DIY CNC for milling steel - or close enough
Hi everyone,
I cant decide whether to go fixed gantry or fixed table, but first a little story time!
About half a year ago i decided to build a CNC myself.
I started reading lots of good information online... Turns out CNCs are pretty complex.
My first idea that it would cost about 200$ and mill metal was very quickly pulverised.
The longer i kept reading the more i began to understand how all the precesions and rigidness of the structure add on the price size and weight.
slowly rising the budget until i feel like i could possibly get it to work. (I might still be too naive and thats why im here)
Currently i am in the pre-design phase, where i think about what i actually want before i start creating it in fusion 360.
Here is a list of answers to unasked questions that might help you in helping me decide:).
- Budget somewhere 1000-6000$ (i prefer a good value rather than cheapest)
- Id like to build it myself in order to learn everything about it and be able to to any reparations or upgrades myself, its a cool project
- I expect to spend about 2-3 years on this build
- Id love to mill tool steel (of course not hardened), I will also do a lot of milling on aluminium, G10 and wood. I understand steel is tough but if the price is low then having a CNC that deals with aluminium easily is also a success.
- From steel i would cut out shapes (eg. horrible waterjet replacement), mill it flat and do lots of engraving.
- Size
- At first i wanted to have a small one (400x400mm) but seeing as the price doesnt change much and that larger sizes are much more capable i am currently thinking about 1000x600mm (Open to discussion)
- i dont have any garage or any dedicated hobby room yet and moving is very probable so i need to be able to get it through a door. Or even up the stairs.
- This also limits the weight as i need to be able to carry with 3-4 people max.,Ideally the table and the machine would be possible to disassemble in order to have lighter pieces but thats a topic for another day
- Future planned upgrades: 4th axis, vacuum table
- havent thought about water cooling of milled material or electronics much but i like servos
- Tools i have at my current disposal are a handheld drill, some files and sandpaper :D The design will have to be solid enough so that i can get all parts manufactured and assemble it without many changes (welding is a big questionmark)
So with knowing all that:
Fixed table:
+ Can fit for example an entire sheet of metal in the 1000mm space with undefined length
+ Better used space (my space is limited)
+ More common DIY design
+ Moves a stable amount of weight
+ better for 4th axis or vacuum table (or any other table accesories really)
+ Easier to design in a way thats disassembled from the table, at least i think. a moving table needs some square and large table to put the rails on
Movable table
+ More rigid
+ Probably easier to put together (squaring and adjusting the ball screw seems easier than with a moving gantry where the ball screw cant be in the middle)
I dont want to give up space and usefulness of a fixed table
I dont want to give up rigidness considering my goal
Basically its a question of "Can a DiY fixed table CNC be rigid enough to mill steel"?
Thank you everyone for your input,
i want to start designing but cant decide what to go for.
Re: DIY CNC for milling steel - or close enough
I think you need to keep looking. Have you seen what Stef110 built? https://www.cnczone.com/forums/verti...rum-posts.html
Re: DIY CNC for milling steel - or close enough
A mill that big (1000mm x 600mm) capable of handling steel effectively sounds like a full-sized knee mill, and would not be something I'd want to move up any stairs. My advice would be to move first, preferably into a place that had a garage or ground-floor workspace, and then look for a used CNC mill with a blown or obsolete controller suitable for retrofitting. These come up frequently, often at scrap or near-scrap prices, and would be a lot easier and more cost-effective place to start than from scratch, especially considering your tool kit (or lack thereof).
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
TigFur
Hi everyone,
- Tools i have at my current disposal are a handheld drill, some files and sandpaper :D The design will have to be solid enough so that i can get all parts manufactured and assemble it without many changes (welding is a big questionmark)
So your budget of up to $6000 is reasonable if you know what you're doing and do most of the work yourself. But are you thinking that you will get someone else to manufacture this for you, a custom piece of equipment, and buy all of the expensive parts you need for this budget?
If you were making a router, you can order the T-slot aluminum from places like 8020, and they will cut it and machine the ends to all of your lengths as per your order. Then you'd still have to source all of your other parts and invariably, have to make some of them.
But you want to mill steel. Lots of Cast iron is typically needed to do this.
From a design perspective, to answer your questions, I'd start looking at this design:
https://www.vulcanmachineco.com/
Thanks to pippin88 for that link.
The rising gantry offers many advantages over a traditional mill. But this machine only has a cutting area of 13" x 13" on X and Y. I would prefer if it had 12" x 24". To do this I believe you would need a second ballscrew for the Z and it would become more of a dual column.
In Reality
Find a used machine of some kind and fix it up with new controls or buy a 2nd hand mill that has been CNC converted or buy the vulcan machine or something similar.
So many people say they want to mill steel. It is not easy. You need an extremely rigid machine and a spindle capable of good low RPM performance.
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
maxspongebob
That looks awesome and it is a large moving table build. Id believe this has much better precision than any of the old mills i could find around.
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
awerby
A mill that big (1000mm x 600mm) capable of handling steel effectively sounds like a full-sized knee mill, and would not be something I'd want to move up any stairs. My advice would be to move first, preferably into a place that had a garage or ground-floor workspace, and then look for a used CNC mill with a blown or obsolete controller suitable for retrofitting. These come up frequently, often at scrap or near-scrap prices, and would be a lot easier and more cost-effective place to start than from scratch, especially considering your tool kit (or lack thereof).
Thats also a good suggestion, If i had a place and means of tracel getting a ton heavy mill might be an option. Though most of the milles i see around second hand have probably worse precision than a cheap table drill i buy at a hobby market seeing how theyre near to 100 years old.But it still might be cheaper to straighten up everything and change rails etc. than creating a new one from scratch.
I took a quick look around and found second hand s small one for 1000$ that i might fit and carry already - OPTImill BF 20V (its a drill/mill) or a larger one that i definitely cant carry - opti uf 100, are those good for retrofitting?
Just trying to see what i should look for if i go this way.
Re: DIY CNC for milling steel - or close enough
Yes thats what i was thinking, and if possible find people who help me for a more reasonable price.
From all the answers so far is is clear that a basic moving gantry is not sufficient and would only be good enough for aluminium. (especially with this much travel area)
So it seems i have to get a smaller travel area.
Retrofitting is a valid and reasonable option, although not as fun.
The double column/vulcan design is really cool, that would probably make it possible to have a solid table. It gave me some new ideas.
Thanks for the suggestion
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Re: DIY CNC for milling steel - or close enough
Hi Tigfur - To move forward with milling steel, you need to downsize your axes. So your 1000x600 will become 600x300mm (600mm is actually a huge span to make stiff enough for steel) the small size is doable and is more in line with a std small mill. I suggest a plate steel or plate aluminium build. I really suggest you build a small one 300x300 then use that to build a bigger one. Do not weld anything. Bolt everything together. A search on this site will show up some plate build mills. You will need to research the collet and spindle head. You'll use an R8 or maybe a BT30. You need to consider this will be a wet machine so will need an enclosure. Maybe it's best to buy a small bench mill and convert to CNC I'd seriously research that. A small version of the mills attached is a good start if you want to DIY. Steel is a big stick to chew you will need to go from zero to rocket scientist quite quick..
Since you have hand tools and workspace consider a small mineral epoxy machine. You can make MDF moulds and cast your machine elements. Has advantages over plate builds and welded builds. You can tailor your geometry, its 10x damper then metal at least and is in line with all the top end machines out there...Peter
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
peteeng
Hi Tigfur - To move forward with milling steel, you need to downsize your axes. So your 1000x600 will become 600x300mm (600mm is actually a huge span to make stiff enough for steel) the small size is doable and is more in line with a std small mill. I suggest a plate steel or plate aluminium build. I really suggest you build a small one 300x300 then use that to build a bigger one. Do not weld anything. Bolt everything together. A search on this site will show up some plate build mills. You will need to research the collet and spindle head. You'll use an R8 or maybe a BT30. You need to consider this will be a wet machine so will need an enclosure. Maybe it's best to buy a small bench mill and convert to CNC I'd seriously research that. A small version of the mills attached is a good start if you want to DIY. Steel is a big stick to chew you will need to go from zero to rocket scientist quite quick..
Since you have hand tools and workspace consider a small mineral epoxy machine. You can make MDF moulds and cast your machine elements. Has advantages over plate builds and welded builds. You can tailor your geometry, its 10x damper then metal at least and is in line with all the top end machines out there...Peter
Thanks that all makes sense. I like the middle picture of the builds you posted, it looks very clean and solid.
For the epoxy, you mean cast all of the parts and body from epoxy? Any examples of a build like that? I have never seen anything like that. Ive seen casting of rail bases etc but not an entire machine.
Though smelling epoxy for weeks might not be something i enjoy
Re: DIY CNC for milling steel - or close enough
Hi Tigfur - There are a couple of huge threads on epoxy granite here just do a search. Epoxy doesn't smell much and if you don't want the smell use a vacuum bag approach. Many of the high end machine builders use epoxy granite for there machine beds and composites are increasingly being used for other parts. Worth some research. Peter
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Re: DIY CNC for milling steel - or close enough
Hi Tigfur - The Katran build is very good. He also uses raydent ( I can tell this as they are black) coated rails so they don't rust really good!! Peter
https://www.cnczone.com/forums/verti...09634-cnc.html small plate mill
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
TigFur
Yes thats what i was thinking, and if possible find people who help me for a more reasonable price.
I don't think that you're going to be able to get a custom cast iron casting, mold made, poured, stress relieved, and machined for cheap. Plus then you need some lifting tools, like a forklift, to work on it.
You don't have a welder or experience with this, plus then also you have to make things flat.
The one thing you might be able to get away with is using aluminum solids, bolting them together, then fill with epoxy concrete.
Solid aluminum extrusions typically come out very flat to start with.
If you check out the Linux_Fan build, you can see how he made his gantry.
https://www.cnczone.com/forums/uncat...aluminium.html
Quote:
Originally Posted by
TigFur
From all the answers so far is is clear that a basic moving gantry is not sufficient and would only be good enough for aluminium. (especially with this much travel area)
Not sure what you mean by "moving gantry". The Vulcan has a moving gantry in the Z direction. The entire machine also weighs 2440 lbs.
A couple of my favorite builds where the gantry moves in the long axis are:
Linux_Fan
Thom_Concept
Both do a super job on Aluminum. I believe Linux_Fan said he was using his to cut stainless steel as well, but I have not seen a video of it. Thom_Concept has a few videos on YouTube cutting steel, but I don't believe his spindle is suited to higher torque at lower speed, so it's nothing compared to his aluminum cutting videos.
Stef110 did a fantastic job on his mill. Cuts aluminum like a boss, but I don't recall any videos of it cutting steel. Plus you're not going to build that for 6K, and he knows how to build things, has the tools, experience, etc.
Actually, when I look at the Vulcan Machine Co. YouTube website, there are only two videos, and they are both cutting aluminum.
I have a Mini Mill, from busy bee tools, similar to a G0704 at home, it's kind of a turd. People have converted theirs but do get it to do a decent job in aluminum they needed to upgrade everything, including the spindle. I don't think mine would ever be good at milling steel.
If you are thinking of making a DIY machine to mill steel, please find at least a few good examples of DIY machines that can do it, with some videos. With all the build logs on here, it should be easy to find some success videos cutting steel like a boss right? I look forward to seeing what you find.
If you look at this video, they need to use a tiny bit to get a high speed spindle to cut steel decently enough, which is perhaps an option for you. I wouldn't say that this machine with this spindle cuts steel "well" in general though.
https://www.youtube.com/watch?v=d8IgJFfTqME
The Katran build is really decent. But is not suitable for steel work, he even says so in the build log.
Quote:
Originally Posted by
TigFur
Retrofitting is a valid and reasonable option, although not as fun.
Is failing fun? Is wasting 1000's of dollars fun? All things to consider.
Here's the challenge....find some vids of DIY machines that actually cut steel well. I think you're stuck with finding a used full sized mill, and yes, they sometimes go for scrap value. Either that or a Tormach, or the aforementioned Vulcan, but it would be nice to see some videos of how it handles steel. I like the Vulcan design because of the rising gantry, also the fact that it uses linear rails instead of "ways". But I would prefer it if it was 24" x 12" for a cutting area.
Re: DIY CNC for milling steel - or close enough
Quote:
Originally Posted by
NIC 77
..find some vids of DIY machines that actually cut steel well.
Only DIY CNC machine I know which fits that description (fixed gantry, moving table) and I have seen several videos of it milling steel and even stainless steel (small cuts though) - it's a hobby machine after all:
https://www.youtube.com/watch?v=Klk6T1IBowU
Personally I'd build a moving gantry machine (on side walls, like those large CNC mills) to get swarf under control, while having the linear rails out of the splash-zone (comes with higher weight and less accessibility, so might not be ideal for apartments).
Another one to look out for which looks like it's being built inside an apartment:
https://www.youtube.com/watch?v=zvqjIOG0fi0
