Can anyone tell me the size to purchase for T-slot hold down clamps? Or maybe they are universal and I am dumb.
rNot sure what you are asking but if you are looking for bolts and knobs, most track can use 1/4" hex head bolts of an appropriate length with a knob or wingnut. some people use nylon bolts so that if they get cut the router bit will live on.
You can try these POWERTEC-T-Track-Threaded-Woodworking-Fixtures/dp/B0824G61RW/ref=sr_1_3?c at the dreaded amazon. I make my own knobs out of hardwood or plywood with a t nut or threaded insert.
Many of us make wooden hold down struts out of plywood Ior hardwood scraps with a slot along the center and a rebate at the end this can be placed on the bolt to hold down the work.
If this does not answer it for you, try being more specific.
YouTube has lots of examples of hold downs you might like.t