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View Full Version : Looking for information to help buy my first CNC machine



mholt1985
18-12-2011, 12:09 AM
Hi All, Im looking for a little help in deciding which machine to go for, or the benefits of each,

Im a graphic designer looking to branch into 3D Plaques, signs, memorabilia and prototypes.

Im looking to machine in wood and plastic, and if the Machine could cope with metal then Im sure I would find it useful.

And hopefully a machine that will cope with at least A3 media.

My budget is sub 1500 for all the equipment needed, although if its possible to acquire a good quality machine for less than 1000 then I would prefer that option.

Im looking to machine in wood and plastic, and if the Machine could cope with metal then Im sure I would find it useful.

I have looked at the CNC 6040 in both 3 and 4 axis, my understanding is that X is left/right, Y is Forward/Backward, Z is Up/Down. Therefore Im assuming the 4th axis will help with 3D objects and prototypes.

4 Axis 6040 - 1390 - http://www.ebay.co.uk/itm/4-AXIS-CNC-6040-ROUTER-ENGRAVER-DRILLING-AND-MILLING-MACHINE-/320813928122?pt=UK_BOI_Metalworking_Milling_Weldin g_Metalworking_Supplies_ET&hash=item4ab2000eba#ht_16280wt_989

3 Axis 6040 - 1210 - http://www.ebay.co.uk/itm/CNC-6040-ROUTER-ENGRAVER-DRILLING-MILLING-MACHINE-AA-/120716208448?pt=UK_BOI_Metalworking_Milling_Weldin g_Metalworking_Supplies_ET&hash=item1c1b3f2940#ht_15750wt_1079


I have also looked at refurbished machines, the one below requires Software and Interface & Driver Kits, which adds a further 350 from the same seller.

3 Axis MDL-2-TR-UN - 414.50 - http://www.ebay.co.uk/itm/220882464115?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_946wt_1079

Which software do you advise? is mach3 any good? or are there better options for a similar price?

Is it best to buy separate kits or ready to use kits?

My apologies for the number of questions, unfortunately the number options is so extensive Im running round in circles not knowing enough to make a decision.

Finally as a budget machine what are opinions of the below option? are there any better options you know of?

3 Axis 3020 - 508 - http://www.ebay.co.uk/itm/140625033059?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_27707wt_1079

Thanks for taking the time to look, I really appreaciate any help you may be able to give.

Kind Regards
Martin

JAZZCNC
18-12-2011, 08:12 PM
Ok i'll shoot first.!

The first 2 machines look ok at first glance and they are in some ways. . . BUT! . . . Now first let me say I don't have any hands on experience of these 2 machines but I do have expereience of machines that have been or are built in similair ways so I'll just point out the areas that would concern me and leave the rest to you.!

1st: It looks like it use's un-supported round rail which is not very good choice and prone to flex greatly reducing accurecy. . . . BAD very very BAD.
2nd: The gantry doesn't look very ridged and considering it use's un-supported round rail and the not so clear or close photos I imagine they just fasten into the sides which won't give much stabilty again allowing flex. . . .flex is bad and the weak link in machines like this.
3rd: The ball screw mounting in the gantry side looks a bit jubious and again I suspect not the best implimentation.
4th: They give little info on the control box and the components it's made up with. Again I suspect it will be a weak area and very probably using cheap all-in-one 3/4axis drive board. This is ok until problems arise then you lose all drives and your screwed unless your into electronics and can replace chips etc.
The control box or should say drives and breakout board etc are the heart of the machine and if weak or cheap they will fail sooner or later or cause much heart ache in other ways like missed steps or other mind numbing issues.
5th: Bit less of a issue but still possible.! The vfd is a weak cheap chinese make (Huansang) and an area I've had personal trouble with and wouldn't recommend. That said to be fair theres folks who have them and they are ok but like I say something to be aware off.
Also the Spindle is only ER11 which will restrict cutter selection to 7mm shanks.

Personally (and unfortunatly something I come across too often) I think they look ok to folks new to cnc because of the spindle and ali construction etc but if you look closer some important areas are skimped on and to be honest not easily corrected without major work. Often this is not realised by folks with little experience untill the machine is bought and it won't do what they want or perform upto expectations leaving them very disappointed.

Like most things in life you get what you pay for and really that applys to cnc to some degree as well.

Regards the Other MDL model I won't even go there.!!! . . . But I can put you intouch with someone who wll tell you every short coming of it if you have time or really feel the need.!!

m.marino
18-12-2011, 10:39 PM
The two Chinese models I have questions about as something does not seem right about the way the bearings are set up on the rounds rails. As far as the MDL router, contact me off list and I will talk to you about my experience with them. Repeatability is the key point and a hard lesson to learn. I was where you are three years ago and will gladly offer any information I can to help you on your way to a wonderful learning experience and hopefully avoid some of the traps I fell into.

Michael

tumutbound
20-12-2011, 02:02 PM
I have one of the 6040 machine you mentioned. Still in the process of getting it set up
Mechanically it's OK. A few rough edges to construction but nothing major, The controller is very basic and in my case, had a bad driver for the X axis. Spare boards are available but it's a pain to have to source one and install it, especially in a brand new machine. Forget about warranty as it will require that you send any faulty item back to the seller and to pay shipping on the replacement - not cheap!
The only thing I have concerns with the machine is the limited Z travel, only 70mm or so. You may want to consider this if larger (thicker) items are to be machines. This also limits the size of items that can be used with the 4th axis
I'm considering a 4th axis for mine as it will help offset the freight cost of buying a new driver board.

Due to the dead driver, I haven't been able to fully test it. As I have a Gecko G540 controller I'm going to use it instead of the controller supplied.
It's not a good time of year though to be tracking down the necessary bits and pieces I need, everything is shutting down for Christmas.

JAZZCNC
20-12-2011, 04:29 PM
I have one of the 6040 machine you mentioned. Still in the process of getting it set up
Mechanically it's OK. A few rough edges to construction but nothing major

You may think that now but come back in 6mths and report on how it performs.! . . .I'll have a small waiger you don't think it's so mechanicly OK then.:whistling:

Defiantly dump the supplied control box if you have G540 it's a fantastic bit of kit.

tumutbound
21-12-2011, 09:32 AM
You may think that now but come back in 6mths and report on how it performs.! . . .I'll have a small waiger you don't think it's so mechanicly OK then.:whistling:

Defiantly dump the supplied control box if you have G540 it's a fantastic bit of kit.


If you have practical experience with the 6040, what areas do you see problems with? I don't expect it to be a particularly fast machine, given the testing of working axis I done so far, but sufficient for what I want to do. Any feedback is most welcome.
The VFD supplied with the spindle is not great with quite a few users replacing them with a name brand unit.

I've gotten most of the bits I need to set up the G540 but need to pick up some suitable cable for the steppers, hopefully tomorrow or it will be sometime in the new years before shops are open again.

JAZZCNC
21-12-2011, 12:27 PM
If you have practical experience with the 6040, what areas do you see problems with? I don't expect it to be a particularly fast machine, given the testing of working axis I done so far, but sufficient for what I want to do.

Like I said in my first post I dont have any hands-on experience with this exact machine but I do have plenty of experience of similiar built machines. Mainly because I end up helping those that bought them to either fix them or replace them with better design and components. Often selling and replacing with a new machine because it's cheaper and easier.
Unfortunatly I see too often people buy these type machines thinking they are better than they really are only to be sadly disappointed. This was my main reason for posting to make aware the not so obvious and just hopefully make them stand back and look a little closer.!! . . . . When on a budget and new to CNC machines it's bit like looking at Women when you have the :beer: goggles on.? . . . .Man do you regret it in the morning.:confused:


The problems don't tend to be speed related, thou it does affect feed rate to some degree. It's more poor design and mechanicly related to do with the un-supported rails and flimsy build of the gantry and Z axis. They tend flex and twist, this only gets worse as the new-ness wears off. How much is hard to say and like you mentioned will greatly depend on the Type of work and material you work with.
What I would say is if you have need for high accurecy and desire to cut harder materials, Ali, brass even some of the harder woods then prepare to be dissapointed and work very very slowly.

boldford
22-12-2011, 11:20 AM
Perhaps the panel would like to express their view on how these machines would handle Sika modelling board. I'll be more than happy to exchange notes with the original poster as I'm seriously thinking about one of these machines.

JAZZCNC
22-12-2011, 05:33 PM
Perhaps the panel would like to express their view on how these machines would handle Sika modelling board. I'll be more than happy to exchange notes with the original poster as I'm seriously thinking about one of these machines.

It won't have any trouble at all handling modeling board from a mechanical strength point. Where it will struggle is with obtaining the correct feed rate to give best results IE Finish and tool life with some materials.

With only a 5mm pitch screws and I would hazard guess an under sized power supply along with crappy drives mixed and compounded with other aspects of the design and build quality then you'll be under 4mtr/min of usable cutting speed (Not to be confused with rapid feed). Which for most plastics and softer materials, even most woods, would be considered on the low side for feed rate. Cutting too slow will give a poor finish resulting in edge burning on some materials like balsa wood or thin ply plus greatly shorten the tool life.

This is where so meny new folks fall foul and don't see the potential problems with machines like this.! They think because they only want to cutt soft materials it won't be a problem.?
The reallity is that soft materials often need high feed rates for reasons stated earlier and these machines struggle to run at these high feed rates.
If pushed to run at there max they wear out very quickly drasticly reducing the machines life. The quality and accurecy is reduced because the poor gantry design can't handle the high lateral inertial loads without flexing and basicly they are just not built or spec'd to do the high feeds required.

My experience is that those that buy this type of machine while at first think they are ok but soon start to realise there down sides resutling in several different out comes.
1: Struggle with it, working around it's limits and bad points untill it becomes so annoying or restrictive they build/buy there dream machine.
2: Struggle with it, working around it's limits and bad points untill it becomes so annoying or restrictive they try to upgrade it and blow even more money trying to turn a sows ear into silk purse. (never achieved)
3: Instantly see it's bad points and get rid (Often they've had a little cnc experience before but got caught trying to take the quick cheap upgrade route)
4: Don't realise and just think cnc rubbish and either go back to the old way of doing it or give up on it all together.
5: Don't realise blissfully unaware producing crappy work and burning cutters up thinking thats just the way it is.!! . . .Untill one day they see a good machine strut it's stuff and then penny drops or they realise it's not them doing something wrong.

In most all cases they are well pissed off in the end.!!

boldford
08-01-2012, 10:00 AM
Your obviously unimpressed with these far eastern machines. What would you recommend for a similar sized machine where the budget is limited

JAZZCNC
08-01-2012, 12:32 PM
Your obviously unimpressed with these far eastern machines. What would you recommend for a similar sized machine where the budget is limited

Argh this is the problem and why these chinese machines have appeal.? . . .It's very difficult, infact I'd say not possible, in this country or EC to buy a machine off the shelf that's specd the same but built properly without the weak area's for the same amount.

This is why so meny build there own machines, DIY is about the only way you'll get near a correctly built machine with a similiar spec for around the same money, even then it will be close call sub 1500 if you want all the trimmings like 4th Axis.!

m.marino
08-01-2012, 12:33 PM
Options for lower budget Machines include:

Steel box section as while weight increases which makes moving the beastie a problem the rigidity also increases which aids in accuracy.
Down sides is that it requires very accurate cutting (but that is a common to all materials); it is required to be coated with something to stop oxidation from getting a start; may require welding which then brings it's own problems.
Up sides is the weight it brings for a base helps decrease vibration massively; has a low expansion rate to temperature changes (not non just low); With a little bit of looking and shopping around can be gotten for a lot less then profile or Ali' box section.

Recycled Profile, IF you can find some one or some where that deals in break down of machines that are past their useful lifespan you can get good profile on a discount. Upside it is profile which is light compared to steel and yet retains the rigidity needed for repeatability/accuracy.
Down side is that it will most likely have some work hardening in the section and the will be drill marks and such. Which mean you have to be a bit careful in choosing what you want to work with.

Also starting with an air cooled spindle like a Kress or something a bit better (again look around for folks selling on equipment in good condition). That or save up and get a water cooled unit though realize a good a good VFD is not cheap nor the proper wiring and in line filters to have it work at it's best.

Depending on what you are doing with it Trapezoid Screws with spring loaded anti backlash nuts can be as accurate as you might need. This is where a serious sit down and looking at what you are going to be doing in real world here and now terms can help massively. It is why my second machine that Jazz is building is custom and built towards a goal of specific usage. The frame and structure of a machine is from what I have experienced only about 40 to 50% of the overall cost. Steppers/Servos, drivers, BOB, computer, spindle, vacuum for cleaning, and many more add up quickly and from personal experience are equally important.

Another option entirely is start haunting the equipment auctions and chatting with a few folks here who know where there are auctions of equipment. Go and look a few times and get a feel of what you are looking for. See if one the folks here is heading to one that you can go with. You would be surprised what you can get used industrial machines for at times. Depending on what you plan on doing, refurbishing an older machine might give you an affordable answer to your goal. Yes most of them are heavy as heck and will need work on them. Look around and talk to folks here and at model engineer swap meets and other places the similar minded people meet (robot war groups come to mind) and you might fins what you want exactly or so close that it does not matter.

Good luck and keep asking questions.

Michael

Jonathan
08-01-2012, 01:05 PM
This is why so meny build there own machines, DIY is about the only way you'll get near a correctly built machine with a similiar spec for around the same money, even then it will be close call sub 1500 if you want all the trimmings like 4th Axis.!

That's what I was about to say. The only way is to either do the research and DIY, or give someone who knows what they're a clear specification and get them to design and make it for you. I think DIY is the best option as in making the machine you'll learn more about how it behaves and what to look out for.


Down sides is that it requires very accurate cutting (but that is a common to all materials); it is required to be coated with something to stop oxidation from getting a start;

Cutting accuracy depends on how you're joining it. If it's just welded then you can make sure it's clamped accurately and rigidly whilst you weld and small gaps can be filled. For my frame I started off milling all the ends nice and square and milling a chamfer on. Then when I started welding it I realised it's a bit of a waste of time so I just cut it with my metal bandsaw (same as Jazz's), which at the time was cutting quite square and nipped the burrs off. Either way it helps a lot to have a milling machine and metal bandsaw. Frame cost me about the same as steppers and drivers.