Is my fret board thick enough?

I’m building my first tenor and the fret board is 3.8mm before final sanding. The neck is a tiny bit cocked back to account for a very slight radius on the lower bout - so a straight edge layed on the fretboard has about a 3.8 gap where the bridge will be.

I’m going to be using a smaller gauge fret wire that looks similar in size to vintage Martin ukes and I'd like it to have a reasonably low action...do I have a safe amount of clearance?

I’ve read on the forum that people are ballparking thickness between 3.5 and 4mm but I'm wondering if that's for a thicker gauge of fret.

Thanks.

Just measured a fretboard I'm working with and it came out to 3/16 inch (4.8 mm). I never actually thought much about FB thickness because in the end the action is dictated by the height of the nut and saddle and not by the height of the fretboard.... Not sure how to answer your question about fretboard thickness and thin gauge wire, but I think the tangs on fretwire are all about the same size (I should verify this but I'm too lazy) and it is the crown of the fret wire that dictates its "thinness" if that makes sense.

Personally I've never been into the fretwire thickness fetish thing although some people swear it makes a difference. When I compare the sizes by playing I honestly can't feel a difference but that might just be me. One caveat to using the thinner stuff in that it is a little less forgiving when you level your frets in that there is less "meat" to file away. I use the thin stuff because I bought a bunch of it and have to use it up, but honestly I don't really care.

Just did a search and in fact the tangs are a bit shorter in the narrow stuff but the difference is tiny. 1.37 mm versus 1.67. You have plenty of meat on your fretboard.

My fretboards are .090" thick same as Martin Sopranos...fretboards on a lot of banjos are just veneers at .050" thick..I recently replaced a damaged "top of the range" vintage Ludwig Banjo uke and it was .060" thick..and a load of old original ukes from the 1900's had no fretboards at all...thick fretboards are a recent guitar thing.
.now shoot me.ld:

The fretboard on my Martin is very thin. It looks almost like they put the bars on the neck and put veneer in between them.

A lot of old banjo ukes where fretted directly into the neck, no fretboard at all.

Thanks all. I’ll go ahead and glue it down.

I was worried that the saddle might need to be crazy low to get the right geometry...or that I might want to make an allowance in case the neck settles forward.

Here is how I calculate the bridge thickness.
Your gap at the bridge is 3.8 mm without frets.
Lets say your fret crown is 1 mm ( you need to measure that) this would give you 4.8 mm once fretted. You typically want a 2 mm action at fret 12. This will add 4mm to your height at the bridge. So your saddle top would be 4.8 + 4 = 8.8 mm over the top.
The bridge should be about 3/4 of that reading = 6.6 mm
The saddle would be 1/2 of that = 4.4 mm
The saddle groove would be 1/4 = 2.2 mm
The portion of saddle exceeding the bridge would be 2.2 mm

This seems to me a bit thin for a bridge, but may be still workable. Others members may confirm that. If you want a thicker bridge, change the neck angle by flossing the heel. Or laminate may be a 2mm layer under the fretboard that would match your bindings, etc..
A quick way to find the clearance at the bridge is to place a 1/8" (3.2 mm) drill rod where the 12 fret would be and a 1 mm shim at fret 1. (This is assuming a 1 mm fret crown). Then a straith edge laid on these 2 points will give you the top of the saddle at the bridge.
Then use the calculation above.

Thanks Alain. I’ve been trying to picture exactly that. I’ve read online that too low a saddle is a bad thing but I think I've been imagining a scaled up version of a soprano bridge. I'll just try to make sure I get a nice string angle between the pins and saddle.