What is a mill?

[bigblock10]

Hi guys,

What is a mill and what does it do? what kind of parts can you make with them?

I see them on tv sometimes making rims with the big cng ones, but what can you make with a cheeper bench top one? not realy looking to buy one, its just this stuff it fun to learn about


DEREk

[greencactus3]

pretty much anything you want, with much more precision than a drill and grinder.

think of a table with a spindle floating over it, which you can move in the x,y,z coordinates individually.
(many mills allow more motions as well)
and you can use a mill to do more than drill holes. you can 'mill' faces,surfaces .... again, pretty much anything.
awesome tools. wish i had one in the garage, but at least i have access to a few at school if i need

[greencactus3]

http://www.youtube.com/watch?v=QsmiIeAkE-o



this is probably one of the coolest videos ive ever seen (if you dont wanna see it all, at least watch from about 7 minutes into the vid)

CNC mill. not cng

[CRead01]

Most standard mills go in the x,y,z axis but pretty much only in straight lines. so if you need an angle you have to either turn your vice or your setup. acuracy is good being to a thousandth. a benchtop one can be handy but there for more mild milling. if you want to do circles angles or to run programs you would have to go cnc. You dont have to have a large milling center like a mazak or anything to go cnc. they do have them for a standard mill also.

[Va Boy]

I own a index mill. I make things like lntake spacers, mounting brackets, or just about anything you need fab. that is not circle. My mill is not cnc. Use lathe for must. circle fab parts.

[Jim Nilsen]

I own a index mill. I make things like lntake spacers, mounting brackets, or just about anything you need fab. that is not circle. My mill is not cnc. Use lathe for must. circle fab parts.

What model Index do you have? I just bought a model 55 that works great for $250. I still have to pinch myself because i always wanted a mill but never thought I would have one this big.

[flynbrian]

I have ran mills, engine lathes, turrett lathes, cut-off saws,bandsaws,surface grinders, CNC mills, EDM machine, Tapping centers, and countless other machine shop tools and welders & plasma cutters since 1990

Mills are one of the first tools I learned to use. Very handy piece of equipment. Bridgeport is one of the best brands...Index is decent. Comet is a cheapie but still ok. Even some of the Taiwan mills are decent. But Chinese and Japanese mills are touch and go...Seen some real junk.
Proto-trak mills are a hybrid between a manual machine and a CNC...They are very nice for bolt circles and milling angles & pockets.
Mills are basically in laymens terms a giant very heavy duty drill press with bearings in the head that can handle side loads unlike a drill press. then precision knee and X&Y axis tables. many are varible speed and some have different power feeds...some in all 3 axis, but they remain mostly a manual machine. some have adjustable stops that allow it to shutoff at a point then you can dial in to a set number....A mill is ten times easier to operate with a precision digital readout in place.

You can buy additional axis tables that mount with T-slots to the mill table... But they are pricey and usually used on CNC equipment.

I have two lathes at home. A lathe is said to be the only piece of equipment able to reproduce itself...Albeit a tall order in most cases.

I have been wanting a small mill for awhile. Hard to find a little one that isnt worn out for cheap that doesnt need 3 phase electric.

A Turrett lathe is similiar to a Engine lathe except on the tailstock it has a rotary turret, and instead of a dial handle it has a lever, when the lever is ran back the turrett turns itself to the next tool...They are pretty neat too. You can drill, chamfer, tap etc. and more without ever lifting a chuck key or changing a tool besides flicking the handle back to advance the next tool. They were common on war ships in WWII.


A mill is useless in the hands of someone not properly trained. They can be capable of holding tolerances within just a few Thousands of an inch or less if set-up and ran correctly. A operator has to know the direction of "Slack" in all the lead screws, be very adept at speeds and feeds for various different tools, good at setting up stops and fixtures, must be a wiz and keeping it clean and keeping all the tables straight and lined up using dial indicators and magnetic bases.
A un-trained person could get hurt very easily. Many vocational schools have good introduction classes on running basic machine shop equipment. Its a very rewarding experience. MAKE SURE, to wear your safety glasses!

[flynbrian]

Also forgot to tell ya there is vertical and horizontal mills, Horizontals are un-common by comparison...They have a shaft that comes out the head towards the operator and then it has a bearing support on the end....Most of the cutters have a keyed hole in them and they are designed for cutting slots and grooves mostly....There are countless versions but they are not overly useful for a hobbiest.

Vertical mills are basically available in two styles, fixed base with a head that cranks up and down and "Knee mills" where the head is fixed and the base cranks up and down. Knee mills are good for hobby shops...I imagine that a fixed base might be slightly more rigid for heavy cutting though.
Most knee mills have the ability for the head to be swung out side to side at any angle and some even in & out (towards or away from the operator) Which makes them the most diverse with set-ups.

[rubadub]

Heres a picture of a dividing head.

Ellis Dividing Head

These dividing/indexing heads work quite well in the home shop.

Anyway I was a tool maker in a tool and die shop and used to make reamers, cutting tools, pressing tools all from scratch.

If you have one of these, a mill and a lathe, a 5 gallon bucket of water with a little salt mixed in it, a small electric oven used for heat treating metal, there only about two feet square, should be able to find a used one I would think.

You can turn the piece of steel down in your lathe, then put it in the dividing head and mill some flutes or teeth in it, maybe six or even four will work.

You can take a hand file and file in a little clearance on the teeth, put it in the oven, I'm not going into detail here, get it hot, quench it in the bucket of salt water.

It will be really hard, then take it on the lathe or by hand, don't let your fingers touch it, and shine it up with a little emery or sandpaper, then you put it up at the opening to your heat treat oven, takes about 10 or fifteen minutes, hold it there with some tongs or whatever until it just starts to darken, a real, real light shade of brown, then you have annealed it to some degree and it won't break as easy but will be able to cut metal.

I don't think that a lot of people know you can make a lot of things at home, and heat treat steel to different hardnesses, ( is that a word ) anyway, thought I should mention this.

Rob

[jackfrost]

good stuff, guys

[flynbrian]

Cool, I have not seen one of those dividing heads before...We have a electronic version of that as a 4th Axis on a Cincinnati Machine we have in the shop I used to work in.
Brother also makes a 4th axis rotary table...But I have not seen a manual one before.

[Larry Callahan]

Now here is a mill. LOL