How to Attach Project to CNC Wood Router?

Attaching the workpiece securely to the machine is a significant step towards a successful project. So, today I will discuss 4 methods of how to attach your project to a CNC wood router along with their pros and cons, respectively.

Methods to Attach Projects to CNC Wood Router

Top Clamping

This is the simplest and common way where a workpiece is secured with slotted clamps. All you have to do is simply position the clamp above the piece, then fix the screw of the slotted clamps via the slot. The clamp screw should be threaded through the router’s bed. 

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Here’s the tip: use a shim piece on the clamp’s backside, which is roughly equal to the width of the workpiece. But, check the project before clamping it. Many material pieces will have bowing prior to clamping them on the machine.  In the top clamping procedure, the convex side of the piece should face down so that its edges are raised above the surface. 

Pros: 

  • quick and easy clamping procedure

Cons: 

  • can actually include bow to the workpiece based on how the material is clamped
  • reduced access to the stock edge
  • heavy cuts on the workpiece can push it away

Edge Clamping

Edge clamping method is seldom used. Still, it is important to have a space in your workholding repertoire. In this procedure, you have to apply pressure to the stock from the opposing sides just like the way a vise holds the piece. Well, a couple of ways are there to achieve this. You can make toe clamps or try out the affordable edge clamping solution where you have to use wedges and blocks. 

With a wedge and block combination, you can simply fix a block in position, then slide up the workpiece to it. On the other hand, another block is fixed to the opposite side, on the table, leaving some space to accommodate the wedge between the block and the workpiece. Then you can gently tap or hammer the wedge with a maul. Press down the workpiece as you work in the wedge, ensuring that it has not raised the piece from the spoil board or bed. 

Pros: 

  • complete access to the top surface of the workpiece 
  • fast clamping procedure if it is a good wood routing system

Cons: 

  • can include bow to softer or thinner material
  • not more secure than vise clamping 

Vacuum Clamping

Vacuum clamping is an effective procedure  which requires you developing a little knowledge of science. In this method, air pressure of 14.7 pounds force/square inch is applied (which is equal to atmospheric pressure on Earth), minimum about the sea level. Let’s understand it with an example, consider that you have a 5×5 (that is 25 square inches) workpiece and you achieve a perfect vacuum of only 80% around. 

This 80% multiplied by 14.7 multiplied by 25 square inches equals a hold-down force of 294 pounds. So, in the same way, if the area of the workpiece was 100 square inches (10 by 10), then the value of hold-down force would have increased to 1,176 pounds! Under such a force, if you try pushing off the workpiece of the vacuum plenum, you will literally push the entire CNC router away from the table without even budging the workpiece. 

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Some vacuum clamping mechanisms need a bigger vacuum pump, there are manufacturers that offer vacuum systems involving air compressor mechanisms to generate vacuum using a venturi vacuum generator. You just have to arrange the gasket for the vacuum plenum that matches the shape of your vacuum system, place the gasket on the table, then place the workpiece and finally, turn ON the valve of the generator.

Pros: 

  • parts can be taken on and off real quick 
  • flat projects really fit this sort of clamping system
  • produces intense workholding force
  • gives you complete access to the upper part of the project

Cons: 

  • The material put on the clamp can be cut through all the way. But, you have to be more strategic regarding the position of the vacuum gasket relative to the workpiece
  • You have to keep some thousandths of an inch of the job uncut at the bottom so that you don’t break the gasket seal of the vacuum system 
  • Small workpieces are not fit for vacuum clamped machining 

Vise

A vise is basically seen in the metal workshops or metalworking industries and mills. But, you can also employ it in your woodworking shop as well. The real challenge is when you use a vise with a profile that is too low to let gantry clearance. Again, if you have a homing switch/switches, then you can consider the corners of the “fixed” vise jaw to be the origin of your project’s coordinate system. It improves precision in work and repeatability (if you have a bulk order for the same kind of project).

Pros: 

  • Greater amount of workholding force
  • Easy to both clamp and unclamp the project
  • Allows complete access to the upper side of the workpiece

Cons: 

  • Only comparatively smaller wood pieces can be clamped 
  • Be careful about the accidental collision with the iron vise 
  • Less sturdy or thinner workpieces are susceptible to collapse or bow 

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