Seeking advice for cnc machine purchase

[aarggh]

The follow on from the previous split responses Danny:

-- Structure: Cast iron > Steel > Aluminum > Cardboard (little joke there!) Most of these use a combo of the first three I think.

My 6090 is a real behemoth made from very a substantially welded frame, and cast iron top assembly/frame.

-- Rails: Linear are better than Round Supported Rails - thanks to Ian for this info. So far I'm seeing Taiwan Hiwin Square rail. Jinan JCut denotes square rails with "B" suffix vs "A" for round in the model number (Thanks Ian) do they all follow this convention?

Manufacturing in China for a lot of this sort of machinery is done more or less like a (government subsidised?) collective or umbrella company, with minor cosmetic differences between the products different sellers have, so they are all somewhat similar in options and specs, so yes, 6090B would generally infer linear rails. Very similar to the current situation on Ebay where there might be 10000 different 6040 sellers, but there's maybe only 10 or 20 (or more) real distinct umbrella corps that trade under the different accounts. So buying from seller doesn't mean a great deal over buying from another except for the end specs and individual seller performance.

-- Spindle: 1.5KW or better water cooled & brushless preferred. How do I research these? One company offers a 2.2KW Changsheng. Anyone have one of these?

They'll all be offering slightly different variations, mine came with a Sunfar, my 6040 came with the generic Huang-something, just query the specific one they will supply for YOUR machine and google to see if it has issues. Chinese spindles and VFD's are very, very, cheap, so I take it with a grain of salt and don't really see much of an issue with whatever they supply. My spindle has lasted way longer than I expected, so I consider it a bonus.

[aarggh]

Hello this looks like a good place to ask ....I just ordered a Chinese 6012 (2x4') router and I've requested that they video a performance test to show accuracy and integrity before I send the balance. Can anyone out there suggest a good run test for these machines? I figure right off the bat it would be good to see if the cutter is in the same plane as the table - anything else? Ian?

I just asked for videos of MY machine in action and luckily they did some hard hogging and also finer engraving work which was good.

cheers, Ian

[Markphd]

Hi All,

We would prefer a unit ready to run, but many warn that the motion controllers are pretty terrible (black box, blue box, etc). Do any companies offer good controllers with these yet, or is the best route still to buy one and retrofit it with a G540 or Leadshine controller?

Danny

Since I have taken a step off the reservation (not using Mach 3 or LinuxCNC) and opted instead to purchase Planet CNC's USB based controllers with a variety of different motor drivers, I believe that these represent a good value. Mind you I have not pushed these controllers to the limits of what can be done but I have not had any problems that I could identify with them either.

Would it be too ambitious to try to buy a frame and source all the components ourselves?
We would like to get up and running as soon as possible, but not at the cost of having to replace inadequate or dead components later.

You said it, time vs money. I would opt to get a complete machine (minus the electronics) and install the controller/drivers/motors that I wanted. I am actually building a modular setup that I can use to run multiple kinds of machines (at different times) e.g. Lathe, router, mill. The electronics are fairly easy to sort out to be honest. I purchased a 3040 router, converted to CNC a 44991 HF mini-mill with a CNC fusion kit, and I am in the process of rebuilding my 7x16 mini-lathe (which was originally a 7x10 HF machine) into a CNC lathe. These projects take time and money to do right, so if production is something that is more important, buy a complete solution that is tested by the community at large and has support (e.g. like a Tormach or similar setup).

[*]Quote from JohnDeere630: "I don't use USB to control steppers because USB is not a real-time protocol. I use the parallel port because it is a real-time system"

• Is this true? Has anyone experience this issue with USB?

This is someone who has no idea of what they are talking about. True that USB does not allow you "real-time" access to the hardware, but that's not a big deal. You don't need real-time hardware access at the G-code level if the USB controller is properly designed and implemented.

[quote][*]What is a list of components needed to complete a 6040 frame?

• Spindle: Prefer 1.5 or 2.2KW water cooled
• Variable Frequency Drive (NES1?)
• Power supply - should be 48w or higher
• Stepper Drive (like G540, but preferably USB like a Leadshine MX3660 or MX4660)
• Motion Controller (UC100)
• Shielded cables
• Mach 3 or LinuxCNC? (Are these compatible with USB?)
• Add limit switches
• Cables should be grounded at the controller end and on both ends for the spindle<->VFD to earth the mill frame.

You probably can't go wrong with the Gecko as a motor driver... I have used a bunch of the "knock-off" Chinese motor drivers to include drivers from Longs, WanTai, etc. Only one has ever failed/gave me a problem out of the 10 or so I own. The stepper drives should be directly wired to the motion controller (vs a USB connection - I don't believe I have seen a USB motor driver) and the motor controller needs to speak to the motor driver in "real-time".

The power supply should be lower voltage than the maximum that your drivers can handle. So if your motor drivers are 60v max, your power supply needs to also be below 60v. I would recommend a 500 watt power supply, motor drivers capable of handling that voltage (preferably DSP based motor drivers), and motors appropriately sized for your application. (I am using 400 oz/in motors which are overkill and perhaps even slowing down the machine due to the fact that rotor inertia is higher on a bigger motor - I still had no problem getting 60 ipm rapids with 36v).

Hope that helps!

[Teddyo]

I just asked for videos of MY machine in action and luckily they did some hard hogging and also finer engraving work which was good.

cheers, Ian

Thank you Ian, After having your machine for so long is there any tests you perform to see if it's calibrated right? I was thinking of having them route a large rectangle to see how well the spindle stays in the xy plane and a large circle to see out well it's closed. I wonder if there is any way to see how well the spindle is perpendicular to the xy plane? Any other ideas?

[A_Camera]

Quote from JohnDeere630: "I don't use USB to control steppers because USB is not a real-time protocol. I use the parallel port because it is a real-time system"

Is this true? Has anyone experience this issue with USB?

He doen't seem to have a clue about USB vs. parallel port. USB is not used for controlling steppers, USB is connected between the PC and the steppers via a motion controller. USB is just a communication interface. That motion controller buffers the G-code, converts to pin signals (input and output signals) and outputs to the necessary pulses to drivers (normally through a BOB) in a more even and stable flow than ANY parallel port can ever do because the parallel port is dependent on the PC, which is normally an old Windows PC, and on hardware which is old and outdated.

In terms of real time... well, USB is not a real time protocol, it is a serial protocol, just like Ethernet, RS232, RS485 and many others. It is NOT possible to have a real time protocol unless it is parallel interface, so that is true. On the other hand, it is NOT necessary to use real time protocol at all, since the motion controller handles that part MUCH better than a PC can handle a parallel port, even if you run Linux. If you have a good and reliable USB motion controller than it is not a problem, it handles the flow of G-code better than parallel port does.

Ethernet is even better, but the biggest advantage of Ethernet (apart from higher flexibility) is that it is completely isolated and it has a built in error handling for handling communication errors, it is much less sensitive to noise than USB is. USB can lose contact with the PC in a noisy environment. This is basically non-existent with Ethernet, so you are better off with Ethernet controller than a USB controller. It is slightly more expensive, but worth every penny.

I had UC300USB before but now using UC300ETH. Both are excellent products, well made and very good support. Beware of the fake UC100 controllers sold on eBay. If you want to buy the products of CNC Drive then you better buy them directly from the manufacturer.

Spindle: Prefer 1.5 or 2.2KW water cooled
Variable Frequency Drive (NES1?)

Water cooled - air cooled... never ending story. I prefer air cooled. Have a 1.5kW and never regret the decision of buying it. If it stops working I'll buy another air cooled one. The argument that in a dusty environment the fan is a problem is just nonsense. If you use your CNC is dusty environment you must have a dust extractor regardless if you have water cooled or air cooled spindle. The argument that water cooled is quieter is also nonsense. Yes, it is quieter if you only milling air and not running the pump, but once you start cutting real material, even plastic and wood, than the cutting noise and the noise of the vacuum cleaner or whatever dust extractor you have is far above the spindle noise. Both water and air cooled have a minimum usable spindle speed of about 6000rpm, so even in this respect there is no difference. Buy whatever you prefer, water cooled is the buzz word on this forum, but there are quite a few people who have issues with water cooled because of the cooling fluid (which is NOT supposed to be pure water) and because of failing pumps and leaking tubes, but if you are not worried about any of that then of course, why not buy it and see it for yourself.

I chose a quality VFD, I think that is worth every penny extra. Never had any problems with it, setting up was really easy and is well documented.

Good luck.

[dalcini]

Ian, Markphd,
Thanks for all the excellent information! I really had not anticipated this much help when I began posting questions.

Researching specifications of the parts of the machines quoted to me has been a challenge but I'm making progress. I'm putting all the information into one spreadsheet which contains the specs of all three quoted machines, along with a list of information that one should request from additional vendors. When finished, I will share it here as a sort of RFQ template so that others may also benefit from all the knowledge you guys have shared. I need to get answers to some additional questions from all three vendors to fill in some information gaps, but we should have a pretty good comparison matrix for our purchase after that. My brother and I hope to have enough information for a purchase some time this week or next.

[JQ_Quint]

Hi Danny - I bought a 6090b from jcut a couple of years back, other than initial difficulty setting up the spindle in Mach properly (& some minor rewiring ) it's ran with zero issues ever since..!

I router 18mm mdf 3mm passes 10m/min, just making a vacuum table so I may be able to push performance a little more after that, but I'm happy at those production rates.

Would I buy another, well I was only messaging Mandy from jcut last week about the next size up, so yes I'd buy off them, just maybe go for a slightly larger table next time round for my application. Like you I'd also love a toolchanger but probably couldn't justify it...


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[dalcini]

JQ_Quint,
Thanks for sharing your experience! We've narrowed the field to 3 suppliers and Jcut is one of them. I have to say that hearing from owners who have bought these units is the best confidence boost I've found. It sounds like Jcut does a pretty good job putting these things together. I'm just getting ready to share a matrix that I put together for myself to aid in shopping for a 6090 router. This will be my way of giving back some of the great help that everyone here has shared with us.

[dalcini]

Hi everyone,
Here's a link to a spreadsheet where I compiled (what I believe to be) a bunch of relevant information for the purchase of a 6090 router. I wanted a way to compare apples-to-apples on the specs of these units, and am using this currently to get quotes from the three companies listed. From the link below, you should be able to view, edit, and even download a copy of this as an excel document. Hopefully everyone will find this useful.

My disclaimer: I don't claim to be an expert on this stuff - in fact quite the opposite at this point. If you see a mistake, irrelevant line item, omission of something important or useful, or any other opportunity for improvement, I welcome your edits and feedback!

Please edit responsibly!

https://docs.google.com/spreadsheets...it?usp=sharing

[jddewilde]

Hi everyone,
Here's a link to a spreadsheet where I compiled (what I believe to be) a bunch of relevant information for the purchase of a 6090 router. I wanted a way to compare apples-to-apples on the specs of these units, and am using this currently to get quotes from the three companies listed. From the link below, you should be able to view, edit, and even download a copy of this as an excel document. Hopefully everyone will find this useful.

My disclaimer: I don't claim to be an expert on this stuff - in fact quite the opposite at this point. If you see a mistake, irrelevant line item, omission of something important or useful, or any other opportunity for improvement, I welcome your edits and feedback!

Please edit responsibly!

https://docs.google.com/spreadsheets...it?usp=sharing

I orderd a 6090 cnc router from Donglian on Alibaba. It is built with heavy box tubing and heavy side plates for the z axis. Rack and pinion on the X and Y axis. 3 kw spindle, and a large control cabinet. It will be here in 2 weeks. Michael at Donglian has been very responsive to any and all questions

[dalcini]

@Jddewilde - wow, that looks like a pretty stout gantry. Linear rails in both Y and Z - which (unless I'm mistaken) I have not seen previously. It's certainly a nice looking machine, and the increased Z height will surely be nice too. I'll be interested to get your impressions when you receive it.

[aarggh]

I orderd a 6090 cnc router from Donglian on Alibaba. It is built with heavy box tubing and heavy side plates for the z axis. Rack and pinion on the X and Y axis. 3 kw spindle, and a large control cabinet. It will be here in 2 weeks. Michael at Donglian has been very responsive to any and all questions

Very substantial frame and gantry build! You'll definitely be happy with them. You won't however be happy with the table, as the aluminium profile they use is fairly thin and tends to flex quite a bit, especially when clamping materials down. It also is usually extruded and fitted a little less than desirable. For my machine I bought a large sheet of 20mm thick solid aluminium sheet to replace mine with, but after putting a temporary 40mm thick sheet of HMR (Highly Moisture Resistant chipboard) on it some years back, never got around to it as the sheet has well and lasted many years beyond what I thought it would. Which is good as I have too many things on the go all the time anyway.

When you get the machine best bet would be to immediately pull the top off, clean all the sand and swarf that will be encrusted underneath it on the frame (free sand direct from China! Yay!), and then re-enforce it from underneath when you re-attache it to reduce flexing and movement.

cheers, Ian

[dalcini]

Ian, I assume you're drawing on your experience with your Jcut and inferring that Jddewilde's table will be made the same way, correct? Tonight I'm reading through another thread from someone who bought a Jcut 6090B here:
http://www.cnczone.com/forums/chines...6-finland.html

Great information on what to expect - and it looks like he experienced similar issues with the table.

P.S. - I'd be interested in everyone's feedback on the quoting guide. I've already asked vendors for all this info - hopefully I'm not making an a** of myself!

[aarggh]

Ian, I assume you're drawing on your experience with your Jcut and inferring that Jddewilde's table will be made the same way, correct? Tonight I'm reading through another thread from someone who bought a Jcut 6090B here:
http://www.cnczone.com/forums/chines...6-finland.html

Great information on what to expect - and it looks like he experienced similar issues with the table.

P.S. - I'd be interested in everyone's feedback on the quoting guide. I've already asked vendors for all this info - hopefully I'm not making an a** of myself!

Hi Danny,

Yes, looking at the pic the aluminium extrusion looks identical to mine (it's pretty much the same on all these variants), and not really up to the same build level of the machine in general. It will usually be supported at the ends, with a middle cross support. So this actually leaves an awful lot of ability for flex to occur depending on what your machining and how aggressively you're machining. The other thing to consider is any flex means vibration and also the accompanying noise. A little flex means the machine will likely sound like a screaming banshee when your machining something like aluminium. The trick is to strengthen all the parts which in turn dramatically helps to dampen noise and vibration.

Obviously the gantry can only weigh so much given the components used to push it around, but the frame and table simply can't be too heavy or too solid!

cheers, Ian

[JQ_Quint]

@Jddewilde - Linear rails in both Y and Z - which (unless I'm mistaken) I have not seen previously.

The 6090b I had from jcut has linear rails on all three axis....


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[JQ_Quint]

Hi everyone,
Here's a link to a spreadsheet where I compiled (what I believe to be) a bunch of relevant information for the purchase of a 6090 router. I wanted a way to compare apples-to-apples on the specs of these units, and am using this currently to get quotes from the three companies listed. From the link below, you should be able to view, edit, and even download a copy of this as an excel document. Hopefully everyone will find this useful.

My disclaimer: I don't claim to be an expert on this stuff - in fact quite the opposite at this point. If you see a mistake, irrelevant line item, omission of something important or useful, or any other opportunity for improvement, I welcome your edits and feedback!

Please edit responsibly!

https://docs.google.com/spreadsheets...it?usp=sharing

Good work !

Wondering whether it's worth adding motion controller (make & connection)... I settled for an ESS , but if I'm honest I'm out of sorts as to what's available today...but at the time I was encouraged to go Ethernet over USB and parallel port.., & the smooth stepper seemed to be flavour of the month.


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[aarggh]

The 6090b I had from jcut has linear rails on all three axis....


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Mine too!

[aarggh]

Another thing I'd highly recommend for these 6090's that use the same extrusions for the table, is some brush strips along the side of the table, which greatly helps keep the dust off the rails. I bought mine from a crowd that sells the industrial roller doors with spiral brush strips, truck bodies, etc. They coke in various sizes but the 75mm long one in the 8mm square molded rubber insert fits just beautifully in the groove along the edge of the extrusion.

The crappy left shows the brush sticking out above the rail, the even crappier pic on the right shows the rubber inserted into the groove of the extrusion.

cheers, Ian

[JQ_Quint]

Another thing I'd highly recommend for these 6090's that use the same extrusions for the table, is some brush strips along the side of the table, which greatly helps keep the dust off the rails. I bought mine from a crowd that sells the industrial roller doors with spiral brush strips, truck bodies, etc. They coke in various sizes but the 75mm long one in the 8mm square molded rubber insert fits just beautifully in the groove along the edge of the extrusion.

The crappy left shows the brush sticking out above the rail, the even crappier pic on the right shows the rubber inserted into the groove of the extrusion.

cheers, Ian

Super idea....


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[erik65]

Hi Danny, thanks for starting this topic. I recently bought a 6090 laser engraver/cutter from China for a new business startup and my next purchase will most likely be a 6090 CNC router, as a great addition for my product ideas. Probably somewhere in Spring. I just started searching the web, or actually this great forum for all kinds of info about these machines and I stumbled across your yopic with already so much useful and up to date info in it. It's great to see that experienced forum members have pleasure in sharing their knowledge.

So you bet I will follow your 'adventure', it will help me a lot with my final choice.

BTW, making a spreadsheet is a good idea, I did the same for the laser Engraver purchase, where I started with 8+ Chinese companies. It's better not to put price details in it, now one of the suppliers stepped into your topic (although I guess they 'all' scan this and other forums).