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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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pyro project w/metal content
I just built a load cell test stand for characterizing our gerbs.
There's a .pdf with photos and schematics at www.pyrobin.com/files/ just click on "load cell test stand.pdf" (Yes... it _may_ get a paint job. G) LLoyd |
#2
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pyro project w/metal content
Interesting! The electronics and cabling is straight forward but a few
questions for those of us who don't do this for a living: -What's a gerb? Suspect it is somewhat equivalent to a shotgun barrel but......... -What's CATO? Suspect the first word is Catastrophic...... -Do you have any more detail on the load cell mounting, especially how the over run protection screws mount and work (both the thrust boss and the load cell itself) Lloyd E. Sponenburgh wrote: I just built a load cell test stand for characterizing our gerbs. There's a .pdf with photos and schematics at www.pyrobin.com/files/ just click on "load cell test stand.pdf" (Yes... it _may_ get a paint job. G) LLoyd |
#3
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pyro project w/metal content
On Oct 1, 9:15*am, RoyJ wrote:
Interesting! *The electronics and cabling is straight forward but a few questions for those of us who don't do this for a living: -What's a gerb? *Suspect it is somewhat equivalent to a shotgun barrel but......... -What's CATO? *Suspect the first word is Catastrophic...... -Do you have any more detail on the load cell mounting, especially how the over run protection screws mount and work (both *the thrust boss and the load cell itself) Lloyd E. Sponenburgh wrote: I just built a load cell test stand for characterizing our gerbs. There's a .pdf with photos and schematics at www.pyrobin.com/files/ just click on "load cell test stand.pdf" (Yes... it _may_ get a paint job. G) LLoyd I'm guessing a gerb is a section of a rocket motor, or maybe just a tube filled with rocket fuel used to test 'the mix', eliminating differences you'd see between different nozzles. CATastrophic Overpressure? Dave |
#4
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pyro project w/metal content
RoyJ fired this volley in
m: Interesting! The electronics and cabling is straight forward but a few questions for those of us who don't do this for a living: -What's a gerb? Suspect it is somewhat equivalent to a shotgun barrel but......... -What's CATO? Suspect the first word is Catastrophic...... -Do you have any more detail on the load cell mounting, especially how the over run protection screws mount and work (both the thrust boss and the load cell itself) There are a couple more very fuzzy cell-phone pix at http://www.pyrobin.com/files/les%20t...2008-04-08.jpg and http://www.pyrobin.com/files/les%20t...2008-04-08.jpg that show how the load cell mounts under the thrust boss. It's shimmed under the mount end to allow the free end to travel down under pressure from the load post. The three crash-stop screws limit the travel of the load cup. But since the load post is not rigidly attached to the end of the load cell, the cell may over-travel under its own inertia after a violent over-thrust. A single large, fine-thread screw in the base, right under the end of the load cell arm (centered along the axis of the load post), prevents that inertial overtravel. A "gerb" is the correct pyrotechnic name for a "fountain". "Gerb" is derived from the old French word for "Sheaf of wheat", which roughly describes the pattern of sparks a gerb makes. Gerbs are a main-line product of all close-proximity pyro manufacturers. Because fuel variations occur, we sought to characterize every fuel batch. Measuring thrust and duration with a fixed weight of fuel at a fixed fuel density and a fixed nozzle size does that nicely. CATO means various things depending upon what rocketry guy you ask. Among them are "CAT(astrophic) O(verpressure)" and "C(atastrophe) A(t) T(ake)O(ff)". Basically, it means the device goes BOOM, instead of acting like a rocket motor. When it does, it really slams the load cell; thus, the need for protection. Most load cells of this beam type can withstand only 25-50% overload without permanent deformation. LLoyd |
#5
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pyro project w/metal content
I was thinking the load cell was one of the pizzo hockey puck unit.
Picture makes it much clearer. So the inertia issue is not with the actual load cell but with the pin that drives the load cell. And the thrust boss has it own stop. I have some projects in mind that are totally unrelated in terms of end application but the setup would work great. Thanks. Lloyd E. Sponenburgh wrote: RoyJ fired this volley in m: Interesting! The electronics and cabling is straight forward but a few questions for those of us who don't do this for a living: -What's a gerb? Suspect it is somewhat equivalent to a shotgun barrel but......... -What's CATO? Suspect the first word is Catastrophic...... -Do you have any more detail on the load cell mounting, especially how the over run protection screws mount and work (both the thrust boss and the load cell itself) There are a couple more very fuzzy cell-phone pix at http://www.pyrobin.com/files/les%20t...2008-04-08.jpg and http://www.pyrobin.com/files/les%20t...2008-04-08.jpg that show how the load cell mounts under the thrust boss. It's shimmed under the mount end to allow the free end to travel down under pressure from the load post. The three crash-stop screws limit the travel of the load cup. But since the load post is not rigidly attached to the end of the load cell, the cell may over-travel under its own inertia after a violent over-thrust. A single large, fine-thread screw in the base, right under the end of the load cell arm (centered along the axis of the load post), prevents that inertial overtravel. A "gerb" is the correct pyrotechnic name for a "fountain". "Gerb" is derived from the old French word for "Sheaf of wheat", which roughly describes the pattern of sparks a gerb makes. Gerbs are a main-line product of all close-proximity pyro manufacturers. Because fuel variations occur, we sought to characterize every fuel batch. Measuring thrust and duration with a fixed weight of fuel at a fixed fuel density and a fixed nozzle size does that nicely. CATO means various things depending upon what rocketry guy you ask. Among them are "CAT(astrophic) O(verpressure)" and "C(atastrophe) A(t) T(ake)O(ff)". Basically, it means the device goes BOOM, instead of acting like a rocket motor. When it does, it really slams the load cell; thus, the need for protection. Most load cells of this beam type can withstand only 25-50% overload without permanent deformation. LLoyd |
#6
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pyro project w/metal content
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#7
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pyro project w/metal content
RoyJ fired this volley in news9mdnRoQiaZ-
: I have some projects in mind that are totally unrelated in terms of end application but the setup would work great. Thanks. By the way, those beam load cells are going for cheap these days. Aeroconsystems.com sells them in various ranges for $30.00. http://www.aeroconsystems.com/loadcells/index.html LLoyd |
#8
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pyro project w/metal content
On Tue, 30 Sep 2008 11:57:32 -0500, the infamous "Lloyd E.
Sponenburgh" lloydspinsidemindspring.com scrawled the following: I just built a load cell test stand for characterizing our gerbs. Since when did you start associating with a bunch of hunchbacked aliens from the thirteenth moon of Yavin? (Yes, I googled "gerbs" There's a .pdf with photos and schematics at www.pyrobin.com/files/ just click on "load cell test stand.pdf" (Yes... it _may_ get a paint job. G) Polish and wax the load cup and paint or anodize the base a deep, wonderful cobalt blue. - If the gods had meant us to vote, they'd have given us candidates. -------------- |
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