Hornady/Pacific M Scale not quite right

[metricmonkeywrench]

I recently received a Hornady/Pacific M Scale from an older gentleman for the best price of all-- FREE. The story is that he got it as a part of package deal for some skeet/trap equipment but doesn’t reload himself so he has no need for it. The scale appears to be in like new shape has no damage and even came with the instruction sheet. My quandary is that across the board it points to .2g above the 0 mark on the graduated dial plate with any weight from 5g up to 250g (didn’t bother to go lower than 5g any higher than 250g). If I move the 10ths poise .2 more than the desired weight it will balance right out to 0 (ie if you want 5.1 set the scale to weigh 5.3) At least it is consistent no matter what the weight or how many times I check it. I went thru the general check of ensuring the weights are in the notches, checked the knife edges, pivot point wear, bent beam, wonky magnet dampening, level base and so on and even though I shouldn’t have, I messed with the adjustment nuts on the pan end of the beam to see if that would make a difference. Unfortunately the results were all the same. Balance to 0 on the dial plate and no matter what weight is put on the pointer ends up .2g above the 0 mark. The only thing that I have not moved is the dial plate which in my mind will not make any difference as the .2 would just move with a different 0 point.

As to the process, I am using a set of RCBS test weights along with the 250g weight from a 10-10 which weigh out perfectly on my daily driver RCBS 5-10 and Frankfort Digital (the 10-10 is under repair but that's a different story). All the desired weights were checked against these 2 scales.

I know from reading that generally these scales usually very accurate but it is normal to be +/- .02. The .02 off out of the box seems pretty off the wall. Unless someone has an idea on how to calibrate one of these or a magical solution the only option I seem to have is to start out with a -2 zero or break out the sharpie and write “add .02 to desired weight” on the side which will make the scale more user friendly but doesn’t really fix the real issue.

[Gewehr-Guy]

Weigh the pan and file off .2grns from the finger tab of the pan. I have used mine for over 30 years, but have never checked it against test weights. Maybe I'll weigh some assorted bullets on another scale and check mine, but then I won't know which scale to trust if one is off.

[Carrier]

I believe the two nuts on the end of the beam is to calibrate it. I don't have the M scale but do have one of the newer Hornady beam scales and I had to adjust those nuts to get it to zero from 0 to 300 grains with test weights. But like was mentioned maybe taking a little off of the pan though hard to put back on once taken off.

[abunaitoo]

Correct. The two nuts are to calibrate the scale.
I would check to be sure the pan and hanger are the correct ones.
On the two I have, both are all aluminum.
I know some scales use iron hangers.
When I got mine, I put it on a flat table and made sure the bottom of the scale was even to the table all around.
I then used the two screws to zero the scale.
I like them because it's so heavy compared to other scales.
I cover mine with a cloth when not used.
Keeps the dust off of it.

[metricmonkeywrench]

Well, tonight's tinkering didn't go so well. Though trial and error I finally tacked on a small piece brass to the large major weight with some nail polish and finally got the mid range 250g to 0 out. Then things went south, anything under 10g still ends up ends up with the same .2g split. Removing weight from the pan required a corresponding adjustment to the nuts to retain 0 with a leveled base and ultimately the same 2g split. So I am beginning to believe my issue is with the minor weights. It's a theory but I believe I now need to remove material from probably the 1g weight since the small weight would be difficult to work with to lighten up that end of the beam. I will probably have to remove the weight I added to the major side.

[country gent]

Make sure the surface for the scales is level in both directions. A leveling plate can be made with a piece of flat stock metal plastic or wood. 1/2" in from each corner on one end drill a 3/8" 24 tapped hole and on the other end 1/2" in from end and on centerline drill a third 3/8 24 hole. Use set screws to adjust to level in both directions. This gives a level solid mount for the scales. Set scales on it and zero scales with everything set to zero. Some scales use a screw to adjust initial zero under the pointer end some use a small set of jam nuts on the beam, some have both. With set to zero use check weights to check readings.
If its reading off and further adjustments don't help. Check the bearings and knife edges for dust dirt and wear. Sometimes a light rub with a pencil eraser cleans them nicely. Blow the v bearings out with canned air. Look for bent parts causing rubbing or friction. Also if oil dampened you may have to experiment with the weight amount of oil in the pot.
Start with a solid level mounting surface, work slowly and carefully. Use check weights in set increments from 0- upper end of scales. Not sure how to adjust magnetically dampened scales

[country gent]

You might try a small piece of paper cut and folded over the finest weight. 1/2" X 3/4" tracing paper with a slot cut to set over the beam on each side. This add on will be around .2 grns and should show you if you theroy is correct. Also some scales have a primary pan under the scales pan that holds weights to zero the scales. ( usually lead shot in various dia)

A couple drops of nail polish on the bottom of the pan may get you where you need to be also.

[Carrier]

I would also contact member 1066 who is a scale guru. He would be able to steer you in the right direction.

[metricmonkeywrench]

Thanks to all for the ideas and things to check. Keep them coming, I'm not ready to throw in the towel yet.

I wish it was as simple as working with the pan weights like an RCBS scale, been there done that.

My dedicated scale shelf is level in all directions and I am using a small keychain level (a neat give away from MSC) on the base to maintain that zero. Knife edges and pivot bearings are fine under magnification.

No dust or dirt is gumming up the works

The pan and hanger appear to be original.

The scale is weighing "heavy" so adding weight to the pan or beam is not the direction i need to go.

[Mike67]

I have the same scale only it is .2 grain under when empty. I attempted to calibrate it without success and finally decided to use it for rifle only as .2 is not as significant on a 45 grain load.

[str8wal]

I have the same scale only it is .2 grain under when empty. I attempted to calibrate it without success and finally decided to use it for rifle only as .2 is not as significant on a 45 grain load.

You can add a small strip or two of tape to the bottom of the pan if it weighs light. Conversely, remove a little material off the handle of the pan if it weighs heavy.

[country gent]

He first needs to find out if the .2 off is cumulative or is constant. does the amount off grow as weight is aded or is it the same .2 off regaurdless of the weight on the pan. Cumilative gain may be a problem in the brearing and removing from the pan will change it on both ends of the scales or knife edges. Consistant gain, removing adding may fix it. on cumlitave gain the actual weights may be off. The way to check tis is check every graduation in the scales .1 grn scale then every graduation in the 1 grn then every grauation in the 10 grn beam. This should show which beam weight is off and how much. It may be the beam is itself though. Calibrating and or rezeroing a damaged worn scales can be tedious work. It sounding more like the knife edges may be worn or damaged and dragging.
If the scales does repeat to a given weight every time you can make it very accurate by setting it with check weights. Add up the desired charge and place on scales, then set beams close and set zero to this weight with the adjustment screws nuts.
It would be interesting to know the go / no go specs of different manufacturers for scales used in reloading. Where the pass fail point actually is. is it .1 grain off , or is it more or less than that. Another area that may be off is the notches in the beam itself. If these are off the sliding weights wont sit where it needs to be. Almost all these scales usea leverage point to measure with also. so a little bit off is magnified thru the leverage.

[Moleman-]

If it's reading .2gr heavy, can't you slightly loosen the inner adjustment nut, then tighten the outer nut against it. Test and repeat until you can get it to zero? .2gr wouldn't be much of a change. Perhaps a rotation of less than one facet of the adjustment nuts. I have the same scale and have checked it from time to time with weights from another scale and it has always ballanced out correctly so I've just left the adjustment nuts alone. I also keep it in the box when not in use to keep it clean and from getting bumped.

[Dan Cash]

I take it, from your description, that when all the poises on the beam are set to zero, the scale reads .02 grains off. If so, ensure all poises set to zero with scale on your level shelf and adjust the nuts on the beam.

[tazman]

I have an inexpensive Lyman beam scale that is doing the exact same thing. I have a set of check weights and mine is off by .2 grains all the way from empty to the full set of check weights.
I simply keep it in mind and set the scale .2 grains heavy when I set a powder charge. No problem.

[1066]

The old Hornady M type is good solid, reliable scale, well worth a bit of tinkering to get it up and running again.

If I understand correctly, your problem is that if you zero in the usual way, with all poises at zero and showing zero on the scale, then anything from that point up the range shows .2 off when checked with check weights.

If this is the case, then the problem is one of the poise weights is not locating down in it's zero notch correctly. This might be a small burr or just compressed debris, a careful scrape might do the job. Just a couple of thousands out on the large weight is enough to show .2 on the scale.

To get the best out of these scales the beam should be fairly level when at zero, unfortunately the design of the scale mean that to get the beam level the adjusting screw needs to be jacked well up.

To re-set the locknuts, set all poises to zero, with the pan in place, screw the level adjuster about 2/3 or 3/4 out, then zero the beam by adjusting the lock nuts. Once the locknuts are adjusted they should never need moving again unless a new pan is used etc. Please don't shave bits off the pan or weights, it's a one way ticket.

Here's one I tricked up some time ago.



and a video review of the new Hornady beam scale.

https://www.youtube.com/watch?v=buRAm2aL6ik

[metricmonkeywrench]

1066 exactly how you stated it. After another hour tonight i surrender. I've removed my previous weight addition to the heavy weight scrubbed the notches and reset over and over with the same end result .2 off to the heavy side. The nose high was a great tip and by eye the beam seems to set at a better angle. It seems to respond the best when the dampening tab is centered on the magnets.

[beemer]

Just a thought, my buddy had a set of RCBS scales that the tab that goes between the magnets got slightly bent. That shifted the weight enough to throw everything off a couple points across the board. Some careful adjustments and some check weights got it cleared up.

I like those scales, I bought one of the last set of oil dampened scales that Hornady made. Purchased a set of M scales years later. I bought another set for a spare. I prefer the 3 poise lay out, just easier for me to set up.

Dave

[metricmonkeywrench]

Well after getting a bit frustrated and stepping away for a while I went back to the scale tonight. After the numerous adjustments I still end up .2g over on anything off zero. However a new revelation was discovered tonight. If the tenths poise is moved the scale reacts properly, ie if I zero the scale and move the tenths weight to .4 the needle reflects a .4 change on the scale indicator. With the scale dial I can read the .0 through .6 change. Using the test weight combinations 0-9 read correctly, so I don't believe my issue is in the tenths poise.

When moving to the full grain poise that's where things go sideways, any movement off of 0 results in the .2g error. So short of going after the full grain poise with a file I'm not sure how else to adjust out the .2 error. I've been over the poise notches and knife edges numerous times and cannot find any other fault.