Pit props mushrooms etc in AXL tricone

[mistercanetoad]

I have just bought an AXL tricone on ebay...seems to be okay for the price. I had to take it apart to sort out a buzz, and wondered about general construction and modifications etc. I would be most grateful if anyone could help me out with a bit of information.

I have read about moving and modifying the mushrooms/pit props. The AXL has three, one towards the strap button end and two beneath the cone tray. I have tried a modification suggested in on many forums that consists of moving one prop beneath 17th fret area and removing the central one. It sounds different, not good or bad really,but doesn't seem to make the great improvement suggested by some who have tried it. What is the main function of these props? Are they purely structural or do they act like a violin tone post? Is there an optimun placement for them?

The guitar has a neck post that runs to within a couple of cm of the end of the guitar. A grotty little block of wood holds the strap button on. Should the post reach to the end of the guitar? It is screwed to the bottom of the cone tray in three places with a shim under the third screw from the neck. There is no shim in the centre and this tends to pull the tray a little out of shape. I presume a shim would be a good idea here too.

Are there any other ways of improving the sound of these budget tricones, cones would seem to be an obvious one.
Finally what is different about a £2000 + National apart from general craftsmanship and attention to detail.

cheers

[LouisianaGrey]

The support posts are structural, they do not act like a violin sound post. This is true for every kind of resophonic guitar. I usually take out the centre one and just move the others a bit towards the neck and tail so that they still sit under the walls of the soundwell. It seems to work OK to my ears.

I like to screw the strap button with a long screw through the tail block into the end of the neck stick, which should be touching it. That's what they used to do on the single cones, I don't understand why they don't do the same on the tricones but they often don't seem to bother. Maybe it just depends what size screws are handy when they're doing it. If there's a gap, and especially if the tailpiece is only screwed to the tail block, then eventually the tail of the guitar will be pulled out of shape by string tension until the gap closes up.

The early ones had better fitting neck sticks so they didn't have so many shims but all of the recent Chinese tricones I've opened up had little bits of wood shoved (not glued) in odd places to pack out bits of the insides. The stick should be packed so it's tight to the bottom of the soundwell, again especially if the tailpiece screw does not go into the end of the neck stick, because that's partly what keeps the neck positioned correctly in the body. Otherwise you're just relying on the small screws under the fret dots.

National cones, heavy strings and a proper setup will improve the tone. They frequently don't cut the string slots in the nut and bridge properly. Is it a brass or steel body? The last AXL I worked on was a steel body and had a harsher tone than the brass bodied ones. Straight out of the box it sounded better than a brass Regal I had in at the same time, but when they were both fitted with National cones I thought the Regal sounded better than the AXL.

[mistercanetoad]

Thanks for your advice Pete, I have ordered new National cones and will sit down with my woodworking tools and see if I can get the general construction tightened up a bit here. I guess anything that vibrates or rattles or does not make a good contact takes energy from the strings and cones. As for the mushrooms, granted their main function is structural, the optimum position would seem to be beneath the sound well. Why remove the third? I have read a fair few accounts of people moving these things closer to the ends of the neck stick to "free the back up". Is this really the case or one of those factoids that spring up online from time to time?

The sound of this thing (Bellbrass AXL) is okay but a bit dull and quiet but I hope for good things. My main down the pub / on stage resonator is a cheapo Regal spider type. The construction on this thing was apalling. They had even routed the hole in the top about a cm too close to the neck, fortunately the well was in the right place! After a bit of remedial work and a quarterman cone it sounds as good if not better than some expensive name brands that I have tried.

cheers Dave

[Michael Messer]

Hi Dave,

It sounds like Pete has got you on the right track!

Regarding your question about the pit props and their optimum positioning - their are many differences between an AXL Tricone and a 1920s National, so positioning the pit props is something you should experiment with, and take advice from people who have upgraded AXLs. Pete Woodman definitely knows about these guitars. One thing I would advise and try to work with, is that National (the original company) really knew what they were doing and very little that they did can be improved on.

Keep in touch and let us know how you get on with your upgrading.

Shine On,
Michael.

[Colin McCubbin]

As Pete says, The neck stick should travel all the way to the wood block at the tail of the guitar. Metal bodies are not as rigid in compression as wooden ones, especially at the string tensions/gauges used on resonator guitars, and the purpose of the neck stick is to resist the pull of the strings and stop the body from buckling or shortening!

On old Nationals where the block is missing or shrunken, it is very common for the body to have buckled under the tailpiece and/ or the top/side seam to have opened at that point. I've also seen tricones that have a pronounced fold in the body top between the coverplate and end of the fingerboard for the same reason,.

I have never seen any of the new instruments you are describing, but am really amazed if they are not doing this!

The usual 'old' way is to have a fairly substantial block of wood against the end of the instrument and, then for a small wedge to be inserted between the end of the neck rod and the block to fill any gap. Finally the strap button screw goes through block and wedge and into the end of the neck stick.

[mistercanetoad]

Thanks for all the info folks.

I've done a bit of remedial work over the weekend. I'm posting the details here for gen interest and as info for anyone else who feels daft enough to start delving into the innards of one of these beasties.

I've put a good sized tight fitting block of hardwood between the tailpiece and the end of the neck stick and moved the strap button so that a screw goes through all three. The general stablity of the guitar feels much improved and I think the sustain is a little better with both ends of the strings on the same bit(s) of wood. I tried different positions for the pit props but didn't notice any great differences, the most important thing seems to be a good tight fit. I've got them under the ends of the cone tray. I've replaced the grotty bits of broken off ply that were used as shims with properly shaped strips of wood glued on to the neck stick and the cone tray is now not pulled out of shape and is flatter. Annoyingly, despite this, when I put it all back together it buzzed like an angry bluebottle. It still did it without coverplate and it wasn't the tailpiece. I tried swapping the cones round, tried different tunings to put more pressure on the bridge....these guitars could test the patience of a saint!! I've finally got it something like with the cones sitting a little off-centre. There is a patch on one edge of the cone tray where the casting is a bit rough and low and the buzz seems to stop when this is avoided. Does anybody know of anything I could use to level the bad area, I was wondering about some kind of epoxy. Has anybody got any general buzz bustin' tips?

Anyway the buzz has gone for now and the tricone is sounding pretty good, I can see why people like the sound! I've got some new cones on the way from the USA so will probably have some more fun in a couple of weeks!

Dave