East Grinstead Target Shooting Club
A Centre of Excellence for Smallbore Rifle Shooting

Air Range Upgrade 2017

04 Dec 2017

Existing Setup

The existing setup has 4 firing points with two Rika target changers that are about 25 years old and two others that date back to the early 1980's. The other two older units have been repaired on several occasions and the switches are getting dodgy again. We also have to dismantle and reassemble this setup 5 times a year when we use the air range as the marking room for open shoots and as additional space during the Christmas shoot.

Apart from the time taken to do this it is very frustrating when the support strings or hauling strings get knotted up and make it difficult putting the range back together.

Proposed Setup

Fit the units on the ceiling, extend the target carrier to hang down from the ceiling carrier, and relocate the buttons from the ceiling unit onto the old casings placed on the table.

Google is a wonderful thing but following some time researching this we couldn't actually find anyone that had done this before. So this is how we did it.

Step 1 - Buy the kit

  • Two new Rika units complete with pellet catches, target carriers, support cord and hauling cord.
  • Two new Rika pellet catchers.
  • Four new target carriers (in the end we only needed the target wires).
  • Aluminum bar and tube to suit.
  • 150 x 25 x 3000mm treated wood
  • 144 x 18 x 2400mm timber
  • Screws and bits and bobs as necessary

Assemble the kit for Lane 1 to prove the prototype. In other words, check it will actually work before taking Lanes 2, 3, and 4 out of commision and preventing use of the range!

Step 2 - Sort out the Electrics

Take one new unit and remove the baseplate and plastic cover.

OK, all 240VAC mains. Replace the cover and give that to an electrician then! See Step 11.

Step 3 - Install the Pellect Catcher

Trim the 150 x 25 x 3000mm treated wood to length to fit along the ceiling for Lanes 1-3. Each pellect catcher is secured with 4no screws. So the wood was fixed to the wall with more than 12no screws.

New pellet catcher was fitted directly above the existing pellet catcher. Complete unit was used as it contains all the fixings for the support ropes and the pulley for the hauling rope.

Step 4 - Install the Ceiling Mount

The ceiling rafters run across the firing point at 400mm centres and the ceiling is made of softboard so these are used to fix the units in the correct location. Cut the 144 x 18 x 2400mm timber into 4 equal sections 600mm long. Screw one section of wood to the ceiling. As the support cord terminations are offset, this needs to be located so that the pulley of the ceiling unit is directly above the pulley of the existing table unit.  Screw the baseplate of the first unit to the wooden support.

(TIP: Make sure that it is the correct way around as there is a hole in the centre that the plastic cover fits in and it isn't actually in the centre!)

Step 5 - Lighting Changes

The exisitng lighting units have a large metal shade to protect them from stray pellets. In order to fit the units on the ceiling these needed to be changed to a smaller shade to allow the cords to pass. A new unit was manufactured and fitted. Thanks to Richard Nichols and Southern Sheeting for their help on this.

(New shade on the left, old shade is on the right.)

(New shade fitted.)

Step 6 - Create the New Hanger

Take the new target carrier that comes complete with new hauling cord. The original idea was to drill a hole through each side of the carrier for the drop rod to go through but this proved impossible as the whole of this area is part of the slide that allows the position of the target support wires to move sideways to suit.

The "tubes" through which the support cords travel are reasonably long and can be used to clip the carrier into place. First, trim the base so that the aluminum bar can lay flat across the bottom. This was achived by careful use of a stanley knife(*) while holding the carrier in a vice.

(* other knives are available but I wouldn't recommend one where the blade is broken off as these can break when not expected if you lean on them too hard. Neither would I recommend a scalpel type craft knife as they are a bit lightweight for this task.)

(TIP - use a brand new blade it is so much easier! The old blade was a bit past it's prime).

Drill a new hole in the carrier to replace the one that is no longer useable. The trimmed carrier looks like this. The new hole proved to be a little small so was redrilled a bit bigger before the cords were installed.

Take one of the SWA clips and cut it in half with a hacksaw so it looks like this.

Cut a length of aluminum bar and drill a hole at each end to match the centres given by the clips.

Assemble the carrier with the nuts finger tight as shown below. Five washers were used between the clip and the aluminum bar so that clip applied some pressure to the tube when the nuts were tightened. The photo shows the top of the complete carrier.

Repeat the above using one of the new target carriers for the bottom end of the hanger.

Having strung the cords, the whole hanger looks like this and weighs a bit over 700g. The lower nuts were used to adjust the height of the target holder to set the target in front of the existing pellet catchers.

Apologies for the temporary electrics used for testing.

Initial trials showed the complete carriage was far to heavy and the upper carrier kept binding on the carrier cord and stopping the travel. Back to the drawing board!

Step 7 - Create New Carrier (v2)

A quick calculation showed that reducing the M6 threaded bar to M3 would still leave us with quite a heavy carriage. Some small diameter (smallbore?) plastic tube was located in Malcolm's garage. We also found some small diameter galvanise wire in store in the air loft. A quick bit of weighing and measuring esimated that the wire would weigh 54g and the plastic tube 94g. Version 2 of the carrier was therefore made up of two target carriers and two bits of bent wire.

TIP - The wire came in a coil and was therefore not very straight. Take a length of wire and put one end in the vice. Put the other end in an electric drill. Pull the wire tight and then pull the drill trigger. The wire twists into a spiral and hey presto, a straight bit of wire!

Trials showed a marked improvement on v1 but the travel was too fast. An examination of the drive electrics showed there was no potentiometer or other method of reducing the drive motor speed. Therefore, the simple solutuion was to reduce the diameter of the drive pulley on the unit.

Step 8 - Modify the Drive Pulley (v2.1)

The original pulley took 3.2sec to complete the 10m distance. The aim was to slow the speed of travel by reducing the size of the drive pulley.

Malcolm quickly made up a minimalist pulley (v1) not much bigger than the motor spindle made from a piece of aluminum tube he had in stock. This needed a significant tension on the hauling cord to create sufficient friction to stop the motor at the end of the travel and made the motor sound as if it was straining so it was abandoned in favour of version 2.

Another pulley about halfway betwen the original and v1 sizes was turned out of a square bar of aluminum (v2). The new version took 3.6sec (3.1m/s). Slower, but not as good as v1. So v2 was turned down to be smaller and the groove was modified to grip the hauling cord better to create pulley v2.1. This increased the travel time to 4.6sec (2.2m/s). Markedly slower than the original and much less momentum when it comes to stopping at the end of it's travel.

(Original pulley with the v2.1 on the table.)

Step 9 - Modify the Stopping Arrangement

Even at 2.2m/s the carrier arrives back at the firing point promptly! The original setup stops the target carrier because the carrier cords are supported at a wider spacing than the target carrier so the carrier is stopped as it approaches the end of it's travel by the change in spacing of the cord. The new carrier needs to be stopped more gently to prevent it swinging up and hitting you in the teeth!

Another search of the scrap (I won't throw that away in case it comes in handy) box and Malcolm found a very useful bar with a ring at each end. This was used to widen the spacing of the carrier cords at the firing point end. This increased the deceleration distance and softened the stop. Together with a bit of bracketry and pipe insulation the whole setup looks like this.

Step 10 - Modify the Carrier.

Trials of the new pulley showed the hanger had a tendency to swing left and right like a pendulum when it arrived at the target end. This was sorted with a bit of bent wire coathanger guide to prevent the movement. Subesequently this was changed to a piece of aluminum bar bent to suit.

During this process the wire verticals were replaced with small diameter aluminum tube. Slightly heavier but more useable. The lower target carrier was swapped for a piece of flat aluminum bar and a couple of bulldog clips. This was fixed to the verticals with a spring loaded washer.

Trials of this setup showed it worked OK. So attention was turned back to the electrics with cable and connectors being ordered. Further modifications were made to:

  • shorten the bracket off the ceiling to increase clearance for air rifles,
  • revert back to the wire target carrier instead of the bulldog clips so it could be used one-handed by air rifle shooters.

Step 11 - Get the Electrician in

The 7-core cable arrived along with 6+E connectors courtesy of TLC and CPC respectively (other electrical suppliers are available).

(6+E Plug and Socket)

Given that there would be four 7-core cables and a mains cable in the trunking some 50x50 trunking was fitted on the same planks used to support the units. A 3m length was just right to span across the 4 firing points. This trunking was drilled to accept some flexible trunking from the unit.

A second piece of trunking was run up the wall. Prior to fitting this section was drilled to accept the four 6+E sockets which would be solder connected to the 7-core flex in the trunking.

(Trunking pre-drilled to accept 6+E sockets)

This section was spaced of the wall about 12mm using a secondhand bit of timber so that it cleared some existing trunking at ceiling level and the panelling at the lower level. The trim on the top of the panelling was cut and the ceiling coving was cut slightly to allow the two sections of trunking to be fitted. The panelling and coving are left over from the time this end of the air range was still a part of the clubroom.

(6+E Socket fitted to trunking)

The power circuit was turned off. A fused spur was fitted adjacent to the existing double socket. The existing ring main was extended to suit. This required a section of 2.5mm cable about 150mm long.  A quick search showed that we didn't have any. So an expedition was sent up into the loft to acquire some by shortening an existing cable that had excess length! A section of trunking was fitted between the fused spur and the wall trunking and a hole drilled through the back of the wall trunking so the flex taking the power up to the first unit could be fitted.

(Fused spur and trunking)

The buttons were removed from the ceiling unit. The first one took 20 minutes, the second 2 minutes! That would be what they call a learning curve.

A suitable length of 7-core flex was fitted between the unit (together with some essential internal rewiring) and the 6+E socket. The flex for the power supply was also fitted to the unit together with a suitable length of flexible conduit.

(Nobby wiring in the unit for Firing Point 4)

The old unit was gutted and fitted with the buttons from the ceiling units. More 7-core flex was connected to the desk unit together with a 6+E plug. The desk unit was plugged in and the circuit turned on. Testing showed the system worked ok.

(Button unit positioned on desk, 7-core flex fed into trunking)

Repeat for FP4. In addition trunking was added to the front of the desks to carry the four 7-core flexes away from the desk. This kept the flex out of the inadvertent fire zone on the target side of the button units. Doesn't happen often but we're all human and it isn't a 5 minute job to rewire the 7-core flex.

Repeat for FP2 and FP3.

The redundant rocker switches on the desk units were removed and blanked off. The holes left where the button switches were removed from the ceiling units were fitted with blind grommets.

The whole setup was completed just in time for the Christmas Shoot. All we have to do now is decorate it.

Many thanks to Nobby Humphreys for his work on the electrics and Malcolm Brain for developing the target carrirers and modifications to the units.

Written by Administrator on Monday December 4, 2017
Permalink - Categories: news, 2017

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