Thread: Small Mill Machine - Looking To Buy

Originally Posted by goingbush

CNC not even on my horizon, CAD way out of my depth , The local metal cutters cringe when they see me come in with a cardboard template of something I want Plasma cut from sheet , it would be so much easier with a CAD file, not going to happen though !! But I do love the DRO mostly because it makes backlash in the lathe or mill slides mostly irrelevant , and Im hopeless at reading a micrometer .

I totally understand the reading of a micrometer...eye sight not as good as once upon a time. I definitely see the advantage or even 'need' for a DRO. Especially for accuracy.

CAD would be lovely to have but I believe is expensive....(probably going to get told different now).

I think I need...in fact I know I need to research CNC to see if it is something I would ever use or justify in cost!

I have ben quoted for delivery of the Mill you have. Thinking I might hold back until I can drive and have a road trip down to pick one up...if this is what I buy.

Despite having a mill I will often take a simple drilling task to a pedestal drill or even cordless hand drill

Seems like you have a mill in mind. Try and get digital readout included if you can.

What accessories are you thinking of getting?

Clamp kits are very useful if not a must. Fairly cheap.

A run of the mill (pun) hardware vice is not so good, it will get you by on some things, otherwise get a milling vice or resort to the clamp kit. Good vice is some what expensive.

Some squared blocks are handy and a right angle square is a necessity. Check the square against a point on a straight edge, rule a line from the point, flip the square and make a second line from the same point. If the lines are exactly on each other full length then fine. otherwise divergent lines indicate the rule is not square. A good square is cheap - I use a made in the USA fibre plastic handle stainless blade from Bunnings.

Carbide scribe for marking steel. Don't get the retractable type. Cheap.

Centre drill is good for creating an accurate start hole in the steel. It is designed not to wander as it starts the hole. Cheap.

High speed steel mills and drills are fine for many applications, but is a little flexible. Carbide cuts most things, is far less flexible giving more accurate results, keeps a keen edge longer, but don't drop it or it will shatter. You will also have to think about how you are going to sharpen all these things. High speed steel moderate cost, carbide a bit more.

Some mills come with a regular chuck, has a broad range of capacity, ok for general drilling and depending on the quality may get adequate milling results. Collets are better, but you need many collets to cover the range of drill sizes - and don't skimp on the quality of a collet set - real cheap sets have few flutes in the spring body allowing the cutting tool to walk out of the collet and into your mill deck. Reasonably expensive.

Sometimes you will want to centre a hole that needs upsizing, or bring an edge into alignment with your cutting tool. Here you will need some sort of edge finder. Fairly cheap.

A good mill can be run in reverse, often for a choice between regular and step climbing(?) (terminology escapes me). If reversible then probably avoid chucks and the like that are screwed on, unless the vendor can guarantee they will not unscrew when in reverse - the better option is a mill that has draw bars to hold the tool on. Not that you are at the lathe stage (yet), but the same principles apply, preference being cam lock chucks instead of threaded chucks.

FreeCAD is...wait for it...free!

I did about 2 of the short beginners online tutorials before being able to take off on my own.

The cost in time is another matter.

There are a few free or very cheap CAD systems. Some of the less expensive go on to require add-ons and more dollars.

My understanding is CNC relates well to solid modelling ie FreeCAD.

CNC at the moment does not get on well with mesh modelling.

You can do sophisticated design using mesh surfaces - creating creatures for movie animation for example. Simple to pull/push/drag mesh to make an adjustment to get the shape you want. However, CNC sees a rough, ill defined surface, sometimes with gaps in the framework.

In solid modelling you take for example standard well defined shapes like cubes, circles, cones etc then add them, subtract then, difference them etc until you get the shape you want. You can also use lofts, rotated profiles, sweeps etc for shape development. More time consuming, but the math behind the program can work with this to give clearly defined shapes that CNC can use.

Goingbush - taking a cardboard template to the local sheet metal shop - shear luxury lad (think Monty P) - in my time in Darwin cardboard was almost impossible to find, and if you did finally get a template, on paper bark, it would have to be flown down south at great expense, not to be seen for months, and the returned product entirely unfit for purpose.

Chilly, if you are looking to down the lathe route in the future, you could go this way first as a lathe can be used to mill when set up correctly, i.e. cutting bit in the chuck, piece on the bed??

C

Good milling vices are big and expensive,, especially if your after good quality work. I've not seen many that are small and "right" without being very expensive,, but then everyone's budget is different.

I'd just go blocks/clamps and work with that, cheap and fairly easy.
As far as holding blocks/plates etc go,,, make them. Good practice for you if your learning,, whether your learning the machine or just generally learning to machine. All you really need to start with is a decent square as said, and my first blocks were just scrap pieces of angle and flat I acquired and then managed to get some bigger stuff to work with. Mind you, for me, this was easy because of where I was working.

Speaking of clamping , Clamp Kit & 1-2-3 blocks are invaluable,
some imagination was needed here

Save abit longer sell the missus or kids but get a second hand turret mill .2nd hand bridgeport would be my choice.Bought ours 35 years ago 2nd hand and still does nice work The thing with the Bridgeport Pacific or similar is they are set up to take a slotting head wich adds a new dimension to the machine Internal or ex keyways ,splines dog clutches.
I wouldn't worry about DRO at first. Our other mills have it but I am happy to use the Bridgeport with just a Quill DRO scale and a magnetic base with a dial indicator

Just my thoughts AM

I have a lot of experience using AutoCAD (and a bit of SolidWorks) and lately have been playing around with 3D printing, which is basically CNC with building up material instead of removing it. You can make basic solids quite easily, I do a lot of rapid prototype design in (formerly google, now trimble) SketchUp which is ultra user friendly. Use a watertight plugin (makes sure your solid is a solid, with a contiguous internal void) then export it.

I haven't looked, but I am sure there will be a CNC community writing algorithms to translate 3D solids to CNC commands.

The main problem with CNC as opposed to 3D modelling is that you can only work from above (unless you have a nice big multi-axis industrial machine), so you need minimum 6 re-clampings of the work, with either very accurate repositioning or some adaptive feedback to the cutting head that finds a reference point on the work.

Looking into modelling and 3D printing small plastic parts that are traditionally injection moulded can be very cost effective for bits of trim, buttons, non structural mounting brackets.

There are also some really great emerging technologies in 3D printing metallic objects and prototypes. You can send your file off to an online service like 3D Metal Printing - Star Rapid, Shapeways - 3D Printing Service and Marketplace and Online 3D Printing Service
| i.materialise

If I had the time it would be great to get a database of 3D models for land rover parts that are hard to find or expensive happening, where people could print at home in starch/resin/nylon/etc. or online through other material providers.