By dumbbell is meant, not a piece of exercise apparatus – though the original dumbbell was just that, simulating the action of bell ringing – but a weighted wheel in a frame which can be rung full circle in the English style, in which for each pull of the rope a bell turns ‘full circle’ from approximately upside down to approximately upside down, rotating in one direction at one stroke and the other at the next.
17th century dumbbell
modern mini-dumbbell, John Norris design
Unlike its 17th century predecessor a modern dumbbell can be linked by a sensor to ringing software on a home computer or dedicated ringing simulator
It then forms an excellent learning aid, providing opportunities for extra practice at times to suit the ringer, facilitating the development of listening skills, ringing by rhythm and the learning of new methods. While not intended to be an end in itself, ringing a dumbbell is also challenging and fun, even though it lacks the ‘apres-ski’ of ringing in the tower.
There need be nothing ‘high tech’ about the theoretical design of a dumbbell but there can be considerable head scratching and experimentation involved when it comes to practical decisions on materials, size and weight. A dumbbell with a full size wheel, typically 4ft. in diameter, may pose significant space and stress issues for the average home.
The ‘mini’ dumbbell described in the downloadable DIY Instructions (5Mb) is designed for home use and can be installed in any convenient location with sufficient headroom beneath, typically in a loft with the rope falling through a ceiling boss to a ringing position on the landing.
The design uses an MDF wheel, 22" in diameter, 2" thick and weighing approx. 10 lb, with cutouts in the upper quadrants and 6 lb of steel weights attached to the lower half. The wheel is mounted on a headstock in a wooden frame approx. 29" long and 17" wide, the overall height being 27". A ½" spindle through the headstock runs in self-aligning ball bearings and a papier maché bell is fitted to the headstock, the whole ensemble loosely representing a bell in a traditional frame. (The bell is little more than whimsy but takes advantage of the space provided by the frame width, designed for stability.)
To accommodate a mini-dumbbell to this design, space is required not less than 29" long, 17" wide and 27" high, plus a little extra to allow for access.
[Reservations are sometimes expressed by potential purchasers about the need to cut a 2" dia. hole in the
ceiling for the rope. Given the size of the loft hatch the small hole needed for the rope seems almost immaterial.
However, there may be alternatives, depending on the layout of the house:-
For example,
Mount the dumbbell with the long wheel side, suitably supported, over the edge of the trap.
Mount the dumbbell wholly over the trap, either on a trolley on rails or on a short tower, allowing the rope to fall through the hatch while preserving access to the loft.
Mount the dumbbell over the stairwell.
Mount the dumbbell on a portable tower in a spare room.]
COMPUTER
The computer can be a standard WindowsPC running Abel, Beltower or Ringing Master
or a RISC OS computer (e.g. an Acorn RiscPC or A7000) running Stringing.
Any PC running Windows98 or later is likely to be adequate but visit the software websites for
details of minimum spec.
SENSOR and INTERFACE
To enable the dumbbell to be ‘rung’, a sensor is required and a means of interfacing it to the computer. With the optical system recommended, a light source in the sensor projects a beam towards the wheel and a reflector strip on the wheel reflects the beam as the mock bell passes bottom dead centre. A photo transistor in the sensor detects the reflected light and the brief output ‘pulse’ is passed via a suitable interface to the computer. The sensor and interface may be separate items or may be combined in the same unit.
There needs to be a delay between the moment when the reflector on the wheel passes the sensor and the normal striking point. This can be provided either by the interface or by the ringing software. Abel, Beltower and Ringing Master all offer this facility and the end result is indistinguishable from creating the delay in the interface.
OPTIONS
For a WindowsPC:
1: Alan Griffin ‘Photohead with Interface’ (PWI):
Specially designed to suit mini-dumbbells, the PWI comprises sensor and interface in one small unit, 75mm x 50mm x 25mm, mounted on the dumbbell frame. Signal delay between the reflector passing the sensor and the moment of strike is applied in software. Abel, Beltower and Ringing Master all include provision for this.
[For DIY enthusiasts, constructional details of the ‘budget’ version are downloadable in two pages here:- Page 1 and Page 2. This is electronically identical to the version available for purchase, illustrated above, but is housed in a film canister with a non-detachable lead.]
2: David Bagley single bell interface (SBI):
The SBI comprises sensor and interface in separate units. The signal delay is provided by the interface, not the ringing software. For further information visit David Bagley's website www.ringing.demon.co.uk.
Note that the Griffin and Bagley systems both plug into a serial port at the PC. If using a PC not equipped with a COM port a serial to USB converter will be required (available from Maplin Electronics at about £20).
For an Acorn RiscPC or A7000:
A Bagley sensor (just the optical sensor, not the complete SBI) and a Griffin RISC OS interface are needed and also a Watford I/O card. Details of Alan Griffin’s RISC OS interface are given in the Stringing manual (see below). A Watford I/O card can be purchased from CJE Micro’s.
(Stringing will appeal to RISC OS enthusiasts and may be the program of choice if a suitable Acorn computer is to hand. However, it does not offer such a wide range of features as Abel, Beltower and Ringing Master.)
COSTS
A mini dumbbell built to the design described can be constructed using all new materials and good quality self-aligning ball bearings for about £70. Depending on the availability of suitable materials already to hand it may be possible to cut the cost considerably, though it is unwise to skimp on the bearings – with such a relatively light wheel good bearings are important to ensure free running and pleasant handling.
Ready built items are available as follows:-
PC Option:
Dumbbell, rope, ceiling boss, Griffin ‘Photohead With Interface’ and lead,
ready to plug into a PC serial port £140.
(Not included: PC, ringing software)
RISC OS Option:
Dumbbell, rope, ceiling boss, Bagley sensor, Griffin RISC OS Interface,
Watford I/O card, Stringing and S/H RiscPC £215.
The above prices do not include carriage,
typically about £40 by courier including return of the empty packing case.
For further information, enquire for details or telephone 07774 863184.