Adding Sacrificial Straight Surface to Table Saw Fence: What and How?
High up on this weekend's suckat list (things I suck at doing) is adding some sacrificial straight and flat surfaces to my extruded aluminum table saw fence that has T slots already in it for doing just that.
The previous owner to my fence already added a sacrificial surface, but I find it deficient in three ways:
1. He put the mounting bolt precisely where the big bold instruction label still in tact on this 30 year old fence stated NOT to put a bolt... directly in the path of the saw blade. Automatic fail. Must be changed.
2. He used CDX plywood. Not exactly the smoothest surface to run boards along.
3. He only mounted a surface on one side of the fence. I want a surface on both sides of the fence.
4. He didn't make the sacrificial fence long enough to cover the base fence, which creates a catch point when introducing sheet material to the table. It also reduces the ability of the fence to keep the material aligned prior to being cut.
So this means a redo, and rather than limit myself to just correcting his mistakes, I thought to put post my intent on this wonderful board of woodworking talkers, in order to seek some advice to help me avoid making mistakes of my own. So please post your experiences, thoughts, recommendations, and past mistakes that you would do differently next time, on adding sacrificial surfaces to fences.
The first question I had was regarding materials.... UHW plastic, vs Baltic Birch Plywood, vs MDF, vs Yellow Pine, vs Melamine... I've read a smattering of recommendations for each, only to be faced with lack of local availablity of the most preferred materials. I still seek advice on the pros and cons of each type of material, but in the meantime, I'm going to make a practice run at this with MDF as an interim improvement over the CDX and nothing that I have now.
The second question I had was regarding elevation... how much higher than the original fence should the sacrificial fence extend above the factory fence?
Third question: Fence float... should the sacrificial fence extend no lower than the factory fence, in order to float easily across the table? Or should the factory fence extend a millimeter or two below the factory fence to practically an interference interface with the table, in order to prevent slivers from sliding underneath the fence?
The fourth question is hardware orientation. With T slots in the aluminum extrusion, should I slide square nuts into the extrusion slots, and mount bolts through the sacrificial fence surface, with the bolt heads recessed? Or should I slide the heads of short square headed bolts into the extrusion slots, and capture the sacrificial fence surface with nuts recessed into the material? Pros/cons of each? Is there yet another, better way to make the attachment? Different type of hardware altogether?
The final question is one that I haven't and cannot ask, because I don't know enough to think of it. But you might, so please ask and answer those unknown questions with regard to mounting sacrificial surfaces onto extruded aluminum fences.
It shouldn't much matter, but I happen to have an Exact-I-Rip fence with one T slot per side on the vertical surfaces of the fence, and two T slots on the top surface of the fence.
Thanks in advance for your assistance!
Last edited by Mad; 06-02-2018 at 03:46 PM.