Properly clamping a part is perhaps one of the most important steps in your CNC Fixture machining workflow.
Indeed, your attachment system will directly affect the vibrations produced during machining. These vibrations are significantly linked to the quality of the cuts, the longevity of your tools, and the noise generated by your machine.
However, there are many fastening systems, and making a good choice is not an easy task. The article below compares 8 different types of CNC fixture system and ranks them in terms of safety, cost, ergonomics, adaptability, and compatibility with different work areas.
Wood Screws
Attaching a part to your martyr with wood screws may seem too simple, but it is worth comparing it with other CNC fixtures.
This is one of the easiest and most ergonomic ways to clamp a workpiece. It’s quick to set up and very affordable. You don’t need anything except a screwdriver and a few screws.
The two main advantages are that this fixing system is strong and secure and that it allows you to place the fixing point wherever you want.
However, it has one major drawback: it will quickly damage the surface of your martyr. You will have to change it regularly or turn it over.
Two other problems with this system are that you can’t face it all the way if the screws are in your part, and a programming error can quickly cause your cutters to strip on the screws.
To sum up, screws are not the ideal way to fasten a part if you work on your CNC milling service daily, but we highly recommend working with this system if you are starting in the CNC fixture milling industry.
You’ll have time to refine your clamping system after you’ve learned from your mistakes and honed your machining skills.
For
- cheap and easy to set up
- ensures a strong and secure clamping
- suitable for (almost) all room heights
Against
- quickly damages the martyr
- cannot be used for surfacing operations
Composite Nails
If you work with wood, a composite nailer may be the perfect CNC fixture solution for you. This is one of the fastest ways to fix a part. With a nailer and a compressor, you can fix your parts in seconds and release them just as quickly once the job is done.
Its main advantage is that composite nails prevent damage to your cutter if you make a mistake in the G-code.
For
● very fast
● strong and secure attachment
● no risk of damaging your strawberries
● allows you to machine the entire surface of your part
Against
● cannot be used with all materials
● an initial investment is required
Double-Sided Tape
Using double-sided tape is one of the easiest ways to secure a workpiece. It’s simple to set up: cover the bottom of your workpiece with tape and stick it to the work surface.
The first thing to know about this system is that it will only work with high-quality tape. Otherwise, the part will easily come off due to the cutting forces, which can quickly become dangerous and cause splatter.
We also recommend using this system with a full protective enclosure around your CNC fixture to avoid any safety issues.
This system can nevertheless prove very useful in many different situations:
- For working with very thin metal sheets or wood sheets that cannot be easily clamped with any other system.
- When you don’t want to leave tabs on your part for a perfect finish. You need to make sure that the gluing surface of your part will be large enough so that it stays in place once cut from your blank.
In any case, the type of cutter you use will be very important CNC Fixture. Indeed, up-cut cutters tend to lift your part and detach it from the double tape, while down-cut cutters push the part onto the board.
For
- cheap and easy to set up
very useful for sheets or parts without tabs
Against
- maybe dangerous, not the safest
- does not work for all machining
Grasshopper Clamps
At first glance, toggle clamps seem to be the ideal solution for your CNC fixture milling machine. They can clamp or unclamp a workpiece very quickly, but they also show limitations in daily use.
Toggle clamps are perfect if you always clamp pieces of the same thickness: they are very fast and very easy to use CNC fixture. However, as soon as you have to adapt the rubber part to another height, it becomes complicated and you lose the advantages of these clamps.
In addition, they clamp the piece on the upper surface, which does not allow surfacing operations.
We only recommend using toggle clamps for special jobs, such as producing batches of identical parts for example. They can also be very practical for fixing a martyr to the machine frame, which allows it to be replaced very quickly when it is too damaged.
For
- the fastest tightening/unlocking system
- can clamp workpieces of different thicknesses (with adjustment)
Against
- is not ergonomic if the thickness of the part changes too often
- almost only suitable for T-slot frames
- does not allow surfacing operations
Clamping Blocks
Clamping blocks are one of the most commonly used clamping systems by CNC fixture users because this solution is strong, easy to clamp or loosen, and ergonomic.
You can easily order kits online, containing blocks of various sizes to accommodate most configurations with your workpieces. Note that you will need a work area with a T-slot or a grid of threaded inserts to use them.
If you do not intend to cut very hard materials, you can also mill these blocks yourself, to the desired size and thickness, in many materials, such as plywood, aluminum, or hard plastic.
The only real downside to clamp blocks is that you can’t surface the part you’re working on because the clamps cover it.
You’ll also need to be careful when generating your G-code to avoid any collisions between the clamps and your spindle.
For
● ease of clamping and loosening of the part
● can clamp (almost) any thickness
● robust and secure system
● you can mill them yourself
Against
● only suitable for threaded or T-slot inserts
● does not allow surfacing operations
Eccentric Clamps
Eccentric clamps are a very interesting workholding system for CNC fixture. They use the lateral forces on your part to clamp it to your work area, which provides a very secure clamping system without the need to place anything on your part and therefore allows you to completely surface it.
As with clamp blocks, you can find kits online or make these clamps yourself in many different materials.
Their main drawback is that they require the use CNC fixture of T-slots or a grid of threaded inserts. You will also need a large number of them to ensure that your part is securely fastened.
For
● ease of clamping and loosening of the part
● can clamp any thickness
● robust and safe system
● can be milled to meet your needs
Against
● only suitable for threaded or T-slot inserts
Suction Cups
Vacuum cups are an extremely versatile way to clamp a part to your CNC fixture. This system typically consists of multiple suction cups, which can be moved and clamped to your work area. They are connected to a vacuum pump that will suck up your part, holding it firmly clamped.
One of the main advantages of this system is its speed: in no time at all, you have moved your pads and you can clamp your workpiece with the push of a single button.
However, there are some drawbacks to this. You’ll need a vacuum pump, which makes it a more expensive clamping CNC fixture system than we’ve covered in this article.
Also, if you have to go all the way through your workpiece, you’ll need to position your stamps so that you don’t mill them, or have a perfectly flat work area, which can be a bit tricky.
For
● very fast clamping system
● can clamp any thickness
● robust and safe system
Against
● expensive
Suction Table
Finally, you can also opt for a complete downdraft table, which is the simplest solution if you have a large format CNC fixture milling machine and you are in production where the loading/unloading of your material has an impact on your profitability.
One of the main advantages of this CNC fixture system is its speed: in no time at all, you can clamp your workpiece with the push of a single button.
This method has one major drawback, however: you’ll need a vacuum pump, making it the most expensive clamping system we’ve covered in this article.
For
● very fast clamping system
● can clamp any thickness
● robust and safe system
Against
● very expensive
● cannot clamp all materials
