We have always loved our CNC vacuum table that came with our Multicam machine. We have t-slots on 2 of our other machines and dread every part of holding down parts. That was until we created our own t-slot hold downs (info available on our website here). Since the use of these holdowns, we have not only accepted t-slots as a viable option, but have found that they offer advantages in certain situations. The problem I have with most hold downs is the fact that they cover up some of the cutting surface. Ours do not.
The only major problem with the vacuum is if your carve introduces a hole in your work piece. This would create a loss of vacuum and part loss. We have vacuumed down spoil boards and screwed down parts to the spoil boards, but that doesn’t let us use our fancy t-slot hold downs.
A student has a project that is going to require 2 sided machining that is going to require really tight tolerances and our Multicam machine is the best to make this cut, but we have 2 problems. We will be creating holes so the vacuum is unusable and we need to flip the part and accurately realign the part for consistency on both sides. We decided to make a t-slot table for our machine that has a dedicated home corner that is machined accurate by the CNC machine. Since the table top is removable, it needs to be able to realign as well to the machine bed.
We decided on a plywood base with aluminum top. The plywood is easy to cut slots in and an aluminum top is easy to machine. We CNC cut out the slots on the CNC machine so they are also machined accurate to the machine, but that was really unnecessary. We table saw cut the top aluminum slats.
This table is likely to get 5% of the use on this machine. It is still so nice and much easier to use the vacuum table. This however will be more accurate. We screwed down a small block of wood to the home corner and machined an L shape into it and have a dedicated home position for that spot. The table can be removed, the machine turned off and we can always find that home again. There will be a post about the project we are planning for it, but this is our finished table. It took about 2 hours from concept to completion.