beam scale knife blades?

[leadhead]

Anyone ever stone the knife edges on there beam scale, and if so,
what did you use to do it? I see a couple of nicks on mine and was
going to try to smooth them up a might. Any info will be grateful.
Denny

[Winger Ed.]

Depending on the brand, they will usually give ya a new set or sell them pretty cheap.

I've hacked around trying to work on one of mine, and it never did work exactly right.

[Bazoo]

I've got an RCBS 505 that I sent back to RCBS for inspection and calibration. It returned with the same nicks it has but smoothed some. It works with no issues. I was kinda disappointed but I guess they know what they are doing.

[leadhead]

I have an old Pacific/Hornady scale that I've had for 30+ years
and it still works ok, but I think it could be better. I don't think
I can send it back.
Denny

[1066]

I don't think any company is going to send out spare knife edges that you can fit yourself. As long as the tips of the edges are not damaged they can usually be touched up to remove minor burrs and dull spots. Ideally it's easier/better to remove the knife edge from the beam, then the edges can be taken to a flat stone. The idea is to just do the minimum to remove the burrs, not reshape the metal.

The knife edge should come to point exactly inline with the edge so if/when the tip touches the bearing end plates the beam rotates around a single point for minimal friction. If there is any damage or curve to the tips, the tip of the edge scribes an arc on the endplates and the scale will always be unreliable.

As no knife edges are available for these scales I have resorted to making my own - a slow and tedious job.

Chipped tip - beyond repair



Hand made replacement

[leadhead]

1066..... Nice work. I have some skills, but I couldn't do that.
I do have skills with sharpening stones though. I will see how
bad they are and go from there. Thanks for the info.
Denny

[Bazoo]

1066, thanks for sharing. The skill required for that is impresive.

Must be why they didn't replace mine, the tips are not damaged.

[ascast]

Have you checked with calibration weights? Check for accuracy and repeatability. Maybe you don't have a problem.

[Martin Luber]

You have to clean the blocks too. My scale went out of calibration due to accumulated dust in pivots. Cleaned with alcohol, then l cleaned the blocks. Smile

[leadhead]

I just touched them up a bit a little while ago. They were not really that bad.
I checked the scale with known weights and it is right on the money. It's good.
Denny

[ioon44]

I also have touched up the blades but they were not showing any damage. I always use check weights.

[leadhead]

My Pacific scale doesn't have blocks. There round stainless V shaped rings that
the knife edges ride on. Pretty simple way to make it work. Just wipe off with
a rag now and then.
Denny

[kokomokid]

My Pacific scale doesn't have blocks. There round stainless V shaped rings that
the knife edges ride on. Pretty simple way to make it work. Just wipe off with
a rag now and then.
Denny

How wide an area does the knives ride on in the V shaped rings? Will one grain of powder move the scale from a dead rest? Thanks LB

[leadhead]

The rings can't be more than 1/4" wide..... I'll have to go and check about the
1 grain of powder. I'll let you know.
Denny

[leadhead]

I went and checked and the beam will move with one stick of 4895 but it's really
hard to see. Three sticks of 4895 weighs one tenth grain. That's what my scale
says. That's starting to cut weights pretty close isn't it?
Denny

[kokomokid]

I went and checked and the beam will move with one stick of 4895 but it's really
hard to see. Three sticks of 4895 weighs one tenth grain. That's what my scale
says. That's starting to cut weights pretty close isn't it?
Denny

Thanks. I have a camera set up like 1066 shows in one of his videos and it will show any movement on my 20 inch screen. Think the camera was like $5 shipped from China.

[country gent]

We had a small fixture made at work for grinding those knife edges when they were needed for gauges and tools. Set on one flat it allowed you to grind the 2 edges on that side and on the second side the second 2 edges and would keep them centered. Normally you roughed in one side the the other to machine zero then set for finish and ground flipping over. Could grind one in pretty quick from a dowel pin or core pin each pass.
A block 2 1/2" square with the vee on back and the top thinned to maintain center of knife edges. A small set screw locked the pin in place.

[1066]

We had a small fixture made at work for grinding those knife edges when they were needed for gauges and tools. Set on one flat it allowed you to grind the 2 edges on that side and on the second side the second 2 edges and would keep them centered. Normally you roughed in one side the the other to machine zero then set for finish and ground flipping over. Could grind one in pretty quick from a dowel pin or core pin each pass.
A block 2 1/2" square with the vee on back and the top thinned to maintain center of knife edges. A small set screw locked the pin in place.

Here's my jig :

[mf79]

I have some pharmacy scale weights I can use if I have to calibrate, all pharmacies have to have a scale so if anyone needs to use a weight and does not have one maybe ring scale to a pharmacy and they may lend to use there

[jsizemore]

I used brownell's ceramic stone files. I have the set of round, triangle and square. I flush the blocks to remove dust with a condiment squeeze bottle of denatured alcohol.