First Build. Few Q's.

Hey everyone!

As the title suggests, I've embarked on my first (CNC 4 AXIS) build journey, and would be great to get some feedback, or a solid push in the right direction from the community.

The goal is to build an extremely solid, but compact machine. I don't plan to move this machine much, if ever, unless I have to. More just looking for an extremely well made machine utilizing the best possible parts and components given the current tech available and also cost to a certain degree. Primarily looking to do Aluminum milling with as much precision as possible. Speed is also an important factor, but I'd easily give up speed for quality.

after a lot of back and forth, I've decided the total footprint for the Machine needs to be kept under 26" MAX depth. I understand this obviously won't be the size I can mill on, but just to say I need to keep these dimensions into consideration.

I've spent the greater, or maybe worst part of the last 4 days reading countless forum posts and def too many CNC build videos on YouTube and now I'm here hoping for some more specific feedback based on my needs. I've gone ahead and purchased maybe, 70-80% of the hardware required for the build directly from McMaster and Amazon based off the BOM in the posts below,

Platform CNC - Designed by Brian Oltrogge

and also this

Benchtop PRO 2424 2' x 2' CNC Machine Kit | Avid CNC


I took the liberty of upgrading as many if not all of the electric/mechanical components and features since this build is quite dated now.

The base and general frame/design is still up in the air, But I've gone ahead and purchased nearly all the parts in various sizes, shapes and finishes to allow myself some options, but it's also really helpful and much faster at the moment to just order the stuff and design by hand vs me juggling my time with the design/learning process done via Fusion360. btw, Fusion 360 is incredible and been having lots of fun learning it, but there's nothing like picking up some expensive aluminum "LEGO" and doing the design process by hand. ;]

Now, aside from the structural side of things, here's the electronics I already picked up.

https://www.amazon.com/Centroid-Acor...1876911&sr=8-1

https://www.amazon.com/Geckodrive-Bu...1877295&sr=8-4

As for the motor, I've decided to go with Clearpath servo's vs the usual 4 motor stepper kit, and Hiwin Rails vs belt and bearings. I'm learning most of this as it's happening so forgive me in advance for my lack of knowledge or my general ignorance on things that may seem extremely basic to some if not most of you.

funny enough, the one thing I haven't even looked into yet is the spindle.. But I'll wait to finalize the cake before splurging on the icing.


With all that being said, please let me know if anything seems overkill, while allowing me just a bit of overkill/future proofing for the inevitable expansion down the road.

thanks in advance.

t.

For primarily cutting metal bar stock the rigidity of a milling machine is hard to beat. Aluminium sheet goods different story if that's the goal.
With a 26" depth restriction a C frame mill wouldn't have much Y travel so that's one of the reasons a router may have more appeal.
Some of the heavy duty DIY router builds showing up here look a lot like bridge mills, the closer your router resembles one those builds the happier it will be cutting metal.
Of course what's possible in a build will depend on your access to tools, some of the posters here have workshops that resemble mini-factories.

Hi NetM - In regard to the structure which you have said little about it will need to be much stiffer then you thick. The Pro 2424 is probably stiffer then the Oltrogge and you will need to be stiffer the the Pro. Peter

Hi,
Clearpath servos are too expensive for what they are. They are good quality, no problems there but for the same money you can get either DMM (Canadian manufactured in China)
or Delta (Taiwanese manufactured in China) but twice the power and every bit as good quality wise. Also because they have a separate servo drive they have way WAY WAY
more control options and tuning aids.

Craig

Hi,
don't forget the spindle, it is, if buying quality, the MOST expensive part of the whole machine.

When I built my mini-mill I, like you, put the purchasing decision about the spindle off. It was a mistake because when it came time I had already blown my budget.

It must be said that the plethora of cheap Chinese spindles are good value and mostly they last OK, but if you want quality you'll have to look elsewhere and quality
spindles are eye-watering expensive. My favored German manufacturer has a 2.5kW (can be run on a single phase VFD) 42,000 rpm with HSK toolchange for a mere 5400 Euro!!!! That's just the spindle,
no VFD, no coolant pump, no air compressor for seal air or toolchange.

Craig

As Pete said, you don't have any information on the frame. This will have the biggest impact on the machines performance. The best components are only as good as the frame they're bolted to.

And neither of the machines you linked to are ideal solutions for precision aluminum milling.

And I'm with Craig on the Clearpaths. Clearpaths are great, as a drop in replacement for stepper motors. But if you are designing a new machine from scratch, AC servos will provide much better performance for the same or less money.

Like Ger said, the frame is your weak link. Both those designs you pointed us to were gantry routers, which work okay for wood, but less well for aluminum. A step up in rigidity would be a "bridge" design, where the Y axis travels on a fixed gantry and the table moves underneath it. This requires more room (maybe you can make the width of it 26" and give it more room on the sides) but since there's no constraint on the weight of the bridge, it can be made quite rigid. It still won't be as good for metal machining as a real mill, but will be better than the moving gantry plan.

Hi,
there is a company not far from where I work and they have a HUGE double column mill, the same design style that awerby is recommending.

I've never seen this machine operating but I would swear the X travel is 3m or more and Y travel has to be more than a meter. You can only see it by
looking through the windows in the walls that surround it, and the walls look like they could house a family of four!! The cast iron columns are about 600mm square,
I don't imagine they are solid but they sure look sturdy!!

A fixed gantry can be made to be very stiff. What is required then are long linear rails and a very stiff base to mount then for the X axis.

Craig