Short answer: Flip the top upside down, set the legs where you want them, mark the holes, drill pilot holes to the depth of the threaded inserts, drive the inserts in with an Allen wrench, and bolt the legs on. That is the whole job. Our metal table legs ship with RAMPA threaded inserts and bolts sized to the leg, and an instruction sheet with the exact drill bit and Allen wrench size for that set. Most people finish in under an hour with a drill, a tape measure, and a wrench. This guide walks through each step, the mistakes we see most, and how the process changes for live edge slabs, butcher block, epoxy tables, and thin tops.
Why threaded inserts instead of screws
A threaded insert is a steel sleeve with coarse threads on the outside and machine threads on the inside. You drive it into a pilot hole in the underside of the top, and the leg then bolts into it. Compared to running lag screws or wood screws straight into the top, inserts give you three things:
- A stronger hold. The insert's outside threads grab a lot more wood than a screw does, and the bolt threads into steel, not wood. You can tighten it properly without stripping anything.
- Legs that come off and go back on. Unbolt the legs to move the table, refinish the top, or ship it. Screws loosen a little every time they come out. A bolt into an insert does not.
- No splitting. The pilot hole is sized to the insert, so there is no wedging force on the wood.
Every set of cast and steel legs we sell comes with the inserts and bolts in the box. Wood legs are the exception; they attach through aprons and joinery, not hardware, and the materials guide covers that.
What is in the box
- The legs
- Threaded inserts, one per bolt hole
- Bolts and washers to match
- An instruction sheet with the drill bit size and Allen wrench size for that specific set
That last item matters. Insert sizes are not the same across all of our legs, so the drill bit and Allen wrench sizes vary from one collection to another. Use the numbers on the sheet in your box, not a number from a video or a forum post about a different leg.
Tools you need
- Power drill
- Drill bit in the size on your instruction sheet
- Allen wrench in the size on your instruction sheet
- Tape measure
- Pencil or marker
- Adjustable wrench or socket for the bolts
- Masking tape
- Combination square (helpful, not required)
Optional but worth having: a drill guide or a scrap block drilled square to keep the bit straight, and a moving blanket or cardboard to protect the finished top while it is upside down.
Step by step
1. Flip the top and position the legs
Lay the top upside down on a soft surface. Set the legs on it where you want them. For a dining or work table with two trestle legs, center each leg side to side and set it in from the end of the top. We use 12" to 18" from the end of the top to the outside face of the leg. That gives knee room for someone at the head of the table without cantilevering the ends out so far they tip. Dry fit with a chair if you can. The sizing guide goes deeper on placement and on how wide a top each leg can carry.
Measure from both ends and both sides so the legs are square to the top and match each other. A combination square against the edge of the top and the mounting plate makes this fast.
2. Mark the holes
With the leg held in place, mark the center of each bolt hole through the mounting plate. Then lift the leg off. Marking through the plate is more accurate than measuring the hole spacing and transferring it.
3. Drill the pilot holes
Wrap a piece of masking tape around the drill bit at the depth of the insert, so you have a visible stop. Drill each hole straight down to the tape. Two things go wrong here:
- Drilling at an angle. The insert follows the hole. If the hole leans, the insert leans, and the bolt will not want to start. Use a drill guide or sight down the bit from two directions.
- Drilling too deep. On a thin top this means through the top. On any top it means the insert has less to grab. The tape flag prevents both.
Clear the chips out of each hole before moving on.
4. Drive the inserts
Start each insert into its hole by hand or with pliers, then drive it the rest of the way with the Allen wrench until the top of the insert is flush with the wood. Do not leave it proud; the leg will not sit flat. Do not sink it below the surface either.
On softer woods like pine, poplar, or some cedar, a drop of wood glue or epoxy in the hole before the insert goes in helps it hold long term. On hardwoods like walnut, oak, maple, and ash, dry is fine.
5. Bolt the legs on
Set the leg back over the inserts, drop the bolts and washers through the mounting plate, and thread them in by hand first to be sure they are started straight. Then tighten with a wrench. Snug is enough. You are pulling the plate flat against the wood, not compressing anything.
Flip the table over, check that it sits level, and you are done. If it rocks, the floor is usually the reason, not the table. Our steel legs ship with adjustable feet levelers for exactly this.
Adjustments for different tops
Live edge slabs
Slabs are the most common top for our legs and the process is the same as above. Two things to watch. First, the underside of a slab is often not flat. If the mounting plate rocks on a hump or bridges a dip, plane or sand that spot flat before you drill so the plate sits fully on the wood. Second, slabs are wide, and wide boards move across the grain with the seasons. On a slab much wider than the mounting plate, some builders slightly elongate the outer bolt holes in the plate direction that runs across the grain, or leave the outer bolts a quarter turn less than tight, so the top can move without stressing the joint. On most tables this is not necessary, but it is worth knowing about if your slab is very wide or your climate swings hard between summer and winter.
Butcher block and glued up panels
The easiest top to attach. Flat underside, consistent thickness, hardwood. Follow the steps above with nothing special.
Epoxy river tables
Put the inserts in the wood, not the epoxy. Position the legs so every bolt hole lands on wood. Inserts hold in cured epoxy, but wood is the better anchor and it is what the sizing on your instruction sheet assumes.
Thin tops
Our legs are sized for a 1" to 2" top and thicker is fine. Under about 1", the insert may not have enough wood to grab, and you risk drilling through. Options: glue a hardwood batten to the underside where each leg mounts so there is more material to thread into, or call us before you drill and we will talk through it.
Plywood and MDF
Inserts hold in plywood reasonably well if the sheet is thick enough. They hold poorly in MDF. For either, a hardwood batten under the mounting area is the fix.
Stone, concrete, and glass
Threaded inserts are for wood. For a stone or concrete top you need a different anchor and usually a plywood or steel sub top between the leg and the stone. Call us and we will tell you what we have seen work.
Adding a stretcher rod
If you ordered a stretcher rod, attach the legs to the top first, then fit the rod between them before you flip the table over. The rod bolts to the legs, not the top, and comes with its own hardware and instructions.
Common mistakes
- Using a bit size from somewhere other than your instruction sheet. Too small and the insert will not drive. Too big and it will not hold.
- Skipping the tape depth flag and drilling through the top.
- Drilling at an angle so the bolt binds.
- Driving the insert past flush so the plate sits on wood instead of pulling tight against the insert.
- Overtightening the bolts. Snug is enough. Cranking on them does not make the table stronger and can crush the wood under the plate.
- Mounting to an unflat underside. Flatten the spot first.
Frequently asked questions
Do the threaded inserts and bolts come with the legs?
Yes. Every set of cast and steel legs ships with RAMPA threaded inserts, bolts, and an instruction sheet with the drill bit and Allen wrench size for that set. Wood legs attach through joinery and do not include hardware.
What size drill bit do I need for the inserts?
The size is printed on the instruction sheet in your box. Insert sizes vary between our leg collections, so use the number on your sheet rather than a size from a video or another set.
Can I use screws instead of the threaded inserts?
You can, but we do not recommend it. Inserts hold far better than screws, let you remove and reattach the legs without wearing out the holes, and do not split the wood.
How far in from the ends should I mount the legs?
We set the outside face of each leg 12" to 15" in from the end of the top on a standard dining table. Check knee room with a chair before drilling.
Can I take the legs off later?
Yes. That is one of the main reasons we use threaded inserts. Unbolt the legs to move, ship, or refinish the table, and bolt them back on to the same inserts.
How thick does the top need to be?
1" to 2" is typical and thicker is fine. Under about 1", glue a hardwood batten to the underside where the legs mount, or call us before you drill.
Stuck on a step or working with an unusual top? Send us a photo or call 1 (800) 920-8066 and we will walk you through it. Browse all metal table legs, or read the height and size guide if you are still choosing.