Need Advice On CNC Vertical Mill Parts DIY Epoxy Granite Hard Milling Steel

Hi I'd like to DIY a CNC vertical mill, I need some advice. I've read the FAQ section, and done some searches on the forums, but there is so much information spread out, it's hard to form a strong idea.

I have looked at used CNC vertical mills, unfortunately Australia doesn't really have a manufacturing industry anymore, so the used market has pretty slim pickings. Of the few I have found they're all about 30 years old worn to crap and I'm not confident I'll be able to get them running properly, they start about $7k+, then you need to spend more to fix them.

My goals to build are;

• I have a 240V 15A plug I'd like to use in my shed (I could potentially get an electrician in to install a larger one, but I'd prefer not to if possible).
• Hard mill carbon steel.
• High probability to made from epoxy granite.
• Build price between $5-10K AUD.
• Accuracy is more important than speed.

So, what would you build for ~$7-8K?

Does someone have a parts list from a different thread they liked?

The head, are they belt driven servos or just a normal 3 phase motors?

I wish there was a store in Australia I could call up and order parts from and pester with questions, but everything I've found is just completed routers for hobbyists.

I would like to consolidate all the knowledge I collect to make it easier for new people to digest, maybe make some plans that are open source.

Thanks for any help.

Regards,

Pat.

Something similar to this, it's the Syil X7. A little smaller though, because it needs 25amps.

This might be a thread to consolidate my ideas, could be a little all over the place, sorry.

https://pbs.twimg.com/media/EPCYz5WX...jpg&name=large

I think you'll need more than a 15A circuit (RCD etc) for a start.
I had a 16A for my garage (before I even built a mill) and my budget 2000w miter saw used to trip it on start up.
I had to replace with a 32A.

You don't say how large the machining envelope on this machine is supposed to be, or what its proportions are. This is critical, both to how well it will perform and how much it will cost to build. If it's relatively small, like the Syil machine above, then epoxy-granite is a good choice for a monolithic frame. I haven't seen it used much for larger machines, though. Producing a mold for the components won't be a trivial task; ensuring that the surfaces you'd be attaching rails to are perfectly flat and orthogonal takes some experience and planning. Starting with a small mill and scaling up the design when you've had a chance to evaluate it might be a good way to go.

Spindles for milling steel, as you might know, are different from those used for materials up to aluminum in hardness. They need to spin much slower, with greater torque. They're harder to find off-the-shelf, and take more pre-planning to integrate into your castings. Most manufacturers of milling machines use cast iron because once it's cast roughly it's relatively easy to machine flat and square; this is not the case with epoxy-granite, which needs to be cast that way at the outset. On the other hand, it doesn't move around much after it's cured; cast iron usually needs a year or so of "seasoning" before it's put into service.

You might consider building a hybrid frame, using hollow steel components and filling them with something later to dampen vibration. There's an interesting thread on this that's active now: https://www.cnczone.com/forums/mecha...rum-posts.html The advantage is that if you use thick-section steel you'll have enough to mill flat, you can weld parts together, and it's much easier to put fasteners in steel than into epoxy-granite.

Hi Pat- I'm in northern NSW. I've started designing a benchtop mill. You need to start at the spindle. Decide what collet etc and power and speed you will need by looking at similar designs to what you want. Maybe start looking at manual machines and convert to CNC, may save a lot of research and build angst. My mill design is a gantry type with BT30 collet. Does take a long time to sort out envelope, spindle type and power etc, then there's the structure. I'm going the moulded composite path as well. Peter

Thanks for the replies guys.

The fuse/rcd is 20amps I think (20 or 40), but the socket is a 15amp one with the thicker earth. Are cnc's usually hard wired in or use a plug, or DIY ones anyway?

I have thought of using RHS 250x250x9mm steel, welding on 25mm plate, and filling with epoxy granite. Only problem is can only buy in half and full lengths. Would be a lot easier than trying to make a mold that will hold 200-300kg of epoxy granite without deforming.

Spindles are quite the rabbit hole. Aliexpress has a few, but I don't really like the idea of it being hit and miss with a product coming from overseas. Kind of potentially high and dry if I have issues. Would like atc/pneumatic spindle for quick tool changes.

I have thought of converting an existing manual mill, but for the same price or less (excluding spindle because I haven't found a nice solution yet) I can build a stronger one with a bigger machining volume. Most of them have tilting heads which I'm not really a super big fan of trying to hard mill steel, I'd like to minimise potential weak spots.

I'm not sure on machine volume yet, maybe 400x700mm.

Either BT30 or BT40 collet, but I need to find a nice source of spindles first, I'm a little flexible. Here's a Chinese spindle situation I'd like to avoid. There's also another video on youtube where the retention clips (I don't know proper name) for the pull stud looks pretty crap.

Cheers,

Pat.

https://ae01.alicdn.com/kf/U58e3188b...b0b1f5343t.jpg
https://ae01.alicdn.com/kf/U7a34b163...8f974d883v.jpg

Hi Pat, I am in Qld and also looking for a mill with similar specifications. The Syil X5 and X7 are the closest benchmarks I've found to date, the machining envelope of the X5 (X:275mm, Y:155mm, Z:230mm) is acceptable and seems similar to what can be achieved converting smaller 'bench top' manual machines. The increased capacity of the X7 is desirable for the maker/ hobby market (X:400mm, Y:300mm, 380mm) and it seems a manual machine conversion would start with a much larger turret machine.

You might be interested in Fox's granite gantry type build that started with a surface plate and required a very modest investment in tooling and process: https://www.youtube.com/user/piterfox3d/videos He has a thread on cnczone but I don't have a link at hand.

Peter, is you bench top mill a commercial project? I'd be happy to support an Australian design if possible, cheers.

It depends on budgets and your size needs in the end.
If you consider converting a manual machine you want something like the PM-728VT
https://www.precisionmatthews.com/sh...recision-mill/
Next size down the PM-30MV type machines
https://www.precisionmatthews.com/shop/pm-30mv/
Then next is the PM-25MV type machines
https://www.precisionmatthews.com/shop/pm-25mv/

The last 2 you're bound to end up wanting to up the spindle speeds eventually.
I wouln't touch the mini mill Sieg X2 types with a barge pole ever again!

If you end up looking to spend that much money on the Syil in the end, you may as well save for a Tormach.

Hi RubeG - Yes it will be a commercial mill kit. I got all the way through to near to costing on a moving column design then decided that the Z axis was not stiff enough. Then regrouped and decided to go with a lifting gantry design. This means a big redesign. So when I get my current router built that's the next project. The router is called YaG and it will make the moulds for the mill. Glass fibre composite parts with epoxy metal fibre infill. Peter

Hi Pat.
I know exactly what your going through.
After finishing my diy cnc router i wanted more.
I built my diy for cutting ally and it does so not bad.But it only has a 1hp motor and i have gotten real tired of manual tool changers after just a couple of months.
I've always wanted a real vmc but i don't have much room and only single phase power which limits my choices.
I also looked at the syil x7 but by the time you add all the extras like tool changer, bt spindle, servos etc you're looking at least aus 30,000.
And your right in Australia finding a used vmc is rare. I think there is about 10 at the moment under 30,000 online.
I thought of building a cnc mill as i really want to be able to machine steel.
Anyway i lucked out and found a fadal vmc for a great price. Its old 1995 but runs and from my research is easy to fix and has parts aplenty.
Im in the middle of cleaning it up at the moment but can't wait to get it cutting.
I have to say that after getting it in my shed and going through it there is no way in hell i could build anything near as soild or robust as it. I was actually very intimated by it as it is huge compared to my router.
But i know that now I'll be able to accurately cut steel day to day with this.
I think if you really want to be cutting steel keep looking for real vmc. One will come up sooner or later.
Here's a pic of my fadal and if you look to the left you will see my tiny diy router.

Attachment 445646

Forgot to add, vmc will be up and running soon and when it is I'll be doing a fair bit of learning the fadal controls. So will be looking for things to practice on.
If you decide to build and in not too much of a hurry and need some steel cut i may be able help out.