Greetings from Nottinghamshire

I am wanting to buy/build a cnc router, primarily for wood working (birch ply) but with the option to machine small non ferrous metallic components infrequently.


A specific job I have for the cnc router will be to machine audio horns – see attached picture. Attachment 18230 I will profile layers and glue them together. The maximum size I will be making is around 700 mm x 500 mm. I don’t expect to 3D machine them but to 2 ½ D machine them with 1-2mm steps, which will be sanded post assembly.



I have been looking at a number of posts on this website and others and estimate that a cnc machine is going to be £1500 plus just for the parts. I have no real desire to build the machine, so I had been looking at commercially marketed machines too.

What is the general opinion about Chinese steel framed machines in the £3K sector, as I feel that this is the level I would want to compare too? Buying may be cheaper as a couple of hundred quid can be lost with a few errors. I am also time poor currently.



I have little NC experience – last time I was involved it was on punch tape! I am a professional design/stress engineer with a varied past, from designing complicated handling delivery systems to designing large fabrications for the aero industry. No machine/fixture design experience unfortunately.


If I am to build, ( deep down the engineer in me wants too) I feel comfortable with the mechanical side of designing the gantry and rails – after following a number of the build threads on this site, I am starting to understand the pro’s and cons of different arrangements.

I think I have decided on a few things.


Machine Size - obviously it would be nice to be able to nest and machine a full 8 x 4 sheet. I cannot fit it in my workshop, and for the once a year job – I could not justify it. To build the largest wooden horn I will ever get asked for a 900mm x 600mm bed will be adequate. In the z axis I was going to stick with around 150mm, anymore than this and the work piece will vibrate, never mind the machine.

For the X Y & Z slideways, I was thinking profiled rails. 20mm Hiwin or similar.

I just have a concern with accumulating dust/debris on the rails – are the wiper seals on the carriages – that good? (The answer to this will decide on whether I mount the rails on the top of the frame – or protected down on the side)
I have been looking into how to purchase the Hiwin rails and carriages economically – I see you can get the carriages from BST in china for a good price – but its not really economic to ship the rails. Is there any reason why I could not have the carriages shipped and purchase the rails in the UK? (Different standards/specs etc)

It also seems to be cheaper to buy single longer rails. I was also thinking I would get a couple of longer rails and cut them into my 3 lengths – I assume they can be cut with a disc?



The frame I was going to use aluminium profile sectioning – having used it for a couple of “work” jobs it seems to allow a robust construction without the need for a full fab/machine shop. (Obviously if I had a 2 metre bed machining centre I would fabricate and have the rail pads machined – post fabrication). I am hoping if necessary I could fill the profile rails with sand (concrete maybe) to damp out vibrations – reduce cutter chatter.






I was thinking of using 80mm x 160mm profile for the Y carriage. With similar for the x axis support structure ( twin x axis ball screws).


I am waiting on some info back from a friend who is a HGV coach builder– to see what aluminium sections he can get me for free.



What I don’t have a clue about is the electronics and what is current and is best for this application and what is OTT. From reading threads on this forum, it seems like this bit I sort out after I have finished the mechanical side, I would like an idea of the cost of a “good” 4 motor & controller system.

Sorry for the epic first post……

Steve

In short- take the calc and you will see that ball screws, machining, Hiwin rails, carriages, spindle and VFD bought altogether from BST will save you a lot, even if shipping is costly. have been there, done that :single_eye:

Hi Steve
Welcome to the forum
Have a look @ this
http://www.aliexpress.com/item/Linea...3-b80a321ce5ef
Regards
Mike

Sorry about the multifont post - looked okay on the ipad - but wrong on the PC.

Well thanks for the link to the bellows - that can definitely mitigate the risk of dust/chipping on the bearings.

Regarding buying everthing from BST - i have been expoilting some of the free postage offers they have had for the ball screws so almost have all of those, seem reasonable quality ( can only come to some SKF ones i used a few years back). I haven't been that lucky so far with import duty - and think that i will be financially worse off importing the rails from china. So back to my original question is there any reason why i cannot buy the rails and carriages seperately, my worry would be getting the carriages onto the rails if they are a very tight fit - i assume that a chamfer could be machined onto an end -to ease fitting.

I don't have a lot of luck with imports either but a lot of chinese sellers are using european distribution warehouses which then negates the problem for the buyer and still works out a lot cheaper than buying from UK suppliers.

Keep us updated regarding the rails and price, i have been collecting bits and bobs and have 20mm HIWIN carriages but on AliExpress most of the sellers seem to sell rail with two carriages. missed a couple of 1Meter rails that were on sale from a forum member.
Regards
Mike

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I have been looking at a number of posts on this website and others and estimate that a cnc machine is going to be £1500 plus just for the parts. I have no real desire to build the machine, so I had been looking at commercially marketed machines too.

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Welcome to the forum Steve. I would be careful of buying any stuff until you have a design sorted out as that is one of the biggest mistakes people make as the plan will evolve and change over time. Also don't buy any electronic kits and they are never matched or correct.

There are one or two people on the forum that do build bespoke machines and usually to much higher quality than you can get for the same money. Good luck with whichever way you decide to go.

Clive, Thanks for the words of wisdom. I was only going to purchase the rails and the ball screws. Which will be the same for what design style I chose.

Can somebody give me a link/picture to some examples of the build quality of these "bespoke" machines, to give me an idea of what my potential diy effort will be up against.

I like this one
/threads/9694-Hello-from-Slovenia-first-time-CNC-builder
Dean(JAZZCNC) had input on this one so can't go wrong if you follow his lead.
Mike

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Originally Posted by Stressedwoodman

Can somebody give me a link/picture to some examples of the build quality of these "bespoke" machines, to give me an idea of what my potential diy effort will be up against.

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Here you go one designed just for cutting wood and light aluminium work.

Attachment 18254Attachment 18255Attachment 18256

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Originally Posted by JAZZCNC

Here you go one designed just for cutting wood and light aluminium work.

Attachment 18254Attachment 18255Attachment 18256

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Nice paint job how about a pic. of the control box:star:

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Originally Posted by Clive S

Nice paint job how about a pic. of the control box:star:

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Here you Go.!

Attachment 18267Attachment 18268

Just starting to collect all the essential bits (linear bearings etc). I am just going around (again) if it's more economic to get the hgr20 rails in the uk. I was going to get the rails from " cnc4you" but have questioned if there hgr20 rails are Hiwin, or a patent part, still waiting an answer. Does anyone know if they are, and if not a uk stockist I can get a quote off.

btw - just getting my head around importing all the standard parts into NX, so I can post my machine design, for your critic.

I bought some rail and carriages from CNC4YOU a year or two back. Can't be definitive about the rails as I can't see any markings on them but the HGH20 carriages are clearly marked Hiwin.

Got a response back from cnc4you, they are an equilivant rail. The million dollar question is are they going to be as good as hiwin ones? Experience anyone?

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Originally Posted by Stressedwoodman

Got a response back from cnc4you, they are an equilivant rail. The million dollar question is are they going to be as good as hiwin ones? Experience anyone?

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I think they will be more than good enough for a hobby build I would doubt that you could tell the difference.

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Originally Posted by Stressedwoodman

Got a response back from cnc4you, they are an equilivant rail. The million dollar question is are they going to be as good as hiwin ones? Experience anyone?

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Have you tried Fred at BST because I doubt you'll buy them cheaper in UK or even get close on price and they are genuine Hi-win.

Got a quote back from Fred. I have also got a quote from "transmission CNC" for the same which significantly less - anyone used them, seem to be a medium preload fit which I am not sure if that's an issue or not.

Hi
Could you post a link for transmission CNC
I have been looking for Hiwin rails and do not find Fred to be the cheapest supplier. are the rails from transmission CNC etched Hiwin.
Mike

Here is the link
http://www.aliexpress.com/item/HIWIN...999.263.UMYDXN

No one got an opinion whether medium preload is too much or not for a medium sized CNC router.? I am finding difficult to predict what sort or resistance this would be from the data sheets. I don't want to end up needing bigger motors just to move things.

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Originally Posted by Stressedwoodman

No one got an opinion whether medium preload is too much or not for a medium sized CNC router.? I am finding difficult to predict what sort or resistance this would be from the data sheets. I don't want to end up needing bigger motors just to move things.

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Medium preload should be fine...

Higher stiffness at the expense of life span and force required...negligible for home build :).

Stiffness values http://www.automation4less.com/pdfs/hiwinaglg.pdf

.Me

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Originally Posted by JAZZCNC

Have you tried Fred at BST because I doubt you'll buy them cheaper in UK or even get close on price and they are genuine Hi-win.

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I saw BST mentioned somewhere in a post earlier too, while browsing for Bellows and Wipers (neither of which I installed when I finished the machine!) - is it BST Automation on Aliexpress you refer to? I think a couple of years ago I read Chai from Linear Motion Bearings was good so I sourced from him. Where do people tend to source these days (I might need another ballscrew if I can't get the wooddust out of this one!) and what's the quality like?

EDIT: Oh or these? BST Linear

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Originally Posted by mattnedgus

I saw BST mentioned somewhere in a post earlier too, while browsing for Bellows and Wipers (neither of which I installed when I finished the machine!) - is it BST Automation on Aliexpress you refer to? I think a couple of years ago I read Chai from Linear Motion Bearings was good so I sourced from him. Where do people tend to source these days (I might need another ballscrew if I can't get the wooddust out of this one!) and what's the quality like?

EDIT: Oh or these? BST Linear

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Chai is a good guy but BST seems to be the place to go to now. I have purchased from both and been happy though.

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Originally Posted by Clive S

Chai is a good guy but BST seems to be the place to go to now. I have purchased from both and been happy though.

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I was happy dealing with Chai but it's always nice to see what others have to offer (and I wasn't sure if Chai was still going) - did I have one of the links right for BST?

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Originally Posted by mattnedgus

I was happy dealing with Chai but it's always nice to see what others have to offer (and I wasn't sure if Chai was still going) - did I have one of the links right for BST?

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Yes the link is http://www.aliexpress.com/store/314742 he has a gmail account on there and Fred always answer his emails I would contact him via email for a quote.

I believe Chai is still in business.

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Originally Posted by Clive S

Yes the link is http://www.aliexpress.com/store/314742 he has a gmail account on there and Fred always answer his emails I would contact him via email for a quote.

I believe Chai is still in business.

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Cheers Clive, much appreciated! I received an email back from Chai regarding bellows (they don't do) so he's still on the go which is good to know!