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Let me start with this; I'm trying to find the root cause of difficult fret wire installation of two different SM fret wires. I've spent a lot of time gathering dimensions and experimenting with techniques wich could cause the problem. I enlisted the help of a colleague who arrived at a similar poor performance. His solution was to glue the fret ends/ beat the frets in. My "rather" is to find the root cause so I don't have to go thru this on every other batch of fret wire. I did not intend to write a novel, but the post is rather long because it includes measurements and variables that I could control and alter:

Situation: Two different batches of fret wire (all the fretwire I have) has been problematic since I started using it. No problems whatsoever before. Fret Hammer installation.

The lot of 148 SM fret wire is .0285” tang + barb thickness. Fret ends won’t stay seated- too loose?

One lot of 155 SM fret wire is .032” tang + barb thickness. Can’t tap the frets in without unreasonable extra force- too tight?

I have almost a pound of each of this fretwire. Its been problematic since I started using it. StewMac doesn’t list a dimension or spec for the overall tang thickness including the barb- and I have wire at both ends of the workable thickness. I’m not crazy about buying more; this variance is over 10% !

Is there a nominal normal thickness of Tang/ Barb thickness for a .022” slot?

I could continue to throw money at it (buy $200 more SM fretwire). I already bought a new SM fretsaw. I would rather understand it and find the actual root cause. I’m baffled and stumped. (OK so I just ordered one stick each of 148 and 155 fret wire from SM for comparison- that’s certainly in budget.)

Back Story:

Humidity controlled shop and seasoned FB blanks.

Loose fretboard, radiused and tapered.

148 wire (.028 thick barbs) is too loose and fret ends won’t stay seated. 155 wire (.032 barb thickness) can’t be seated without very unreasonable force (Fractal Press or hammer).

Slots are .021+” thick (.020 go- .022 nogo) with feeler gauge semi-slip fit.

New .022 kerf StewMac Fret saw- replaced the old one- I thought the saw was the problem.

NEW slots are clear of all debris.

FB radius appears perfect, 16”with sharp and square edges (slot ends).

Radiused wire at 16” and 14”- tried both

Slots are Plenty Deep (maybe too deep at 50% over depth?) Checked with gauge

148 fretwire caliper .028” thick tang with barb

155 fretwire caliper .032 thick tang + barb

Fret hammered on hard surface plate and leather covered wood bench top.

A SM wire with .028” tang + barb thickness is not tight enough, ends wont stay in slot.

Two different fret boards, one Ebony- one Ziricote, with similar slots. Different hammers, multiple techniques: End to Center, Center to End, Doug Proper’s hammer on hammer, many small taps…...

The fractal press will press the looser frets in, but I cant use the press to fret the extension (I prefer to install these frets after neck is installed). Fractal press will not press in the tighter #155 frets without unreasonable and excessive force.

I have to say in closing that I bought this batch of fret wire from a highly rated seller on EBay, it did not come from SM directly. Could be a hint as to why the bard thickness' deviates so far from typical, whatever typical may be.