Mosrite MKA-2

[Simon Barden]

The bone nuts should be fine. I normally buy mine from UK eBay or Amazon sellers because it's not much more in actual outlay (though % wise it's a big jump) and they arrive sooner.

Straight shaft pots normally come in two sizes, 6mm or 1/4"(6.25mm) and need a knob with a grub screw to stop the knob from slipping. Splined shaft diameters are measured on the outside of the splines, so you will probably still have issues with the new pots as the internal splines on the knob will have a less than 6mm diameter.

You can of course, gently squeeze the two sides of the splined pots together, which will help get the knob started on the shaft, but it may end up sitting high on the shaft as the splined section will remain the same diameter at its base.

I'd be tempted to try and count the number of splines on the inside of the knob. If it has 18, then you need a coarse spline split-shaft pot. Use a marker pen to mark each spline as it's counted to avoid confusion. This seems the most likely cause of the knob not fitting as the splines on the shaft won't fit properly into the splines of the knob.

Once you've got some finish on the headstock, that will reduce the tuner hole diameter slightly (so allow the finish to go over the edge of the tuner holes) and will make a tighter fit for the bushings, so I'd wait until you've got the headstock all finished before worrying about the bushings.

You are certainly going to need to do something with that nut. On a zero-fret guitar, the nut is only there to stop the strings moving sideways as the strings should rest on the nut. At the moment the slots are far too shallow and won't allow the strings to rest on the zero fret.

You are going to need to remove the nut and cut the new nut off the guitar, as the zero-fret will get in the way if you try to deepen the slots in situ. The nut will be quite fragile as the slots will be deeper than on a normal guitar, so that base section will be thinner and weaker as a result. You don't want a lot of excess height on the nut, as the 'teeth' on the outside of the low and high E strings are then likely to catch on something (clothing etc.) and snap off. The higher the 'teeth', the more leverage there is on the base of the nut and the more likely it is to snap at the base of the E string slot.

You'll need to deepen any pre-cut nut slots, then file down the base of the nut so that the string can run between the 'teeth', but not rest on the bottom of the string slot as it runs back from the zero fret to the tuner. You want the height of the teeth such that the top of the string is level with the top of the nut. Also, round off the edges of the nut, so that a) it doesn't hurt your hand and b) it is less likely to catch on anything and snap.

I'd be tempted to make the nut slot deeper using some needle files. It looks like it's been cut on a bit of an angle, so it's deeper on the top E side than the bottom E side. A deeper slot means you end up with a bit more meat in the the base of the nut, making it stronger.

I am a fellow Ramones fan. Saw them twice; Hammersmith Odeon in 1978 (probably on the Rocket to Russia tour) and 1980 at Exeter University on the End of the Century tour.

[Mosrite Slab]

Thanks Simon,

Yes I can confirm the straight shaft pots won't be any use so into the spares box for a future project they go.

I squeezed the split shaft together on one of the pots I had with a small metal clamp and in the process dropped it on a tiled floor breaking off a terminal. Nevertheless this game me something to go to town on as practice and I now think I can get it on low enough with a tight fit. I tried it through the selector hole rather than ream out the volume/tone holes in the scratchplate and with a bit of packing out it should be OK.

Just a quick general question though, apart from copper tape on the back side of the scratchplate, should there be any insulation between the pots and their locking nut and washer and the tape? Also why do they have a small protruding rod at 90 degrees to the plate? (As photo).

The bone nut arrived today, looks fine.

[Simon Barden]

No insulation required. That little tab is an anti-rotation tab. Some Fender-style scratchplates have a small hole drilled in them which the tab fits into, which helps stop them turning if the securing nut becomes a bit loose. With a rear-mounted control cavity, if the wood's soft enough, it can dig itself in and do the same thing. But often people just cut the tab off.

[Mosrite Slab]

Thank you.

The roller bridge arrived today and what a lovely piece of kit it is, well worth the additional Royal Mail and HMRC fee as usual. Another drawback though, the diameter of the posts are considerably less than those for the kit supplied Tune O Matic. I could ream the holes on the bridge to fit the kit posts but the new ones are nicer looking so I'll have to dowel the pre-drilled holes and redo them.

Talking to a friend the other day, he's offered me the use of his carpentry workshop when it comes to spraying and finishing but I think I'll also take the opportunity to use the drill press for this task also.

[blinddrew]

Talking to a friend the other day, he's offered me the use of his carpentry workshop when it comes to spraying and finishing but I think I'll also take the opportunity to use the drill press for this task also.

Sounds like a nice option to have!

[Fretworn]

I wonder if that bridge is a retrofit for a Jazzmaster or Jaguar style guitar? Looks a bit like one. The MKA-2 has a tuneomatic style bridge, this might explain the difference in posts. The only issue is that TOM bridges are mounted at an angle whereas Jazz/Jag bridges are not. This is worth looking into first to ensure you mount the bridge correctly.

[Dedman]

also tunomatics are a fair bit taller as I found when fitting one to a Jazzmaster

[Simon Barden]

It is a proper Mosrite-style bridge. As Fretworn says, the bridge angles are also different, and your selected bridge, with its deep roller saddles, will work best when installed at right-angles to the strings (which will entail re-siting the bottom E side post hole).

The downside of the Mosrite bridge with fixed height saddles is that it looks to be configured for a smaller radius neck than the 12" radius of the kit neck. Original Mosrites had a 7.25" radius neck whilst some of the later copies probably had 9.5" radius necks (following the Fender fashion). So your middle strings will probably be higher from the board than the top and bottom Es. As the bridge is a roller bridge, there's no easy option of simply filing a deeper notch, as there is with a TOM style.

[Mosrite Slab]

It's been a while since I last posted, nothing has been straight forward with lots of mistakes but with patience I think I'm at a stage I'm happy with.

Here's what's been going on.

1. I blocked in the factory bridge post holes by enlarging the diameter and epoxy two-pack filled in the holes and banged in the ash dowel I got off ebay. Then disaster struck, after re-drilling for the narrower posts the high E hole was too sloppy so I thought I'd set the post in epoxy and take it out just before it hardened. Idiot me did it with the screw half up so the epoxy set in the thread and no matter what I did I couldn't get the screw out ending up stripping the slot. Try as I might I couldn't get a replacement bridge post and screw alone so I had to order another set, thankfully it arrived without customs fees.

After it arrived I did a set up, took some photos and was only while looking at them that I noticed the bridge wasn't straight, the top post was a couple of mm out of parallel so out came the dowel again and now it's fine. Another headache was re-drilling the earth wire bridge hole, how on earth do the factory have a drill which goes around corners??!! I got there in the end but it much higher up.

Next disaster was the nut, a gentle tap to remove it and it was gentle took off part of the retaining fingerboard behind it. A small enough piece to glue back but when the new nut arrived it was wider than the original. I filed it and made a right pigs ear, nothing was straight and while trying to slot it in another large piece of fingerboard broke off.

Back to ebay to see what to do to rescue the project and I came across brass and chrome nuts for Gibson's and accoustics. Mosrite's had metal nuts so I didn't have a problem there. Slightly too wide and high I ordered a couple and while waiting for their arrival chiseled off the remaining rosewood back to where it meets the neck timber. Lots of filing and fettling to get everything square and flat, taking a lot more care and time and then the grinding down of the metal nuts, smoothing off the ends and a rub down with wet and dry. Looking at the photos a bit more needed there but they site beautifully although I'm not sure which one to use yet, the brass one is the nicer and better fit but the chrome one look more authentic although sanding this has exposed the brass underneath.

I'll make up my mind later as despite what I said in an earlier post that zero fret is high, you can slip paper under it. It may not be a bad thing when it comes to setting up but I'll decide if it needs pulling and refixing lower come the day, one of the nuts make compensate but I won't glue them in yet.

Finally, re-shaping the headstock, daunting to the extreme but I'm happy with the result. It's not quite right as the outer Bart Simpson things are too narrow to start with, I've done the best I can and a bit for fine filing and sanding is required.

I bought a Seymour Duncan P90 stack for the neck pickup, overkill but with the amount of effort, head scratching, tears (nearly), frustration, time spent watching Youtube tutorials and finally patience leading to a result I feel it was worth it.

[Mosrite Slab]

A few more pics.