A question I get asked regularly is "does the piano have an ironframe?". When I enquire as to why the customer asks they give me a shrug of the shoulders and say that "a friend" told them to make sure the piano has one. So I think the best thing is to give you few straight forward pointers on this topic. The photo with this blog post shows the interior of a Yamaha upright U3 piano which is one of the biggest pianos available on the market. But regardless of the height of any piano it will have an ironframe inside in proportion to the size.
All pianos manufactured since 1900 have an ironframe of some sort, this is a rigid castiron component of the piano onto which the piano strings are attached and when connected to the tuning pins contribute to retaining the tension required to keep a piano in tune. This also makes up a large amount of the weight of a piano as the frame needs to be sturdy enough not to warp under the tremendous pressure across the scale when a piano is tuned to concert pitch (A440). Based on piano design particularly in upright models sometimes it is not clear that an ironframe is there and unless the bottom panel is removed it is not easy to see. Grand pianos as an example have a frame which is clearly visible as in most cases the tops are normally open and the frame can be seen without any obstruction.
In simple terms all pianos currently on the market will have an ironframe as part of their initial construction and this should give customers peace of mind when looking to buy from reputable dealers throughout the sector. If you have any other questions regarding piano construction drop me an email and I will be happy to reply. Jeff Thornton.