Quote:
Originally Posted by Track/S
It is the same to exert force on the thread or in the hex area, it will not do any damage, the BMS tool when applying force by screwing it twists the electrode in the direction of tightening
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Ok great it's not touching the ceramic body, that's really good to know.
So the thing is for the BMS tool to twist the electrode it must be able to have enough friction against the electrode itself to exert a torque to it. But since the surface area between the contact is so small, and since friction force is defined as coefficent of friction X normal force - we can't actually exert much normal force since the electrode deforms as it flexes down so friction force itself isn't going to be very high either. So the combination of a really small surface area and low amount of friction means you can't exert a high enough torque to twist the electrode. Atleast in theory you can't, and I've never seen this style of tool actually twist the electrode before. Also since you can thread the spark plug deeper into the tool just by holding and twisting it from the electrode, the spark plug would rotate within the tool long before the electrode would be twisted and warped. So it shouldn't ever happen.
On a side note I actually have that exact same tool in your photo on the right, and those screws are really sharp and it made marks on my spark plug electrode while screwing them down. This is why I got the BMS tool, because the bolt on the bms tool is smooth and doesn't damage the electrode.
Overall im actually liking that tool you showed, it seems like a really really good option since it only exerts a force down on the top of the electrode and there is no additional rubbing. However, the reason why I prefer the BMS tool is because it allows me to pick up the tool for a closer visual inspection and reposition it sideways or whatnot without having to hold the spark plug into the tool or worrying about it falling out. But it's just personal preference at that point.