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Anyone into CNC, or perhaps looking to get into it?
I am wondering about putting my plans out as G Code, and it would be useful to have a discussion about the practicalities. For instance, what bed size do people use?
Model boat plans are a bit specialist for most CNC boards. They worry about cutting hard materials - we mainly use balsa and ply. Their machines are usually square - ours would need to be long and thin. They use big commercial routers and spindles - we could get away with smaller motors and dental burrs.
I picked up one of these over Christmas, and am currently going through the learning curve. But it doesn't seem to be all that difficult....
Our local Makerspace has just acquired a laser cutter. The accuracy and clean nature of the cut are breathtaking. The edges are razor-sharp and the cut width is in the order of 0.1 mm.
I know there are a few fossils out there who will huff and puff about new technology and extolling the virtues of half a Gillette razor blade but heed them not. Google Makerspace, find your local branch and join-up. If they haven't got a laser cutter they'll have a lot of other machinery which will enable to do far more than you can manage on your kitchen table.
- but the associated safety provisions would mean doing the cutting in the shed rather than the kitchen.... and the cost is not extortionate.
At the moment I'm more interested in getting up to speed with the technology and the associated costs. Open Source is a wonderful invention - it means that all of your software is free, and the hardware is low-cost because there has been no R&D investment associated with it. I reckon that you can get a cutter with a 1 sq ft bed for 300-400 pounds at the moment, and the prices are coming down all the time....
Have a look at the Banggood website. They are selling A3 sized laser cutters for less than £200. It is sold as an engraver with a 2500 mW laser but this can be upgraded. It should cut ply up to 3mm albeit with multiple passes
It comes as a kit with "Chinese" English instructions so you will need your modelling skills to assemble it.
They are fairly flimsy as a stand-alone, but, if fixed to a stout MDF board, it should be sturdy enough
Having built (well, assembled really) i am currently building a small CNC router with 3D printed parts. See https://reprap.org/wiki/Cyclone_PCB_Factory. Currently redesigning to be driven by GT2 belts and pulleys as I have some reservations about using 3D printed gears from the point of view of back-lash and wear. The stepper motors are driven from an Arduino Mega running the GRBL g-code interpreter. There are a host of free g-code generator tools to be found on the internet. Some of them are a bit "knife and fork" but there are some useful ones out there and there is lots of helpful information too.
I'm doing the eShapeoko - I wanted a more rigid machine for general purposes, and I liked the fact that you could specify the X and Y axis lengths. For cutting model boat parts you rarely want something as wide as 1 foot - but you often want items of length greater than 1 yard. The eShapeoko has standard sizes as extreme as 15 inches by 60 inches, and can easily be extended. I've gone for 18 x 36 inches - should be fine for EeZebilts...
One of the things that's a bit annoying with GRBL is that it doesn't currently do tool radius compensation. I'm using an arduino with grbl as well, and if I cut my plans as drawn they will all be a tool radius out. I am currently looking to use a 0.5mm tool so the effect will be small - but if you know of a better driver interpreter...?
Which is where laser cutting leaps to the fore with a tool diameter around 0.1 mm.
The Cyclone is a pcb cutter which uses a taper-point tool so there is no offset.
The goal is to mount a laser rather than a Dremel.
Point taken on the smaller parts . My initial thought was that, with a larger platform, you could cut multiple parts from a larger piece of material in one pass. Unfortunately, you can't walk away from a laser cutter to let it get on with things as you can with a 3D printer. You are looking at a potential bonfire and the bigger the job, the longer you have to stand and watch it.
I'll probably go for a laser cutter in the end. A big CO2 one - but these are powerful tools, and i'd like to have a reliable cutting bed before experimenting with something that might cut the shed in half!
The obvious answer is to use some driver software that does handle tool radius compensation - I understand that the Tiny board firmware is now open source with a new name - G2Core. I think it needs a bit more poke than an Arduino Uno, though.
I intend to simply slot sheets of balsa into it and crank out kit parts - which means a single pass cut. One issue is how to hold the sheet of balsa down without interfering with the cut. I was wondering about a vacuum base.
If you want to observe a laser cutter safely, I hear that the Yank modellers are sealing them in enclosures, and viewing progress through a webcam, which is one answer....
Not much point uploading a .pdf, unless it has some unusual conversion software. CNC machines work off G Code.
The work area is critical for model boat work. Typical parts are long and thin. The eShapeoko I am building is a nominal 1m x 500mm, which lets me do a 36" keel piece. I would like to put out G Code for cutting the EeZebilt boats, but am not sure how to standardise it so that many CNC machines will be able to use it. Different CNC controllers seem to use subtly different G Code commands...
Using downloaded pdfs, I use a reverse engineering package to get my cnc program (in G code). It worked with all the machinery in our factory, laser, oxy,/acetylene profiler, pulsa and proteus punching machines and also cnc machining centres. Most commercial cnc programs come with reverse engineering. Hope this helps you. Cheers Colin.
We used a package called aplicam, it suited all the machines once, you told it the machine zero settings it worked it all out for you. And all we had to do was put dimensions on to the pdf files, or trace using a graphics tablet. It was the best system I used in all my engineering life from school to retirement. I wish I had a copy of it now, it was originally DOS operated in the 70's, and when I retired it was up to Windows 10. Cheers Colin.
I'm thinking about interchanging boat plans as CNC files - so I'm thinking about the sort of machines people are going to have at home. There are a lot of 'cheap Chinese' machines on EBay for £200 up to about £500 - but these will be used for engraving, and will have cutting tables of about 8" square. Boat modellers really need a long axis.
The Shapeoko is an 'open source' hardware design - much like the Rep-Rap, and the great thing about it is that you can specify the axis sizes - so you can have a machine which is a foot by six feet if you wish. I have just bought a UK kit for one called the eShapeoko - 1m x 500mm - cost about £500. But there is so much to consider - calibrating the machine, choosing a spindle drive, picking a software set....