Guide written by:
Lucas, Antique wood-worker, Gloucester
This is no run-of-the-mill tool! Milling machines are especially geared towards carpentry work, letting you produce intricate assemblies with the greatest of ease. Guide, diameter, cutting depth, blades, biscuits... Allow us to introduce your new favourite tool!
What is a milling machine?
The world of milling machines is a bit of minefield because manufacturers often use the term to mean various different things. To give a simple definition, a milling machine is a tool equipped with a high-speed rotating cutter for cutting wood or other materials (such as aluminium or plastic).
Here, we will focus mainly on the favourite tool of any woodchip lover: the biscuit or Domino milling machine (don't panic, all will be revealed!)
Below, in case you're curious, are some of the many other types of device that the phrase "milling machine" may refer to.
Peg or trunnion milling machine
For making glued wooden joints with cylindrical milled pegs.
Shadow seal milling machine
Used to make expansion joints, e.g. between floor and wall.
Plasterboard milling machine
Like the grooving machine, this type of tool is used for grooving and bending plasterboard.
Aluminium milling machine
Milling machine for use on aluminium.
Construction milling machine
Industrial-type milling machine for professional drilling, boring and milling.
Mini rotary tool machine
Since they take a milling head, these can also be included in the same category.
The milling machines we're talking about here are designed to make wooden assemblies: the milling head of the machine will cut into a piece wherever you want it to, and all you need to do is insert some small wooden "biscuits" and some strong adhesive to ensure an ultra-sturdy, unbreakable assembly.
The brand Festool has its own system, Domino, which has a distinct shape and offers even greater durability for your assemblies - but it's also more expensive!
Performance and characteristics of milling machines
Ranging in price from around £60 to well over £1000, the choice is vast! Since it actually makes little difference to their performance, all ourmilling machines have comparable power ratings:750-800W on average. In terms of weight, they can easily exceed 5kg but a lighter model of 2.5 - 3kg is a wise choice, especially for beginners.
The vast price range mainly comes down to overall tool quality: design, precision of control, and the motor.
Motor with electronic regulator
An electronic regulator prevents dangerous jumps and misalignments. To include in your checklist! A high-frequency (high rpm) motor guarantees a clean finish of cut, but you don't need to worry too much as assembly components aren't supposed to be visible!
Control quality can be boiled down to three checkboxes: if you can tick them all, congratulations, you've got a decent machine! You need to pay attention to cutting depth, height stopadjustment and front plate tilt range. In all three cases, you need an effective clamping system which won't slip out of line after three or four passes... Micrometric adjustment systems are highly recommended. The front plate is tilted for mitre cuts and chamfering work; sophisticated machines have rapid-action stops (e.g. at 0°, 22.5° and 45°), very convenient indeed!
Even if you only plan to use your milling machine on an occasional basis, it's always better to invest a little more than to end up with a poor quality model that will put you off woodwork for life!
Battery-operated models are starting to become available, but are currently quite expensive and only justified if you really need the flexibility they offer. If this is the case, a minimum 18V battery is recommended - and no less than 3 Ahbattery life; 5 Ah if you can stretch to it!
What sizes of milling blades can you get?
There are three standard sizes - 0, 10 and 20 - to be chosen depending on the size of pieces you're assembling. S6 and H9 are rarer but can also be used!
For a biscuit milling machine to be worth investing in, it must be compatible with the three most common sizes at least, or use will be rather limited.
If you want to use S6 and H9 size blades, the cost of the machine will increase, as you'll need one that can take 3mm blades (standard thickness being 4mm).
If you're looking at high-end machines, choose one with a pre-setting system. You choose the type of biscuits and the machine sets its cutting depth automatically!
What's a trunnion milling machine?
Here, the assembly is made with trunnions, or cylindrical pieces of beech wood. How does it work? Two drills spaced 32mm apart (standard layout) pierce your piece of wood in parallel... Then you glue and assemble as normal!
When choosing, it's just like with a biscuit milling machine: think about weight, power, performance and simplicity of controls, including angular adjustment.
High-end trunnion machines can operate with trunnions from3mm to 12.2mm in diameter.
This system is more economical in the long run,since trunnions are cheaper than biscuits and you can even make them yourself.
However, some carpenters claim that trunnion assemblies are less robust. But if you just want to redo your kitchen, you're golden!
What's a domino milling machine?
High quality machine lover? Then the Domino milling machine is made for you.
It works like a biscuit milling machine, except the assembly components are square, stronger and up to 14 x 140mm in size! Once again, this system works on the tenon-morticeprinciple.
As always, look at the same key factors as well as any extra accessories offered by the manufacturer - transfer stops, end grain stops, roundwood stops, angular stops.
It's simple - it's all geared towards making your life easier, as long as you've got the cash.
If you want the Rolls Royce of the milling machine world, go for a Domino machine. If you still manage to mess up your assemblies, choose a different hobby!
Final advice before choosing?
Allow yourself to find your bearings in the vast market of milling machines and keep in mind what you want - i.e. what type of work you want to perform, and how often you'll need to use your machine.
Pay attention to performance characteristics, as well as the range of accessories available to expand the scope of your machine.
From the small-scale biscuit, to the trunnion, through to the rather impressive Domino XL machine, you are truly spoilt for choice!
Learn more about woodworking tools...
To find out more about woodworking tools, follow our editors' advice and check out their other guides:
How to choose your drill bits?
How to choose your grooving machine?
How to choose your router?
How to choose your edge-planer?
How to choose your frame cutter?
How to choose your clamps?
How to choose your screws?
How to choose your drill?
How to choose your circular saw?
How to choose your workshop vacuum cleaner?
How to choose your mortiser?
Guide written by:
Lucas, Antique wood-worker, Gloucester, 27 guides
After some time busting my hump at construction, specifically at renovation, painting, carpentry, laying kitchen and bathroom tile, I decided to get my degree as a Carpenter. And I did well because nothing is more pleasant than working on a timber frame or designing a wooden house. Everything about woodworking fascinates me, and building my own home in this material is one of my goals. I’m also a follower of construction tools: I love to learn about innovations, the way they’re used, the tips and tricks, or the performances of each new tool on the market, whether it’s for woodworking or not. I would be happy to advise you and help you with your choices. Happy Tinkering.