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Stewmac/Matt Vinson Style Neck Jig

Discussion in 'Luthier's Corner' started by Gilmourisgod, Nov 14, 2016.


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  1. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    Lots of discussion over time on the efficacy/necessity of the Stewmac and similar neck jigs for accurate fretwork. At $600+ for the Stewmac extruded aluminum version, cheaper alternatives were bound to surface. It's a very nice piece of kit, but obviously way overkill for any but full time pro Luthiers. A few TB'ers have built the Matt Vinson wood version as detailed here:
    http://api.ning.com/files/HAVVJu2zj...69br/How_To_Build_a_Neck_Jig__Matt_Vinson.pdf

    I've decided to try my hand at building one, with lumber and some of the hardware/dial indicator on hand, I expect to spend about $36 total, including a second dial indicator from HF for $16.99. This seems worthwhile for my anticipated lifetime output of 4-5 basses and the odd re-fret. See progress photos below. I have yet to mount the headstock jack, dial indicators, or a second higher platform or levelers for the bass. I intend to use it as-is to do final leveling on the fingerboard, since the neck can be fully supported. I used the Vinson dimensions to locate the support rods, nut strap pulldown, and dial indicators. With the nut aligned with the strap pulldown eyebolt, note how much of the neck is still on the wood platform, unsupported by rods. Methinks this dimension set was optimized for guitar, not bass. I can still simply drill more holes and add another support rod, and move the nut strap pulldown farther out, but is there an ideal location for the dial indicators in terms of position along the neck? Stewmac no longer makes the headstock "mini-jack" shown in the Vinson build docs, I'm trying to cobble something together using a turnbuckle. As you can see from the use of simple thumbscrews instead of fancy plastic knobs, the goal is CHEAP where it doesn't matter without sacrificing usefulness. Any comments, critiques, ranting highly encouraged! Thanks for looking, and please post any photos you have of similar purpose-built neck jigs. I'm a total geek, and love seeing the ingenuity applied to such devices.
    IMG_4724_zpsusorlrdt.
    IMG_4725_zpssqywpyyf.
     
  2. xaxxat

    xaxxat Supporting Member

    Oct 31, 2008
    One way to make a headstock jack. Go to 1:00 of the video.

     
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  3. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    That guy is an amazing machinist, never tried my hand at metalwork, and its a whole different set of tools... sigh. Might have to suck it up and buy a legit swiveling stand from McMaster Carr if this turnbuckle idea falls through.
     
  4. wraub

    wraub

    Apr 9, 2004
    ennui, az
    previated devert
    Not much to add here, but that bass is looking mighty fine...
     
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  5. Means2nEnd

    Means2nEnd Supporting Member

    Well oddly enough Gilmourisgod I own the actual extruded aluminum neck jig and vice and floor stand I actually bought it from Tom Clement right here on TB. I also made one for myself and also some other means of excellent neck support for doing fretwork on my bench and on my Stew Mac vice.

    This whole thing brings up some points of discussion I would be interested in hearing from the other builders here and also (WWBJD) that stands for “what would Bruce Johnson do?” I need to get stickers of that for my car and shop. Kidding but actually totally serious at the same time….

    Now when I started to put my shop together I saw one of those amazing looking aluminum neck jigs on the Stew Mac site and drooled with anticipation in actually having one not knowing what the heck I would actually use it for mind you. Even at that point I built one as close as possible before I bought the real McCoy from Tom in the same feeble state of gas for luthier supply madness. I have bought many tools that lay dormant still in the original wrapper because in actuality I never really needed at all but hopefully may one day use.

    Here is the thing for me I do build basses and guitars from lumber and also do set ups and fretwork for many musicians in the area. I really didn’t have a full understanding although I thought I did about these jigs or fixtures. You got to ask yourself what I am actually trying to achieve at the moment. Is it a new neck? Am I fixing a twisted or warped neck what the heck am I going to use one of these for? I don’t want to write a super long post but I have thrown a ton of money at this same thing and wasted time, thought, energy, and space in my shop.

    I get it you can set an guitar or bass on one lock it down and either keep a neck straight as an arrow for new fret installation or fretboard correction or leveling or lock an instrument in and simulate string tension laying down or upright to fix a problem that only occurs with tension and compression when the strings are on. Sounds simple enough and makes total sense….. Well that depends, and there is as many ways to build or fix most bass and guitars as there are builders so this is my story and what works for me personally someone else might have a completely different and correct for them method.

    I find “locking” the neck down and level is actually 99% all I actually need to do for most of what I do. I am no master builder just a guy who tries time to fit 10-15 hours a week with a partner building and doing set ups, small repairs, and fretwork. Most of all the musicians I know are like me a little older and for the most part are bringing me excellent or at least mid-level instruments that don’t need anything major. I build bolt on necks and actually I find I have a machinist vice I lock with clamps to my bench clamp the heel into and found a way to use one of those neck supports lined with cork to actually get even full support on the neck actually even better than those neck jigs because most of the whole neck is supported right on my bench and have a stand next to my Stew Mac vise to use the SM neck support. I will show a picture of how I got it to actually work by teetering it on a copper pipe so it finds the level of the neck perfectly and stays there. I do use my homemade neck jig but I have to say for me getting a guitar set up correctly in those jigs and having it locked down tight enough to sand, file, crown and general work is a pain in the arse and is not as stable as they are cracked up to be in my opinion. I like them most of all for working on acoustic guitars because the body is so big and it just works well for them and I haven’t had a neck I have made or one come through my shop with the issue of warped or twisted under pressure and tension bad enough that I couldn’t remedy it on my bench the way I do now. Also I pose a question so if you set the instrument in one of those jigs with the tension simulated there will be relief in the neck correct? So how are you going to level it now? You can’t use a straight edge or leveling beam because it won’t match the natural curve of the neck. I have figured out a way actually it’s not perfect but it’s the best thing I have seen to do it. I bought a truss rod from SM inside of an aluminum U channel the Martin style ones and there is a flat side and I actually use sticky sand paper in rolls and stick it to that side and then I can put a slight bow to match the curve in the neck held in that position and it works amazingly well but the thing is I have yet to actually really need it.. It’s nice to know I have the ability to do it but I’m not a full time repair guy or builder.

    Sorry I could go on and on but I’ll post a picture of me using my homemade one to work on a 60’s Guild acoustic and it worked awesomely well much better than trying to do it on my bench but for almost everything else I’ll post another picture of my benchtop method that shows how I got that neck support to work and stay level. You can’t see the heel in the vice clapped down but I think you will get the picture. I will say I do have the most expensive rag holder and stand to lean wood against…my SM aluminum neck jig. Not knocking them at all I am glad I have both but in the grand scheme of things with the way I figured out how to do what I do on my bench and vice they get used rarely but are excellent when the time arises.

    I am looking forward to hear from the other saw dust makers..

    clamp 2.
    clamp.
     
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  6. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I often wonder that myself.....

    Oh man, this goes way back. I'm sorry if I sound like an old geezer recalling stories from back during the war.....

    I built my first neck tensioning fixture in 1994 during the days when a group of us were developing a cool new bass for the SWR company. That project is a story in itself. The SWR basses had very thin flexible necks, and we initially had real problems getting the necks leveled and trued.

    My tensioning fixture worked very well, and solved the problem. It loaded up the neck using real strings at full tune, then the neck was locked into position. The strings were loosened and swung off to the side, and a router cut the radius of the fingerboard surface. After slotting and installing the frets, the neck went back into the fixture, put back under load, and the frets were leveled with a flat beam. It was a good process.

    Remember that 1994 was still BDC (Before Digital Cameras). I'm sure I have pictures of that first tensioning fixture somewhere in my filing cabinets, but they are in actual film negatives and prints. Remember film? I still have that original tensioning fixture here in my shop. I found it recently, stacked in with some other old fixtures in a space behind some workbenches.

    Forward to 1996, as I was just getting going on the first of my Ampeg-style Scroll Basses. I built a new 2nd generation version of the tensioning fixture to use on the Scroll Bass necks. It worked on the same principles as the earlier one, but was more rigid, and had a special assembly to hold the Scroll headstock.

    Here are some pictures of it from 1996, taken with my first digital camera, which took only black & white images. It's funny, they look like they are from the 1950's, taken in some secret military location!

    RADIUS01.

    The basic design is that the headstock and the heel are attached to separate fixture assemblies. The headstock is held only by its tuner post holes. Steel pins go through the holes, and the strings hook onto them. The heel of the neck bolts to the body end of the fixture using the normal neck bolt holes; they thread into the brass bar inserts in the neck. So, structurally, the neck is mounted just as it would be in the real body. The fixture body has a dummy bridge and tailpiece at the right locations, so the scale length and action can all be set just like the real thing. And yes, that's a set of Chromes on there, to make sure the tension is right.
    The key thing is that the head and body assemblies float in the vertical plane, between the two side plates. Note the wide vertical slots in the side plates. When those big knobs are all loose, the head and body assemblies can slide vertically and tilt a bit. As the strings are pulled up to tension, the neck is free to pull into whatever curvature it wants to. Then the eight big knobs are tightened, and the headstock and heel are locked rigidly into that position, in relation to each other. That's the true, under-load shape of the neck. No need for any other supports or straps or anything. The strings can be loosened and swung off to the side, and the neck remains just as if they were on there.
    RADIUS02.

    Another detail: With the strings on and up to full tension, but before locking down the knobs, I adjust the vertical height of the neck at both ends, in relation to the two round rails on the tops of the side plates. This sets it all up for routing the fingerboard surface. The head and body assemblies each have a single small jacking screw down inside, which pushes against the fixture's base. I adjust the height at each end using the jacking screws, checking it with this simple bridge gauge. Then, I tighten the side knobs and lock it all down.
    RADIUS03.

    A closer look at the headstock. I made a loop on the end of each string, so they can be quickly be slipped on to the steel pins that simulate the tuner posts.
    RADIUS04.

    The strings are tightened from the tailstock end. These four aluminum bars pivot at the bottom. The 10-32 socket head cap screws are turned with that T-handle to bring the strings up to tune. The bridge is an aluminum plate with the four holes drilled at the correct spacing and radius. It can be adjusted by the two bottom jack screws.
    RADIUS05.

    Here it is with the strings detached and swung off to the side. The router has a curved bottom base, which slides on the two round aluminum tubes attached on the tops of the side plates. It cuts the radiused surface of the fingerboard straight and true, while the neck is still held under the same loading as it was while strung up. I slide it down and back, tilting it a few degrees on each pass. That's the same way I radius my fingerboards today.
    RADIUS06.

    That's the basic idea of what I came up and how it works. I think my original tensioning fixture actually pre-dates Dan Erlewine's fixture. I'm not sure when he made up his first one. I think mine is better, hah! (Dan is a good friend of mine, and a great guy). I'll tell more of the story later, including more development and what I do now.
     
    Last edited: Nov 16, 2016
  7. Means2nEnd

    Means2nEnd Supporting Member

    oh boy oh boy oh boy this is going to be awesome!!! I'm like totally ready to play hooky from work to sit like a 5 year old on Christmas Eve for santa waiting for the rest of you story and pictures. I think you may have the greatest untold (except for pieces) luthier machinist story ever.

    Seriously thank you Bruce I am looking forward to it. How do you feel about the need to use one on every neck new or old and do you find them completely necessary?

    I do totally appreciate the time you take posting all the pictures and explanations I know you are full time at this. It has a huge impact and leaves me inspired and helps me tremendously.
     
  8. fenderfour

    fenderfour

    Sep 3, 2015
    Seattle, WA
    Why use a common 2x4? It's not a very stable starting point, no where near as rigid as an aluminum extrusion. Most 2x4's are Hemlock or "White Wood", which sits at about 500lbf on the janka scale. Rock maple (1500 lbf) would be a better material for pulling a neck flat.
     
  9. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    I think the first generation Stewmac jig was Rock maple, guess they didn't think that was rigid enough either, now it's all aluminum beam sections. I could probably stiffen the hell out of this just by adding piece of plywood along the bottom edge of the 2x4 to form a "T", or maybe bolting a steel bed rail to one side. I have a couple fundamental questions I'll try to pose coherently tonight, hopefully you all will Humor The Noob!

    Thanks for posting those photos @Bruce Johnson, more incredible jigs and fixtures, I was secretly hoping you'd notice this, my little low budget jig looks pretty pathetic by comparison.
     
  10. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    So, Bruce, your method is to obtain and lock in the curvature of an back-carved but unradiused neck under string tension, then cut the radius?
     
  11. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Means2nEnd;

    I guess I shouldn't have gotten you all wound up about these tensioning fixtures. The remainder of the story kind of goes downhill. I used the tensioning fixture for the first several years of production of my Scroll Basses, through my Series I and Series II models. But, it got to the point where it wasn't worth the trouble. I had learned enough about building neck structures, and refined my process enough that my necks were becoming predictable. I could radius and surface the fingerboard with the neck unloaded, and when I strung it up, it would go right to the relief curve that I wanted, every time. The extra work of pulling them up to tension wasn't making my necks any better or more precise. So, I stopped doing it.

    There's no question that the technique worked with the SWR necks. It allowed us to true up springy necks that changed shape a lot between loaded and unloaded conditions. And it helped me during the early development of my Scroll Bass necks, allowing me to see what my necks were doing.

    The use of the fixture to radius fingerboards with a router worked very well, and I still use it to this day. Around 2004, I upgraded the base holding fixture again, making it longer and stiffer. I also made it adjustable in width, so I could cut necks to 4" radius, which I introduced on my Series IV model Scroll Basses. I narrowed the body and headstock holding fixtures from the tensioning rig, and used them to hold the Series IV necks while cutting the radius. But I removed the hardware for doing the tensioning and stored it away.

    Here are some pictures of the neck radiusing rig in 2008, longer and set up in the narrow configuration, cutting the 4" radius on a Series IV neck. By this time, I had also mounted it on its own rolling bench frame.

    IMG_2388B.

    IMG_2390B.

    IMG_2392B.

    These days, I use the radiusing fixture several times a week. I radius the fingerboards of all my own bass necks in it, as well as all the necks I build for other Luthiers. I've cut around 1500 necks in it, to date. I haven't used the tensioning rig part of it in about ten years. I still have all the parts, and with a little bit of work, I could set it back up again. I haven't had the need.

    As a general summary, these tensioning fixtures are most useful when dealing with necks that are springy and uneven. That is, when you load them up, they don't naturally curl up into a nice even relief curve. By using one of these fixtures to simulate the loading, those necks can be cut to correct for the uneven bending. But, if you build necks that naturally curl up nicely, then the tensioning isn't necessary.

    I still think my method of holding and locking the neck is the most accurate way to do it. Clamping it only by the headstock and heel, and maintaining the bending of the headstock in relation to the heel, is the best way to replicate the loaded condition. That's the way that the strings actually work; pulling on the headstock, bending it forward. And it held the position rigidly. During the development, I was checking the neck contours with dial indicators, in relation to the rails. Between strings on and strings off, the necks were staying in position within a few thousandths of an inch.

    In comparison, Dan's style of fixture brings support rods up against the back of the neck and headstock, while pulling down at the nut with a strap. Trying to do the same basic thing, in a different way. To me, the problem with it is the strap; it's too hard to lock in the correct bending of the headstock, which is a critical part of the loading. If I were building a fixture of that type, I would rework the way the headstock is held to make it more rigid. And clamp it through the tuner holes.

    Also, remember that my tensioning fixture was designed for production use. That is, making new necks of the same type, one after another. It was optimized for quick cycle time. It's more complicated to build, but not very flexible in use. Dan's fixture was designed for repair shops, to be used on random instruments that came in the door. It needed to be very adjustable, and it was desirable to be able to hold the neck while attached to the real body. That all influenced why he went in that direction.

    Any of you who want to continue with these mad experiments, should look at combining the features of these two approaches. My design could be modified to make it more adaptable, and/or Dan's could be made more solid and repeatable. Get those heads scratching.
     
  12. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Pilotjones;

    Yes, to me, that's the optimal sequence to make a true neck. Cut the fingerboard surface as one of the last steps, with the back of the neck shaped to the final contour, and the neck clamped in the loaded condition. I was doing that for a long time on all of my Scroll Bass necks. That's the best way to do it, although not necessarily the most efficient.

    When I developed my new AMB-2 model Scroll Bass in 2012, I went all through my build process and fixtures, looking to reduce the labor hours and keep the cost down. Without sacrificing the quality of the final product, of course. I rearranged the neck sequence and saved some significant time. On the AMB-2's, I now cut and radius the fingerboard surface, and even install and level the frets, before shaping the back of the neck. The neck is cut to the final thickness and width profile, but is still rectangular in shape.

    This has saved me time in the process and, so far, I haven't had any problems with the trueness of the fingerboard surface or the accuracy of the frets. They remain true after the final shaping of the back of the neck. It all comes down to consistency of the process; repeatable steps and dimensions. The endless quest of efficiency and quality.
     
  13. Christopher DBG

    Christopher DBG Commercial User

    May 18, 2015
    Westerly, RI
    Luthier/Owner, Christopher Bass Guitar
    Excellent and informative post as usual @Bruce Johnson . For years I've assumed I either did not understand how those neck jigs worked or was ignorant to why people used them. Turns out I understood the mechanics but your post provides the answer to the the why, or in my case the why not have one.
     
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  14. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    It's Humor the Noob Time:
    Might have been advisable to have a full understanding of how and why this type of jig works BEFORE building one, albeit crudely and cheaply. Reminding me of this would be uncharitable. Let's set that aside and see if I've got this right.

    1. A perfectly flat (along the string paths) fretboard is a good thing. That's been a bit of a challenge for me, as anyone who reads my Hossenfeffer thread will know. This is a simple continuous 10" radius FB, no cone shapes or compound radius at this point in my abilities. I carved the neck two weeks ago, and after a few changes of weather, the NECK (as measured along the nicely contrast-y neck/fingerboard joint) reads as dead flat with DA trussrod at neutral. This either means I have a nice stable piece of wood, or the CF rods embedded in it are doing a good job. The FINGERBOARD may not be perfectly flat, I plan on using the jig with the neck support rods to flatten it with my handy new precision ground aluminum sanding beam.

    2. I hammer in the frets, maybe still in the jig. The act of fretting the now flattened fingerboard MAY induce a slight backbow due to the fret tang pressure. That backbow can (hopefully) be eliminated by tightening the trussrod.

    3. The now fretted (but un fret-leveled) neck is securely mounted and strapped down to my Vinson jig, strung up, tuned to pitch, and rotated into playing position to add gravity effects. This should induce some degree of forward bow in the neck. At this point I become confused about something. All the videos I've seen of people using the Stewmac or Vinson jig show them using a slotted straight edge to get the FINGERBOARD perfectly flat prior to setting the dial indicators in contact with the back of the neck, and then zero-ing them out. This seems odd to me, because ultimately the neck needs some relief. I can't determine relief accurately before the frets are leveled, so should I be trying to get the neck dead flat under string tension, or adding in some small relief before zero-ing the dials?

    4. Assuming I did this right in step 3, I rotate the jig back to horizontal and take the strings off. The dial indicators show some deviance from zero now that the string tension is gone, different pull of gravity, inherent stresses in the neck, etc. I fiddle with the nut strap pulldown and headstock jack until the dial indicators are as close to zero as I can make them. I bring the support rods back up into contact with the back of the neck to lock this in. I now have a fretted neck that mimics how it "wants" to be when under string tension, tuned to pitch. If I set the trussrod for a perfectly flat FB in step 3, I have locked in a flat fingerboard in a state of tension mimic-ing string tension in playing position.

    5. I now level the frets in the jig using my sanding beam with everything locked down, which in a perfect world would mean 20 frets that are all exactly the same distance above a flat fingerboard. They won't be, of course, but the leveling cancels out variation from fret to fret. Note that RELIEF has still not entered the picture unless I accounted for it in step 3.

    6. I crown and polish the frets, string the bass up, tune to pitch, and only now, I again adjust trussrod to introduce something like .015" of relief at the 7-9th fret, complete a general setup, etc. The bass plays perfectly with no fret buzz and low action. I have a beer and congratulate myself smugly.

    I apologize for my ignorance on this, but I'm sure it's perplexing to other amateur builders. Any clarification on this process, or why it's ultimately a waste of time or the best idea since sliced bread, greatly appreciated. I'm realizing that my jig would be indistinguishable from scrap lumber you'd find in @Bruce Johnson dumpster, but 'Im hoping to get some use out of it anyway!
     
  15. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    Bump??
     
  16. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I assume you are waiting for my response? Sorry, I had busy day and night shifts yesterday, and didn't get much TB writing time. I'll answer you soon.
     
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  17. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    @Bruce Johnson
    You have contributed a lot more to this discussion than anyone could hope for from a busy full time professional, hope I didn't come off pushy by bumping. I was actually hoping someone who still uses one of these jigs would weigh in, not necessarily you! I'm sure you have better things to do with your time, and greatly appreciate input from you and the other pro luthiers who post on TB. Thanks again for all your posts.
     
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  18. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    A quick side diversion:

    Speaking of wacky home-built specialty Luthier machines, did you happen to notice this contraption off to the left side of this picture? I had a quick chuckle and groan when I saw it. Another example of what happens when creative minds are left alone unsupervised in a shop full of tools.

    RADIUS06BX.


    I dug through my digital image archives, and I have hardly any pictures of this machine. These are all I could find.

    AMPHDS~2B.

    Yep, it's a 3-D neck carving machine, a double-pattern-follower type. My own more complex variant of the Dupli-Carver idea.

    If you aren't familiar with the Dupli-Carver machines, they've been around since the 1950's. It's a metal pantograph mechanism with two arms. On the end of one arm is a metal follower pin, on the end of the other arm is a router. You mount a pattern part on one side, under the follower pin, and a wood blank on the other side. Fire up the router, trace all over the pattern with the pin, and the router carves the wood blank into an exact duplicate of the pattern. Like magic! In the ads, the guy is usually carving up a 3-D eagle medallion.

    These machines have been for sale for a long time in the back pages of woodworking magazines. Dupli-Carver was the original brand (I think) and later several other companies sold copies/variants. I have a real Dupli-Carver that I bought about 25 years ago from a friend. He had bought it and modified it to try to cut guitar necks with it, and gave up. I messed with it a little bit and also gave up on it. The basic problem was that there was too much deflection in the pantograph mechanism. Small jiggles and bumps made big gouges in the workpiece. The precision was unuseable. And it was really slow. I still have it. Maybe someday I'll find some practical use for it.

    So, of course, I thought about it and decided that I could make a much better version, solving its inherent problems. A special machine for quickly carving my Scroll Bass necks! This was 1996, as I was getting the whole Scroll Bass thing going.

    My machine was a twin-pattern-follower. Two identical hand-carved neck patterns were mounted on the bed, one on either side of the workpiece neck in the center. The cutting head had the router motor in the center, and the twin follower pins on either side. The aluminum follower pins were the same size and shape as the ball-nose router bit. All three rigidly in a line, to eliminate the deflection problems.

    The head assembly was mounted in a linkage that allowed it to float freely in the vertical plane, but kept it square in two axes. The whole assembly rolled up and down the length of the bed, on tracks under the bed. The head was suspended with springs from an overhead frame, so it would float over the workpiece. Light pressure on the two handles would guide the pins down the patterns, with the router carving the neck. Like magic.

    It was a very cool machine design. I put a lot of thought and work into it. There were many technical issues with getting the patterns and workpiece correctly lined up with each other. I made special holding fixtures that would hold the necks face down, and another set that would hold them on either side. I wanted to use the machine to carve the entire back of the neck, and most of the scroll headstock. I spent about a year getting this machine built.

    AMPHDSCRBX. AMPHDS~5BX.

    Unfortunately, after all that cleverness and work, the machine was a dismal failure. It basically worked, and was pretty accurate. But it was incredibly slow to use. And the surface finish was rough and ripply. Each neck would have taken several hours to carve, and several more hours of hand smoothing. Several times longer than traditional hand shaping. With no real advantages. In the pictures, you can see attempts to carve a scroll headstock. I don't think I ever finished a complete neck with it, it was so frustrating to use.

    I played around with it for about a month, and gave up. Another bad idea, brilliantly executed. That happens a lot in the R & D business. I took it all apart. 20 years later, I still have many sections of that machine lying around or salvaged for other uses. The base frame became the bench holding a row of drill presses in my machine shop.

    I changed direction and worked out a sequence of routing fixtures and templates as my process for shaping necks. Much faster and more efficient.

    As an addendum, I've started work on a new router-based pattern-following neck shaping machine. I think I've figured out a much better approach.
     
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  19. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    Regardless of it's eventual utility in accurate fret leveling, I did find the jig useful in final fingerboard leveling. The neck had developed a tiny backbow over the past week, I was able to dial that out with the trussrod. Others were right in questioning how rigid a common 2x4 would be, answer: not rigid enough. I think I can greatly stiffen it by adding some steel bedrail scrap bolted to it, and building a vertical leg with a leveling foot on the end instead of the jury-rigged stand shown. The fingerboard still had some very slight high spots at the two ends, I was able to get it dead flat using the jig.
    IMG_4830_zpsj77yszzs.

    IMG_4831_zpsw56lgsff.
     
  20. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    Well,
    After a bit of Youtube scrounging, the best instructional video I've found detailing the use of these jigs is this 11-part, excruciatingly detailed and seemingly endless series. I can't fault the guy on level of detail, but some serious patience is required to get through it. I have now watched the entire series, and feel like I learned a few things doing it. Thank god for Youtube! Because this is TB, I'm sure somebody will pipe in that this guy is incompetent or otherwise misinformed :D, but to my novice eyes, seems like a pretty useful primer on the entire fret leveling and polish sequence. He goes through pretty much all the available fret leveling and crowning tools on the market and explains pros/cons. Parts 2 and 3 cover (in exhausting detail) the use of the original wood version of the Stewmac jig:


    Like most of the other less detailed versions of neck jig tutorials, he does NOT account for any relief in the neck while jigging the guitar up, and uses a slotted straightedge to set the fingerboard as close to dead flat as possible prior to zeroing the dials. Unless somebody has any alternative approaches they feel like sharing, I'll use this guy's process on my build in progress. Thanks everyone who chipped in on this thread.
     

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