The front and back sound chamber membranes are a rubber sheet. Using the type of rubber that take a lot of usage (self healing) before needing patching. Corflute overlay springs back significate over the bullet hole.
To repair and up-keep sound chamber a 16 inch by 79 inch roll of rubber for approximately $75 with glue is available. Cut a 20″ patch and glue over center area. It takes about 2 men 2 hours to accomplish.
The picture in the slide show are a target with just under 1000 rounds through it.
Our oldest targets in Australia are between 6 & 7 yrs old and have had 35,000 plus shots put through them.
Questions & Answers
Q: Why do you use rubber membranes, which require maintenance? Isn’t it simpler to have the sensors attached to the outside of a conventional target?
A: The rubber membranes form an acoustic chamber that isolates the sensors from numerous environmental effects which are detrimental to accuracy and reliability. The chamber is precisely described in the article Acoustic chamber targets: what you need to know. In fact our very first experiments with projectile detection were with sensors mounted outside a conventional target. It did work, but there are significant problems with accuracy and reliability, namely:
- The dramatic error due to impact angle variation can be for example 7 cm at 300 m, or 13 cm at 900 m.
- The Doppler Effect, caused by wind, can result in errors up to 5 cm
- Parallax error, where “conical” sound wave from the projectile is distorted due to environmental effects, or where the shooter’s position is not perfectly aligned with the target; these errors can be of the order of feet, dependent also on projectile speed
- Interference from projectiles firing on nearby targets, and other external noises.
- Accurate positioning of the sensors is critical to accurate performance, which is difficult to ensure on a conventional target frame. HEXTA target frames are designed for rigidity and built to high tolerances.
Our oldest targets have over 35,000 rounds through them with the original rubber. They have been patched as needed.
During our market research, the clear message from all shooters was that they would not compromise accuracy and reliability for a cheaper product. So we went for the “chamber” design. Our aim has always been to minimise errors wherever possible.
Please refer to the article Acoustic chamber targets: what you need to know and question “We are able to manufacture wooden target frames ourselves. We would like to get an estimate for supply of electronics, software, sensors, wireless connection, cabling etc”
- Target weight: 140 lbs. / 63 kg target box only.
- Maintenance: Periodically the rubber needs patching. You would likely do that once or twice per yr. That depends on activity and how much the shooters punch out the middle. The roll of patching rubber is 2000 mm X 400 mm. A patch between 200mm X 200 mm or 400 mm X 400 mm is usually sufficient. The roll is worth about $80 CDN.
- Also required a special tape cost approximately $30 CDN. Good for around 20 patches.
- Take 2 people about 20 min.
- Software calibrated for a 7.82 mm bullet hole.