Cooker and oven knobs are a bit odd in many ways as there are a multitude of different colours, sizes, fittings and general styles. Because of this there are very few that are generic and will fit any old appliance, in fact, there's really none that can.
What we tend to find is that as any form of knob on a cooker or oven is considered to be a "cosmetic" part that it is not uncommon to find that they are specific to one particular model never mind a range of ovens.
Due to this it is almost impossible to get a control knob for your cooker or oven without the correct model number from the rating plate. DO NOT trust the information in the handbook as it will almost certainly be a generic instruction manual covering many different models of cooker or oven and not specific to your own cooker or oven.
But the control knobs being specific to particular models has a very unpleasant side effect...
High Price For Plastic
We often are shocked ourselves at some of the prices for cooker and oven control knobs but, when you think about it, it is in some ways understandable.
They are specialist mouldings normally from a heat resistant plastic produced in low volumes. That means that they will cost more to produce in lower volumes once production of the cooker stops as, no doubt, the styling will have changed. So, they usually seem disproportionately expensive in relation to the original cost of the oven or cooker.
Then you have the metal coated or metal knobs which seem to not break as often but, when they do, they can be hideously expensive to change. Just look at the Rosieres control knobs in the shop and you'll see what we mean!
All that said, we still think that some manufacturers really do take the Mickey with the pricing of these spare parts. A typical example is the De Dietrich control knobs which are just a ludicrous price and, there's no alternative to using the pukka spare part from De Dietrich.
But when you get a retailer that adds a "standard" markup to all spares then the cost can ramp way out of control and you get stupid prices on control knobs. So do watch where you buy and, if you don't see the spare part that you're looking for in the shop it can pay dividends to ask us to source the control knob or knobs that you're after.
Other Reasons That Control Knobs Are Unique
Apart from the styling that can make it nigh on impossible to use anything other than the genuine part, which applies to both examples above from Rosieres and De Dietrich, there are other reasons that cooker and oven control knobs are model specific.
The main one is what we refer to as the "shaft offset". This is the angle that the "D" shaft (it usually is one) is set to in relation to the markings on the knob itself. Get the wrong offset and the knob will be anything from a few degrees to anything up to 360? out of kilter. If that's the case you'll have no clue what you set the control to, which isn't really very good or the point of replacing the knob in the first place as normally the markings have worn off them.
Asides from that you also have the shaft size to contend with. Although they are generally relatively standard sizes there are some that are different and, if you buy the wrong one it may well not fit at all.