GTA
General Discussion To Gateway To Airguns => The Shop => : TCups May 04, 2008, 04:44:46 PM
-
Attention machinist:
Can you make a simple knife edge beam scale similar to this diagram? Two separate pieces: a knife edge fulcrum on a reasonably heavy metal base, and sort of an A-frame balance beam, I am guessing ~ 6 in. long and about 3/4 in wide. On the underside of one end of the beam a counter balance weight to offset the weight on the other end of a small block with a threaded bolt with a knurled head going through it. The size and weight of the bolt should be so that it can be turned with the fingers and can be screwed in or out to "zero" the balance of the beam. The top of the beam doesn't have to have a pans. Just countersink two shallow "cups" into the beam, one on each end, centered and precisely the same distance from the knife edge of the fulcrum. Each should be a bit larger than the size of a .22 ga pellet, but machined so that a pellet set in the cup would center precisely in the cup. Then, by zeroing the beam with the adjustment screw, and consistently using the same reference pellet on one end of the balance, you could compare the weight of another pellet on the other end, and quickly sort out those that are obviously heavier, about the same weight or obviously lighter than the reference pellet. Send me a PM and let me know. Thanks.
-
Tom:
Found your beamscale pdf.
What do you think of a straight beam notched across the centerline with tapped holes in each end for calibration screws?
The fulcrum could be a replaceable single edged razor blade as mentioned in my PM.
The real trick, as you have noted, is to get the pellet precisely located every time. Also need to know how sensitive you need this to be ie. 1 grain, 1/2 grain, 1/10 of a grain.
Mike
-
Well Mike it seems your have paid your dues as a machinest..:) When I was a kid, I wanted to be a machinest...:) Loved to work with the lathe, mills, etc. I thought it was allot easier than working with wood.. hehe. I know I have said this before but the GTA is very fortunate to have you as one of its members. Sure would like to talk to you some day. If you do not mind PM, me with your phone number.. Would love to talk at ya for a couple minutes..:)
Gene
-
Gene:
"Senior moment" subsided a bit and found source of your request. Please check PM for the info.
Mike