ATC spindle advice

[Richco]

Hello All,
This is my first post hopefully I in right section,I am planning to build vertical metal cnc milling machine I been reading lots on the various forums which confused me,I want to build my machine with ATC spindle I saw there are many spindle heads which are very expensive,this machine which I am going to build will be hobby use not for professional use please advice me what KW and RPM should I need for a good metal cutting machine mill build,I am thinking to use high speed servo motor and spindle head please advice me what should be more than enough to build a good machine.
Thanks

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[spumco]

Someone may blast you a bit for asking very vague questions, but I'll try to steer you in the right direction so you can do reaearch - and sort of understand what you're reading.

1. What "metal" do you want to cut? (different metals require different spindle speeds for a given diameter cutter or drill)

2. How large of a mill are you planning to build? If you can determine a general size for the mill, you can look at similar sized commercial/hobby mills and see what motor power, RPM range, and other specifications are common.

3. What do you mean by an "ATC" spindle? Do you mean a belt-driven spindle which can be used with a tool changer (power draw bar), or do you mean one of the integrated "ATC" spindles usually installed on routers. Looks like a large diameter spindle and has the motor built-in.

4. What tool taper do you want to use? R8, ISO20, ISO30, BT30, CAT40, HSKxx, etc.? This will help narrow down available selections.

5. Why are you considering building a mill when there are quite a few hobby-grade mills available? You will be spending a staggering amount of time learning a wide variety of topics before you can even use your mill. And if your questions are an indication of your experience level, there's a good likelihood that the mill you build will not be particularly rigid, accurate, or enjoyable to use when cutting 'metal'

6. If you are doing this for the education, consider converting a manual mill to CNC before building one from scratch. There are a number of manual mills with CNC converions 'kits' available from various sources.

[ljvb]

... edit for brevity ...


6. If you are doing this for the education, consider converting a manual mill to CNC before building one from scratch. There are a number of manual mills with CNC converions 'kits' available from various sources.

I'm also knew here, and in the same situation as the OP, so I don't want to start a new thread. But I would like to respond to this particular question... The problem I see with using an existing "cheap" mill like the G0704 or PM25, is that you are looking at 2k initially for the mill (taking into account shipping, taxes, and various other costs that innevitably show up when putting a new tool into your "work shop"). Then there is the cost of the kit (assuming you go that route), another $700 to $1k (based on my recent searches), then stepper motors, control boards, software, another $500 to $1500 depending on what you get....
That is a considerable amount of money to get to a fully functional CNC mill.

Those of us on a budget would ultimately have to cut corners, that may mean cheaper motors/drivers, or cheaper bearings/slides, or cheaper spindle motor replacement...

Now I am in a slightly different situation, I already have a CNC, a 1m x 1m Openbuilds machine being controlled by a RPI running cncjs, and I am an engineer by studies (although I have been in IT security for over 2 decades).

The way I see it, a mill is basically a base with x and y tables, a support and z axis head, which can easily be built using various methods (I plan on going to the steel reinforced epoxy granite route). The cost of a manual mill will be put towards better quality linear rails and ground ball screws, and mid range AC servo motors (nema 24 or 34, have not decided, and the cost difference is minimal to me) and Nema 56 2hp 2800rpm AC servo to drive the milling head, all from the Technik Clearpath SDSK line.

The problem I am having, is I come from the spindle/router side of the world, and in one direct drive unites rather than belt/gear heads driven by a motor/servo. Finding a decent head is the problem. I'm personally indifferent to the standard to use, I don't plan on using the ATC capabilities, at least not with a tool changer, push button or actuated tool changes are appealing, but not necessary. But, using a standard that has a wide selection of tool holders is pretty important, so I have been looking at R8 or BT30, but I am not limited to that. I came across glockcnc, but they seem to be perpetually sold old and I am not at the point where I can pre-order anything.

So, the question is, where does one get a decent headstock for between $300 to $700 that does not have completely crappy bearings.....

I am not sure if I can post links yet (I just signed up here after lurking for a few years as a guest), but this is basically the path I am going to follow (if the link does not work search youtube for "Joerg Beigang")

[spumco]

So, the question is, where does one get a decent headstock for between $300 to $700 that does not have completely crappy bearings.....

Build it yourself from steel plate.

Build a steel box and either weld it or bolt it together. Bolt trucks on the back, and make a big hole in the middle for a cartidge spindle.

If you watch Simpson36's videos, you can see one of the mills he's built in the past has a scratch-built head. Looks like it was fabricated from 1/2" plate, all bolted together.

https://www.youtube.com/watch?v=k2F6100RKOE


Then you should be able to add a decent cartridge spindle and stay under your $700 budget.