Which Glue/Adhesive to Use?

Don’t use MDF, maybe something thicker and stronger? Could you use a machine screw and nut if that wouldn’t interfere with anything? Are you limited in the thickness? What is the jig for?

If you are concerned about it, epoxy. If you really want to be sure it holds, scuff up the bottom of the T-track before epoxying it in.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

Could you back the MDF face with a plywood backer? Even using plywood I usually double up the top when I am routing in metal t-track. I don’t bother if I am routing the slot with one of those t-track router bits that cuts the slot rather than using a metal one which is a 2nd option if you want to keep the jig smaller and lighter. I have had good luck routing a t slot into MDF directly in the past.

Liquid nails or Epoxy would probably both work in that case but I wonder how secure it will be long term. You might end up pulling up pieces of the MDF with the track over time.

Don’t try hot melt glue it will harden before you reach to the end of the slot. I too say liquid nails or similar.Alistair

-- excuse my typing as I have a form of parkinsons disease

Two part epoxy that works on metal, glass, and plastic.

I would have suggested a dual purpose track that can be secured from the bottom with T nuts, hex heads, etc. to avoid your current dilemma.

MDF is flat and easy to work but prone to absorbing moisture. Not good for a table top over time, not to mention its poor ability to hold fasteners.

-- Brad, Texas, https://www.youtube.com/user/tonkatoytruck/feed

Mike, have you ever had to scrape any brand of wood glue off from your bar clamps? Sticks pretty good doesn’t it?

I use Titebond II for 95% of my woodworking, that’s what I use when installing T-track in the jigs I make, works for me.
Epoxy will work great if you will never want to remove and reuse the T-track or have to replace the material which it’s glued to, in that case you will be grinding the epoxy off the T-track.

To your point of 3/4” MDF or Melamine.
IMHO;
If your jig is going to get a lot of use or is having to hold extreme racking clamp pressure the the 3/8” thickness under your T-track will fail over time, this is when you need to double your thickness of MDF or Melamine or switch to Baltic Birch or similar plywood for your jig components.

Best Regards. – Len
Work Safely and have Fun.

-- Mother Nature should be proud of what you've done with her tree. - Len ...just north of a stone's throw from the oHIo, river that is, in So. Indiana.

Thanks, everyone for your ideas.

The jig is designed to be used to flush-trim long (edge) lengths of lumber – to the straight (factory) edge of the mdf. I have 5 foot runs of maple that I want to join and make into a coffee table top.

I’m going to use the factory mdf edge to rout (with a flush trim bearing router bit) each mating surface of the maple boards. So as a solution, I may affix some plywood to the bottom of the jig so I can screw the t track through the mdf into the plywood. It’ll be heavy, but the t-track will definitely stay in place when anchored in this way.

-- Mike from Lansdowne, PA