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Boovey
17-06-2012, 01:15 PM
Hi everyone ,
I asked this forum a while ago what cnc should I buy , a Chinese one or have one made . I have 4000 and I want a cutting area of 1220 x1220 .
so I went and bought a Chinese one gm cnc and I wish I hadn't as I took it back 2 days later for a full refund , I have my refund and I'm looking for a decent cnc router good enough and accurate enought to build furniture and one off shop fittings .

I live in the midlands so travelling to see machines running isn't a problem , I just don't want to spend my hard earns on junk , all info would be greatly appreiciated as I'm new to all cnc machining ,
thanks

Boovey
17-06-2012, 05:43 PM
Jazz cnc do you mean ?

Jonathan
17-06-2012, 05:54 PM
Jazz cnc do you mean ?

Yep.

To get a good machine for a remotely reasonable price you have 3 options (in order of cost):
1) Make and design it all yourself
2) Pay someone to make the more difficult parts and assemble yourself
3) Pay someone to make the whole thin.

You can make a good machine with any of those options, it just depends how much time you can devote to it. With any of these options the forum will help you a lot to make decisions and find what works best. Currently I can't take on any more parts as I'm busy making another CNC router, which will take a long time to complete with the limited amount of time I can devote to it.

As you have found the hard way, all the Chinese machines make compromises and a lot of 'proper' machines in our price range do too. They're designed to be cheap so they skimp on important parts, but if you make it yourself or get it made to your specification you can make sure it is up to the job. Whichever way you decide it's a good idea to read around on the forum (and other sites) to see the common mistakes. Virtually all build logs start by making the same mistakes, and after much discussion they are generally corrected.

Boovey
17-06-2012, 06:20 PM
What do you think to this on eBay 270995632021 (http://www.ebay.co.uk/itm/270995632021?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch% 2Fi.html%3F_sacat%3DSee-All-Categories%26_from%3DR40%26_nkw%3D270995632021%26_ rdc%3D1) if you have a minute to look at it as I'm too busy to build one , even if I had an idea to build one I haven't the time
thanks

John S
17-06-2012, 06:38 PM
Doesn't look bad and Worksop is only 3/4 of an hour away.
I'd make the trip and see.

Boovey
17-06-2012, 06:41 PM
Will do And thanks for your time

Boovey
17-06-2012, 06:52 PM
I will go have a look

Jonathan
17-06-2012, 07:19 PM
It's certainly worth a look. It's better than most, however the X-axis drive is worrying:

'All machines have Ballscrew x axis with rotating ballnut'

Having a rotating ballnut is excellent for good feedrates, but the description and photo appear to show only one ballscrew on the X-axis. This will severely compromise the rigidity of the machine. Think what happens when the tool is cutting towards the ends of travel on the Y-axis - there is a force pushing the gantry, but the support (i.e. the ballscrew/nut) is a long distance away so it will bend and 'rack' the gantry. If you're only cutting MDF then you would get away with it, but it will still limit your productivity and surface finish. For 5k you should be able to do better than that. This is a typical example of the manufacturer trying to save money since it would cost them (very roughly) 250 more to add another ballscrew and motor (has to have another motor as rotating nut).

The only person whose objective is to ensure you have a high quality machine is yourself.

John S
17-06-2012, 08:04 PM
For 5k you should be able to do better than that. This is a typical example of the manufacturer trying to save money since it would cost them (very roughly) 250 more to add another ballscrew and motor (has to have another motor as rotating nut).

The only person whose objective is to ensure you have a high quality machine is yourself.


I disagree with this strongly. it looks a nice machine, well made and made in the UK so higher costs.
There is a limit where a manufacturer can throw in all the bells and whistles and still make a profit to stay in business.
Jonathan's estimate of 250 is insane as he's only counted the cost of the screw, nut and motor.

Now throw in all the mounting hardware, driver, building up etc and that 250 is no where near.

Presumably Jonathon you are paying business rates on that 100' x 80' shed in your back garden just as you are reporting everything you earn to the revenue ?

It's a no win situation, buy Chinese and it's crap no matter what level you buy at, buy British and you are getting ripped off and attacked by the garden shed brigade wanting to buy everything for nothing but sell their product at high prices.

JAZZCNC
17-06-2012, 08:08 PM
Bovey this machine looks well built . . BUT. . don't be seduced by the sight of all the trimmings it shows in the picture and the description.

It says Vacuum and dust extraction built in but it doesn't actually say comes with Vacuum pumps or dust extraction machine.? . . It does say starts from 4995.
Vacuum pumps can be very expensive and it shows 2 so I would be asking some questions to exactly what you get for 5K.?
I would also want to see the machine in the flesh and if you don't have much experience with CNC machines then suggest you take someone with you who does.? It very easy to blind newbies with science and bull shit and unfortunatly lots of company's rely and pray on this.!!

Every thing Jonathan says regards single ballscrew I fully agree with.!!

Jonathan
17-06-2012, 08:48 PM
Now throw in all the mounting hardware, driver, building up etc and that 250 is no where near.

I did say very roughly. From eBay a 1500mm ballscrew with the bearing mounts is 115 but he's using a rotating nut so the bearings will be more expensive - call it 160. One additional 3Nm motor and 80V driver is 75 max. Better PSU needed, another 15 to supply the extra motor. Another two pulleys and a belt, 15. That's 160+75+15+15=265 so I think very roughly 250 was a reasonable statement as clearly I wasn't including labour.


Presumably Jonathon you are paying business rates on that 100' x 80' shed in your back garden just as you are reporting everything you earn to the revenue ?

I might not pay revenue but I do pay VAT.


It's a no win situation, buy Chinese and it's crap no matter what level you buy at, buy British and you are getting ripped off and attacked by the garden shed brigade wanting to buy everything for nothing but sell their product at high prices.

Who said anything about charging a high price? Imo the prices charged in the CNC industry are usually extortionate. I try to lead by example by charging around 6-7 per hour for time. My objective is education, interest and not making a loss, not looking after other people's profits.

Why not ask them how much to add a second ballscrew? They might say it's too much work to change the design, but it can't hurt to ask.

Also in the listing there is far less information than there should be. It doesn't look like any of the pictures have the actual machine that listing is selling - the AR1200. Some of the bigger ones have vacumm bed and other nice things, you can bet that costs more.

Musht
17-06-2012, 10:46 PM
Quick google brings up:

http://www.youtube.com/watch?v=BAnYg-_IsZ8&feature=channel&list=UL

Cheers
Adam

Jonathan
17-06-2012, 11:04 PM
Quick google brings up:

http://www.youtube.com/watch?v=BAnYg-_IsZ8&feature=channel&list=UL

Cheers
Adam

Well at least it's got two motors on the X-axis, but if that's what you get for 5k I take back what I said about it being worth a look. The machine in that video has lost most of the good things from the ones in the eBay listings. It uses supported round rails and worse small unsupported rails on the Z-axis badly orientated, plus the spacings between the bearings looks small. Rack and pinion not ballscrew, router not a proper spindle...

These are all things you should look for - profile rails (generally Hiwin is used), ballscrews on all axes (no need for rack on such a small machine), proper spindle not a router. Once mounted properly supported round rails aren't too bad, but since you're willing to spend 4k ish you should be able to get profile rails which will increase the rigidity which is the among the most important aspects of the machine.

The title of their other video of that machine says it all really - Low cost CNC Router (http://www.youtube.com/watch?v=tHCTk85-pKA&feature=relmfu), not 'High quality CNC Router'. The video shows the machine cutting pretty fast (due to the rack and pinion), but what about important things like resolution and surface finish? Not a clue from their video which is why you need to go and see it cutting.

John S
17-06-2012, 11:17 PM
I might not pay revenue but I do pay VAT.



Who said anything about charging a high price? Imo the prices charged in the CNC industry are usually extortionate. I try to lead by example by charging around 6-7 per hour for time. My objective is education, interest and not making a loss, not looking after other people's profits.



So you pay VAT on the 6 -7 per hour you charge then ?

I have no objection with what has been said about the ballscrew just how costing is worked out.
You are working out of a shed that mummy and daddy are paying all the expenses for and you are trying to tell registered business's how to do their job ?

Jonathan
17-06-2012, 11:42 PM
So you pay VAT on the 6 -7 per hour you charge then ?

VAT is a tax levied on goods and services. I pay VAT on the things I buy, which a business may not have to. Surely I do not qualify for VAT because:

'When you must register for VAT:
Your turnover for the previous 12 months has gone over a specific limit - called the 'VAT threshold' (currently 77000)'

Plus it says I don't pay income tax below 2710, so that doesn't apply to me or many of the 'garden shed brigade'.


You are working out of a shed that mummy and daddy are paying all the expenses for and you are trying to tell registered business's how to do their job ?

Please don't jump to conclusions, sadly that is no longer the case.

Jonathan
18-06-2012, 12:20 AM
No prices on the site, so probably too expensive, but this has all the features I mentioned:

http://www.maxicamglobal-cnc.com/MAXI-S%201224.html

JAZZCNC
18-06-2012, 12:24 AM
VAT is a tax levied on goods and services. I pay VAT on the things I buy, which a business may not have to. Surely I do not qualify for VAT because:

'When you must register for VAT:
Your turnover for the previous 12 months has gone over a specific limit - called the 'VAT threshold' (currently 77000)'

Plus it says I don't pay income tax below 2710, so that doesn't apply to me or many of the 'garden shed brigade'.

Nope any business pays Vat just the same has you, diference being they can claim it back. . . BUT they must then charge VAT on any labour or product sold. . . .Either way the Customs and excise want there cut.!! . . . . Mess with them and they bite hard.!!

So if your so sure then get intouch with Inland revenue and tell them all your undeclared earnings, I'm sure they won't mind you not paying tax on your 7 hourly rate because your working out the shed.!!

Being self employed I see John S point completely regards costings and UK business pricing. I'm also one of the first to condem Uk business's for ripping UK buyers off but in this instance I don't think this company is doing that if the machine turns out to be all that it's made to appear.? . . . Thou I do suspect that won't be the case.!!

Oh and the machine in the U-tube video was actually using belt drive not R&P.!!

Jonathan
18-06-2012, 12:31 AM
Oh and the machine in the U-tube video was actually using belt drive not R&P.!!

Fair enough, I was wrong - it is belt driven. That makes it worse, so lets hope it's ballscrews for the five grand.

John S
18-06-2012, 12:36 AM
What are you smoking ?

The whole conversation started off on fitting an extra ballscrew, clearly says in the ebay advert ballscrew with rotating nut.

I don't know why i bother, I don't have an axe to grind or anything to sell. It just gets repeatedly tiresome pushing fooking prams out of the way all the while.

JAZZCNC
18-06-2012, 12:42 AM
Fair enough, I was wrong - it is belt driven. That makes it worse, so lets hope it's ballscrews for the five grand.

Not really.!! Belt drive is far more accurate than R&P unless high quality precision ground which is expensive so defeats the point when building a cheap machine.

But yes for 5K I wouldn't expect or want either.!! . . . I actually suspected the original Ebay machine used R&P on the Y axis has I couldn't see any signs of motors or screws but now I'm thinking it may use belt drive but again either isn't good enough at 5K.!

AdCNC
18-06-2012, 12:49 AM
I try to lead by example by charging around 6-7 per hour for time.

Fookin ell Jonathan i charge between 35-40 per hr but i suppose my garden shed is abit bigger :-P and i have to charge for the Dreaded VAT.

At the end of the day You get what you pay for regarding quality of jobs done and components/machines bought.

I can sympathise with Jonathan but i feel your pain JohnS ;-)

Musht
18-06-2012, 12:57 AM
To be fair the video was found via Google , not linked from ebay listing and is a year old.

Specifications subject to change etc...

Possibly drop the vendor an email with some of the questions asked here, coming across as a well informed potential customer saves looking like this ;-)

http://www.youtube.com/watch?v=dSINO6MKtco

Did another company completely Strike themselves off the list even with apparent attempts to correct?

Cheers
Adam

John S
18-06-2012, 01:06 AM
At the end of the day You get what you pay for regarding quality of jobs done and components/machines bought.



Yup and for 6.00 you are going to get a blinder, that lad puts his prick in places I wouldn't put my umbrella.

Tenson
18-06-2012, 03:41 PM
I don't know what that means John, but it sounds pretty rude and personal. You might want to calm down a bit :)