Alan Evans Posted March 8, 2012 Share Posted March 8, 2012 When forging longer heavier tapers on the power hammer and such I calculate the volumes and divide by the cross section of the parent bar and then centre punch or corner fuller cold depending on the piece. You can then be quite precise in forging down to a fixed size in the middle of the bar and working the tip out last in the subsequent heats which is obviously safer. Opposite way to hand forging a taper where you start at the tip. I made up a little spreadsheet for calculating taper volumes and have it in my phone. It works on round, square, flat or polygonal section if anybody is interested I can post the formula here. A really good habit I have got into is to chalk a squiggly line down the face that I have put the marks on, that speeds up finding the mark on the hot piece by a factor of four (or eight on an octagon)! The squiggly line is also useful if you are doing a punching and drifting sequence to ensure that you can achieve the same barrelling offset of the swelling by always starting squiggle up; squiggle down second operation etc. Quote Link to comment Share on other sites More sharing options...
ironstein Posted March 8, 2012 Share Posted March 8, 2012 I would be interested in your taper volume formula. Always interested to find new ways to calculate tapers. Quote Link to comment Share on other sites More sharing options...
r smith Posted March 8, 2012 Share Posted March 8, 2012 I will second that Quote Link to comment Share on other sites More sharing options...
iron quake Posted March 8, 2012 Author Share Posted March 8, 2012 Yes please post the spreadsheet I'd use it for sure. I like the squiggle line idea also. Any thing to speed up the process for an old guy with crappy eye sight.Thanks Everyone Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted March 8, 2012 Share Posted March 8, 2012 Herewith the spreadsheet if I can work out how to attach it to the post. Ah bother, it comes up saying "Error You aren't permitted to upload this type of file" any ideas anyone? Looks like only images allowed. I think I will have to add screen shots and paste in the actual formulae, see below. I can email the .xls file or a .csv if you send me a PM. It will work with any units, provided you are consistent! mm cm metres or inches The titles should be fairly self explanatory. It calculates the frustrum of a cone or pyramid, frustum means flat topped. You put in the surface area of the TOP end and the surface area of the BASE and the length/HEIGHT. The formula calculates the VOLUME of the frustrum/taper and then the next row shows the length of bar of the base area dimension required to get the taper out of. In the PARENT BAR row you have to enter the cross sectional area of the bar you are starting with in cases where this is not the same as the base area of the taper. Say you start from 60mm square which then steps down to 50mm square parallel for a section and then goes into a taper to 30mm, so you would put in B4/360 or B4/36 if using cm. The last two rows show the weight of the taper volume in kilos depending whether you used mm or cm. This is the only time I ever use cm because it keeps the numbers more manageable. I have not worked out the multiplier for inches/lbs but I am sure one of you will be capable if you need it. Using any form of calculation for forge work has necessarily an element of fudgery! You might need to allow a bit extra for oxidisation / heat loss depending on the atmosphere and speed of your furnace or fire; either a powerful carburising or neutral atmosphere fast heating furnace or having to take lots and lots of slow heats in a hand cranked coke hearth.... If you can do it all in one heat because you have a huge powerhammer... The other thing this formula does is remind you of the different type of tapers available and their characters. The formula calculates a straight taper, straight sided. If you forge an elegant hollow sided taper from the volume it will obviously come out longer, if you forge a stubby cigar shaped / full sided taper it will come out shorter. I find that if I am going to subsequently bend or form the taper a straight sided one seems to work best, the eye moves along it at a uniform speed. This is the formula from cell B4 =B3*(B1+SQRT(B1*B2)+B2)/3 The screen grabs show the highlighted cell contents in the formula bar below What a pallaver for a simple spreadsheet...digital life rules! Quote Link to comment Share on other sites More sharing options...
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