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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Camshaft
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<blockquote data-quote="oexing" data-source="post: 105277" data-attributes="member: 1493"><p>Publishing one´s measuring machine´s accuracies may be veeery impressive but at these numbers all this does to me is rolling my eyes . . . . I have limited resolutions on my test stand for cams to 1 micron (1/25 of one thou) and 1/4 of one degree on the rotary encoder. I am not interested in anything better as I know from my professional life being retired toolmaker , accuracies in REAL life are quite different from what academic people believe in their imagination. All these numbers may have some meaning for computer calculations to arrive at some result in the CAD exercise but in the toolroom you are happy to see one thou or half of it close to the desired size, no way near 8 decimal places in existence. In fact, when you get a new cam from any company, you are lucky to see a base circle with less than two thou runout, all other base circles with runouts all over the place. </p><p> Anyway, this is not our concern, we just had a look at cam lobe shapes for comparison and evaluation from other cam data bases in order to be able to assist buyers in finding suitable camshafts. I do have a few programs from Perfrmance Trend, cam analyser and cam grinder. BUT, big question is,how do you arrive at the cam shapes ?? And right here all postings are veeery hazy, it is quite obvious that the start has to be the valve lift diagramm. I can provide 40 different computer calculated files , different in lift numbers, acceleration , and duration, three decimal places - in millimeters, one micron that is. </p><p> Now the REAL hard work is to model all levers, rocker finger shapes, cam follower details, into a CAD program that handles these kinematics to transform in the end valve lift numbers into cam lobe shapes !! I was toolmaker in life , with all traditional skills, but CAD was not one of these. So is there a chance to get any info here on suitable programs for such calculations , Fusion 360 , not so much ?? I believe Performance Trend can analyse dynamics in the valve train by simulation but only AFTER a cam was fabricated, it does nothing for designing a cam. </p><p> So the procedure to arrive at a particular cam shape , starting with valve lift numbers , is definitely my big question but I guess that haziness about details will continue . . . </p><p> Valve bounce and other adverse effects are seen mainly in race type engines and I believe there is no universal solution in all cases and has to be dealt with individually. Most Vincenteers will be more interested in smooth operation by mild acceleration and quieting ramps so no radical fast wearing shapes acceptable. </p><p></p><p> Vic[ATTACH=full]26313[/ATTACH]</p></blockquote><p></p>
[QUOTE="oexing, post: 105277, member: 1493"] Publishing one´s measuring machine´s accuracies may be veeery impressive but at these numbers all this does to me is rolling my eyes . . . . I have limited resolutions on my test stand for cams to 1 micron (1/25 of one thou) and 1/4 of one degree on the rotary encoder. I am not interested in anything better as I know from my professional life being retired toolmaker , accuracies in REAL life are quite different from what academic people believe in their imagination. All these numbers may have some meaning for computer calculations to arrive at some result in the CAD exercise but in the toolroom you are happy to see one thou or half of it close to the desired size, no way near 8 decimal places in existence. In fact, when you get a new cam from any company, you are lucky to see a base circle with less than two thou runout, all other base circles with runouts all over the place. Anyway, this is not our concern, we just had a look at cam lobe shapes for comparison and evaluation from other cam data bases in order to be able to assist buyers in finding suitable camshafts. I do have a few programs from Perfrmance Trend, cam analyser and cam grinder. BUT, big question is,how do you arrive at the cam shapes ?? And right here all postings are veeery hazy, it is quite obvious that the start has to be the valve lift diagramm. I can provide 40 different computer calculated files , different in lift numbers, acceleration , and duration, three decimal places - in millimeters, one micron that is. Now the REAL hard work is to model all levers, rocker finger shapes, cam follower details, into a CAD program that handles these kinematics to transform in the end valve lift numbers into cam lobe shapes !! I was toolmaker in life , with all traditional skills, but CAD was not one of these. So is there a chance to get any info here on suitable programs for such calculations , Fusion 360 , not so much ?? I believe Performance Trend can analyse dynamics in the valve train by simulation but only AFTER a cam was fabricated, it does nothing for designing a cam. So the procedure to arrive at a particular cam shape , starting with valve lift numbers , is definitely my big question but I guess that haziness about details will continue . . . Valve bounce and other adverse effects are seen mainly in race type engines and I believe there is no universal solution in all cases and has to be dealt with individually. Most Vincenteers will be more interested in smooth operation by mild acceleration and quieting ramps so no radical fast wearing shapes acceptable. Vic[ATTACH type="full" alt="26313"]26313[/ATTACH] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Camshaft
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