Adjustable Clamp-On Gate Hinge Plates for Steel Gate Posts
Step-by-step guide made from Indy Farm Life's YouTube video.
Fabricate and install bolt-on clamping steel hinge plates for heavy-duty driveway gate posts. By welding barrel hinges to a removable front plate clamped to a 6x6 steel post with four bolts and a backing plate, the gate height can be adjusted or replaced without cutting or re-welding the post.
The full step-by-step Spetz Specs for this project (every part, size, diagram and step, free): Adjustable Clamp-On Gate Hinge Plates for Steel Gate Posts Spetz Specs.
- Difficulty: intermediate
- Finished size: 6 in x 6 in x 12 ft posts
Disclaimer
- This project involves structural welding, setting heavy steel posts in concrete, and hanging 350 lb steel gates. Wear proper welding PPE, use safe lifting and support equipment for heavy steel components, and consult a qualified fabricator or contractor if you are not experienced with structural welding.
Safety
- Support the full 350 lb weight of each steel gate securely before loosening the four clamping bolts to adjust the vertical height.
Must know before you build
- Weld the barrel hinges to bolt-on steel clamping plates rather than directly to the posts so gate height can be adjusted if a post settles.
- Fill 6x6 steel posts with concrete and rebar for critical strength to support 350lb gates.
- Securely support the 350lb gate before loosening clamping bolts for any height adjustments.
Tools
- String line (layout string line) (optional)
- Laser level (rotary or line laser level) (optional)
- Welder (metal welder)
Materials
- Steel gate post (2, square structural steel tubing, 1/2 in wall thickness, 6 in x 6 in x 12 ft)
- Angle iron (2 per post, steel angle iron)
- Concrete (3 yards per post, poured concrete)
- Weld-on barrel gate hinges (2 per gate, two-piece lift-off barrel hinges with grease zerk, 7 in)
- Steel clamping plates (2 plates per hinge, flat steel plate)
- Bolts (4 per hinge, hex bolts)
- Nuts (4 per hinge, hex nuts)
- Lock washers (4 per hinge, split lock washers)
- Rebar (steel reinforcing bar)
- Steel driveway gates (2, metal swing gates, approx. 350 lbs each)
- Grease (lubricating grease)
Step by step
Step 1: Set the steel gate posts in concrete
Set the 6x6 steel gate posts with bidirectional angle iron braces into concrete footings on each side of the driveway.
- Brace the 6x6 steel post base with angle iron. Position the 6 in x 6 in, 1/2 in wall, 12 ft tall steel post in the footing with angle iron extending in two directions at the base for lateral stability.
- Tip: Attach angle iron going off in two directions at the base of the steel post to provide lateral stability in the footing.
- Align the opposite driveway post heights and pour concrete. Check the height alignment between the two driveway posts with a string line or laser level before pouring the 3-yard concrete footing, and fill the hollow interior of the 6x6 steel post with rebar and concrete.
- Tip: Run a string line or laser level across the driveway before pouring concrete to get the tops of the posts lined up.
- Tip: Fill the hollow steel post with concrete and rebar in addition to the surrounding footing so the post never settles and remains reusable for future gates.
- Common mistake: Relying solely on pre-pour leveling without a way to adjust the gate height if soft ground causes a post to settle while curing.
Step 2: Install the bolt-on clamping hinge plates
Weld the barrel hinge halves to the gate and front steel plate, then clamp the assembly around the post using four bolts, lock washers, and a backing plate.
- Weld the barrel hinge halves to the gate and front steel plate. Weld the upper female barrel half of the hinge to the vertical gate frame and weld the lower pin half (with the grease zerk on the bottom) to the front steel clamping plate, then position the front and rear plates around the 6x6 post with four bolts passing along the outside faces of the post.
- Tip: Weld one side of the barrel hinge to the gate itself and the other side to a flat steel clamping plate rather than directly to the post.
- Slide the hinge plate to height and tighten the rear lock nuts. Slide the clamped hinge plates vertically along the 6x6 post to the desired gate height, then tighten the four nuts with split lock washers against the rear backing plate to lock the hinge in place.
- Tip: Use lock washers under the nuts on the rear backing plate to lock the clamping hinge assembly in place once leveled.
- Adjust gate height or swap the bolt-on clamping plates as needed. Loosen the four clamping nuts to raise or lower the gate if height adjustment is ever needed, or unbolt and remove the clamping plates to install new plates and hinges if replacing the gates in the future.
Step 3: Mount and lubricate the lift-off barrel hinges
Fit the upper barrel hinge halves onto the bottom pins, grease the bottom zerk fittings, and test the swing of the gates.
- Set the upper barrel hinge onto the bottom pin and grease the zerk fitting. Lower the upper half of each barrel hinge onto the lower hinge pin and apply grease through the zerk fitting located at the bottom of the barrel.
- Tip: Use two-piece lift-off barrel hinges with a bottom grease zerk so you can lubricate the pivot pin and lift the gate off if needed.
- Test the swing of the 350 lb gate panels. Swing the 350 lb steel gate by hand to verify that the greased barrel hinges move smoothly with minimal effort.