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STEPCRAFT Vacuum Clamping

STEPCRAFT and vacuum clamping

We get asked a lot of questions about vacuum table system on the STEPCRAFT so we have dedicated this page to try to inform how they work and why the spec is the way it is.

our specifications are designed to fullfill the following criteria

  • Provision of safe reliable pump system that runs on single phase
  • Provision of all filter and safety pressure fittings to prevent fire risk from overheating and damage to the pump
  • Provision of work holding performance even when machining breakthoughs
Pump system specifications

The pumps we provide range from 0.75kW up to 3kW. For the STEPCRAFT the recommended pump system is the 1.1kW system as it runs off single phase and will provide good performance up to the 840 sized travel.

The pump systems have the following features

  • Side channel blower design for high under-pressure levels even when there is flow into the pumps though the table. This is a very important feature for good performance.
  • The pumps have 50-70CFM capacity allowing a significant level of under pressure to be achieved.
  • The systems are supplied with a filter to prevent any unwanted particulates getting into the pump
  • The systems have an underpressure valve system which is tuned by us to ensure optimal setup for pump safety and vacuum system performance
  • If you do not manage the underpressure levels with a safety valve then your system is a fire hazard
  • We offer an optional pressure gauge in line in the system also. this allows you to monitor the pressure from the pump
WARNING! don't be fooled.....

The image of the pump here shown is typically used in vacuum bagging and vacuum processing. These pumps are a lot less expensive than a turnkey side channel blower system. the reason they don’t work well is as follows

  • These pumps do provide a very high level of vacuum pressure (99.99%). However this is only with no flow. when the table is covered 100%. As soon as you induce flow (machine a breakthrough) they loose all vacuum pressure.
  • With typical flow rates of 3-12 CFM these systems cannot maintain the vacuum pressure for machining parts through full thickness. Any exposure of the table surface and the pressure is lost
  • if you only want to engrave or machine features into a part and you keep all the table covered and your part is not porous then this pump will work
  • if you want to mill out shapes from the work piece then this pump is not the correct choice.
  • We tried a range of pumps of this type and spec and they don’t work.
The "Through the MDF trick"

Watch the video here shown of the STEPCRAFT machining out an interface panel from gravoply. The part is held “through” the MDF.

  • The 3mm MDF is porous. Place the MDF onto table then place the part on top of the MDF
  • The part is then held through the MDF and can be machined.
  • This has a number of advantages. 1) the part is held perfectly flat for engraving. 2) you can apply spray adhesive and the table holds down the work perfectly for adhesion and allows machining of very small parts.
  • You can also machine through the thickness of the material. So in this case the 2mm gravoply was machined to a depth of 2.3mm. This way there is no finishing, the part is cut clean and the MDF takes the over cut so the table is undamaged afterwards
STEPCRAFT Vacuum table setup

To setup your STEPCRAFT CNC router system with a vacuum table system there are a few steps to optimise your installation.

  • The table needs to be mounted to the machine. The table splits so you can fasten the base plate to the machine and then fasten the table to the base plate
  • Once installed its a good idea to skim the top of the table with your machine. This ensures optimal tram setup for Z axis accuracy.
  • The end results is a trammed flat vacuum clamping system. We use this system in house for a variety of our production parts. its a very quick and efficient way to hold your work
  • The video here shows the setup process