How to tune beam scale ?
- Thread starter Hal
- Start date
I've done pretty much what 1066 does but carry it one step farther. I won't accept the "error" when checking with increasing test weights. After working on pivot points so the scale will reliably return to zero, I then start adding check weights in 10 grain increments when checking the large poise position. As I find errors, I "adjust the position of the poise in it's notch. It's not unusual to find either a small "burr" or a little extra paint that will keep the poise from centering exactly. A very, very, careful application of an X-acto knife blade, used as a scraper, and correct this error. To back and re-zero, repeat. I rarely use settings above 60 grains for the large poise that's where I stop. For the smaller poise "notches" same process, just more time consuming due to the need for greater precision.
Maybe not a process someone would be interested if they do it for pay. Would make the process very time consuming and thus expensive. Since I'm retired, time is what I have. It also helps that I used to do this kind of work for a large Aircraft manufacturer in a test facility. It really is a matter of patience and a steady hand.
Maybe not a process someone would be interested if they do it for pay. Would make the process very time consuming and thus expensive. Since I'm retired, time is what I have. It also helps that I used to do this kind of work for a large Aircraft manufacturer in a test facility. It really is a matter of patience and a steady hand.
BoydAllen
Gold $$ Contributor
Before I did anything but deburr the notches, I would take a look at whether the movable weight needed a slight adjustment. I have done this by using a weight standard that is at the top of the range that I will be using for powder. If the movable weight is about the same distance from the pivot as the support point of what is being weighed, any dependency will show up as an error of the same amount as the weight is off, but as the weight is moved farther from the pivot, the influence of a given error is increased. Another issue that gets involved is the relatively coarse resolution of the pointer and scale setup on a typical reloading scale, which is compounded by its size. Parallax is also a significant issue. If you have a web cam, setting it up as a very close fixed position "eye" gives a very good magnified view of the pointer and scale.
BoydAllen
Gold $$ Contributor
I have used an inexpensive diamond lap. http://www.knivesplus.com/eze-lap-sharpener-ez-lc.html
After I have the edges shaped I knock the burrs down by rubbing them with a small piece of wood. The knife edges are not made of particularly hard material. Also, I make no claim of expertise. I am just relaying what I have used and done. When I am evaluating the edges, I look at them straight on, and if I can see shiny spots, take that as an indication that they are dull. I take care to take the same number of strokes on all sides and edges, working slowly, and inspecting as I go.
After I have the edges shaped I knock the burrs down by rubbing them with a small piece of wood. The knife edges are not made of particularly hard material. Also, I make no claim of expertise. I am just relaying what I have used and done. When I am evaluating the edges, I look at them straight on, and if I can see shiny spots, take that as an indication that they are dull. I take care to take the same number of strokes on all sides and edges, working slowly, and inspecting as I go.
Here's a post on this very topic, from Boyd Allen. The information in it really helped my scales performance!
Boyd Allen
Registered User
Join Date: Feb 2003Location: FresnoPosts: 4,440
Clean and don't oil the agates that the knife edges sit on. Sharpen the knife edges so that when you look straight at the edge there are no visible shiny spots, and then burnish the edge with the side of a mechanical pencil lead. Spread the wire bail that supports the pan holder so that it can not shift from side to side on its knife edges, but does not press against the abutments at their ends. Level the base of the scale by pulling material from the cavity in the pan hanger and then adding small bits to the pan till the beam pointer is perfectly aligned with the center mark of the scale (with the base level), and then add the material to the hanger cavity. Borrow or buy a set of check weights, and check the accuracy of the scale at several weights. Consider if the main sliding weight needs adjustment. If it needs to be increased, this can be done with paint, and fine adjusted by scraping. (An easier way is with Scotch tape. leaving a tab sticking out to trim for fine adjustments, buy cutting off small pieces, and then sticking it down.) If your scale has a built-in plastic cover, consider not using it to avoid a static charge. I now store my 10-10 in the cardboard box that it came in, with a sample of "Formica" in one end, so that I can leave the leveling screw down, without punching a hole in the box, over time. Practice with a fixed weight to learn the tricks of using the scale so that it does a better job of repeating. (electronic scales have their own set of tricks, so this is not unique to balance scales.) Another thing that I have not done, is to mount a needle on the pointer scale (doesn't affect the balance of the beam) to make the scale easier to read. I have an inexpensive USB webcam that I use to project the image of the end of the pointer and its reference scale onto my computer monitor. If I remember correctly,it cost about $35. I have also figured out how to throw charges into the scale pain, with it on the scale, without powder bouncing out. With this setup I can shave a little off the time that it takes to throw and trickle a charge. The last frontier is the pan hanger hanger (the bent wire piece) if I can make it more stable on the knife edges, I will truly be finished.
Boyd Allen
Registered User
Join Date: Feb 2003Location: FresnoPosts: 4,440
Clean and don't oil the agates that the knife edges sit on. Sharpen the knife edges so that when you look straight at the edge there are no visible shiny spots, and then burnish the edge with the side of a mechanical pencil lead. Spread the wire bail that supports the pan holder so that it can not shift from side to side on its knife edges, but does not press against the abutments at their ends. Level the base of the scale by pulling material from the cavity in the pan hanger and then adding small bits to the pan till the beam pointer is perfectly aligned with the center mark of the scale (with the base level), and then add the material to the hanger cavity. Borrow or buy a set of check weights, and check the accuracy of the scale at several weights. Consider if the main sliding weight needs adjustment. If it needs to be increased, this can be done with paint, and fine adjusted by scraping. (An easier way is with Scotch tape. leaving a tab sticking out to trim for fine adjustments, buy cutting off small pieces, and then sticking it down.) If your scale has a built-in plastic cover, consider not using it to avoid a static charge. I now store my 10-10 in the cardboard box that it came in, with a sample of "Formica" in one end, so that I can leave the leveling screw down, without punching a hole in the box, over time. Practice with a fixed weight to learn the tricks of using the scale so that it does a better job of repeating. (electronic scales have their own set of tricks, so this is not unique to balance scales.) Another thing that I have not done, is to mount a needle on the pointer scale (doesn't affect the balance of the beam) to make the scale easier to read. I have an inexpensive USB webcam that I use to project the image of the end of the pointer and its reference scale onto my computer monitor. If I remember correctly,it cost about $35. I have also figured out how to throw charges into the scale pain, with it on the scale, without powder bouncing out. With this setup I can shave a little off the time that it takes to throw and trickle a charge. The last frontier is the pan hanger hanger (the bent wire piece) if I can make it more stable on the knife edges, I will truly be finished.
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