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martin54
18-09-2012, 07:11 PM
OK so recently I bought a Book on how to build your own CNC machine having read on another forum about someone who had actually done it on a very low budget.
After buying the book & reading it I set about starting a build but also started to look around on the internet as a matter of further research & to try & source parts.
That was when I first came across some of the forums like this one & having read quite a few threads now with input by some people who obviously know what they are talking about it would appear that alot of people see these machines as a waste of time & money.

So the question really is where do you start with something like this?? For starters I wouldn't really know where to start designing a machine & what makes a good design & what doesn't so even if I some how managed to design something it may well be worse than the machine in the book lol. Secondly if you do get to the stage where you have a usable design how do you go about manufacturing it? From some of the posts I have read on here you need a machine to make a machine (chicken & egg) so how do you get round that one.

Kind of in an awkward situation now because I have made quite a bit of the book build machine & I thought things were going really well but now I am not so sure & don't know if I would be wasting my time finishing it off. If I don't finish it then I will have to completely rethink everything because the cost of building a machine is going to be far higher than I had at first thought.

TrickyCNC
18-09-2012, 07:54 PM
???? what happened ?

I thought you were happy with the one your friend made ?

what ever else you have to decide, you need a budget . If you have loads of money spare, then you will build a very different machine, than if you need to do it on a shoe string.

Then you need to have a real good think about what you want it to be able to do, when it's built. What do you want to use it for ?

What are your skills ? woodworking ? welding ?

What tools do you have / can you get hold of ? wood/metal ?

what are your resorces ? do you have a free/cheap supply of something that would help with the build ?

etc.etc.

lots of questions if you really want to think about it :)

Rich

martin54
19-09-2012, 02:35 AM
I was happy with the machine that Phill built which is why I bought the book & started to make it but then I found a couple of CNC forums on the net & started reading. Read quite a lot of posts where people said that they weren't a lot of use & were a waste of time & money. Things like them being to flimsy & problems with the rollerskate bearings etc etc.
Main reason for going down that road was that it was a very cheap machine to build & as I don't have a lot in the way of money it seemed like the best way to go but it doesn't really matter how cheap it is if it doesn't work properly lol. Chances are if I had started reading the forums before I started to build it I might not have bothered with it at all.
It was to cut Foam pvc, & composite board mainly but it would have been nice if it would also cut some woods & possibly acrylic, I knew that it wouldn't stand a chance with anything like Aluminium but I thought that might come latter if I got a better machine in the future.

I'm ambidextrous I can work with either wood or metal lol but the main problem when it comes to metal is that I don't have any tools that are really suitable or access to any so that's a bit of a non starter. Reasonably well kitted out for wood though because of the business I still run part time. Don't have any sort of cheap supply for any sort of materials to speak of, no one falling over themselves to give me stuff either.

irving2008
19-09-2012, 06:30 AM
Then I'd finish what you started. Yes, they arent the greatest machines in the world, but they do work if constructed well and, if nothing else, will get you up the learnng curve. And the Mk1 machine can be used to make the parts for Mk 2. I don't know the details in the book, but don't buy the motors/electronics without discussing it frst. Why? because these things change quickly, costs are coming down and its likely whats in the book is out of date already. Plus those parts are likely to migrate to Mk 2 so its wise to plan ahead to ensure a sensible investment, or at least know what the sunk cost will be if you choose not to migrate them.

The problem with the Internet is sorting the wheat from the chaff... yes, you'll find a lot of people who'll say those machines are rubbish, don't bother... but often they'll be people who've been 'in the business' for years, run machine shops with several jobs going at once, etc.. from their perspective they are right, but that doesnt change the fact that as a beginner's machine it serves a purpose. There are also those that disdain building anything you haven't designed yourself, on the grounds that unless you have done so how do you know it'll work? Again, there is some truth to that, understanding why something is the way it is is important, however my argument is that you can spend forever debating the finer points of layout and design. Build something, use it, learn its weaknesses and use that knowledge to develop better parts or design a better machine.

Any machine will cut anything given time and a very limited depth of cut. Yes, that machine wont cut aluminium the way a bigger/stronger machine will (actually it will, but you have to do it in very small cuts so it takes a long time and accuracy isn't great, but it will manufacture the parts for a Mk2 if thats what you want to do).

So go for it!

TrickyCNC
19-09-2012, 10:21 AM
^^^^ yes, what he said ^^^^

you have seen my machine - made from wood ! it works well.
In fact the bearings let it down, and I'm going to make a set from angle and skate bearings to IMPROVE it.
have you seen the round rail thread ? where I defend wooden builds ? LOL

I asked if you were happy with your friends build for this very reason. if you are happy with what his can do, then yours will be at least as good.

If you want to put up photo's of your progresss so far, we can help, and suggest a few things to get the most out of the design.

If you fear getting a bashing from the wood haters on here, then send some pics to me by email, and I'll help.

the most important thing to do though would be to think /show share and research each part you make. including electrics and drive. Like I siad, it will be AT LEAST as good as your friends machine, so you know already 1ST HAND how it will work.

Irving mentioned those that have been in production shops and using top quality gear, might think it's rubbish (comparatively). But worse, for me are those that read such comments and repeat it blindly every time the work MDF shows up ! Thats the way the internet works unfortunately. Someone will read and repeat, whithout knowing 1ST HAND if it's true or not !.

Save from a sheet of wood, nearly everything you use to build your machine can be used again if you decide anything needs improving, so you have nothing to loose really.

So, let us know what you have done so far, and we can go from there :)

Richard

martin54
19-09-2012, 01:39 PM
Thanks for the input guys, much appreciated, I had been thinking it might be best to just finish this one as it is pretty much done & the only thing that's really needed cost wise is the electronics & motors. Those I was going to get from diycnc as a complete kit, the system 4c with nema23 3nm motors. Reasoning for that was that it would save me the trouble of having to make a box to house everything & funny enough I found the link to this forum on Roys website.

TrickyCNC
19-09-2012, 02:33 PM
do you have a link to the driver/motor kit ?

is your MDF bare, or have you painted it yet ?I
f it's bare, and already built, you can stiffen it considerable by drenching it in ronseal wood rot repairer(less than a £tenner) . It's basically an epoxy type resin that soaks into the wood , or in your case MDF, causing it to be more like a plastic composite, which is much more rigid after it has dried.

Like I said, let us know (with pics- would help) how far you have got, and we / I can have a look and make other suggestions like this , that might help improve things, very easily and cheaply :)

Rich

martin54
19-09-2012, 02:51 PM
Yer I was priming it as I went as I know MDF can be a problem with moisture.

This is the driver kit
CNC Systems (http://www.diycnc.co.uk/html/cnc_systems.html)

Haven't got any pictures but will be up at the unit tomorrow so will take some then

TrickyCNC
19-09-2012, 04:04 PM
I have one the same as this

3Nm CNC Stepper driver Kit - 3 Axis for CNC. | eBay (http://www.ebay.co.uk/itm/3Nm-CNC-Stepper-driver-Kit-3-Axis-for-CNC-/220992304733?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item33742af65d)

which on first impressions is much better for less money ?.

Only had a quick look. I'll look better later when I've finished work.

Rich

TrickyCNC
20-09-2012, 10:12 AM
ok, after a bit more poking about on that web site, my suspicions were confirmed in the spares section. The chip on the driver is the 6560, which is generally known to have issues.

I , personally, wouldn't use them even if they were a lot cheaper (which they should be). He has the kit at the same price as one using 542's, which are much better and respected drives for on a budget.

Musht
20-09-2012, 10:11 PM
ok, after a bit more poking about on that web site, my suspicions were confirmed in the spares section. The chip on the driver is the 6560, which is generally known to have issues.


The 6560`s can be a bit fragile, as I`ve learned, but easy to change out, once you`ve done it once....

More limiting , as Jazz continually points out ;-), is the maximum voltage is lower than any other drive, so changing motors will only happen with the drives as well.

542 drives can stay around with bigger motors and are less fragile to start with, in this case cheaper.

MDF frame gets you a working test bed to learn a bit about software and probably get the cash back in for MKII ;-)

motoxy
20-09-2012, 11:01 PM
The guy that did the signage on my van is putting up professional large scale lettering that is ally faced board. Looks brilliant. He has built the mdf book router. He admits its a bit slow but he has time and it makes him money. Interestingly he also gets plaudits from signage forums. Of course metal construction is better but the mdf builds work and some of them work just dandy.

martin54
21-09-2012, 01:02 AM
[QUOTE=motoxy;35987]The guy that did the signage on my van is putting up professional large scale lettering that is ally faced board. Looks brilliant. He has built the mdf book router. He admits its a bit slow but he has time and it makes him money. Interestingly he also gets plaudits from signage forums. Of course metal construction is better but the mdf builds work and some of them work just dandy.[/QUOTE


That will be Phill Fenton from "The Right Signs" then, know Phill well & it was because of Phills build blog on the sign forum that I bought the book & started to build one myself. I've been to see Phill & have a look at his machine & I also know what work he has done with it BUT having read quite a bit on forums about these machines in general I had doubts placed in my mind on a number of issues mainly referring to the maintenance & upkeep of these machines & the fact that it was difficult to leave them running & walk away to do something else while it got on with it's job. Phill has not had his machine for very long & it has not really done that much work but already he has had to replace a threaded bar on the z axis, also I noticed when I visited there was a bit of wear on the ally runners used for the linear rails that I paid little attention to at the time. These are 2 areas that I have read concerns about on the forums so that made me take more notice.

I have already said that I was going to finish the build which I will, as has been pointed out it is still a way to get started & as the machine is just about complete as long as I make sure I buy electronics that I can migrate to a new machine then it won't cost me much extra money to finish. Already spoke to Jazz about it plus some posts on the forum that have been helpful so have a good idea what to look for now.
As with most things new I am sure it will be a steep learning curve, this will at least start me out & get me use to using software like cam & gcode software that I have never used before.

Thanks for the input so far guys, it's been a big help & much appreciated.

TrickyCNC
21-09-2012, 08:54 AM
The ally runners will wear, with steel bearings rolling on them, depending on how hard you use the machine. They will also harden a bit when they settle in.
If I was committed to using angle, I'd go for steel angle and spend a bit of time getting it straight.
Personally though, I'd go for steel pipe in replacement of ally angle, like on the early solsylva designs (Bearing Trials~Solsylva CNC Plans (http://solsylva.com/cnc/bearing_trials.shtml) )

This is one of the reasons I suggested you post photo's, so we can see how far you have got with your build already.

Richard

martin54
22-09-2012, 01:00 AM
Richard I was going to take some pictures & post them but then wasn't sure if it was really worth it, most of it had already been done, all the parts were cut & it was really a case of just putting it all together. Probably wrong (usually am lol) but I didn't think it would be worth changing a lot at this stage on this build, you mentioned pipe rather than angle ally for the rails but that would have been a major change & probably a lot of reworking/cutting of parts.

TrickyCNC
22-09-2012, 12:19 PM
if it's that far along, then I can't see what you have to loose ?

Get some decent drivers and motors with a view to the future, and put it all together.

You can use it to build an enclosure for the elctronics, and use it to make the MkII if you decide you need to.

Richard

martin54
22-09-2012, 12:29 PM
if it's that far along, then I can't see what you have to loose ?

Get some decent drivers and motors with a view to the future, and put it all together.

You can use it to build an enclosure for the elctronics, and use it to make the MkII if you decide you need to.

Richard

That's what I am doing now Richard but having had the doubts put in my mind & being completely new to all this I wasn't sure at the time of posting if it was worth the time it would take to finish it. If I hadn't made the post & just soldiered on with it I would already have made the mistake of buying electronics that would probably not have migrated well so at least saved myself a fair bit on that side.
Not actually sure what I will be able to use it for as far as constructing a MKII is concerned as the new machine would need to be a better & stronger design but I will look at that again when the time comes. By then I would expect to have learnt a lot more about design & construction from places like this.