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Model Forum / General / Models / February 2009Does this exsist?
Hi Looking for some kind of 'feeler-gauge' that can identify a specific gearwheel. What I need to identify is the size of the teeths. As far as I can remember I have seen a tool like those on this page: http://www.primavvs.dk/shop/gevindtaeller-20241c1.html But only with cutouts for each size of tooth. Does anybody have a hint to where I have to look for such a tool? PS. it is Module size (2MOD-4MOD) and DP (6DP-14DP) that I'm looking at.  SignatureUffe Bærentsen Uffe B�rentsen wrote: > What I need to identify is the size of the teeths. Do you want to determine the module? Do = (N + 2) * Mod Do: Outer Diameter N: Number of teeth Mod: Module Or to determine the wear: <http://www.messmittelonline.de/start.htm?d_5104_Zahnweitenmessschieber417.htm> Nick, too lazy to go to tinyurl.com SignatureThe lowcost-DRO: <http://www.yadro.de> > Uffe Brentsen wrote: > [quoted text clipped - 7 lines] > N: Number of teeth > Mod: Module That formula does not give me the answer in Mod or DP or does it? Another baddie in this is that I can have say a 10-12DP gear. The teeths are one DP size and the OD is the other DP size. > Or to determine the wear: > http://www.messmittelonline.de/start.htm?d_5104_Zahnweitenmessschieber417.htm I can't see how that gives me the Mod or DP of the gear. The point is that I have both Mod and DP and absolute no marking on the gears :-( Found this for calculation: http://www.flexoexchange.com/gorilla/cpdp_article.html And this: http://www.engineersedge.com/gear_formula.htm But direct measurement of one single teeth? No. SignatureUffe Bærentsen >I can't see how that gives me the Mod or DP of the gear. > [quoted text clipped - 9 lines] >But direct measurement of one single teeth? >No. Uffe, go here: http://www.hpcgears.com/ If you go to the Technical Section, you can download the entire PDF catalogue, around 43Mb, or order a printed one. Alternatively, go to the Spur Gear page and select either Module (metric) or DP gears from the pull down menu, then select the size. This will bring up a PDF of the catalogue page, and on each page they print a silhouette of the tooth form at actual size. If you print the page with the PDF scaled to 100% this will give you a rough and ready gauge of sorts. Peter > On Sun, 1 Feb 2009 20:45:31 +0100, "Uffe Bærentsen" > [quoted text clipped - 27 lines] > > Peter Having arrived at the size of the teet how do you decide what the pressure angle is. I need to do this as I have a spur gear to make for a vintage car speedo drive and I know that often a pressure angle of 14 1/2 degrees was used in the 1920's > > On Sun, 1 Feb 2009 20:45:31 +0100, "Uffe Bærentsen" > [quoted text clipped - 34 lines] > > - Show quoted text - Roll the gear through modelling clay and measure the angle of the teeth of clay rack, this is the PA Peter On Feb 3, 1:08 pm, petercolma...@hotmail.com wrote: > > > On Sun, 1 Feb 2009 20:45:31 +0100, "Uffe Bærentsen" > [quoted text clipped - 38 lines] > teeth of clay rack, this is the PA > Peter Elegantly simple; thanks. On Feb 3, 1:08 pm, petercolma...@hotmail.com wrote: > On Feb 3, 10:42 am, Anzaniste <a...@nashman.co.uk> wrote: > [quoted text clipped - 42 lines] > teeth of clay rack, this is the PA > Peter >Elegantly simple; thanks. And made even easier if you then cut the clay rack with a craft knife along its length to give a clean edge that you can look at with one of those graticule eyepieces. The difference between 14 1/2 and 20 PA is easily seen. AWEM Uffe B�rentsen wrote: >> Do = (N + 2) * Mod >> [quoted text clipped - 4 lines] > That formula does not give me the answer in Mod or DP > or does it? And now, after some shuffling around? Mod = Do / (N + 2) But this doesn't help to determine wear. You can only determine the module. After that and a book like "gearcutting practice" you can determine the wear (width of tooth changes) with the aformentioned "funny caliper". Nick SignatureThe lowcost-DRO: <http://www.yadro.de> >> That formula does not give me the answer in Mod or DP >> or does it? > > And now, after some shuffling around? Just to clarify my answer: It does give you the module of the gear. There are exceptions when the gear does have a modified profile. Normally, you don't find that. Except in car's gearboxes or other highly specialized gears where there are extreme loads with a little number of teeth and/or several gears are crowded on one axle. But then, you could always use the ... ummm ... howsitcalled ... the medium diameter (average between OD and ID at tooth ground). Face diameter? Too lazy to look that up. :-) Ni-lazy sunday-ck SignatureThe lowcost-DRO: <http://www.yadro.de> > It does give you the module of the gear. > There are exceptions when the gear does have a modified profile. Normally, [quoted text clipped - 5 lines] > diameter (average between OD and ID at tooth ground). Face diameter? Too > lazy to look that up. :-) Pitch Circle Diameter. Where the contact path crosses the line joining the centres. On 1 Feb, 18:29, "Uffe Bærentsen" <leiti_IKKE_SP...@hotmail.com> wrote: > Hi > [quoted text clipped - 8 lines] > -- > Uffe Bærentsen You mean gear tooth gauges ? That's what it reads like to me but no one else has picked up on this ? http://www.josephmarc.com/page-65315.html or http://www.rushgears.com/Tech_Tools/geargages.php John S. > On 1 Feb, 18:29, "Uffe Bærentsen" <leiti_IKKE_SP...@hotmail.com> > wrote: [quoted text clipped - 22 lines] > > http://www.rushgears.com/Tech_Tools/geargages.php Thanks. I will have to take a closer look at those. It looks like what I'm asking for :-) SignatureUffe Bærentsen > Hi > [quoted text clipped - 6 lines] > Does anybody have a hint to where I have to look for such a tool? > PS. it is Module size (2MOD-4MOD) and DP (6DP-14DP) that I'm looking at. In North America, the Boston Gear Company can supply gear tooth/pitch gauges through their dealers. Their catalogue also has a printed one that can be of some use. Steve R. Uffe B�rentsen wrote: > What I need to identify is the size of the teeths. It just came to my mind: If you have two gears that mesh, you can determine the module more accurate by measuring the distance of the centers. a = (Z1 + Z2) * mod a: distance of centers (axles) in [mm] Z1: Number of teeth of gear 1 Z2: ... of gear 2 mod = a / (Z1 + Z2) The method with the gages isn't very accurate. There are DP and Mod sizes that are quite near to each other, and you'll have problems determining of which breed it is. Nick SignatureThe lowcost-DRO: <http://www.yadro.de> >It just came to my mind: >If you have two gears that mesh, you can determine the module more accurate >by measuring the distance of the centers. That assumes that the two gears have been accurately meshed so that their PCDs just touch. Not always a good assumption. Regards, Tony > That assumes that the two gears have been accurately meshed so that > their PCDs just touch. Not always a good assumption. But better anyhow than assuming that the OD is accurate. At least I assume so. :-) Nick SignatureThe lowcost-DRO: <http://www.yadro.de> >> That assumes that the two gears have been accurately meshed so that >> their PCDs just touch. Not always a good assumption. > >But better anyhow than assuming that the OD is accurate. At least I assume >so. :-) That's not at all clear ;-) Regards, Tony >The method with the gages isn't very accurate. There are DP and Mod sizes >that are quite near to each other, and you'll have problems determining of >which breed it is. > >Nick If they're that close, does it really matter which (depending on the application, of course) ...and of course there are CP sizes, too ;-) Tim |
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