Lyman D7 Scale

[ptf18]

I purchased new a Lyman D7 scale in the mid-1970s and have used it for my reloading needs ever since. It is taken apart and store in its original box after every use.

What is the group's opinion of this scale?

Thanks

 

[1066]

The Lyman D7 is a good, reliable, simple scale.
Pro:
Beam lifter, (Lifts the knife edges clear of the bearings when not in use)
Cast metal body, not too light in weight.
Simple two poise system meaning little to go wrong.
Magnetically damped.
Clearly marked beam.
Cup shaped pan platform, locates pan in consistent position.

Con:
Fixed agate bearings (as opposed to floating bearings as used on most RCBS scales)
Rather mean little knife edges - thinner than the equivalent RCBS scales.
Applied tape beam scale rather than a quality etched beam scale.
Beam notches could be a little deeper.

If it's not been abused it will last a lifetime - get a basic set of Lyman/RCBS grain check weights for around $40 and use them regularly, make sure the bearings and knife edges are clean and you should have a scale that will instill confidence and reliably and consistently weigh within a tenth of a grain.

Just my thoughts.

 

[ptf18]

1066 Thank you for your reply. I've always taken care of this scale, disassembling it and storing it its its box when I'm done using it.

The "issue" I've had with it (lately) is "repeatability". Meaning that I'll weigh out... say 50 cartridges... and if (when) I go back to recheck them I'll find that the charge weight will be off by... 1.5gns to as much as 2 gns. Not always off but sometimes.

When loading, I do 10 cases then recheck the scale for "zero". Sometimes I'll find that the pointer (zero) is off by maybe .5gn. I'll relevel the scale to get the pointer back to "zero" and continue the next batch of 10 cases.

Accuracy is not my main concern as is this "repeatability".

I've examined the knife edges under a 10x glass and they seem fine to me. I've Q-Tipped cleaned the agates which are plastic with rubbing alcohol.

It's frustrating to see this variance in powder charges but I don't know if it would be worth getting this scale "tuned"...if its possible to do so on this scale.

Your thoughts?

 

[1066]

There's obviously a problem with your scale, probably something simple that would be easily fixed - as for sending it away to get "tuned" probably not worth the time or money with the D7. What you need is a good straightforward service to get it running as it should.

If you say you have checked the knife edges and the bearings there are a few further places to check. First check the copper damper blade, it's only riveted in the beam and may have a little movement, just a gentle wobble should show if it's firm, if not a spot of superglue will fix it.
With the scale set up normally, get a torch and carefully look down the damper slot, you are looking for very fine hairs of wire wool that have been attracted to the magnets, also check the damper blade is clear in the slot and and not rubbing.
Check the little stirrup where the pan hangs from, it should be completely free to swing.
The "0" scale plate also acts to restrain the travel of the beam, make sure the beam is not rubbing against the restraining frame, the frame can easily be bent out a bit to give clearance.