Posts tagged backcheck
If you own an upright piano and it hasn’t been maintained other than tuning, it’s time to do a simple test. Ever so gently, press some keys down on your piano. The first 1-2 millimeters (1/16″) does it feel kinda loose? If so, you may have a case of something called ‘lost motion’. What is lost motion anyway? Well before we discuss it, take a moment to look at the two videos below. The one on the left has gaps in the parts. Notice how the one green part is moving significantly before engaging the assembly? The one on the right is a snug fit – I just finished adjusting the same piano. So what actually is happening here? Glad you asked. Over time, parts wear and compress and create spaces or gaps between parts. And instead of moving smoothly together, the parts start travel at different times. At the keyboard i would describe it as feeling ‘loose’. It’s called lost motion because the green backcheck is moving without pushing the hammer towards the strings. In essence, the hammer has lost some of it’s power or force due to the gaps between parts – thus the name. And the fix? Easy – there’s an adjustment screw to take out that lost motion. A technician can have that fixed in no time at all. So if you’re feeling like you’d your piano isn’t quite right, do this little check and ask your tech the next time they come to tune because is probably the quickest fix with the most drastic results on a piano that i know of.