Gellfex

Thanks Ansil, but the 100k has been fine so far. My main technical problem has been the damn fancy 1/4 jack having loose connections so when the cord is pulled contacts weren't closing and the signal wasn't getting bypassed to the build in amp. I need to get a better quality one, this was the one that came on the pocket headphone amp.

I should post a photo of the guitar, right now it still has the MDF body I made to work out the kinks, I have a slab of poplar to make a final body from.

As far as the dye goes, I would add a bit of shellac to the mix(best if made from fresh from flakes) This will give you a stable and solid tinted undercoat while keeping the finish thin.

Nitro, and shellac for that matter, are somewhat delicate finishes offering low amounts of protection, not my idea finish for a guitar getting 'heavy use'. a Polyurethane(2 part with catalyst) is IDEAL as it offers good protection and can produce a glass like finish fairly easy. Another option not commonly discussed is polyester. This will produce a nice finish can be a bit easier to work with, but it shoots thicker and could effect tone more. If done right, it should be a good finish. I generally avoid rattlecans especially if you already have a HVLP gun.

I would try for a poly finish, safety being the number one concern. ALWAYS use a respirator(not just a painter's mask), and you need to work out a way to ventilate. Not saying it's wise, but if you plan on only doing a few finishes with poly, you may be able to work out a makeshift ventilation system, but I'm not sure what your abilities/limitations are. 2 part Poly, once the safety concerns are met, might end up being the easier and quicker way to go. Cure time between coats is two days, 5 days to buff, and will require as little as 2-3 spray sessions. Total finish time: about 2 weeks

Thanks, that's interesting advice. I've never shot polyester although I've laid up plenty with glass. The automotive stuff usually has a green tint to it, but perhaps that's due the cobalt and other additive's they use. I haven't shot 2 part poly in ages, not since I used some Imron decades ago, really toxic stuff requiring a supplied air respirator. I have a pretty good spray booth and real respirators, so maybe that's a way to go.

So you think tint & seal it with shellac and then top coat it urethane. But you don't think shooting the 1 part glossy floor product would give me a "good enough" finish given the beater nature of this instrument? I also suspect this will not be the last body I end up making for this one, he's only 12!

Thanks Ihocky, that's pretty comprehensive. I'm not familiar with the tinting and dying products, can you give a few brand & product names? I guess I wasn't planning on a wet sanded finish, (I did plenty of that in my modelmaking days at the start of my career and hated it) maybe I could put the kid to work on his own guitar. But we sure didn't wait weeks to sand, hours at best, it was advertising! But I guess we didn't put on as many coats as you guys are describing.

Like I said, I'm reluctant to put huge effort and material purchase/shipping expense into a finish likely to get more beat up than even the average guitar, despite the gig bag my mother has made for it. I guess I just have to decide among the options and it'll be what it'll be.

Bro if it helps I switched to 2K clears about 10 years or more ago as like yourself the 30 day wait was not good for business and turnaround time for me so the 2K stuff was a must.

Normally even with this stuff I always allow at least 7-10 days cure then cut and polish as take it from me it "WILL" shrink back if you do it less than this time. After nearly 30+ years in the game I have found this is what works for me. Spraying 2K stuff is very very hazardous and do not even attempt to spray if you haven't got a good respirator and good extraction as you will do "PERMANENT" damage to your lungs, search this forum and you will see that almost 100% of guys will agree with what I have said. If its a rattlecan sprayjob that you're doing then again caution is also needed and always always wear a mask no matter what it is you're spraying "YES" even waterbased stuff, hope this helps.

I do appreciate the advice, but you're simply describing a "pro" quality level far above the job requirement! I'm not a luthier, but I am a self employed pro craftsman (entertainment industry) for 30 years. A big part of any job is identifying "how good does it need to be?" You can noodle any job to the point of diminishing returns and unprofitably. I have a cabinetmaker friend who's a marvelous craftsman but can't seem to make any money because he's unable to give quality appropriate to the price point.

I've already put in more hours on my son's "inexpensive" Steinberger style travel guitar than I ever thought needed for taking a neck & hardware off a pawnshop Epiphone SG, making a body and machining a tuning tailpiece. I sure have learned a lot about guitar making, but given the low quality parts I doubt the finish quality will effect the sound much and the boy is going to beat the crap out of it anyway! The current version with an unfinished MDF prototype body is currently at camp with him, it didn't seem wise to do a new body beforehand.

Given all that, is there a good reason why a sprayed or wiped oil polyurethane finish is a bad idea, assuming I can find a red enough stain?

If it was me I would spray the whole guitar with 2-3 coats of a sealer or even clear lacquer then I would tint the lacquer with a red of your choice and then spray shader coats as they are called until the desired red is achieved. Once this is to the colour you want "STOP" and apply just clear coats to your desire until you have good coverage and a nice even coating ie probably with a lacquer 8-10 coats I'm guessing then leave it for at least 30+ days to harden fully then cut and polish, hope this helps

The tinting idea is interesting, but the 10 coats and month to cure + handwork sounds more like for a top line instrument than for a 1st build traveler. Maybe I can tint the oil urethane though.

I've tried both Minwax red mahogany & red oak stains looking for that classic red SG color, and both are not nearly red enough, possibly due to the natural slight green tinge of poplar. I used to have a much redder mahogany but the mfr discontinued it. Do I need to use aniline dye, or is there some other line of stains I should look at?

Also any comments about the most practical clear coat method would be appreciated. I do have a gravity fed HVLP gun and I was eying the can of "ready to spray lacquer" in the auto parts store. At $22 I suspect it's cheapest way to go except for a spraycan, but maybe I should go oil poly instead for a more durable finish, it's for a 12 year olds travel guitar.

JohnH, REALLY interesting idea! Easy to do as I already have a 9V aboard for the headphone amp. The only downside I see is that it remains powered until you pull out the cable. I'm lucky if my 12 year old shuts off his amp, expecting him to pull the cord out when he's done may be too much. Maybe this too should get kicked down the road as a possible tweak on the final version.

Ergonomics have also been occupying me this stage, trying to lay out jacks and pots on a very small field. The 1" Gibson knobs I believe are too big to be set so close, and I think I need to put the 1/8 headphone out jack on the top side of the body where it can't be confused with the 1/8 MP3 in. The amp I bought had RCA L-R inputs but they're a PITA, ugly, and big compared to using a simple male-male 1/8 stereo cord to the MP3. Does anyone know how bad it would be if the amplified MP3 signal accidentally went into the headphone amp output line?

Thanks guys.

After listening to it again I think I'm just going to leave it on the 500k for now and finish the guitar. Right now it's just a prototype of MDF. Then if the kid wants tweaks I can do them, the 100k is smaller dia than the 500k anyway. As for volume, he's been playing the prototype which just has the pickup wired directly to the jack and complaining about no volume pot. The prototype is worrisome in that it won't hold tuning. I'm hoping it's just the MDF and not my tuners, and the poplar body will be better.

Rip, I actually had the 4PDT in my archives from decades ago, I'm a real packrat! Thursday my son's buddy came over with his strat but forgot a cord, so I said "give me a few minutes". I rummaged deep and found 2 1/4 plugs and an 8 ft piece of yellow shielded 4-18 leftover from a job and whacked it together. The kids were wowed.

Thanks for the ideas.

If you have a link to the schematic for the amp, that would help. There are other possibilities here as well:

No such luck, it's a Ebay special, but pretty well done and functional, it was the only cheap one around with a MP3 input

- Use the 500k pot for guitar volume, but when switched have the switch put in two resistors strapped from the outer lugs to the middle lug such that you get a roughly 100k linear pot

The amp REALLY wants a audio taper

- Compromise with 250k pot

worth experimenting

- Use 100k pot and when switched to guitar mode, put a 100k or so resistor between the pot ground lug and ground

Wouldn't having an overall resistance of 200k instead of 500k reduce the output volume by 60%? Or do I misunderstand the effect of grounding the signal on volume?

- Use two different pots so that he can have completely independent controls

Small real estate on a travel sized guitar. It's already a challenge with 4 pots, a toggle, and 3 i/o jacks! I'm kinda concerned about routing the cavity too close to the edge and creating a weak body wall

I'm sure there are others, those are just off the top of my head.

Hi all, really glad I found this site.

I'm building a travel guitar for my son, basically a single pickup Steinberger style headless, but I'm embedding a headphone amp. I've wired up a 4pdt switch so when you turn on the pocket amp it switches the volume pot from external amp mode to internal amp mode. The trouble lies in the fact that the pocket amp wants it's original 100k volume pot and is unhappy with the 500k I've tried, it's range is all in the 1st 30 deg or so. I tried putting a 100k resistor in parallel with the pot, which should make it ~83k, but it curiously seems to have no affect whatsoever.

So do I just use the 100k, lose brightness when it's plugged into a real amp, and it is what it is? Or is 100k simply too low? No one expects it to to be the best sounding guitar ever, I'm not a guitarist and this is my 1st build of one. I scavenged the neck and hardware off a pawn shop Epiphone SG and made my own design tuner tailpiece. The odd thing about it was the volume pots were linear and the tone audio! Did some Malaysian worker have an off day or was that deliberate?

Any ideas on how to reconcile the 2 systems would be appreciated, it seems the amp pot is doing more than simple voltage dividing, and that's where my understanding of these things peters out.