Farm Gate Hold-Back Latch

There used to be an old wooden gate at the boundary of the property, where the access track enters at the West end of the site, but that fell apart several years ago and ended up on the bonfire. While there doesn’t really need to be a gate there, having one provides a ‘spare’ for the matching gate at the entrance from the lane (which is more at risk of accident damage) – and helps stop the sheep running into the wildflower meadow when they’re being moved between the fields either side of the track.

This gate will spend most of its life held open so needs some sort of ‘latch’ to hold it in place. There are few options – ranging from traditional forged steel models to more modern designs – but I settled on the Gate Hold-Back Catch Hot-Dip Galvanised – ABL from Locinox which was £23 inc VAT from local steelwork supplier FH Brundle. This provides 50mm of vertical adjustment and is 500mm tall so there’s plenty of length in the ground to anchor it in place. (Other variants are made from aluminium so are slightly more fragile and also slightly more expensive – though they do offer more adjustment options and can be configured to latch either ‘over’ or ‘under’ a gate or door.)

Locinox ABL Gate Hold-Back Catch in Galvanised Steel

The galvanised steel bolts visible at the left of the photo above were my addition; the unit came with three large holes but adding bolts and nuts provides a much better ‘key’ into the concrete footing to maintain the vertical alignment. (There’s a third bolt-and-nut not visible in the photo.)

The gate sits quite low to the ground so only about 100mm of the latch is left protruding when it’s installed.

Gate latch mounted in the ground, with the majority of its length embedded in a concrete footing

The bottom bar of the galvanised steel gate is a 44mm diameter round tube, which isn’t ideal for ‘catching’ on the latch hook, so I decided to add a 3D-printed rectangular block to clamp around the tube. This took a couple of attempts to get right but worked out pretty nicely using some silver-grey PLA filament I happened to have available.

3D Model of Gate Tube Clamp modelled in OpenSCAD

One refinement I’d add if printing this again (and PLA isn’t expected to last more than a few years when exposed to the weather) is to radius the corner of the block at the back of the gate, to help the latch bar ‘rise up’ when latching it – right now it needs a bit of ‘help’ to lift.

The finished result of the latch holding back the gate using the rectangular clamp block

Temperature and Humidity Monitoring in the Outbuildings – Stage 3

An earlier Post outlined the plan to use IKEA TIMMERFLOTTE Temperature & Humidity Sensors with a GL.iNet GL-S20 Thread Border Router in conjunction with Home Assistant, to monitor the environmental conditions in various parts of the Outbuildings – especially the unheated rooms which are open to the ambient conditions.

I got the TIMMERFLOTTE devices on-boarded to Home Assistant fairly easily and they even noticed they had a firmware update available and downloaded and installed that over-the-air – all without needing any other IKEA-specific ‘hub’ or similar devices. The on-boarding (“commissioning” in Matter terminology) requires a smartphone (iOS in my case) and makes use of some of the built-in Apple software to help the Home Assistant App handle the set-up. For that to work, the smartphone must (temporarily) connect to the same network subnet as both the Thread Border Router and Home Assistant.

While the devices worked fine when tested in the House, they were not working when moved to the Outbuildings – despite them being on the same network Subnet (which gets ‘stretched’ to the Outbuildings – albeit via a few Ethernet Bridges and extra network hops). This was puzzling because everything was expected to work the same in both locations. It turned out to be a firewall issue, related to the use of an extra IPv6 address range: in the House the network traffic only has to traverse the network Switch to get from the Thread Border Router to Home Assistant (so it doesn’t reach the firewall) but with the Thread Border Router moved to the Outbuildings the traffic is traversing the inter-building link so hits the firewall to get to Home Assistant – even though it’s on the same Subnet. Three firewall rules turned out to be required:

  • Allow IPv6 UDP traffic with Source Port 5353 (i.e. mDNS)
  • Allow IPv6 UDP traffic with Destination Port 5540 (i.e. Matter)
  • Allow IPv6 ICMP traffic – to permit Home Assistant to ‘ping’ the sensors for diagnostic purposes

It’s clear the Matter protocol expects a completely ‘flat’ network topology – which isn’t great from a security or problem-solving standpoint. A decent compromise is to have a dedicated and largely isolated ‘flat’ Subnet for Matter / Thread traffic – but to dual-home the Home Assistant server so it can also participate in Matter communications (while using its ‘other’ network interface for all other communications).