Thinking of buying/building machine for PCB milling

Hello,

I am looking to buy a 3-axis CNC router with the main purpose of milling PCBs but also more general purpose - small wood, plastic, foam, thin aluminium control panels.

Looking at all the Chinese 3020 / 3040 routers on ebay, they all seem slightly different, from the pictures but very little way of distinguishing between them by specification or quality. How can I distinguish between them?

Being able to repair and upgrade the machine is important to me and I like the idea of buying from the UK manufacturer/supplier, so that I know exactly what I am getting and be able to buy replacement parts - and Marchant Dice Ltd. / Worldofcnc.com was looking promising. But having emailed them a couple of times and received no reply, so I don't fancy my chances of getting support.

Does anybody have any suggestions as to what I should buy? My price bracket is £500 - £1500 and hoping to run LinuxCNC with it. I am more confident about the electronics and computer side of things, than metal working...


Thanks!

nick.

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Originally Posted by njh

I am looking to buy a 3-axis CNC router with the main purpose of milling PCBs but also more general purpose - small wood, plastic, foam, thin aluminium control panels.

Looking at all the Chinese 3020 / 3040 routers on ebay

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The machines you refer to would be acceptable for everything you listed, except maybe the aluminium, so long as they come with ballscrews. You need ballscrews to get the required accuracy for engraving PCBs. I'd be very concerned if you're planning on using one of those machines to cut aluminium regularly, or are expecting it to do it accurately and quickly.

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Originally Posted by njh

Marchant Dice Ltd. / Worldofcnc.com was looking promising.

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:crushed: :crushed: :crushed:

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Originally Posted by Jonathan

I'd be very concerned if you're planning on using one of those machines to cut aluminium regularly, or are expecting it to do it accurately and quickly.

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Ok. Maybe I don't care about aluminium then :)

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Originally Posted by JAZZCNC

***POST REMOVED ***

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Wow, glad I didn't get any closer to buying from them then!

I bought a 3020 off ebay about a year ago for exactly the same things as you. Mine has leadscrews not ballscrews, and while I understand Jonathan knows a lot more about these things than I do, it seems fine for me. I'm not doing ultra fine pitch SMT on big boards though.

Thanks richie00boy, that is really good to know - how did you choose an eBay seller to buy from?

Just seen that there's a complete setup in the for sale section, only a couple of hundred more than a new eBay machine and you get a ready to run system with PC and Mach 3. Would get you started cutting PCBs straight away and because you like upgrading would be (by all accounts!!) perfect :wink:

My first machine was self built from scrap printer parts (& thin scaffolding type piping would you believe!) - unsurprisingly, it sucked, but it could at least do simple through hole pcbs.

my next machine was imported from Taiwan....surprisingly solidly built but didn't have ballscrews (just simple M10 rod)....a lot better, but nesting (many copies of the same pcb) was not possible ....backlash issues meant that if you cut all the tracks for say 3 pcbs first, when you came to drilling run, the holes wouldn't align with the tracks!)

If you're serious about accuracy & want to be able to do many copies of the same PCB in one session, then I'd strongly suggest that you buy a machine with ballscrews .....the Z suffix on the chinese cnc machines are normally the ones that have ballscrews (therefore 3040Z etc, for example - 2013 Updated CNC 3040Z-DQ 3-Axis Engraving Machine Router Set Mill Device cmh | eBay ...though be aware that the stepper driver boards on these chinese machines are awful & prone to very early problems/failure). I'd be inclined to instantly sell the control box (to someone who no doubt has one that blew up) & put the money towards some m542 drivers...http://www.ebay.co.uk/itm/CNC-Micro-...item27c7454753

For milling PCBs (& all the other materials you mention) I personally have a strong preference for fixed gantry CNC machine (of which there are zilch in the 3040 sizes available on Ebay) & would look at importing one.... http://cnredsail.en.alibaba.com/prod..._aluminum.html - that one is about $1200 delivered + taxes (which would probably result in a final 'to your door price' of £1100)

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Originally Posted by njh

Thanks richie00boy, that is really good to know - how did you choose an eBay seller to buy from?

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It's easier than you think. There were basically two machines, the 3020 type with moving gantry and the sable type with moving table. I chose the 3020 type as it took up less desk space and a recommendation for this type came from a mate who worked with very high end CNC machines, can't remember now what his reason was though. Then I just chose the cheapest seller who shipped from the Portsmouth warehouse. There is no difference between sellers, they are all just drop shippers for the Portsmouth warehouse.

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Originally Posted by HankMcSpank

backlash issues meant that if you cut all the tracks for say 3 pcbs first, when you came to drilling run, the holes wouldn't align with the tracks!)

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I'll have to see if that becomes an issue when I use the machine for bigger jobs. I priced up ballscrews recently and I think I could convert the X and Y axis for about 50 quid.

I do hear a lot of people saying the controller you get is rubbish, but touch wood mine seems OK despite some errors on my behalf not setting it up correctly, which may have stressed it more than normal. That is the one thing I was lucky with, got a mate to help me set it up as settings provided by the seller were not right.

I can let you have the settings file if you need it, should you buy the same machine.

Thanks for the advice HankMcSpank and richie00boy

Searching for ball screw in the title/description or 3040Z really reduces the result set. Think I will probably go for a ballscrew from the start.

It looks like the newer/'updated' models have a black control box, like the ones on Yoocnc 3020 3040 6040 series - carving-cnc.com. Some even have YOOCNC written on them in the pictures.

Good to know that I should expect to want to / need to replace the stepper driver boards at some point.

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Originally Posted by njh

Wow, glad I didn't get any closer to buying from them then!

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Here we go More BULLSHIT SENSOR SHIP the machines are pile of over priced rubbish and that is my opinion based on experience with working on one of them and I've right to express it whether they like it or NOT.!! . . . . . . . .Even your Own Moderator made derogatory symbols he just hasn't got the Boll##ks to put it in words.
Don't see you going round deleting all the post's where he's putting folks off buying from Zapp in favour of buying from China and Gary happens to frequent and support this site.?? . . . . Don't see Mr MD around here much do ya.!!. . .. . . . DELETING POSTS IS WRONG. . . . . . Also You don't delete all the Bast@~d ones where I'm helping people folks do ya . . . . Well let me say any more of my legit post's get deleted and I'm done with this site.!

EDIT: Sorry NJH for this rant on your Thread but SENSOR SHIP really PISSES ME OFF.!!!

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Originally Posted by JAZZCNC

Don't see Mr MD around here much do ya.!!. . ..

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Something funny going on - the same day as your post is deleted; I get an email reply from Kevin Marchant - two weeks after my enquiry.

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We can offer / produce an A4 with ballscrews, steppers, controller, spindle and Mach3 for £1000 + £29.50 shipping

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If that is how long it takes to produce a once sentence quote, I don't fancy my chances of support. I am better off buying from China.

In other news, I asked why the UK postage costs were so huge (£200) on this 3040T-DQ Router and quickly received the response:

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Hello,

Thank you for you are interested in this machine from us.
We have it out of stock from our UK warehouse right now, and the coming batch can be available about 10 days later.
Then we raise the price for controlling sale volume.
Hope you can understand.

Best regards

- tool-zoom

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Item: http://www.ebay.co.uk/itm/-/200933892175
Seller: http://myworld.ebay.co.uk/tool-zoom

The best thing to do is to make your own, it will knock the spots off most things commercially available for the same price and in the process you'll get a better understanding of how they work and therefore (I can only guess as I'm just starting to build mine) will be better equipped to fix them when things go wrong/break.

If you look at, for example, the MD ones and the cheap China ones and then look at the build threads you will see the difference between a "home made" one and a "commercial" one. Making your own will enable you to do things like use supported rails, make the gantry much stronger (and normally a bit lower) use better quality materials for the same price you would have paid for a ready made one. There are enough guys on the forum here who will cast a critical eye over your design and once it's complete do any machining for you if you need it allowing you to assemble it with simple hand tools/workshop tools.

In my opinion a ready bought machine is only really good for scratching the surface at playing with CNC machines, in more ways than one! You will undoubtedly, no almost certainly from my reading various forums, need to update components to get the performance and finish you require. I did consider going down the ready made route before I started but soon dismissed it and now I will end up with a machine that will be capable of cutting Aluminium even though I started out wanting one that would cut Balsa and ply.

As an example of costs the MD A4 ball screw machine starts at £3,555.00 For that you'll get a machine that has a machining Area of 300mm x 220mm x Z Axis 155mm, my machine (when I get my finger out and start making it) should come in well below that and will have a cutting area of 1000 x 500 x 200. As far as I'm concerned it's a no brainer! If size is an issue, i.e. you don't need a machine that big then you'll be able to make a much stronger/accurate machine for half that cost.

Would love to build my own CNC router one day and from reading and learning, it doesn't look as if it is as difficult as I first imagined.

But at the moment I have decided that for now I want to just get up and running and make some PCBs...

Did you not see the 3040 for sale with everything you need in the for sale area? If you upgraded the trapezoidal lead screws to ball screws then you'd almost be there?

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Originally Posted by njhussey

Did you not see the 3040 for sale with everything you need in the for sale area? If you upgraded the trapezoidal lead screws to ball screws then you'd almost be there?

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Couldn't find it before for some reason but found this now:
http://www.mycncuk.com/forums/items-...tor-mach3.html

I don't need a PC - and think I can buy a new one with ballscrews for less...

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Originally Posted by njh

In other news, I asked why the UK postage costs were so huge (£200) on this 3040T-DQ Router and quickly received the response:

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It's a way of avoiding some of the extorionate ebay fees, as you don't get charged fees on postage/carriage, so they include the customs charges in it.

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Originally Posted by m_c

It's a way of avoiding some of the extorionate ebay fees, as you don't get charged fees on postage/carriage, so they include the customs charges in it.

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Not any more - they very recently changed the rules so sellers are now charged the final value fee on postage in addition to the final price.

You do realise fees vary depending on what country you're registered in, and to what country you're selling?

We get stung pretty hard for fees due to ebay's near monopoly in the UK. Other countries where ebay don't have as big a market share get far better rates. It does annoy me selling stuff on ebay in this country, that ebay end up with near 14% of everything by the time you factor in that they also own paypal.

Discovered the 'CNCDudez New 2012 Desktop Mini Muscle CNC Machine' last night:
CNC Design Limited - CNC Desktop Router

Unlike other suppliers Sean actually replied to my email!

Has anyone else here bought one?
I suspect it surpasses my requirements for milling PCBs.

It would be ok for cutting most PCBs, but I wouldn't do much more than that with it. I've already posted my thoughts on that machine here, so I wont repeat it.

Edit 2: Link stopped working again, but you can find it in google cache here, post #19 is mine:

http://webcache.googleusercontent.co...&ct=clnk&gl=uk

Other pages:

http://webcache.googleusercontent.co...&ct=clnk&gl=uk

http://webcache.googleusercontent.co...&ct=clnk&gl=uk

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Originally Posted by Jonathan

It would be ok for cutting most PCBs, but I wouldn't do much more than that with it. I've already posted my thoughts on that machine here, so I wont repeat it.

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I don't have permission to view that page.

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Originally Posted by njh

I don't have permission to view that page.

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Should work now...

Edit, since the link stopped working again, I've copied my post about the CNC dudez 'mini muscle' machine below for good measure:

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Originally Posted by Jonathan

I agree with what Jazz has just said - frankly I'm amazed it has taken until post #17 for someone to mention any of the limitations of this machine. It could so easily be improved for little additional cost. Here's some ideas for you:

Gantry sides are weak and not braced - you have just single pieces of extrusion relying solely on joint at end. This is easily improved by adding diagonal pieces from the top of each to the base frame and a couple of horizontal pieces, or a plate, between them. You'll then end up with a trapezium which is far stronger. It looks like 1/8" thick aluminium angle has been used to mount the bearing blocks on the Y-axis. This is rather thin considering how important it is to make the joint between each axis strong.

Rails are only 12mm, which if you're intending to cut metals regularly is pushing it. This is compounded by only having one bearing block on each X-rail. The fact it's a double length one doesn't compensate for only having one instead of using two with a reasonable spacing. This makes the table more susceptible to racking when cutting near the extremities, especially with just one ballscrew. It's fair enough to have one ballscrew on X for a small machine like this, but with 2 bearing blocks not 4 it's again far from ideal. It looks like you could have two bearings on each rail and increase the spacing without loosing travel and if not for the sake of increasing the lengths of a couple of bits of extrusion to gain back the travel from increasing the spacing, it's well worth it for the rigidity gain.

Z-axis motor mount is flimsy - thin aluminium with small area in contact held only by two bolts. This is easily extended to for instance a U-shape which would offer much better support - 3"x1", 1/4" thick aluminium angle is good stuff for cheap motor mounts. Axial alignment of the Z-axis pulleys is quite a long way off so the belt is constantly rubbing against the pulley flanges which will cause premature wear. Not the end of the world, but still I'd expect better.

In the video the bed is surfaced at a pretty low speed. The machine should be rigid enough to surface it at something like 7-8m/min. Sholud be getting chips not dust...

The axes are running a lot more slowly than they could do with those motors. This is no doubt due to only running on 36V which is half of what you could and really should be using with these motors. The rest of the video shows that the acceleration is set quite low too. It's illogical to compromise the feedrates so much by using a low voltage when the whole idea of making a rigid machine is that it enables you to cut quickly. Also it's interesting to note that you may be able to get better performance with some good quality lower torque motors, since the corner speed is higher for a smaller Nema23 motor so with such a small mass to move you can end up operating past the point where the larger motor runs out of torque. If you add timing belt drives to the X and Y axes the acceleration or feedrate could be improved, in addition to reducing resonance. This may or may not be worth the increased cost, but certainly worth experimenting. I'd go for pulleys anyway since it's clear from past experience with people here that those flexible aluminium couplings are prone to shearing.

The Kress spindle is not a good choice if you're intending to cut aluminium regularly since its bearings will wear out quickly and it's somewhat lacking in power, although given the rigidity of the rest of the machine the latter is not a big deal.

In the video it takes 6 passes to cut through the 5mm aluminium, so 0.8mm per pass (perhaps slightly more since the last pass seems thinner) with a 6mm tool. If you're cutting aluminium regularly that's not very good. A machine this size with a strong frame should easily be capable of more. Also stop plunging with the cutter, especially in aluminium - it's hard on the tool and machine and there's just no need when you can use spiral toolpaths or ramping.

This machine is currently capable of cutting aluminium since having the 4 rails on Y/Z has helped compensate for the lack of strength in other areas.
A good design with 2 rails would easily perform as well, if not better (and by that I mean achieve a higher material removal rate in aluminium) with two rails. That's not to say having 4 is a bad idea, in some cases it's the only way to make a machine rigid enough, but here you might be able to save money by using two (supported rails) and investing more in other components, such as the frame.

For a machine this size it's hard to come up with a design that wont cut aluminium so long as you follow some basic guidelines. The reason is as the machine size increases it rapidly gets hard to maintain the rigidity. For a simply supported beam with a load, the maximum deflection is proportional to the length squared - so for example if you make the machine twice as large with the same material cross section then the deflection will be 2^3 = 8 times greater. Hence, if you keep the machine small which is the case here it's not difficult to obtain sufficient rigidity. There is no clearly defined limit for when a machine fails to cut aluminium and some sellers have been exploiting this for ages to make ridiculous claims, which is of course why it's good to have the video. I can cut aluminium with a screwdriver, but that doesn't mean it's a good tool for the job or that it will last very long.

The bottom two Y-axis rails should be flipped over so that the bottom rail is the other way up. The force rating for these supported linear bearings is much lower in the direction trying to pull the bearing off the rails, so it's best to have the rails mounted opposing to balance out the force rating. Currently the rails are all the wrong way round to counteract the force when you drill or plunge with the cutter, which is partly why you get the horrible noise every time that happens. If you swap them you'll always have 4 in the optimal direction for forces parallel to the Z axis.

If you want to test how a machine will perform in terms of how fast it can remove material and how good a finish it will get then the least subjective way to do it is to measure the deflection for a given force on each axis, then divide the force by the deflection to get a stiffness value in N/mm and compare this to other machines. Anything else is speculation. Even if we define a standard test using the same cutter and material, then measure the result, you can't accurately compare machines since there are so many variables. For example you can push the machine hard to get a better depth of cut, but the surface finish will deteriorate so you now need to have some measure of that, plus if the cutter only lasts a few minutes at that speed it's not an honest test. Again there are a lot of variables to get a good finish - even a weak machine will get a good finish (and hence good accuracy) with a very light cut, so the machine that gets the good finish with a large cut is the better machine. This will be the machine with the highest stiffness. That's why you measure and compare stiffness...
Could also measure backlash, but that's generally unimportant for a router when you have ballscrews, and so is to an extent measuring the size of a cut part or a centre distance with the calliper since, again, there are a number of factors that affect this - on any reasonable machine it'll be within a few 10's of micrometers at the distance most callipers measure, so things like the actual tool diameter, calliper tolerance and cutter wear become a factor. Given a couple of tries I could make a video of cutting an aluminium part with my router, measure it and get it spot on according to the (0.01mm) calliper - all you need to do is make the part once, measure the error and compensate for it in the drawing, then cut it again. The machine would have to be very poor for this strategy to work.

I was expecting "under £1000" to include the electronics and assembly since having worked out how much it would cost to build there's still room for profit in that price assuming you're sourcing the components from China. £1600 is not much less than it cost me initially to make my machine (not including labour of course), with steel frame, and that's 53 times the working volume of this yet capable of cutting aluminium much faster (although I still wouldn't describe my machine as very rigid) for a long long time. For that sort of money, if you want to cut metals, I'd advise buying a milling machine and converting it to CNC unless you really need the additional Y travel. I wouldn't be surprised if you still sell plenty since the UK CNC router market is currently exceptionally limited, so anything better than the CNC3040 is bound to be a hit!

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Good to know but I suspect that I am operating in a completely different level to you Jonathan.

As a complete novice, I think the CNCDudez desktop machine will more than adequate :)

If it is as good as or better than a YooCNC 3040, then I will be very happy.

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Originally Posted by njh

Discovered the 'CNCDudez New 2012 Desktop Mini Muscle CNC Machine' last night:
CNC Design Limited - CNC Desktop Router

Unlike other suppliers Sean actually replied to my email!

Has anyone else here bought one?
I suspect it surpasses my requirements for milling PCBs.

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To my less 'learned' eyes, it looks a mighty fine machine....but surely, if you're only after a cnc machine to mill pcbs, it's a little bit 'hammer to crack a nut' - no?

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Originally Posted by HankMcSpank

To my less 'learned' eyes, it looks a mighty fine machine....but surely, if you're only after a cnc machine to mill pcbs, it's a little bit 'hammer to crack a nut' - no?

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Yes, pretty sure it is overkill for PCBs but once I have to all up and running, would be very interested in trying other materials. Not seen many other UK kits of parts out there...

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Originally Posted by njh

Yes, pretty sure it is overkill for PCBs but once I have to all up and running, would be very interested in trying other materials. Not seen many other UK kits of parts out there...

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One of the last things I learned about procuring CNC machines (I'm slow on the uptake) is to build/buy it to the spec of the main intended purpose. Just about all people asking about buying a CNCs machine say...I'd like to mill a bit of acrylic, but maybe aluminium too. Or I'd like mill pcbs & the odd bit of mild steel(!), etc.

IMHO, you'll get the best results (satisfaction) by buying for the main intended purpose - extreme example to underline the point - you wouldn't buy the missus a juggernaut to go to Tescos etc.

I'd say if you want to mill pcbs, then IMHO you want a *fast* & quite compact machine (less vibrations) ...by fast I mean zippy rapids, (else it gets dreary waiting yonks for all the tracks to mill), but by bulking it up to say, start thinking about milling Ali, then you lose the attributes that your machine needs for the intended purpose.

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Originally Posted by HankMcSpank

I'd say if you want to mill pcbs, then IMHO you want a *fast* & quite compact machine (less vibrations) ...by fast I mean zippy rapids, (else it gets dreary waiting yonks for all the tracks to mill), but by bulking it up to say, start thinking about milling Ali, then you lose the attributes that your machine needs for the intended purpose.

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Bit overwhelmed by some people saying it is too big and solid and others saying it is small and weak.
The "CNCDudez New 2012 Desktop Mini Muscle" (catchy name) is a small machine - the working area is only 310mm, 310mm, 90mm

HankMcSpank: What would you recommend for milling PCBs?

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Originally Posted by njh

HankMcSpank: What would you recommend for milling PCBs?

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A moving table design (i.e. fixed gantry)...this is style of machine is problematic to source because most CNC offerings are moving gantry.
No larger than 30cm in either X or Y plane (to keep associated frame/table vibrations lower)
Ballscrews - absolutely essential
Homing switches - virtually essential.

I could only find one manufacturer where I could buy to the above spec new (vs building my own)...

2013 new design desktop cnc router machine RS-3020 for aluminum, View desktop cnc router machine, Redsail Product Details from Jinan Redsail Tech Co., Ltd. on Alibaba.com (it costs about $1200 ...which is great value, but of course there'd be shipping & taxes on that)

http://hostmypicture.com/thumbs/img6414sma.jpg

http://hostmypicture.com/thumbs/img6415sma.jpg

(nb: my machine above is presently showing a standard 300W air cooled spindle, pending fitting a water cooled spindle over the coming days - hence all the black cables & tubing dangling in mid air near the spindle!!)

...it's the machine I ended up buying (& believe me...I went to the far end of a fart sourcing a machine that will mill pcbs well).

Sure, it's a Chinese machine but far superior to the standard Chinese CNC fayre ....it uses 3 individual decent stepper drivers (e.g. instead of a YooCnC '3 in 1' nasty driver pcb).... http://www.moonsindustries.com/Produ...t_E/SR4_drive/ The gantry uprights are 15mm thick aluminium (very solid), ballscrews...the machine is very very zippy. The machine comes fitted with homing switches (which most don't - ok, not a show stopper, but nicer to have them fitted at the factory)...water cooled spindle etc. it also has one of those cable tidy thingymajigs fitted to allow the cabling to move with the axises neatly)

You can maybe source in the UK from Redsail Cutting Plotter,Laser Cutting Machine,Laser Engraving Machine ...but I don't think they have that particular machine listed (& therefore presumably not in stock)

If your intended purpose is to mill pcbs, then I'd also say to buy CNC-USB vs. mach3 ...as the former has specific integrated features that make milling pcbs much less painful (auto Z levelling, camera point transformations to assist with double sided pcb registration etc)

Check your PM's

If you're not considering making one, then your options are evidently very limited. If I had to choose between the CNC3020 and the misleadingly named 'mini muscle' machine, I'd get the former as they'll both be pretty similar for PCBs and nothing special at anything else, so might as well save your money and get the cheapest one. When you need to start cutting other things, get a machine designed to do it, not just marketed for it.

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Originally Posted by JAZZCNC

Check your PM's

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To be a fly on the wall...

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Originally Posted by Jonathan

To be a fly on the wall...

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I'd swat you ya nosey b'~tard. . . . . . But if you must know then tuff. .:hysterical:

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Originally Posted by Jonathan

If you're not considering making one, then your options are evidently very limited

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Exactly...so when are one of you knowledgeable CNC types going to help plug the gaping gap?!