perspex designs and PCB circuit boards.

18-05-2010, 07:41 AM
OK, sarcasm aside, more information needed...

Whats your likely work-piece size and what sort of machining do you need to do on it?
I know you said 'quantity' but are you aiming for speedy large scale production (=) or is a leisurely pace OK?
Whats your budget?
What skills/tools/aptitude for construction do you have?
You make PCBs so I'll hazard a guess you have some working knowledge of electronics, so would you want to build or buy the controllers?
Machining perspex and PCB on the same machine is doable (at least you didnt ask for steel!), so you are most likely looking at a gantry-style router type solution with a high-speed spindle.

If you've got about 3 - 6mo to spare I'd say build it yourself. IMHO, quantity PCBs are best farmed out to a offshore supplier...

18-05-2010, 09:44 AM
Thanks for the reply irving2008 (sorry about the sarcasm couldnt resist) no harm meant.

1, The peices i need to make are roughly 4" dia and have a number of 5 mm holes drilled in a pattern and made out of A4 size Perspex sheet in a range of thicknesses (2mm to 10mm). The circuit board is the same size but i would like to engrave it rather than ecthing and drill the holes at the same time if possible.

2, I'm only talking about small quantities to start with. something i can set up and leave running and only have to change the cutters for profile/holes.

3, My budget is mostly set by the wife, when she starts noticing things turning up in the post is when i usely stop lol. As long as its not thousands its ok as i plan on doing the work myself so just parts and a plan.

4, I've spent the last 20 years making/Assy aircraft i.e VC10's, nimrod, Bae 146 etc. I also have a workshop i rent out that is fairly well equipped even has an english wheel which i built from plans.

5, I have some knowledge of electronics but not an expert by any means but i can put together most things so yes i would rather build the controller if plans are avalible to cut costs but i wouldnt want to design and build for scratch if that makes sence.

I would also like to cut sheet metal brackets out on it out of ali up to say 16g.

Robin Hewitt
18-05-2010, 09:52 AM
At first glance it all seems so easy, you put together some slides, add screws to move them, motors to turn the screws, something to turn the tool and away you go.

Unfortunately home CNC is rather in it's infancy. Everyone has different requirements, there is no set formula for success on a budget.

You rather have to build a disaster to find out what the problems are. The only real alternative is to read lots of threads on a CNC forum like this and learn by other peoples mistakes. That's why you are getting flak, impatience will get you nowhere in this game. Appreciate that you are not the first to ask a question and that it would take someone hours to help you through the maze, humble is the best approach. We don't get paid for this you know.

There are two basic options, build a router or buy a mill then convert it. Either way there are pitfalls. The routers are flimsy things that depend on enormous spindle speeds to make the cut effortless so it doesn't bend out of shape. The mills try to overcome the bending by sheer weight of iron, but everything will bend, it's just a matter of degree. You quickly become a tolerance junkie.

Perspex has a bad habit of melting. you will need some way to get the heat out of the tool tip.

18-05-2010, 10:33 AM
The other thing is how much space do you have? Are you looking for something bench-top or a floor mount? Spindles and routers are noisy things so something running for hours on end needs soundproofing or operating away from the home!

Well 100mm (4") diameter rules out the tiny micromills as they have a travel of around 60mm on the Y-axis. As Robin has already intimated the key is rigidity. Aluminium is harder than Perspex, but perspex has its own issues (and any reason why perspex and not an alternative engineering plastic that machines better; I guess transparancy is part of it, but there are other acrylics that machine better).

Cutting from the A4 sheet suggests a working area of 300 x 250mm minimum, a footprint of 500 x 400mm would be possible. 10mm depth of cut isnt an issue if done in multiple passes. Perpex needs a high spindle speed, and high feed rate to ensure its cutting and not rubbing else things melt. Some form of mist coolant is also needed. All these add to the budget -

Router's dont have to be flimsy things (Robin is an old-iron man lol) but its true that getting the rigidity to machine hard stuff to fine tolerances is hard to do - fixed gantry moving table is more rigid but has a smaller work area than a moving gantry design for the same footprint and slide rail/leadscrew sizes.

Machining a PCB is relatively easy on a gantry type router, but very fine lines are best etched so dont be expecting to do PCBs for that all-singing PGBA package but basic through hole or SMT stuff works fine. HAve a browse round the CNC mill videos on YouTube to get an idea of the sort of thing.

Some good devices have been constructed from MDF () although the preference would be aluminium extrusion (+)

A common route is to construct a learning one from MDF and use that to a) gain experience and b) make parts for Mk2

For plans look round the web; JGRO, Solsylva, Buildyourcnc.com, mechmate and rockcliff are typical designs. I cant recommend as I've not used any, but several members here have built to these designs - or more usually used them as a starting point...

18-05-2010, 11:53 AM
I have a 1100 sq ft workshop so space is not a problem. I was thinking floor mounted so it can be setup in a corner and not be moved. I think i agree with you on the PCB so i might have to look into converting an epson printer to printer directly onto the board instead of using the press 'n' peel lazer printer method im using atm.

Thanks for the info Irving i will have a read.

1 more queston does Maplins do any kits for CNC that you know of?

18-05-2010, 12:15 PM
Maplins are a joke! If they did it be a toy at best...

If you have that space and access to a welder I'd consider building a steel subframe to mount it on, giving yourself room to put a soundproofing box around it. You'd probably want to look at the 2' x 2' designs (footprint 1m x 800mm approx) to give room for expansion. You wont get a lot of change out of 1000 and could easily spend more to hit your goal.

If you want a kit for the controllers then Roy's stuff at DIYCNC (http://www.DIYCNC.co.uk)is quite well thought of, but many would argue that the savings are not enough to warrant it. If you want to buy the PCB and populate them yourself then Phil at pminmo.com (http://pminmo.com/)has some good PCBs - I would advise you have a good understanding of your needs before purchasing anything... at least have a basic design in mind and some idea of sizing.

Don't be afraid of asking focussed questions... we are always happy to help those who are prepared to do the reading and research for themselves. You can appreciate we get a lot of 'newbies' who just want the answers without the effort. A good many of us here are just weekend hobbyists (like me) but there are others who do it professionally and have experience in spades that is a valuable resource. (they can't help being, with a few notable exceptions, northeners with a strange sense of humour :heehee:)

18-05-2010, 07:51 PM
I'll forget Maplins then lol.

2' x 2' sounds a nice size. I will go through the links and information so far.

Thanks irving i will return.

09-06-2010, 10:45 AM
Received building plans from Rockcliff a few days ago and I have decided on a fixed gantry type CNC made from MDF as my first attempt. Lucky my brother in law has his own woodwork workshop so Im going to get him to cut all the straight lines. I think I will properly build the 24” x 24” machine and should start very soon. I have also noticed you can use these machines as plotters (pen attachment) anyone have any experience with this?