First Build JRM-1DC Single Coil -- ColinS

[ColinS]

14/11/2022 Box Open, start trial fit, nice wood but neck fit will need work.

Went through trial fit. All went together. Neck was tight at first but next day fitted well after getting used to being in the warm.

It has a single P90 with a Tune O Matic style bridge, but unlike the video of scale lengthe measurement there is no tail piece, the strings lock directly into the bridge.

I read Gibson uses a principle like this too on its cheaper models, but wider . But a purist would worry that the strings will meet the individual little "nuts" at a very high angle so time will tell whether there will be short string lives. But , hey I bought a $199 kit that was on sale not a Gibson!

Also the "half scale length" --Headstock nut to crown of 12th fret-- is 313mm
The "half scale length" --crown of 12th fret to individual "nut' on the bridge --can be 313mm but only at at full extension . That is , there is no scope for adjustment. Hopefully that's OK.

Ready to start sanding and Tru Oiling it. Nice looking piece of wood so hope I can keep its initial appearance

[Simon Barden]

Is the neck too tight or too loose? If tight, you could wait a bit as often the neck fit is tight after temperature and humidity changes in transport. Make changes now and you may find that things become a bit too loose in a couple of weeks (though it might stay as it is).

If loose, it's a question of how loose. You'll be adding layers of finish to the neck so you don't want a fit now that's very tight or you won't be able to fit it with the finish on.

If it's a question of getting the end of the neck pocket curve to match the end of the neck curve, then I use chalk on the end of the pocket, fit the neck and then remove some wood where there's a chalk mark until the chalk is fairly even across the end of the neck.

You can also use carbon copy paper to do the same thing.

[ColinS]

Thanks Simon. It magically fitted later in the day. Your suggestion of humidity etc. Most likely

[Simon Barden]

It will probably get a bit looser then after a couple of days.

One thing that you might want to check is the height of the bridge. The supplied kit bridge is very tall and recent JRM-1 builders have found that they can’t lower the bridge enough to get a good string action. The saddles on the bridge are a lot taller than really necessary which doesn’t help the situation. Lightly clamp the neck in place (if you don’t want to screw it on yet) and run a metal straight edge from the 1st feet to the top of a saddle when the bridge is resting on the body. With the inserts and posts in (don't fit the inserts until the finish is on) I think you can get the bridge sitting almost right on the body so you might just want to stick a bit of card about 1mm thick under the bridge. That will give you an idea of the likely minimum string action you can get. You might be fine, you might have a big gap at the 12th fret.

If it turns out the action is high, the normal quick fix for this is a shim in the neck pocket. This is fine on most guitars, but the fixed height dog-ear P90 is then a long way from the strings, resulting in a relatively weak output lacking in bass.

You can buy or make a shim for the pickup to raise it up from the body to get it nearer the strings. Or you could get a replacement soapbar P90 pickup, which should fit nicely in the pickup rout and which is height adjustable.

You can buy a replacement wrapover bridge. These come in various flavours, from the original (Gibson) plain stoptail, a stoptail with fixed intonation compensation ridges, a similar ridged stoptail but with a moveable section (Wilkinson) for better intonation or a lower height wrapover bridge with fully adjustable saddles.

Or you could complain to Pit Bull. The kit originally came with a set-neck which had a bit of an angle to it which suited the tall bridge (the first picture on the PB website of the kit shows a set-neck body, the rest of the pictures are of a bolt-on). Then it changed to a bolt-on neck. But bolt-on necks almost always sit parallel to the body, and that bit of neck angle has been lost. Unfortunately the I assume the bridge selection wasn’t changed with it.

[Gavin1393]

Also the "half scale length" --Headstock nut to crown of 12th fret-- is 313mm
The "half scale length" --crown of 12th fret to individual "nut' on the bridge --can be 313mm but only at at full extension . That is , there is no scope for adjustment. Hopefully that's OK.

I'd be making sure there was some scope to extend 316mm from the 12th fret to the nut particularly at the point where the 'Bass E' would touch the "nut' on the bridge...The treble E would be fine at 313mm

[Simon Barden]

As the bridge post holes are already drilled, there isn't really any scope for moving the bridge, so you are reliant on the bridge having it's own means of intonation. As well as moveable saddles, there are normally two screws at the rear of the bridge that press against the posts and will physically move the bridge backwards to assist intonation if necessary. With moving saddles, this shouldn't be necessary. I don't like to use them if at all possible as they make the bridge more prone to wobble.

I did forget to mention in my types of replacement bridge that the plain stoptail bridge needs the bridge at at angle, with the bass-side post hole about 4mm further back than the treble. The kit looks to have the post holes equidistant from the pickup rout, so isn't suitable for the JRM-1. If you do think about a replacement, check whether it's designed for angled or straight installation.

[ColinS]

Many thanks, Simon.

I'm not super happy with the bridge generally. The angle of the strings from the anchor points to the notches is very high, higher than Gibson uses on it original design, I expect broken strings , we'll see!

Ill check the points you raise when I get the neck on, I've just finished Tru-Oiling and am giving it a week in the warm before I assemble. I like the wood parts but in retrospect wish I'd had a closer look at the mechanicals.

[ColinS]

Thanks GavinI393,

I dont think I can get 316mm on Low E (12th to bridge nut) without plugging and redrilling bridge fixing hole further out,

Ill double check this when I assemble again when oil has cured/dried fully. Then Ill have a word with Pit Bull if it is deficient.

[Simon Barden]

If the low side of the bridge needs to move back a bit to intonate the low E string, then there is that grub screw adjustment available on the rear of the bridge. Though I prefer not to use it, and just move the saddles, it can give up to 3mm extra adjustment.

It’s probably what Pit Bull will also say.

[ColinS]

The need (or not for copper shielding of cavities

I am about to wire up my single P90 pick up and the two potentiometers on my JRM 1DC.

I notice that none of the Pit Bull instruction videos (which all deal with more complicated electronics,multiple pick ups/switches and potentiometers) show any attempt to line the cavities with copper to reduce hum.

I can understand this given that the connecting leads supplied with the kits are of sheathed wire. But copper sheet is advertised and Ive bought a quantity.

What is other people's experience , have you found copper sheet shielding useful, needed or an unnecessary complication?

Thanks.
ColinS

Ah, Ive put the copper in anyway. its a bit like wallpapering a ceiling, hard to do neatly but it does flatten down eventually. Ive soldered an earth lead to the copper in the pick up rout and led that back to the pot rout. see how that goes.

I must admit the guitar does look pretty fabulous with 13 coats of Tru Oil.

Any one got any experience with the twin humbucker Les Paul style model with the pick ups and bridge offered as standard??