[Fierra]

Hi,

We're building a product that utilizes a number of large parts machined from MDF with our 4' by 8' CNC Router Parts machine. Considering the large number of parts, and the frustration involved in using fasteners to attach each of the parts to the table before profiling the parts, we'd like to use a vacuum hold down table.

I've looked into using a vacuum hold down table that consists of a melamine core, and a thin, sacrificial MDF board. This would be ideal, given that we can place sheets of material on this, hit a button, and start. Unfortunately, this idea fails, as cutting profiles for 30 parts from a 4' by 8' MDF board negates the clamp force applied to the whole board, and the pieces will just come straight off.

I've been considering the viability of building a type of 'vacuum jig'. Basically building our melamine grid and rubber cord to match the profile of each part. Considering the time investment, I come here to see if anyone's running a similar idea on their own CNC Router, or if anyone could offer some input on a solution that may be useful for me here.

Thanks!

[ger21]

If you are careful about where you start your cuts, you shouldn't have any issues with vacuum hold down, provided you have the system setup properly. But you do need a fairly large vacuum source for a 4x8 table.

[1Jumper10]

It depends on how much surface area your parts have and how pourous they are. If you use the vacuum jig and gasket the shape of each part and your MDF is fairly thick and thus, relatively non porous, you won't need a large vacuum pump because you're effectively concentrating your available vacuum. But if you're using most of your table, even if you make jigs, you will likely need a decent vacuum source. A 4x8 table is a lot of area to pull vacuum on. A regen blower would be an option. You would need it's high flow to keep up with the leaks. Most anything more powerful than that is going to be at least ~$1500.

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[elfrench]

Try breaking the vacuum table into smaller sections that you can turn on and off. This will allow you to use a smaller vacuum source. A gcode macro could automate the process.

[bostosh]

for individual parts you need ports and bleed lines to them for each part,
why not tabs and a secondary cut-off?