Never been done before balance scale experiment.....badaboom ;-)

[sdean]

Wouldn't you need something like a FX 120 to confirm your accuracy results. Just saying. I have a few other projects to work on.

 

[BoydAllen]

When working on the same scale for my reloading, I am primarily concerned with repeatability. One can evaluate that by weighing the same thing a number of times. If that object is put aside with a note as to its weight, it can be used to check your scale at a later date, to see if anything has changed over time.

 

[shooter74]

When doing this has anyone made new ones or worked on the bearings the blades sit in?

 

[1066]

When doing this has anyone made new ones or worked on the bearings the blades sit in?

Yes, I've made new knife edges for RCBS/Ohaus scales and new bearings for the Redding scales. Not a quick and easy job in my home shop.

 

[shooter74]

Yes, I've made new knife edges for RCBS/Ohaus scales and new bearings for the Redding scales. Not a quick and easy job in my home shop.



https://www.youtube.com/edit?ar=2&o=U&video_id=np2XyJlN3Js

Yeah the thing I had trouble with was getting the v cut narrow enough. Was just wondering what to use the video won’t play on my end.

 

[1066]

Yeah the thing I had trouble with was getting the v cut narrow enough. Was just wondering what to use the video won’t play on my end.

Try it now

 

[shooter74]

Try it now

I’ve watched that several times before thanks. Without a lathe how would you recommend cutting the v’s by hand?

 

[1066]

I’ve watched that several times before thanks. Without a lathe how would you recommend cutting the v’s by hand?

Yes, you could do it by hand ok. Technically the "V" bearing does very little, it just keeps the beam aligned in one direction, in the other direction the end plates check any movement. On some very high spec pendulum clocks, as were used in observatories, the knife edges just sat on flat plates, ideally of infinite hardness.

If you were to file a "V" with a triangular file then polish it well with fine abrasive paper. Ideally you will need some carbon steel that will be able to work then harden. The knife edge is more important than the bearing.

 

[CharlieNC]

Small sharpening stone like a Lansky does a good job sharpening the V edge.

 

[BoydAllen]

On the edges, I take it slow and put the same number of equal pressure strokes on both sides of both edges and then see what I have before doing it again. I might start with two each, and finish with one each, when I think that I am close. If you look straight in at an edge, if the edge looks shiny, that is a dull spot. (on a used scale)

 

[oley55]

On the edges, I take it slow and put the same number of equal pressure strokes on both sides of both edges and then see what I have before doing it again. I might start with two each, and finish with one each, when I think that I am close. If you look straight in at an edge, if the edge looks shiny, that is a dull spot. (on a used scale)

the shiny spots on my knives are towards the outside edge and do not seem to line up over the bearing material, which appears brass in color. I wonder if I relieve the outside edges of the bearings pot metal. Then the sharp knife edges would be riding on the bearing material. Thoughts, pro or con?

 

[BoydAllen]

It is hard for me to evaluate the bearings from looking at the picture. I am not sure what the lighter part in the center is, but it looks like the V goes all the way to the end plate, and I would guess that the knife makes contact all the way to its end. I would sharpen and then test for function, sharpening all sides of both edges the same, even though the dullness is not the same. You want to take the edges down by the same amount.

 

[oley55]

It is hard for me to evaluate the bearings from looking at the picture. I am not sure what the lighter part in the center is, but it looks like the V goes all the way to the end plate, and I would guess that the knife makes contact all the way to its end. I would sharpen and then test for function, sharpening all sides of both edges the same, even though the dullness is not the same. You want to take the edges down by the same amount.

I assume I would need to remove the blade from the beam to sharpen. Does it just press in/out?

 

[BoydAllen]

I don't and I wouldn't, but that is just me. We are only talking about a bit of light sharpening. I hold the beam in one hand, positioning it so that I can get to the side of the edge of the that I am working on, and I eyeball the angle parallel to the existing, then I position the beam for the next side and proceed. The amount of pressure is very light. I use an inexpensive diamond lap. Mine started out as coarse but has worn to more like medium. Both the beam and the lap are hand held during the process. I run a piece of hardwood over the edge when I am through and then the side of a pencil lead lightly.

 

[1066]

I assume I would need to remove the blade from the beam to sharpen. Does it just press in/out?

Yes, if you want to remove the knife edges they are just a press fit. Easily pressed with a small vice, press it into something hollow like a small socket, protect the point you are pressing with something soft like aluminium or wood. Pressing the KE in or out is how you get the copper damper blade to sit central in the damping slot on the RCBS 10/10 or 5-10 scales. They may also need to be rotated a touch to make them right angles to the beam.

 

[oley55]

Yes, if you want to remove the knife edges they are just a press fit. Easily pressed with a small vice, press it into something hollow like a small socket, protect the point you are pressing with something soft like aluminium or wood. Pressing the KE in or out is how you get the copper damper blade to sit central in the damping slot on the RCBS 10/10 or 5-10 scales. They may also need to be rotated a touch to make them right angles to the beam.

Understood, and thanks.......

 

[Webster]

By Thursday we should know. I have been playing with a new old stock Chinese made RCBS 10-10 balance reloading scale that I wrote about in another thread. The scale seems to be of good quality and tuned up OK (within the limits of my skill) but it is apparent that the magnets that are part of the damping system are weaker than my old USA produced scale of the same model. Sooo I ordered some little but powerful cylindrical neodymium magnets that I plan on putting on the bottom of each of the scale's magnets, held there by magnetic attraction, opposite poles facing each other. Just now (early Monday afternoon) after checking on my order with the magnet company, I spent a couple of minutes with one of their engineers to find out if my plan has a chance of working, that is strengthening the magnet field of the damping system. He said that it should. If this works, I believe that it will be the first time that it has been done. On the other hand, if it does not, I will be out ten dollars for some very powerful little refrigerator magnets. I was also going to mention that I would have to remember to keep them away from my flash drives, but taking the precaution of looking that up first, I learned that that is not true, so it is only my hard drives that I need to be concerned about, because I know that they are vulnerable, and verifying that, something that I had not thought of, my credit cards. I will let you know if this works.

Everyone says not to put oil on the bearing but I do. It makes sense that the bearing should have as little friction as possible. All of use know how to inspect and keep things clean. The scale is uncovered maybe 2 hours a month. Harbor Freight has several types of strong magnets.

 

[oley55]

I don't and I wouldn't, but that is just me. We are only talking about a bit of light sharpening. I hold the beam in one hand, positioning it so that I can get to the side of the edge of the that I am working on, and I eyeball the angle parallel to the existing, then I position the beam for the next side and proceed. The amount of pressure is very light. I use an inexpensive diamond lap. Mine started out as coarse but has worn to more like medium. Both the beam and the lap are hand held during the process. I run a piece of hardwood over the edge when I am through and then the side of a pencil lead lightly.

thanks Boyd, I'll dry run that to see how well I can keep it all aligned.

Is the side of a lead pencil to leave a little graphite behind?

 

[JimSC]

update on my magnet mod, it dampened the scale too much and the repeat ability went to heck so I removed the extra magnet. It takes longer to settle but it ends up in the same place now which is the main point for me

I used a piece of 600 grit paper followed by a extra fine diamond hone meant for wood chisels to touch up my M5. I don't use any type of lube either dry or wet and clean the blades and the ways with isopropyl alcohol before each use.

quick edit on lubrication, in my opinion the scale operates more on balance than anything and any type of oils viscosity would act to inhibit the pivoting just my opinion but I tried dipping the blades in Imperial graphite neck lube. 5 minutes later I was scrubbing it off with alcohol. Did not work worth a darn for me

 

[BoydAllen]

thanks Boyd, I'll dry run that to see how well I can keep it all aligned.

Is the side of a lead pencil to leave a little graphite behind?

Yes, but very little.