Reply With Quotethe second result of my google search gave me this calculator........
http://www.engineersedge.com/calcula...calculator.htm
someone has already done the hard bit
Hello everyone!I'm looking for a more extensive chart of class V interfereance (permanent) fits sizes/tolerances of shafts to holes...more specifically on smaller scales of hole/shaft sizes ranging from .040-.125 max. I'm also wanting to pick the brains of you engineers/seasoned machinists out there on intererance fits. I've been out of the machinist trades for a while now, but one of my odd hobbies has me going back to them. I want to know (for sure) if a class V "permanent" interferance fit will hold as stronly as a silver brazed and/or welded part? In my hobby, the standard practice is to silver braze joints and/or small shafts into holes/hard 302 stainless drilled ball bearings of various sizes. As you get to smaller sized bearings, the more dificult this procedure is (the brazing), not to mention after silver brazing there is much clean up required from soaking in chemical soloutions, scrubbing and polishing.I think that a permanent interference fit (if successful in holding as well as a braised part) is a bit more efficient in this case using small bearings like .0625 and allot less problematic.I would greatly appreciate any solid knowledge on this subject.
Thank You
the second result of my google search gave me this calculator........
http://www.engineersedge.com/calcula...calculator.htm
someone has already done the hard bit
Last edited by Android; 01-28-2012 at 05:32 PM.
That's not really what I had in mind/was looking for. What I'm doing isn't really a mechnical part, not in the sense of a shaft spinning in an axel or some other motorized machine.While the parts that I am wanting to make are moved, they are moved incrementally. I just want to know the shaft to hole tolerances in order to get an interferance fit between mating parts and if an interferance fit will hold as strongly as a typical silver brazed/welded part?I can't be having parts popping off.
one of the many thing that affects the performance of the "joint" is the surface roughness of both parts.....
drilled and reamed hole? ground shaft?......maybe just drill hole and turn shaft ...leave it rough.
do you heat the ball and freeze the shaft prior to assembly?
probably .0005" interference would sufficient on such small parts.
a hardened shaft in such a small bearing will probably just swell the bearing
I think just with assemply, the typical practice (in this application) is to heat the bearing and freeze the shafts.I wouldn't want to heat the bearing to where it is annealed or tempered,and I wouldn't get the shfat to drop any colder really that 30 deg. F.I don't think the surfaces being pressed/force fit into one another need to be particylarly smooth,slthough that might make assembly easier.
The problem comparing interference fit to a glued (braze, solder et al) fit is temperature and material coefficients of thermal expansion.
Under ideal conditions for both mating parts, then an interference fit would be about as good as it gets. However, life being the compromise it is, experience can be your only guide. That means try it and see. There is no "rule" that am aware of where an interference fit will be as good as a glued fit over all situations.
Silver solder will only begin to fail at very high temperatures. A brass ball on a stainless shaft while locked solid at 32F, will drop off with a 150F temperature rise.
If it is important that the whatever should not move on the whichever, and I am not sure why you are not elaborating on your "hobby" then glue is the only key.
That is my fault for not elaborating a bit more on my hobby. I didn't know if it would be that important, but it is fabricating stop-motion armatures. Typically rods (or small shafts) are silver brazed into the ball bearings to make any assortmant of joints. Ball and socket joints being the most popular and widly used, but there are other more complicated and/or exotic joints that utilize the same shaft to bearing fit such as collet joints and I think a universal joint uses a bearing to shaft fit?Using smaller bearings makes it far more difficult to silver braze the small ends of the rods/shafts into the bearing which si why I am wondering if an interferance fit might be a better option? There would be little to no damage to the bearing, however the actual pressing of the two maing components togetehr might eb thje only hazzard as they need to be "lined up" fairly precise otherwise damage/breakage will occur.Espcially if heating the ebaring to take advantage of the metal expanding and colling the rod/shaft end to fit the parts together.
Just got to my Zeus book and their Interference fit chart from British Standard 4500A
up to 3mm dia ....shaft is S6 (+.014 to +.02mm) (.00055" to .00078")
hole is H7(+.01 mm bto .00) (.00039" to 0.0000")
Also, check out http://www.engineersedge.com/materia...eview_9862.htmOriginally Posted by Android
and
ANSI/ASME B18.8.2-1995
ANSI Standard Force and Shrink Fits ANSI B4.1-1967 (R1999)
I don't know the metric system hardly at all,only to convert meteric to inch and vice versa. I don't really need to know all the thermal expansion stuff (not that it isn't important).I need to know what the recomended tollerance sizes are for interferance fits/fitting small shafts into holes for a *permanent fit* and if that can hold as well as a silver brated part/joint?I've not been able to find that (of information on it) and I don't have access to a machinist handbook that would have a chart showing this information for class V interferance fits.
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