I haven't seen an answer to this yet, so here goes... At 09:11 PM 2/3/03 -0500, [EMAIL PROTECTED] wrote:
In practice, it's prohibitively hard to get bend point from a deflection board. But you're right that it takes multiple readings to get it from a frequency meter.Here is another fundamental question. I hope you will pardon my inexperience. I rarely see anyone mention using a deflection board. It seems like everyone uses a frequency meter and I'm curious about the reasons. It appears that you can determine flex and bend point from the curve of a shaft on a deflection board, but you would have to take multiple readings on a frequency meter to get the same information.
I tend to disagree, but the issue is not as big as many would have it. In particular, I thought Jeff Sheets was full of it in the latest issue of Clubmaker, where he says that different machines give different readings. The things that make the difference are NOT the sensors or the electronics, as he implies; these are either right or wrong (as in they will give stable readings or they won't). They don't give DIFFERENT stable readings. Different readings come from the clamp and the tip weight.I have heard people comparing frequencies, but I have also read that you cannot necessarily make a direct comparison between readings from different machines.
How do I know?
(1) I'm an electrical engineer by training, and I've designed a working frequency meter. You can get the plans from Clubmaker Online's resource page. (There should be a new issue of the article soon, with photos and descriptions of the clamps; John has the copy already.)
(2) I've attended a "frequency meter calibration party", where three clubmakers brought their [different make] meters. We put a shaft in the clamp and put a weight on the tip, then used the three meters to measure that shaft without changing the clamping or weighting. The difference? 1cpm! That's just one unit in the minimum resolution of the meter. And that's ALL the difference you will EVER see due to sensors or electronics.
The deflection board is inherently as good or bad as the frequency meter. But it is somewhat harder to read than looking at a digital display. Unless someone comes up with a digital deflection board, I think the frequency meter will continue to dominate.What method is more accurate, faster and easier? Or am I totally off base?
Well, actually there are several steps currently going on that are relevant:
* A few commercial shaft measurement tools are available that are digital flex boards, at least in principle:
- The FlexMaster has the purpose of making tip-trimming routine in making a matched set.
- The MultiMatch has the purpose of shaft profiling and research.
Both are "inverted" flex boards, in that they measure the force for a fixed deflection, whereas true flex boards measure the deflection for a fixed force. Also, both are very expensive (well over $1000).
* The NeuFinder, Dan Neubecker's invention, is sort of an inverted flex board that you can build yourself for about $100US. Its readout is a precision dial indicator, not digital but much easier and more precise than your typical deflection board.
Hope this answers your question.
DaveT
