Dust and fume control and ventilation are key in the shop for CNC work, not just for everyone’s health and safety but also for the long-term health and performance of your equipment.

Without proper dust collection and ventilation, health issues will arise over time, and your work will suffer. Proper airflow is essential for efficient cutting and ventilation systems, and accessories like ShopSabre Dust Dock for CNC routing should be used where needed.

In addition to these methods, using a water table or downdraft table can also help reduce dust, fumes, and smoke when operating a CNC plasma machine.

Here is a breakdown of the differences between a water table and a downdraft table and the pros and cons of each.

What is a water table?

A water table is a tank of water, typically 2-24 inches deep, that sits under the cutting surface of your CNC plasma machine. The material to be cut rests on vertical metal bars called slats during cutting, and the water level is usually between .125 and .25 inches below the bottom of the workpiece. 

Some operators with the right cutters can submerge the plate and plasma torch in the water during cutting. Compressed air is used in water tables to control the water level, raising or lowering the water as needed.

As you cut, the debris and smoke are pushed under the surface and into the water under the material. This traps fumes and smoke particles and cools the slag that sinks into the water. The water also reduces the heat of the cut and the material, which can improve the cut quality by minimizing dross and giving a smoother finish. 

Water tables also reduce heat distortion during cutting by keeping parts cool so they don’t crack and warp. This means parts cool faster and can be removed and used immediately after cutting.

Let’s look at the benefits of a water table and its drawbacks…

Water table benefits

  • Improved fume control during plasma cutting reduces dust and smoke by 90-95%
  • Plate warpage is reduced as the water cools the material, making plasma cutting more effective.
  • Reduced upfront costs as you don’t need fans, filters, or external power
  • Quiet operation, as there are no fans
  • Ready-to-use parts and reduced slag
  • Better cutting of thin material by maintaining temperature and reducing smoke and debris

Water table drawbacks

  • Risk of water splashing and leaks (ShopSabre splash guards can help, and all our water tables are leak tested before shipping)
  • Parts may need to be dried
  • Water treatment is required to prevent corrosion
  • A ball valve may need to be installed to drain and redirect water, which can benefit the environment.

What is a downdraft table?

A downdraft table has air from a fan, blower, or suction system that flows down through the table and pulls the dust and fume away from the underside of the cutting area and out of the shop through an HVAC, filter, or duct system. 

During the cutting process, downdraft tables help mitigate fumes and heat distortion like water tables but without the water. 

Downdraft tables have a slightly higher upfront cost than water tables and require additional equipment, but they are a cleaner system to maintain as there is no water.

Downdraft table benefits

  • Improved fume control reduces dust and smoke by 70-90% (fume reduction will vary based on the quality of the fan/pump system)
  • No water to check or adjust
  • Dust and particles can be collected neatly for easy disposal
  • Minimal table maintenance required by a fume table’s unique needs
  • No leaks or splashing to worry about

Plasma Table Downdraft table drawbacks

  • Higher upfront cost due to HVAC installation
  • Additional equipment required (fans, dust collection equipment, etc.)
  • More power usage as you need to run a fan/pump
  • More warpage due to increased heat
  • Longer time to cool parts before handling or using
  • More regulations due to air pollution regulations (see your local regulations)
  • Less smoke collection on nested large area parts (air goes to the area of least resistance)

Get the best airflow in your shop with ShopSabre

ShopSabre’s industry-leading CNC routers and plasmas are designed to help shop owners grow their production through precision, repeatability, and automation at an affordable price.

Our machines are easy to set up and run and to learn to use without formal training. Jim Colt recommends specific water table setups for our CNC machines. 

Ask Our CNC Machine Experts

Our team of experts will work one-on-one with you to find the right machine for you and make sure it works the way you and your business need it to.

Here are a few reasons why ShopSabre can do this:

  • In-house engineering expertise
  • We can fab and test designs in-house
  • We can put designs into production in-house

Shop our CNC routers and CNC plasmas in Minneapolis today.

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