David Love wrote: > The most useful algebraic manipulations are > > R = (BW + FW - (KR x WW))/ SW > > and > > SW = (BW + FW - (KR x WW))/R > Oh there are lots of equally usefull ways of rewriting this equation. I rewrite as BW + FW = ((SW x HR x WR) + WW) x KR . Directly measuring the three lever ratios is very doable and very reliable if you take into consideration what balance weight essentially is. Measuring the weights of each piece is straightforward enough. You can simply stipulate whatever BW you want for any given situation. WW is what it is... so you are left with SW and FW to manipulate. In other words... I get the ratio figure first (as a multiple of the three individual ratios), use that to decide what SW curve I want... then use the above equation... which is nothing more then an age old method for calculating the combined affect of multiple levers, and install what I need to yeild a specified Balance Weight. ((W1 x R1 x R2) + W2) x R3 etc. etc.. = Counter Balance Force (in our case BW + FW). Another very usefull rewrite is BW = (SW x R) + (KR x WW) - FW What might not be readily apparent here is that once you have installed your SW's and FW's... and you know what your R, KR, and WW... then the action MUST conform to your specified BW.... or there is a local problem with the something affecting the R. Great diagnostic tool... simply means that if your BW isnt what it should be for a key, then there is something wrong with the Ratio for that key. Not to forget Stanwoods own patented rewritting... FW = (SW x R) + (KR x WW) - BW While it is against patent laws to use this formula to solve for and install front weights... there is nothing that says you cant familiarize yourself with it for instructive purposes. As far as the second rewrite David sites above... ie. SW = (BW + FW - (KR x WW))/R It should be noted that this is will reveal how a given ratio for a given BW will yield one unique SW curve. It is based on an assumption that the FW maximums needed as constants in the equation are dependable as maximums. Many argue that these are too heavy... others argue that FW's can be heavier. But a change in the maximum FW table means a re-evaluation of what the <<appropriate>> SW curve is for any given SWR and BW spec (also assuming a 9 gram WBW) There is no where any real documentation that I am aware of that justifies any precise assumptions about Maximum FWs. Indeed... I would think that given the variance possible in key inertia for same FW... such a table would be in the end less then usefull to begin with. In anycase... todays maximum table is to no small degree a subjective opinion... which means any assumptions about what SW is appropriate for any given SWRatio is also equally subjective. That being said... there is also a good deal of experience and data that lies behind that subjective opinion.... so untill we get further with figuring in Key inertia into this picture.... its a good reference table. Cheers RicB -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html
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