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smith99
07-04-2014, 02:39 PM
Hello everyone

I am looking to learn cnc machining, I have engineering background but beyond that this is all new to me. Im looking from a hobyist/home point of view so 240v and tabletop size is essential.

I will be working in wood primarily but would also like the option to machine brass or aluminium - speed is not essential when cutting in metal.

Like most people I have been looking on ebay at the 3040 or 6040 machines, something with a ballscrew seems more sterdy and accurate.

Have people got any experience of these machines, I have read that the wiring is cheap so thought I would throw it over to people who have already gone down this road in a hope for their opinions

Budget is a big factor to me, I dont mind second hand but obviously it needs to be fit for purpose.


I really would appreciate some guidance, many thanks

Mike

JAZZCNC
07-04-2014, 10:30 PM
Hi Welcome.

Several problems with the chinese machines, electronics are mostly cheap rubbish and the wiring is poor quality. Depending on the which you buy the Spindles are also rubbish unless they come with the water cooled version.
Strength wise then they are Ok-ish but again they are low spec due to low price so Linear bearings are low quality so become baggy and loose over time, obviously depending on usage determines how quickly but it doesn't take long if pushed hard.
Also thou they use ballscrews most I've seen suffer from poor mounting of them and use either normal deep grove bearings for the Fixed end or very poor quality and fitting angular contact bearings.

I wouldn't recommend a second hand machine unless it's had easy life or/and is cheap and you can give it a good look over.
My honest opinion on these machines is they are Ok for learning CNC but if you want to cut accurately and with decent feeds and Depth's of cut and still have quality finish your better to spend the money on something better or building your own.

Hope this helps.!

smith99
07-04-2014, 10:48 PM
Thanks for your reply, I wouldnt have a problem with building my own but would struggle as I dont have access to a workshop to make the parts.

If the Chinese ones, arent upto scratch what other choices are there and roughly what do they cost.

Gregor
08-04-2014, 01:06 AM
Hi smith99
I have a Chinese 3040 that I have had for about three months,I use it for about 7 hours a week and have only ever used it on hard woods like Oak and phenolic board and it seems to be ok,The spindle on mine only goes up to 8000rpm which if I was buying again I would go for a better spindle,For what I use it for it's ok and I don't push it to hard and I never used it on brass or aluminium.I have posted a few videos off it under the title Chinese 3040 Arrives in the workshop & equipment section.

smith99
08-04-2014, 08:52 AM
how readily available are the spare parts should you need them for the Chinese machines, or is one X axis lead compatible with all machines etc. By any chance you dont live in the midlands do you ?

Gregor
09-04-2014, 03:26 PM
I think you can get parts on ebay ..I don't live near the midlands I live the other side off the irish sea.

smith99
09-04-2014, 03:31 PM
Ive actually spotted this one which looks more robust..

3 Axis Column Type Engraving Machine, High-pricision Ball Screw CNC 3040 Table | eBay (http://www.ebay.co.uk/itm/251354213059?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

What do people think about this type

Gregor
09-04-2014, 04:15 PM
Hi
I am only a beginner so I couldn't advise you on the machine but you might get hit for import duties so you need to add that into the price. When I bought mine it was sent from Portsmouth so I had no import duties .

JAZZCNC
09-04-2014, 04:55 PM
Ive actually spotted this one which looks more robust..

3 Axis Column Type Engraving Machine, High-pricision Ball Screw CNC 3040 Table | eBay (http://www.ebay.co.uk/itm/251354213059?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

What do people think about this type

Can't comment from experience of using this machine on the structure but I can estimate it's strength from my experience. Essentially it still as all the Low quality components the gantry style machine does. These are the cheap round type linear rails and bearings and from the limited pictures they actually look like unsupported type which is the worse case.
Also again the ballscrews will be standard chinese units but they will be connected with same poor setup and bearings.

Really if you look close the base unit is essentially the same base as the gantry machine, probably exactly same just with a Upright coloumn replacing gantry.
While it looks strong it won't be nearly as strong as it looks in practice because the column isn't ridged or fastened to the base anything like good enough, i also suspect the column is just thin aluminium plate bolted together so will be very flexy.!!

Electrical wise then looks like it's using cheap low powered components and the fact they are using 24V and don't actually show them makes me suspect the could be the TB based units commonly found on ebay. These are to be avoided like the plague.!!

Spindle is about the only thing of any note and this is just a standard water cooled spindle.

Unfortunatly I can't point you to anything better that can be bought for same money as it's just not possible to build them for same money and make money.

That said it is possible to build your own much better version for not very much more.!!

smith99
09-04-2014, 06:56 PM
how would i go about getting plans for building my own from scratch, I presume I could buy most of the bits from ebay and cobble it together with relatively few home made parts ?

Where do I go for this king of info ?

Like I say, I really only want to be machining brass as hard as it gets

george uk
09-04-2014, 07:20 PM
I presume I could buy most of the bits from ebay and cobble it together with relatively few home made parts ?

You can, and you do get some use from the cheaper stuff, they just wont stay accurate for long, without adjustment.

What is your realistic budget for the total project, and what space do you have for the machine. what size do you want

Then, can you wield or know a mate that can.

if you can answer them, you will get some help within the budget your looking at. For 1000 to 1500, if you can get the welding done cheep, you can build a reasonable quality starter machine. ( 300 spindle+VDF+fittings, 400 to 500 motors,drivers,card 300 - 450 rails+barings screws+fixings ). 100*better and more reliable than the one you pointed to.

You could do it cheaper than that, or get better quality parts for more, but that gives you a general idea of what it costs to get a decent quality home machine.

george uk
09-04-2014, 08:13 PM
to add to the above, i will try price the machine you pointed to in parts.

New CNC Standard 3Axis TB6560 Stepper Driver Full Kit & Motor/PSU/Keypad/Display | eBay (http://www.ebay.co.uk/itm/New-CNC-Standard-3Axis-TB6560-Stepper-Driver-Full-Kit-Motor-PSU-Keypad-Display-/131140686949?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item1e88981465) 165, may find cheeper--- motors,drivers, card, dongle ----RUBBISH

New WATER-COOLED SPINDLE MOTOR 1.5KW & INVERTER DRIVE | eBay (http://www.ebay.co.uk/itm/New-WATER-COOLED-SPINDLE-MOTOR-1-5KW-INVERTER-DRIVE-/260626036465?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item3cae85b6f1) the same i presume spindle 200

will find the B/screw and bairings pack later, but am sure i see these for 160 the lot.

Then you only have the metal on the machine to price,

longy
09-04-2014, 09:52 PM
I've got to agree those cheap Chinese CNC's on ebay would be ok for learning but like most things cheap you end up buying twice so you don't save in the long run. I know from my own experiences "buy cheap buy twice" but if your looking for bargains eBay's the place found this for 125 Nema 23 3Axis Kit Stepper Motors Power Supply TB6560 Driver Plus Electronics Pa | eBay (http://www.ebay.co.uk/itm/171293506937) if your looking to go the TB6560 way bigger motors than the link George uk posted and cheaper.
Mike

JAZZCNC
09-04-2014, 10:06 PM
I know from my own experiences "buy cheap buy twice" but if your looking for bargains eBay's the place found this for 125 Nema 23 3Axis Kit Stepper Motors Power Supply TB6560 Driver Plus Electronics Pa | eBay (http://www.ebay.co.uk/itm/171293506937) if your looking to go the TB6560 way bigger motors than the link George uk posted and cheaper.

NO NO do not buy this rubbish you'll waste 125 nothing but only the E-stop and aviation connector bits n bobs are worth bothering with.!!

longy
09-04-2014, 10:13 PM
NO NO do not buy this rubbish you'll waste 125 nothing but the E-stop and aviation connector bits n bobs are worth bothering with.!!
Jazz I have notice your not a fan of the TB6560 LOL but the motors should be ok for small machine, he could always change the driver board to better drivers & bob at a later date. Reading the problems on here with some of the cheap drivers it's very true you only get what you pay for.

JAZZCNC
09-04-2014, 10:29 PM
Jazz I have notice your not a fan of the TB6560 LOL but the motors should be ok for small machine, he could always change the driver board to better drivers & bob at a later date. Reading the problems on here with some of the cheap drivers it's very true you only get what you pay for.

Yes I hate the bloody things far to fragile and underpowered, to me they are toys best left to kids to learn on.
Like you say the motors could be used for a small machine but why pay way over the odds for motors when for 75 you could have much stronger motors. The PSU isn't any use because to get any decent speed those motors want to be run with at least 36V and will happily take 48v which is much more like whats needed for router.
Limit switches are rubbish, Solid state relay is bad news for a CNC machine as they tend to fail on. That only leaves E-stop, Fan and connectors which are of any use and for those you'll be paying twice what they cost and that's if it stays at 125 because it doesn't have buy it now.!!

I see this all the time and sadly it's a classic mistake first time builders make.!!

george uk
09-04-2014, 10:56 PM
I think the chinese boards that have motor drivers onboard are totally useless, problem after problem after problem. I would not fit one in a printer, never mind a cnc. But the new chinees boards ( rev 3 ) , with seporate motor drivers seem a cheap, reasonable starter board,

T0rnado69
11-04-2014, 12:39 AM
NO NO do not buy this rubbish you'll waste 125 nothing but only the E-stop and aviation connector bits n bobs are worth bothering with.!!

proberly not the place to ask this but.....

maybe it would be a great idea for all the experience cnc'er that are on here to contribute to a thread that lists what parts would be best to get for small, medium and large cnc's and where from for newcomers, so they dont buy rubbish and end up buying twice.

JAZZCNC
11-04-2014, 02:13 AM
proberly not the place to ask this but.....

maybe it would be a great idea for all the experience cnc'er that are on here to contribute to a thread that lists what parts would be best to get for small, medium and large cnc's and where from for newcomers, so they dont buy rubbish and end up buying twice.

Too many variables to do this accurately and ensure info is accurate and relavent to there build.
Often the best thing new comers could do for them selfs instead of rushing out and buying is to read more build threads and identify a machine of approx size they want then either ask the builder what they used if not stated. Or If that doesn't yield results then post a thread stateing the size and design intent along with materials to be built from here someone will provide the info they need or direct them down the correct path.

Now the real problem why lots of new comers fail or get wrong stuff is they are not prepared to put the time into proper research, instead they flick thru a thread or two then go straight out and buy without any clue to if it's going to work for there design. This lazy approach is a sure fire recipey to waste money and poor performing machine.
If you ask any builder who as built a accurate and successful machine they will nearly all tell you they did shit loads of research before building. When research is done you don't need telling what to buy it will become obvious because you'll know from other machines similair to what you plan on building.
Where to buy changes from month to month and wallet size to wallet size so again not practical really.

Nothing good comes from haste and folks are all to inpatient to take the time to find out whats required but instead want it handed to them on a plate Which isn't always in there best interest to do so.!! . . . . . . The best machines come from patience and research.!!