MIMF

Tenor banjos seem to just use a straight bridge, and the bridge is movable. Can anyone give me any clues about saddle placement on the fixed bridge of a Tenor Guitar and does the saddle itself need any intonation?

I am not an authority on this at all, and I'm sure more experienced ones will chime in soon, but here's my thoughts just to get the ball rolling...
I've only done one tenor banjo. I just adjusted the saddle until the intonation was right and I ended up with a compensated saddle. I can't remember how much it was compensated but it definitely was. Was it supposed to be? I don't know, maybe I did something wrong. But it played right. (Actually it played left, because I converted it to a lefty. )
If the tenor guitar is using steel strings I can't imagine it would not be compensated.
There's my $0.02

Peter -

A tenor guitar will need compensation just as a six string does. Given the shorter scale and lighter bottom string gauges, that combination will vary from the E4/E2 .060/.150 compensation seen on many six strings, but you'll still have the angled saddle, etc. Worth determining the tuning the instrument will spend the most time in and the scale length to be used, then use a fret calculator to find the estimated compensation on the outer strings to fix saddle angle. For a 23" scale length six string, compensation looks like .080/.190 or so, and I would assume dropping the lowest two strings would leave compensation at something like .080/.150 or so at DGBD...for DGAE, etc., there would be some variation. Again, search for a fret layout and compensation tool (StewMac has a basic one, and there were a few in the library) for a specific solution at desired tuning and scale length.

I'm not sure if you are asking about making a tenor banjo with a fixed bridge (wood top I would assume) and wanting to know how to locate the saddle or if you are making a tenor guitar and have never had to add compensation to a fixed bridge before.

If this is your first go at locating the saddle on a fixed bridge- Go to the Stewart McDonald fret calculator page and enter your scale and the type of instrument you are making. It will generate a list of the fret measurements but will also give estimates of how much compensation is needed (how much further you need to move the saddle back). It will give measurements for both E strings (unless it has a drop down for a tenor guitar). The compensation will be different for both as the saddle will need to be slanted. You will probably want to work out the distance for the lowest string based on the angle of the saddle with the two extra imaginary strings. Just draw out the saddle slant based on the 2 E strings and measure the distance for the 4th string. This should work out okay since building in compensation is really just estimation anyway. You may need to make some slight adjustments to the actual bearing surface of the saddle once it is all strung up and settled in. Now that you know how much farther back to place the bridge there are a few ways to locate it on the guitar. I like to locate the bridge after the neck has been fit. I measure from the 12th fret down half the nominal scale length plus the compensation and place the bridge so that the saddle is where I want it. Then mark the location.

If you are doing a tenor banjo with a fixed bridge -- You could do very similar to what was done above but I'll share what I did on a mandolin with a fixed bridge. Since Mandolin bridges have compensation built into them where the distance of the bearing surface is different for each string pair (and the bridge is typically just moved until it plays properly). I made my bridge with a saddle that had the intonation built in like a typical mandolin. I then put masking tape across the soundboard where the bridge would go. I rigged up a temporary tailpiece through the end pin hole and strung it up. I moved the bridge until I was happy with the intonation and marked the location on the masking tape. I had done my measurements first based on my best guess and the bridge ended up pretty much exactly where I calculated it to be, so it probably wasn't necessary but it made me feel better.

This is a tenor guitar. I have built 6 string guitars before adjusted for standard tuning but wanted some guidance for CGDA tuning on a 24.5" scale. I will go back and look at the Stewmac calculator, but really wanted to know if a straight saddle is all that is needed, or are banjo bridges just a compromise?

**The Stew Mac calculator suggests 30 thou compensation on the 1st and 4th strings, so it looks like a straight saddle placement will be fine, I will cut the slot along that line to allow a slight adjustment on the other strings if needed.

Thanks for reminding me of the calculator.

You will have some long stretches to chord a 24.5" scale tuned in fifths, but it should need less compensation than the more normal 22-23 inch scale length.

Why not check some tutorial on YouTube as you get a lot of ideas there regarding saddle placement on the fixed bridge. I set mine with help of that videos.

You will need compensation. A straight bridge on a banjo works because the bridge can be installed slightly off 90 degrees from the neck centerline, which generates the required compensation. For your guitar, angling the entire bridge begins to look a bit odd, so angling the saddle is a better bet.