AF Machining Frequently Asked Questions [FAQ]

Welcome to the AF Machining forum FAQ section.

(*Please bear with us as this section, and the Machining forum itself grows!*)

Just click on the question below to go directly to that entry. Please note that that entries may not appear in order within the thread.

What can be made with machine tools? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4987580#post4987580)

Do I need both a lathe and a mill? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4987603#post4987603)

What is CNC? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4987642#post4987642)

What kinds of materials can be worked with on machine tools? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4988132#post4988132)

Where can machine tools and accessories be purchased? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4991547#post4991547)

Where can metal (and plastic) stock be purchased for machining? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4991557#post4991557)

Which axis is which? (http://www.automotiveforums.com/vbulletin/showthread.php?p=4991742#post4991742)

What's up with Sherline- is it the only option for small equipment?

Inches or metric?

What can be made with machine tools?

Have a look through the Machining Gallery (http://www.automotiveforums.com/vbulletin/showthread.php?t=760483).

Do I need both a lathe and a mill?

Yes. (And no.)
Either a lathe or a mill by themselves are limited tools. They are much more useful together than individually. It is true that some parts can be made exclusively on one machine entirely excluding the other, but it becomes very frustrating quickly to have to work with such a constraint.

That having been said, some lathes can be converted to mills with the addition of a milling column- so that the machine can be easily converted between 'lathe mode' and 'mill mode'. This gives the functionality of both machines at the expense of some convenience and some size capacity (working envelope). However, it can be a very cost effective way to purchase equipment to start machining.

What is CNC?

CNC is short for Computer Numeric Control, and refers to machine tools that are digitally controlled and driven. Parts are made by running a program designed to create that part, instead of traditional 'manual' machines on which the operator controls the motion of the machine by turning handwheels. The significant majority of industrial machining today is done on CNC machines. It is possible to equip even miniature machine tools with CNC, and it's becoming more common in hobby machining.

What kinds of materials can be worked with on machine tools?

Aluminum, brass, and steel are traditionally the most commonly machined metals. Machine tools can cut anything from 'exotic' hard metals such as titanium and stainless steel to plastics, and even wood. (Even small equipment like Sherline tools will cut all of these, and more.)

Aluminum generally is the most commonly machined metal. It's very easy to work with, and is relatively cheap, easy to find, lightweight, and corrosion resistant as well. Many machinists always choose to work with aluminum first, unless it's unsuitable for a particular application. 'Aircraft alloys' such as 6061 and 2024 are excellent for machining use.

Steel is often used when a stronger (or heavier) material than aluminum is needed. It is more difficult to machine, requiring more time (and patience). Commonly used varieties are cold rolled steel (CRS), hot rolled steel (HRS), and mild steel. Tool alloys such as drill rod can also be cut on machine tools, and then hardened to make cutting tools, such as drill bits, end mills, and lathe cutting bits.

Plastics are the easiest materials to machine. Commonly used varieties are nylon, delrin, and teflon. Acrylic and even styrene can also be cut on machine tools, but great care must be taken such that these plastics don't overheat and melt while being cut.

Where can machine tools and accessories be purchased?

These should get you started-
Sherline.com (http://www.sherline.com/) (Sherline also has an online dealer list here (http://www.sherline.com/dealers.htm).)
Harborfreight.com (http://www.harborfreight.com/)
LittleMachineShop.com (http://www.littlemachineshop.com/)
Micromark.com (http://www.micromark.com/)
Mcmaster.com (http://www.mcmaster.com/)

Where can metal (and plastic) stock be purchased for machining?

Here are some online metal suppliers. Most will take orders for 'small lengths' and/or have no minimum orders.
Metal Express (http://www.metalexpress.net/cgi-bin/index.pl?&ac=acHome&mod=core&sid=8ec9bb8b0ff9334b221d97973cfc965c)
Online Metals (http://www.onlinemetals.com/)
MetalSupermarkets (http://www.metalsupermarkets.com/)

For some thoughts on other sources, please see this thread (http://www.automotiveforums.com/vbulletin/showthread.php?t=759524). (And if you have ideas to add, please do!)

Which axis is which?

On the mill the axes are as follows:
X - Left/Right
Y - Forwards/Backwards
Z - Up/Down

On the lathe, the axes are as follows:
X - Tool in and out towards the rotating center
Y - Non Existant
Z - Length of to the bed.

What's up with Sherline- is it the only option for small equipment?

Nope, not at all. But Sherline does make excellent tools, and they are certainly worth considering.

In the 'mini machine tools' category, Sherline tools are amongst the smallest available. However, they are of excellent quality, they have terrific customer support, and they offer a very complete line of accessories.

However, Sherline is definitely not the only game in town. Another popular option are Chinese made 'import' tools. These are available from a number of sources. Generally these machines can be less expensive and larger than Sherline's offerings. Quality of some of these tools can be spotty- however with some attention, they often can be made into fine machines. This can involve partial or complete disassembly and rebuilding the machine, working key components to improve accuracy. A good operator with a well rebuilt 'import' machine can most definitely put out parts that are in every way equal to those that can be made by a good operator on Sherline tools.

When selecting tools, price and size are only two of a number of important considerations. What will be right for you can only be decided after considering all these factors. There are members here with many types of machines. If you need thoughts, opinions, and advice, please read through what has been said about these machines- and feel free to ask questions!

Inches or metric?

This is one of the most important decisions you will make in buying equipment for beginning machining. It's at least as important as brand of machines you buy, the size of these machines, or their cost. Once you select a unit to work in, you will quickly become accustomed to it and begin to think in terms of it. It's easy to buy and use a new machine in your accustomed units- but attempting to change units is a very difficult and frustrating endeavor.

Decimal inches offers a nice advantage, in that it just happens to be a very practical set of units when applied to machining:

1.0" is a useful unit for describing a length of material to be machined.
0.1" is an easy unit to rough cut material to (such as with a bandsaw).
0.01" is an easy unit to do quick 'rough' machining to.
0.001" is a very good practical limit to the accuracy realistically attainable by a good operator with good machine tools.
0.0001" is a good practical limit to the accuracy realistically attainable by a good operator with good grinding tools.

On the other hand, the metric system enjoys worldwide acceptance and use. If you're not in the US (or perhaps Canada), it may be entirely impractical to use a machine that requires fractional inch sized components when you simply cannot easily get those parts.

Of course it's entirely possible to create metric sized parts on a machine with 'standard' units (and vice versa)- but you will need to decide what units will be best for you to work in.