Capable of taking drill bits up to 0.75 inch diameter – Why? It is extremely difficult to purchase straight shank drills over 13mm. The usual practice is to have a 13mm (1/2 inch) chuck and then purchase special cutting tools (such as blacksmiths drill bits of circular hole saws) for the purpose of creating larger holes. Also, since most drills are manufactured with 13mm chucks (maximum) such a size chuck would be cheaper to purchase for assembly. For marketing purposes it is a good idea to offer both imperial and metric sizes to the end user. Customers Decision- Yes. Quite happy with that line of reasoning, use 13mm (1/2 inch) chuck. Also, publish all information on chuck size in metric and imperial.
Operate from 240 volt, 50 Hz power supply – Is this the only voltage to be considered for use? Would dual voltage be advantageous for foreign exports markets. Will push cost of drill up to have this as a transformer and voltage selector switch will be necessary. There are also no power requirements for the motor. What power is required from the motor? A 700 watt motor will provide the capability of drilling 35mm in wood, 13mm in steel and 20mm in concrete. Customer Decision – No. Stick with 240 volt supply. We will adapt design in the future for foreign sales. Motor is to have a 700 watt rating using the material cutting dimensions offered by the designer.
Capable of two speed operation – What are the two speeds to be? A good range, going by industry norm, would be 0-1250 and 0-3000 rpm. This allows the end user to obtain higher torques with the lower speed range but also the ability to cut efficiently with smaller drills using the higher speed range. How will the speed be controlled? One standard solution is via a variable trigger on the butt of the pistol grip. Customer Decision – Use the speeds provided by the designer as this will correlate with the figures given for the different materials to be cut. Control will be via a variable trigger as is standard on many drills already on the market.
Have a hammer action – No comment to be made. Must have a hammer action.
Operate continuously for long periods of time – What is considered to be a long period of time? Customer Decision – No answer to that. Remove from PDS.
Suitable for soft and hard drilling – What is soft and hard drilling? All drills are reliant upon the type of drill bit being suitable for the material being cut. Customer Decision – No answer to that. Remove from PDS
Eccentricity of drilling action must be limited to 0.01 inches, for drill bits up to 12 inches in length -Is the eccentricity crucial to this type of machine? To achieve this sort of accuracy it will be necessary to use very high quality bearings and gearing systems. This will push the cost of the drill up and also any benefit would be lost due to the fact that this is a hand drill and an end user will not be able to drill a hole with such accuracy. Customer Decision – Use of standard sealed bearings and gears is to be allowed, as no benefit would be gained by using higher quality equipment.
Have a minimum cable reach of 5m – Is the cable length that critical? Extension leads can provide adequate reach from the source of power to the drill. The recommended length should be just long enough to allow freedom of movement for drilling. Longer cables represent trip hazards, increased material costs and cable stowage problems. Suggest the length be reduced to 2m. Customer Decision – Use the cable length suggested by designer. Extra cable length will only produce further problems, which will increase cost.
Able to operate internally and externally, within a temperature range of -20ï¿½C to +40ï¿½C
Have no adverse effects from dirt, dust or ingress of oil or grease
Capable of operation in wet conditions
Capable of operation where combustible dusts are present
Whilst all these conditions are quite clear it will raise concerns with regards to the design of the drill. For it to operate under very harsh external conditions the cabling and the plug systems will need to meet exacting safety standards. Also, for the drill to be used in a combustible atmosphere it will need to have special insulation and protection on the motor to prevent arcing and sparking. The standards to be met for this aspect of the design are -:
* BS 4999
* BS 5000
* BS 5501
* BS 6467
Also, suitable caging of the motor would be required to ensure the ingress of dirt and dust does not occur. This all totalled together could push the cost of the drill up. Customer Decision – Maintain all aspects of this part of the specification except that the drill is not to be used in wet conditions. This could lead to higher costs for the production of such a drill that Llamedos Engineering could not justify. Nor could a potential lawsuit in the event of an accident due to electrocution be afforded.
Capable of being dismantled into component parts, for ease of maintenance – What are component parts? Does the customer want to be able to strip down the drill to the nth degree and have everything stripped? E.g. Motor stripped right down to windings, switch stripped down to trigger, etc. Customer Decision – Only allow the drill to be dismantled down to the basic standard supplied parts. This allows us to simply change a defective part as a unit should it be necessary.
Requires no special tools, for dismantling/assembly operations – What is classified as special tooling? Does the customer what any tooling at all or will standard tools such as a screwdriver suffice? Customer Decision – We want to minimise the number of tools that are used to assemble and repair this drill. To this end we suggest that the only tool to be used would be a No.2 crosshead screwdriver. This means that all fixings must either use a screw that can take this screwdriver or they must be snap fixings moulded into the case. All electrical connections can be by spade or bullet connectors.
Component parts to last a minimum of two years, before requiring replacement or rectification
To cost a maximum of ï¿½60.00 – The viability of this figure will need to be determined by taking into account the tooling requirements, material costs and manufacturing costs based on the required tolerances that have to be met. From research on competitive drills this figure should be attainable.
Two thousand required for a first production run
Polymer body shell with two-colour finish – What is required as a two colour scheme? What colours are to be used? Is it absolutely necessary? Customer Decision – A two colour scheme is to be adopted as this will appeal to the home user market that this drill is designed. The two colours to be used are dark purple for the body and all visible moveable parts are to be canary yellow. Exact colours are down the designer.
Pistol grip lower body and upper body steady handle
Metal chuck assembly, with chrome finish – Why chrome finish? Chrome finish will chip and flake. Far better to go with an oil blacked chuck as this will not scratch or flake, is more durable and will not cost anywhere near as much as chroming. Customer Decision – Accept what the designer has said and will accept an oil blacked chuck as alternative
Maximum weight of 3kg
Overall length not to exceed 30cm – No significant concerns here. Allows room for designer to manoeuvre.
Complies with all relevant British Standards – Is the drill intended for foreign markets. If so then further legislation may need to be adhered to, to be accepted in other countries. Customer Decision – As stated in Performance drill will only be for domestic markets at the moment .If a decision to move to foreign markets is accepted later then the drill can be compared against foreign standards.