New Build Advise Ive Got Myself So Confused ! Please Help !

Hello Everyone as everyone normally starts on these things I have been Lurking here and CncZone for Quite a while soaking up as much information as I can although Now because I have read and reread so many different ways of creating a CNC machine I am starting to send myself around in Circles.

The vast amount of knowledge that you all have collectively if amazing so I am hoping to borrow a little.

I am a person that likes to make things anything really. Normally wood is what I am the most comfortable with but now am living with metal a little easier, I have bought myself a Tig welder and learning this too it is all building my tools to build My Ac Cobra replica that has sat in the garage for 4 Years waiting for me.

I want my Cnc to be a general help in the Home I have a 16 Month old daughter that I want to make everything for including a dolls House & for The Metal parts for the Cobra and Machining some Fibreglass Moulds from Foam, I have already bought my rails from Alibaba which I have had 20mm Supported Rails & C7 Screws and these were already machined and all bearings and holders are included and these seem very good quality the rails are 1100mm x 600 mm x 300mm.

Ok so the main issue is What to make it out of Steel or Aluminium Profile for the best strength I know that steel will be more rigid in theory but because of the Profile patterns running to the centre is this so ? are these stronger instead of a square tube, If it was steel I am thinking 50x50 but the main issue is can I weld it and make it without it twisting to get the build quality right, where if I use aluminium Profile I thought 60x60 from These guys ? Profile 6 : Aluminium Profile 6 60x60 I must say that the Aluminium would be my preferred build method because it takes me so long to finish anything these seems a little easier and so I might actually finish it one day.


I want to be able to possibly cut up to very thin steel but don't care really how many passes it would take for it to do it and it would only be occasionally and I wouldn't be after the highest tolerances because Otherwise it will be my hands and a hacksaw to do the job.

I have thought that I could use Aluminium profile and then initially use MDF to stiffen the Sides and the Horizontal slide and then machine the Sides out of 20mm Aluminium after with the CNC to get a better job and make it stronger as I go.

I am sorry to waffle on but I suppose really I am asking the age old Question is Aluminium profile as strong as steel or if ali the way to go for a start in CNC for my Hobby.

Thank you all for the great new hobby you have all enthused me into

Thanks Rob

I built my frame from steel angle and the gantry from alu profile. While this works well for most of the stuff I have been doing it is failing to produce good cuts on some of the things I am pushing it to do now.
So the upshot of this is that I am now designing a new one made from steel box section.
For the most part the frame does not have to be perfectly straight, you can always shim it to get things level.
As for milling steel I wouldn't even think about it.

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Originally Posted by Web Goblin

As for milling steel I wouldn't even think about it.

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I think you used the key word there, "milling", for me I think of router for wood, plastic, foam, etc. and for metal I think of milling machine. When you look at some of the builds on this site though I can see how a router could tackle softer metal such as aluminium if strength and stiffness is built into the machine.

Hey guys thank you very much for the replies, I think you are right I have been trying to get it to be all things and so it has been making the decisions harder, I think that It might come down a little to budget and so I will have a look at the half Steel and Half Aluminium. I thing I have been suffering a little from keeping reading but then never just starting and seeing where i go I suppose once you have some sort of machine its easier to see where to go next.

Ok well first like what has been said forget milling steel. 1: The machine has to be Sooooooo much stronger to do it, 2: The rails you have bought if round type are not upto it, 3: The spindle speeds for cutting steel need to be so much lower than even aluminium you won't find a spindle at sensible money that can do it.

Has for the rest then that's very easily do-able with the right design. Regards Aluminium profile then it's no stroger than steel and will cost far more than you probably realise because it doesn't end at just buying the profile, all the other hidden things like connectors and T-nuts can a nd do cost nearly has much.
It's also no easier to build with than steel and all that applies regards setting rails on same plane etc still applies and is no easier with profile.

Steel is a fraction of the price and again if used correctly with right frame design then easy to get very accurate with not too much effort. Apply a few tricks which you'll find by searching the forum and you'll build a very accurate and strong machine for much less than you will a profile machine.

You'll see many references to whats needed for a good all round machine from both Jonathan and me who often use steel. Just search the forum.!

If you get stuck or are unsure drop me a PM and I'll help if I can.

Hey JAZCNC Thank you so much for the help, Yes the rails are the supported type thanks for the names to search on the Forum, One of the problems I have had is not really knowing what to search for really so head through A little aimlessly.

I would like to make it out of steel really because I would like to get the practice using the tig, Although I was looking around and steel seemed to be a similar cost to the profile but didn't really think of the fixings costings being as high as the profile.

I bought some steel once from Mild Steel Online | No Minimum Order | Free Delivery On Orders £70+ and they currently have a 10% off mild steel but it doesn't say if it is Cold rolled or not as I have read on here that it is better to go for. For the steel cnc design I did favour the high sided cage design with the rails high and then the gantry sitting right on the rails as it seemed more sturdy but I don't know if this is best to opt for or go for the standard gantry design.
I was also unsure how to really get the frame square if I have to buy a digital level instead of a spirit level ?.

I guess if steel was ever really needed a plasma add-on is always possible but when I have watched youtube it doesn't ever seem to be a Sharpe cut.

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Originally Posted by grain_r

Hey JAZCNC Thank you so much for the help, Yes the rails are the supported type thanks for the names to search on the Forum, One of the problems I have had is not really knowing what to search for really so head through A little aimlessly.

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Fatal to do that and you should always ask no matter how dumb you may feel because it's very easy to buy the wrong stuff and chances are someone will know a cheaper source.

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Originally Posted by grain_r

I would like to make it out of steel really because I would like to get the practice using the tig, Although I was looking around and steel seemed to be a similar cost to the profile but didn't really think of the fixings costings being as high as the profile.

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Well all I can say is you have been looking in the wrong places. I'll say it again but said it many times on the forum, go to your local steel supplier and get a price. I can buy 7.5mtr lengths 50x50x3 for around £30 so a good steel supplier will be around the same.

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Originally Posted by grain_r

I was also unsure how to really get the frame square if I have to buy a digital level instead of a spirit level ?.

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Doesn't matter about the level of the machine so save your money. What matters most is that the surface the rails sit upon are on the same plane and parallel to each other.
Has for the frame being square then that's not so important again whats important is the Gantry is square to the rails it runs upon. To square the frame then just carefull measuring across the diagonals is enough.

Like I say search the forum and you'll see many examples of people showing how they set rails on the same plane and some of the tricks like adjustable top rail. Epoxy resin and Epoxy putty along with adjustable top rails make aliagning easy enough.

Steel frame with high sides and adjustable bed is the way to go if you want a decent all round machine.

Good luck.

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Originally Posted by JAZZCNC

Well all I can say is you have been looking in the wrong places. I'll say it again but said it many times on the forum, go to your local steel supplier and get a price. I can buy 7.5mtr lengths 50x50x3 for around £30 so a good steel supplier will be around the same.

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Correct, cost me £32.93 local for same stuff

I advise you to check the Keiton Engineering Co. Ltd - Steel Suppliers

Keiton Engineering are steel suppliers of an extensive range of carbon steel plate and slab. also stockspecialist steels such as ABRO400, Toolox, S690 and RQT.