[jorisrf]

hey guys! i need some advice about a DIY milling machine i want to build out of a benchtop drill press.

i have a benchtop drill press that can go from a minimum of 580 RPM to a maximum of 2650 RPM with a couple of stages in between.

my plan is to buy an x-y table and use the drill press as a milling machine and convert it to cnc.

i know that the smaller the router bit diameter, the higher the RPM needed to cut properly, so my question is, is 2650 RPM enough to mill, say aluminium with a 3mm router bit? if not, what's the best i can do? (ie use a bigger diameter router bit or softer materials)
i dont mind slow feedrates

thanks!

[Chip Chester]

It would be good to research what Jacobs chucks, and Jacobs tapers, do in the presence of side loads. You can surmount the problems with effort, of course. But do check it out.

Chip

[jorisrf]

yeah ive thought about that myself, drill presses dont usually encounter sideways forces, but everyone i asked told me it should be fine.
but still theres probably a reason mills dont use jacobs chucks, ill look it up

do you think the RPM's i have at my disposal will suffice for milling?

[Chip Chester]

Well, the taper will eject the chuck and cutter (spinning at your target rpm) and allow it to dance across the workpiece, table, benchtop, floor, toes... whatever. Done it, seen it, dodged it. No t-shirt. Even if you have the type with a screw to hold the chuck on, that screw could back out just enough for the taper to let loose, and just sit there and spin... instead of mill.

Jacobs chucks on inexpensive pressed won't have the precision of collets and end mill holders. They also can't grab the shank of an endmill very well, due to hardness issues.

Drill press bearings aren't usually made for side loads... although it'll take many machine hours for this to develop into a real issue.

Your milling RPMs available will work for some things... Feed, cutter size, depth of cut, cutting fluid, and rpm all enter into the equation of whether it's right for the material you want to cut. Calculations are in order there.

RPM does not equal power, however. If you don't have the power, then you can't cut in the manner determined by the calculations above.

Reverse is handy, too... Precision in the quill, both extended and withdrawn. Rigidity of the structure under load. Buying a XY table good enough to mill with out-of-the-box will cost more than the drill press. (I'm sure some have done it, but that's usually the exception.)

Then there's the economics -- once you spend the amount of money necessary to get this going, and your projects develop to where you need to move on, you'll never get your money out of it, at all. Maybe not even as a drill press, if you modify it a lot. So it's yours 'til death do you part.

Benchtop mill/drills are not "great" milling machines, but they will mill, and are right for some projects. Spending time on a CNC version of one of them is well-documented, somewhat cost effective, and could have resale value if executed well.

Even better if you can find someone who wants to offload theirs. Then you can get right to chips... even though there's fun in the makin', too.

I really didn't want to write a discouraging post about this, but it looks like I did anyway. Sorry.

At least you didn't want to make a lathe out of it. (Which, I know, folks have done, too...)

Chip

[jorisrf]

it's all good chip, you make some good points, probably not the best idea to use it to mill anything eh.

basically im on a student budget, and im looking to make benchtop cnc machine, but milling machines are a bit costly.
i guess the best idea tho is to hunt for a cheap, used one somewhere and convert that, because i dont have the tools to make one from scratch.

i do have a basic understanding of cnc operation tho, i made one out some old floppy drives a while back with home made circuitry (drivers and breakout board)
so i could save alot of money by making one myself.

do you have any reccomendations or ideas/links for a cost effective way to build myself a cnc mill?

thanks for your input!

[Chip Chester]

Are there hobby "clubs" nearby?
In your position, I would try to connect with someone who has manual machining experience, and maybe equipment, but not CNC or electronic knowledge. Clearly define what you want to be able to do with the machine when you're done, and work backwards from that. Those specs will inform your choices of "style" (flatbed/gantry type, knee mill, etc.) and rigidity -- which will dictate whether you'll need to work in particleboard/pressboard, lumber, aluminum, or steel/cast iron. Finding an orphan mill jumps you ahead in the game. But make sure it's not totally clapped out, or else you'll have a computer-controlled clapped out mill.

I am not the one to guide you thru this process, though. I have some big-mill experience, and a big manual mill, but am just starting the CNC journey. I have some electronics experience, and lots of experience with computers controlling machines... but not computers controlling milling machines.

To that end, I bought a mechanically-sound but electronically shot desktop "educational" mill... Emco PC Mill 30. Very small, mostly sheet steel and aluminum, but mechanically tight (or, as tight as they can get) and a good platform for future mods. The price was very right. It's probably less stout that your drill press would be, but for what I want to do with it (basically inverted engraving of aluminum "nameplates" I think it'll do the trick. But more importantly, on the journey I'll learn what I need to look at CNC for my big mill.

So, I guess look for hobby-type clubs or organizations, robot builders, car 'tuners', etc. to find like-minded folks who may have the right machine hiding in the back of the shop waiting for someone like you.

And I've only been on this site for a few days, but it seems like the place to be for this stuff.

I assume you're reading this link:
Milling machine design and build - CNCzone.com-The Largest Machinist Community on the net!

and there are probably several more just like it.

Learning from other's mista... er, challenges, is a great way to save yourself time and money.

Good luck!
Chip

[jorisrf]

thanks for the advice, ill try to look around where i live

i think it is indeed the best way to find a good priced gem hiding in someones garage hehe.

i have some milling and lathing experience aswell on average size machines, but its at my school, so im not really that experienced yet, but i enjoydoing it! when i convert a mill to cnc ill try to keep the manucal functions aswell.

anyway thanks for your advice and the heads up on the drill press dangers!
and goodluck with your project, sounds pretty cool!