Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

Doing an order from TME already, saw they sold toroidals.
http://www.tme.eu/gb/details/tst600w...del/tst600008/

Though it is 600VA not 650VA.
That extra few watts going to make much difference?

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Originally Posted by JOGARA

Doing an order from TME already, saw they did toroidals.
http://www.tme.eu/gb/details/tst600w...del/tst600008/

Though it is 600VA not 650VA.
That extra few watts going to make much difference?

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That will be fine

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Originally Posted by Clive S

That will be fine

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Awesome! Thanks.

And my caps came yesterday.
https://www.aliexpress.com/item/Free...030086709.html

Might as well shove all 5 on?

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Originally Posted by JOGARA

My idea is to then use 15mm polypropylene sheet instead to get the same sort of light wight properties and strength (small sized case, about 100x45mm).

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In my opinion Acetal (Delrin, POM) is the best material. It is not cheap, but it is stable, keeping it's form even in varying temperature and humidity, machinable and you can handle it as you would handle soft metal, yet it is very strong, you can tap it and use ordinary screws for metal. It is not melting easily and the chips produced are nice. I am using it and in my opinion it is the best for milled plastic cases, though it is not light.

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Originally Posted by JOGARA

Are these China CNC milling machines okay for this?
I have seen them eat 10mm aluminium so this should be fine right?

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Can't speak about "China CNC milling machines" in general since I never had one (built and designed my own) but I am pretty sure they can handle Acetal, as well as aluminium, assuming you are using the right feed rate and spindle speed. My first spindle was a cheap 400W DC motor with the maximum RPM of 12000. I used that one for two years on PCB, acrylic and Acetal and is still working, though now replaced with a 1.5kW 24kRPM brushless 3 phase spindle which is of course better. Never the less, it shows that even cheap motors can be used, but you need to adjust the feed rate accordingly. Anyway, with the DC motor I never really dared to work on aluminium, the new one on the other had cuts aluminium just fine.

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Originally Posted by JOGARA

My understanding of milling plastic is speed and sharp tools to reduce heat and thus the plastic melting.
There is less horse power needed as it is more speed than anything, though I still want a powerful spindle for future proofing..

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It doesn't matter which material you work on, speeds and good tools are always critical. Even aluminium melts if you are not doing it right or use bad tools. Anyway, how fast you have to spin the spindle depends on the type of tool and the material, as well as the feed rate. Use a feed rate calculator, practice and learn. Different plastics behave differently, there are even different material qualities, just like there are different grades of aluminium and other material.

I cut everything dry, not using mist and the only air which is blown around the cutter is the one which is sucked in by the dust shoe, so there is not much cooling. Melting is only an issue if you are using the wrong speeds and feeds, or cut too lightly and the chips are far too small. If you must shave material you must be more careful, it is better to produce chips than dust.

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Originally Posted by A_Camera

In my opinion Acetal (Delrin, POM) is the best material. It is not cheap, but it is stable, keeping it's form even in varying temperature and humidity, machinable and you can handle it as you would handle soft metal, yet it is very strong, you can tap it and use ordinary screws for metal. It is not melting easily and the chips produced are nice. I am using it and in my opinion it is the best for milled plastic cases, though it is not light.



Can't speak about "China CNC milling machines" in general since I never had one (built and designed my own) but I am pretty sure they can handle Acetal, as well as aluminium, assuming you are using the right feed rate and spindle speed. My first spindle was a cheap 400W DC motor with the maximum RPM of 12000. I used that one for two years on PCB, acrylic and Acetal and is still working, though now replaced with a 1.5kW 24kRPM brushless 3 phase spindle which is of course better. Never the less, it shows that even cheap motors can be used, but you need to adjust the feed rate accordingly. Anyway, with the DC motor I never really dared to work on aluminium, the new one on the other had cuts aluminium just fine.



It doesn't matter which material you work on, speeds and good tools are always critical. Even aluminium melts if you are not doing it right or use bad tools. Anyway, how fast you have to spin the spindle depends on the type of tool and the material, as well as the feed rate. Use a feed rate calculator, practice and learn. Different plastics behave differently, there are even different material qualities, just like there are different grades of aluminium and other material.

I cut everything dry, not using mist and the only air which is blown around the cutter is the one which is sucked in by the dust shoe, so there is not much cooling. Melting is only an issue if you are using the wrong speeds and feeds, or cut too lightly and the chips are far too small. If you must shave material you must be more careful, it is better to produce chips than dust.

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Would that mean one should do fewer slower deeper passes, as opposed to faster more shallow passes?

Sent from my SM-G930F using Tapatalk

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Originally Posted by CrazeUK

Would that mean one should do fewer slower deeper passes, as opposed to faster more shallow passes?

Sent from my SM-G930F using Tapatalk

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I don't think there is a simple answer to that, since it depends on the material, but in general terms it is better if the material is not shaved or rubbed off because that generates too much heat and causes melting. So, some times increasing the depth may help, other times increasing the feed rate, or the spindle speed, and again, some times all three. I am not afraid of doing shallow cuts if needed, but in that case I do it with very high feed rate and the spindle speed, feed rate and the quality of the cutter is more critical there.

When I notice melting (mostly when different acrylic qualities are used) then I try to guess if the feed rate is too slow or if spindle speed increase can be a solution, or if deeper plunge would help. I am by far an expert but normally I can guess pretty well based on my experience, adjust and do it right next time. In my experience it is not always working to have pre-calculated parameters, and one which works this time may not work next time if the material is not exactly the same batch. Never the less, when starting with new material or cutter which I don't have experience with, using a feed rate calculator is a good idea because it gives me a good reference to start from. If the calculated values work then I use it or play with different values in the calculator if I intend to change something, for example if I want to increase feed rate to finish a job faster.

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Originally Posted by CrazeUK

Would that mean one should do fewer slower deeper passes, as opposed to faster more shallow passes?

Sent from my SM-G930F using Tapatalk

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It also depends on your machine, in fact it's mostly about your machine and how stiff it is and what type of cut you're doing. If you're slotting then you have to go slower or shallower than if you're doing a 60% width stepover pocketing pass.

I'm about to cut some more samples (see photos below) at work in Acetal and I'll be doing 20mm deep cuts with a 6mm 2 flute uncoated carbide mill, I'm using Trochoidal milling mind so don't try to take that deep a cut normally!!

Attachment 21139Attachment 21138Attachment 21140

Getting close to the point where I want to buy.

Am I better off just trying to buy a VMC like a Tormach 1100?
I have been looking around for one for a few weeks but they are a bit rare over here.

Also trying to find other options though they are at least £10,000 :/


Might it be worth spending a bit more trying to get a decent 6040 like frame rather than messing with a China frame?
The thing is the part I want to make is not that tricky I don't think. Looks like we will be using 15mm thick aluminium.

Surface finish needs to be at a point where I can just sand it down to a fine grit for anodising.

Thoughts?

[edit]
Looking at some videos, it looks to do fine with pretty deep stuff...
https://youtu.be/KVmf_dac8gY

Again within reasonable bounds, the depth of the material really isn't hugely relevant to the machine's ability to cut it... as long as a tool in an appropriate diameter and length can be found then it really just becomes a question of number of passes.

That last piece must have taken ages to machine at that speed and depth, but as you can see most of these things will have a stab at alu.

If going the chinese router path, I do recommend you avoid any round or unsupported rails if alu is on your to-do list, having owned both I can say you will have much less frustration if you get one that at least has proper HG20 rails... take a look at omioCNC - they make some of the better chinese routers imo (I own an X6-2200L at the moment, building myself a new bigger badder one mostly for fun). If you wanted to go sans-electronics they would probably sell a bare frame if asked.

This is an example of a 20mm plate cut on my X6-2200L:


http://i.imgur.com/y6jXlPu.jpg

http://i.imgur.com/XAAhxhX.jpg


https://www.youtube.com/watch?v=kUc4bTgPjoI

Ill check them out. I get what you are saying and from the looks of the video it is totally worth it.

Where do you get your cutting bits?
Not really looked into that yet.

depends, I use a few places.

Shop-apt are quick and good quality, but I generally use aliexpress a lot these days... there's some really high quality stuff on there at decent enough prices, you just have to wait a bit longer to get them. I've also ordered stuff from BZT in the past for some specific bits I wanted (diamond coated ones for CF), shipping was ridiculous though...

Okay so you pretty much sold me the omioCNC...
Few other threads on it show that it is pretty good.

Question is, do you still use the stock components like the controller, steppers, drivers etc?

And what accessories to get?

Ta

Why dont you add to your mental map a what a good DIY cnc can do.

6mm depth of cut aluminum, perfect finish. Not 0.6mm, :smiley_simmons: like on video you were watching but real 6mm at around 2000 mm/min , and slot cutting, mind that.

https://goo.gl/photos/f69ooiHd6JN8Q5Ur5

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Originally Posted by JOGARA

Okay so you pretty much sold me the omioCNC...
Few other threads on it show that it is pretty good.

Question is, do you still use the stock components like the controller, steppers, drivers etc?

And what accessories to get?

Ta

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Hah I'm not trying to sell you on it - just that if you are going the Chinese router direction, that is one of the better ones. It still has it's issues but you pay your money and you take your choices...

I am not using many of the stock components anymore, although there was nothing wrong with them. I changed the motion card mostly because I wanted to try out mach4 and also because I prefer Ethernet to USB... the stock card worked fine with Mach3 though and I didn't run into any obvious interference issues. I also changed the motors over to leadshine closed loop easyservos, the rest of the electronics I kept (PSU, VFD, Spindle) although I'd like to change to a toroidal at some point.

The biggest issue for me is that they (like seemingly all Chinese routers) don't ground the spindle. When I mentioned it they said grounding the spindle can cause interference issues with the USB card, but it's a point of safety so to my mind it needed to be done.

I changed to a 4 core shielded cable for the spindle, and re-wired the box into a star point earth... doing it that way I never had interference issues.

Accessories wise you just need to figure out what you need or want for work holding (vise, clamps, spoil board, vacuum board etc), and a good set of high precision ER collets in the sizes you want is a sound investment. Beyond that just a few cheap cutters to get started with as you will probably break some while getting to grips with it.

Just one more question for everyone. I need to basically set up multiple stations on the CNC to do different operations.

What is the best way to get positional accuracy with the drill bit and workpiece?

I have seen John over at NYCCNC on his Tormach and HASS use a device that sits inside the collect to get XYZ positions as well as a little cube that gets the drill bit position.
Is that an option with Mach3 and this sort of CNC?

Was going to mill a 10mm plate to put vices on that can then be squared and made repeatable. But it is that first setup each time I want to make sure I am a 0.01mm accurate.

Thanks
Jack,

I just recently got one of these... I think it's pretty good for the money and certainly the only one I'm aware of in this sort of price range that uses contacts submerged in di-electric oil to avoid the oxidation problem.

http://www.kurokesu.com/shop/TPA2

Quote:

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Originally Posted by JOGARA

Just one more question for everyone. I need to basically set up multiple stations on the CNC to do different operations.

What is the best way to get positional accuracy with the drill bit and workpiece?

I have seen John over at NYCCNC on his Tormach and HASS use a device that sits inside the collect to get XYZ positions as well as a little cube that gets the drill bit position.
Is that an option with Mach3 and this sort of CNC?

Was going to mill a 10mm plate to put vices on that can then be squared and made repeatable. But it is that first setup each time I want to make sure I am a 0.01mm accurate.

Thanks
Jack,

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I just googled "touch probe mach3" and I get 83,400 hits... :)

...along with pictures, and build instructions of everything, from simple touch plate to complex 3-D probes.

A simple conductive material works fine and will give you the accuracy, but remember that your accuracy depends on what you calibrating with as well. A touch probe is connected to one of the free inputs and you configure that input in Mach3 as "Probe". The thing is that you need a macro to get it working as well, but there are plenty of those available freely if you don't want to write one. Once you have the macro you have to attach that to a button and call it every time you intend to use it. It is pretty simple but maybe you need to spend some more time if you have never done it before.

I am using a simple PCB piece most of the time, it works just fine, but have plans on making something more advanced, but it isn't highest on my priority list.

Repeatable accuracy to 0.01 mm is pretty demanding. I know that on my own machine I can get repeatability to +-0.003mm - one microstep, in other words. However, accuracy is another thing, and apart from anything else you are going to need a decent set of collets. As already said, you can do this kind of probing with a simple accurate block plus a straight plain shank in a collet, or spend hundreds or more. For ease of use, you might also want to look at an upgraded Mach3 screenset. Gerry"s 2010 screen set is widely recommended and includes probing functions - a Google search will find it.

Is it worth paying £735 more for the X8?

X6
(X)355×(Y)510×(Z)85mm
57BYGH76-3A steppers


X8
(X)565×(Y)770×(Z)85mm
60BYGH86-4.2A steppers

Controller wise, the X6 uses Mach3. The X8 has an embedded system.
Does it still have usb input for Mach3?

The nearly double workspace is tempting...
Just don't fancy only using their hardware controller.

Thinking about it, £735 is a lot... Never mind

Bigger is good, if you need the space...

Bigger also however means less rigid for the same given design (as is the case here), so if that space isn't going to be used then it does have a negative aspect to consider.

I'm sure they could supply the X8 with the black control box if requested.

Quote:

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Originally Posted by Zeeflyboy

Bigger is good, if you need the space...

Bigger also however means less rigid for the same given design (as is the case here), so if that space isn't going to be used then it does have a negative aspect to consider.

I'm sure they could supply the X8 with the black control box if requested.

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Went with the X6.
Don't really need the size of the X8, yet :p

Ordered a full set of collects and some 1mm and 3mm bits.

Looking at vices, got 2 cheapo ones from Ali, they look okay but not proper strong.
Will see if they work okay or not. If not, can use them for lighter material at least.

https://s22.postimg.cc/4w9bjlt8h/IM...432475_HDR.jpg

Not fully set up yet. Wish the cables were longer so I could have the controller elsewhere.
Done some tests and it looks to work well.

Just got to get some distilled water and some bits for my air compressor and we should be good to go!


The whole rig feels super strong. Not like steel strong but nothing moves if you push against any faces.


The only thing that came broke was the infamous pump...
https://s22.postimg.cc/x1w40cnq9/IM..._153302318.jpg

interesting, few design tweaks from mine - they are using a different kind of alu for the side arms (mine doesn't have that channel in the front edge) and looks to be using HIWIN, or HIWIN copy I suppose, carriages where mine was using something else.

Glad it all arrived safely, have fun!

Monster thread on CNCzone about that machine, has some good info in it.

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Originally Posted by Zeeflyboy

interesting, few design tweaks from mine - they are using a different kind of alu for the side arms (mine doesn't have that channel in the front edge) and looks to be using HIWIN, or HIWIN copy I suppose, carriages where mine was using something else.

Glad it all arrived safely, have fun!

Monster thread on CNCzone about that machine, has some good info in it.

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Not read threw that thread yet. On my todo list :p



Cut some wood this evening to test it all out.
https://s27.postimg.cc/anugwvtr7/IM...726776_HDR.jpg
(Obviously not cleaned it up or used a 2nd op to chamfer it. "Dog Shed" is what we call my workshop fyi, because the dogs live in it)

Worked really well. Went from Fusion 360 to this in no time.

Water got a bit warm. Using 15L of Halfords de-ionised battery topup water.
What temp should I be concerned at? A few places are saying 30-35C max. I have another 15L worth but I need some for my laser (obviously can go get more).

Thinking I might make a single 60L system with 2 pumps (one for each tool) and also a radiator with fans on to circulate the 60L tank with air cooled water.
Wont really be using both at the same time, but rather have one large tank of water than the two if it is okay to do so.


My Ecocast from Aliwarehouse also arrived. Had some concern about these guys from reading a few threads on here but this lot came in 2 days without a blemish on them.
https://s29.postimg.cc/t3b9jj113/IM...628325_HDR.jpg

Downcut bits will avoid that rough edge that you can get on wood like that, might be worth picking some up. Work well on plastics too for the same reason.

I've always found aluminiumwarehouse ok.

I wouldn't over-think the cooling... there isn't that much heat to dissipate. Mine works fine with a small closed loop system (basically a single PC water cooling radiator and pump). Certainly no need to have a 60L system AND a radiator.

If you want to have a big combined cooling system for both your laser and your CNC then sure, why not. Seems to be over-complicating things though.

Cheers on the machine!. Sth is not right with that wood cut. Try 16000- 17000rpm, bit diamenter depth of cut and 60IPM / 1500mm/min. That generally will work on any machine, even a flimsy one. 16000-17000 on soft wood, 17000-18000 on hard wood. Mdf and similar.

Just got my new vice. Decided against the 2 cheap ones from China that cost £100. Went with a single one for £80 that is built for "light milling". Feels solid enough for what I need.

Holds my 150x100 aluminium perfectly and there is room to put bigger bits in there.
Will work on the mounting of it to the base though.

https://s13.postimg.cc/azsa7h3jb/IM..._115926548.jpg

Only getting 1-2 hours a night to play with it all atm.
Got to finish a load of uni work :/

Also need to work on my speeds and feeds...

looks like it should be fine.

Just beware that your bed won't be level, so bolting the clamp directly to the bed won't give you a level surface either.

Ideally you need to bolt on a spoil board of some description and use the machine to skim it down. That will give you a flat surface to screw the clamp down into.

Quote:

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Originally Posted by Zeeflyboy

looks like it should be fine.

Just beware that your bed won't be level, so bolting the clamp directly to the bed won't give you a level surface either.

Ideally you need to bolt on a spoil board of some description and use the machine to skim it down. That will give you a flat surface to screw the clamp down into.

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Yea I heard about that being a problem and looks like it is a bit off.
Wood enough for a spoil board when working with aluminium?

MDF or similar would be ok as long as you aren't using much coolant. If you have any moisture resistant lying around that is a bit more stable in terms of dimensions and changes in humidity etc but far from essential.

You could also just bolt down a small piece where you intend to put your vice, rather than the whole bed. You would just have to re-skim it if you remove it but that's not a big deal for a small piece like that.

Quote:

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Originally Posted by Zeeflyboy

MDF or similar would be ok as long as you aren't using much coolant. If you have any moisture resistant lying around that is a bit more stable in terms of dimensions and changes in humidity etc but far from essential.

You could also just bolt down a small piece where you intend to put your vice, rather than the whole bed. You would just have to re-skim it if you remove it but that's not a big deal for a small piece like that.

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That's a good idea. I was planning on keeping the vice at the far left side and leaving the rest available to other projects that I need to do.

So this is the case that I am milling out of EcoCast.

https://s29.postimg.cc/eh3smgtjr/Capture.jpg

These are the end mills I have so far.
3.175mm http://www.ebay.co.uk/itm/1824106825...%3AMEBIDX%3AIT
2mm https://www.aliexpress.com/item/10pc...608.0.0.EJZ3Jx
1mm https://www.aliexpress.com/item/10pc...608.0.0.EJZ3Jx

The case is like 75x60mm so I don't want to carve that all out with a 3.175.

Was thinking of getting something along the lines of a 6mm end mill to do the main hogging out.

What is the max these spindles can take?
I have collets up to 12mm.


Also, where is the best place to learn speeds and feeds? I have been testing these 3mm on a bit of this EcoCast and broke 2 end mills within minutes.
One I accidentally knocked into the work piece. The other because I did not know how to correctly set up the Z in Fusion CAM.

Have you thought about using foam etc. to practise on that way it will be more forgiving when you dive into it.

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Originally Posted by Clive S

Have you thought about using foam etc. to practise on that way it will be more forgiving when you dive into it.

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No fun without danger of snapping a bit though :p

The wood carving was fine. Just need to learn about the speeds and feeds for when in Fusion.

6mm Single Flute is my general use bit when cutting Alu unless I need smaller for radius/slots etc. I have a 2 Flute 12mm I tend to use for hogging out plastics, that's the largest I have used so far, works great.

3 Flute roughing bits also pretty useful but I do find them a bit harder to get right without coolant, easy to start welding chips if you're a bit off the sweet spot. Single Flute is much more forgiving in my experience and well suited to the high speed spindle.

G-wizard can be a good place to start for feeds/speeds. Think it has a 30 day free trial.

The only place I found that does larger single flute end mills int he UK is this eBay seller, http://www.ebay.co.uk/itm/6-0mm-Soli...YAAOSw5cNYTbtV
(looking at it, they are not from the UK, yet they put their location as UK...)
Know of any more?

Quite pricey though and around the same shipping time as e-EMS on Ali.

Tempted to buy a dozen or so bits from Ali and pay for the faster shipping.


[edit]
Can find a load of 2 flute on there. http://www.ebay.co.uk/itm/2-FLUTE-CA...DARtSupNGbvLLw

Ordered a 4 flue 6mm and 3mm off Amazon to experiment and compare with.
Just want to see the difference.

I've used these guys before (UK based) for their Belin Single Flute Downcut bits... not the cheapest but good quality.

http://www.cncroutershop.com/uk_en/

They have a good selection of Single Flute upcut bits too, including their own brand.

Other than that I tend to use AliExpress, most stuff comes within a couple of weeks at most even slow boating. I've used these guys before and quality was great.

http://s.aliexpress.com/QRnaE3ia

Roughing bits might be worth looking at too:

http://s.aliexpress.com/j6vqyuAN

Oh and another thought - if you are just doing a small levelled area for the clamp to bolt into, consider using something that will be a bit more resilient than mdf like tufnol kite board or even a skimmed Alu plate. You could thread directly into either and it'll be more moisture resistant.

Also re fusion - set up cloud library and do your own tool library. Much quicker and easier than searching through their generic one and you won't have as many mishaps with wrong feeds/speeds.

Quote:

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Originally Posted by Zeeflyboy

I've used these guys before (UK based) for their Belin Single Flute Downcut bits... not the cheapest but good quality.

http://www.cncroutershop.com/uk_en/

They have a good selection of Single Flute upcut bits too, including their own brand.

Other than that I tend to use AliExpress, most stuff comes within a couple of weeks at most even slow boating. I've used these guys before and quality was great.

http://s.aliexpress.com/QRnaE3ia

Roughing bits might be worth looking at too:

http://s.aliexpress.com/j6vqyuAN

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Quote:

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Originally Posted by Zeeflyboy

Oh and another thought - if you are just doing a small levelled area for the clamp to bolt into, consider using something that will be a bit more resilient than mdf like tufnol kite board or even a skimmed Alu plate. You could thread directly into either and it'll be more moisture resistant.

Also re fusion - set up cloud library and do your own tool library. Much quicker and easier than searching through their generic one and you won't have as many mishaps with wrong feeds/speeds.

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I was just editing my thread with my findings on Ali as you replied. :p

These are the ones that I have spotted on Ali. The second store being about twice the price of the first store.
Saite_Cutter Store
3.175mm http://www.aliexpress.com/item/5pcs-...999.262.ohQh0J
5mm http://www.aliexpress.com/item/Free-...999.268.ohQh0J
6.35mm http://www.aliexpress.com/item/Free-...999.265.ohQh0J

Shanghai CNC HOME Ltd. Co.
https://www.aliexpress.com/store/pro...612.0.0.1GtQBZ


Looks like the Shanghai CNC HOME is the one to go for then if you are suggesting it.
Happy to pay more for the bits if they are better obviously.

Those roughing bits look good too. Seen NYC CNC use them and they just rip through the material.


Was thinking of getting a sheet of Polypropylene for the spoil board as it is pretty strong?
Ideally i'd go Aluminium but I wont be ordering again for a few weeks to make it worth shipping the dam thing.


I have already started putting the tools I have so far in the library.
Did not bother with their stock items as I pretty much guessed that the eBay and Ali stuff would not be on there.

Also got a trail of the G-Wizard and making sure I have the correct feeds and speeds set up for those bits.


I have been reading up on the flutes being up or down.
Isn't the up flute better suited for chip evacuation?
Going to be mostly milling out 15mm deep stock so pulling up the chips rather than having them go down would be better over the down cut bits?

Its not like my vice can't handle it, that thing is a little beast.
(Obviously not as good as the ones you get on the industrial machines, but you know what I mean....)


Again thanks for the help.
Really do appreciate it.

Price isn't necessarily an indication of better quality, if the reviews are decent and the parts look good then have a go - I just linked to the store that I have personally ordered from in the past.

For Alu, yes upcut is definitely what you want as chip evacuation is vital. Ideally one would also be using compressed air (with added bonus points for mist coolant) with a nozzle aimed to blast any chips out of the way.

I initially bought Downcut for some closed cell foam I was machining for custom cases/tool trays. They are mostly of use in softer materials where the top edge can be a bit rough with an upcut bit. Compressed air or a vac shoe can help with chip evacuation there.