I had a waste board with a grip of t-nuts. Got a few uses out of it and realized I had to surface it again., and I felt it was too soon. Decided to go the t-track route. When I took the old waste board off I found saw dust under it :(. I then realized that I had used bolts that were a little too long for hold down, it raised the waste board and saw dust from other holes filled the gaps.
So, if you are using t-nuts or inserts make sure your bolts are not too long!
Yep,
After some similar incidents I decided to just drill through into the Carbide provided MDF underneath to allow some room for the bolts to go though. I also find it hard to spot when I’m jacking up my nice level spoilboard.
One thing I do every time I clean up after a cut, is vacuum every one of the holes in my spoilboard. I’m trying to keep the dust from accumulating.
I was having trouble with variations in depth. I discovered that my bolts were bottoming out and making my waste board uneven.
When I made my cam clamps I used what ever material was in the shop. That meant some clamps were 3/4 inch thick and some 7/8 and a few other thickness. So in the design I made sure that I adjusted the pocket for the washer and bolt head exactly .5 inches. That way no matter the overall thickness of my cam clamp the distance from the waste board to the bottom of the large pocket was always .5 inches.
After surfacing my waste board I measure the distance from the top of the waste board to the bottom of the factory base board and add .5 inches and that would be my maximum bolt length. I use a washer in the bottom of the pocket so that gives me a little cushion so I dont bottom out.
I start out with a 1.25 inch bolt and have a set I ground off to 1 1/8 inch and I have 1 inch bolts as I progress with the surfacing. When my waste board gets to 1/2 inch I replace it and reuse my 5/16 long 1/4-20 Tee nuts. So far it has worked pretty well.
This is a shot of my XL with popular cam clamps. For my XXL i have all oak clamps. My fences have nylon bolts to hold them in place in case I cut into the fence. The bolts in the cam clamps are steel.
That may not be sufficient. If your bolts have bottomed and you’re doing a cut, the dust can get between the spoilboard and the base board. Just sayin’
Well, my bolts don’t get bottomed because I measured them. 
Tex:
I also measure my bolts before using them. I have a variety of clamps (mostly shop made) and they were not made with the degree of attention that they could have been. In addition I use them in different configurations. Even my one set from Carbide3d came with several bolts of different lengths. I find the T-Nut solution works for me and checking bolt lengths is just part of my process.
Thanks to the OP for reminding us of one of the considerations when selecting the type of hold down system you choose.
Bill
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