Michael Minton
Forum Replies Created
-
I communicated with Trevor, and he said the difference (notched/slotted-in versus tapered to zero at the edge) does show up in monopole mobility testing.
I’ve always notched the X braces, and like how they ensure the correct position of the top (and back) when glued on. I may continue to notch for that reason, but then taper to zero once the top has been glued on.
-
I use fiberglass driveway markers from Lowes or Home Depot. They work great and are cheap and easy to get. If you want some extra padding dip them in a tool coating.
-
Fender lost the case on the body shapes. See https://ttabvue.uspto.gov/ttabvue/v?pno=91161403&pty=OPP&eno=246
Guy who practiced down the street from me lost it for Fender. Ouch.
I’m pretty sure the headstocks for the Tele and Strat are still protected though.
ttabvue.uspto.gov
USPTO TTABVUE. Trademark Trial and Appeal Board Inquiry System
USPTO TTABVUE. Trademark Trial and Appeal Board Inquiry System
-
I agree with Zenn. Basically zero likelihood shaving that brace down will have audible sonic consequences
-
There is a little jig called the fret barber. Shaves a little off the fret barbs. You might try using that, or as an alternative, file the barbs a little. Problem with the latter is it is hard to be precise.
-
Or the pore filler reacted with the minerals
-
I put my signature and a (month/year) date on the inside of the soundboard below the bottom tone arm. No date on the label.
-
I am getting way above my pay grade here, but if you accept that
(1) a wolf tone occurs when the impedance mismatch between string and soundboard is minimized and a resonance is created (allowing vibration at that frequency to be rapidly and efficiently admitted to the soundboard); and
(2) by introducing a “pinch” or other aberration in a nut or saddle that alters the break point (or effectively adds another break point) you could change the pattern of reflection of wave energy in the string, change the mechanical impedance of the string, and create another set of standing waves
then potentially you could create another resonant frequency in the guitar top that could produce a wolf note
I’ll send a note off to Trevor Gore to see what he thinks of this conjecture.
-
Hmmm.
F2 is actually 87.31 Hz, so you wouldn’t be finding that on the A or D strings (unless it was somehow producing a half harmonic).
Maybe you meant F3? But F3 is 174.61 Hz. Closer to the main body resonance would be E3 at 164.81. But if the E isn’t a wolf note, F being a wolf note isn’t making sense to me based on the resonance, because the resonance is a full tone away from F.
-
Did my first glue up last night. Everything went well!
Top sits on the tube. About 5 lbs of pressure in the tube.
I hit the rim and the top with a heat gun before applying the glue. Like 4 passes on each.
Then I used a 10 ml syringe to dispense the HHG. With the cap on, I can keep it hot in the glue pot until I’m ready to go. And it is perfect for putting a thin line of glue on the linings and top, fast! Single brush stroke on the rim, and evened the glue on the neck block, and tail block. Mated the pieces and quickly put on 4 clamps. Neck, heel, and around the two upper x brace slots.
Once firmly clamped, added some more air pressure to the tube. (not sure, but maybe up to 10-15 lbs,)
I used Aspire for the modeling of the channel. If anyone uses Aspire and wants that file, PM me. I also made an STL file of the 3D channel cut. Below is a link to that.
-
If you are running Windows, have you looked in settings/system/sound to see if your Umik mic is recognized as an input device? If it isn’t there when plugged in, you can try “add device” to see if Windows recognizes it. Once Windows sees your microphone, you can go into system/sound/all sound devices/properties, select it, and then set parameters and test the mic.
Try that, if it doesn’t work, we can go to step 2.
-
Sounds to me like a hardener/activator/catalyst problem. Could be a compatibility issue with the Z-poxy but I doubt that if the Z-poxy sanded well. The typical problem there is amine blush.
-
One thing that always keeps me going is music I like. I keep repeating the John Hyatt catalog mostly nowdays.
More recently, the Loothalong is helping
-
I agree that the regression basically shows no fit at all. What are the units you are using on the X and Y axis? They don’t line up will values I would expect to see. E.g., what are the deflection units (are 9/5 to 13 in thousandths?), and the frequency units (10-13 doesn’t make any sense to me for frequency units).
-
See the Michael M and Michael B entries in the “Side Bending” thread below
-
Paul, PM me if you need a couple more Mahogany sides. I have tons, and I’ll send you some just for the shipment cost if you want.
-
This seems laborious, but it has served me well. I can’t remember the last time I cracked a side (knock on wood, sic). I use SuperSoft (spritzed on and evened out with a paper towel) and a sandwich that has a parchment paper inner, and an aluminum foil outer (shiny side in). SuperSoft can leave some staining but that is a small price to pay. Like you, I start the bend around 240 at the waist, and move pretty fast. I never set the thermostat above 300 degrees. Where the radius change is small, you can move faster. Where it is tighter, you slow down a bit, but you still have to keep moving.
My diagnosis of what happened to you is you got too hot, and moved too slow, drying things out. If you can hear a very slight sizzle at the edge where the bending is occurring you are definitely warm enough. You should be able to feel the wood give as you bend the upper and lower bouts. 5-10 minutes for an entire side.
All that said, mahogany isn’t the easiest wood to bend, particularly if there is any figure.
-
here is a link to the fretboard gadget.
Guitar fret board maker – Aspire 9.5 – Vectric Customer
https://forum.vectric.com/viewtopic.php?p=239133&sid=fedc06387a97b87ce737a93baec3851a
It took me a long time to work out how to make acoustic necks on the CNC. I use Aspire, not VCarve. Using the method I developed, you need a minimum of about 6″ of Z height when you have a 5″ mill inserted to mill the heel, and many CNC machines won’t accommodate that. You are milling down on the endgrain on the heel. There might be a way to do a 2-sided toolpath so that you could lay the blank sideways to mill the heel, I haven’t worked on that though. I don’t know if using this method you could do it in VCarve.
-
I have a friend who was production manager of the Bozeman operation in the late 80s, early 90s. One of the reasons he left was that he was being forced to build with wood that had not been properly seasoned.
-
I’m glad you got it going Ray.
Do you have the fretboard gadget for VCarve? A very good tool.
-
If you can post your .crv file here that would help.
Are you sure you are set to cut “on” the vector on your toolpath?
-
Try Bruce Creps at Notable Woods.
Great guy
notablewoods.com
Notable Woods, leading supplier of koa, claro walnut, and other tonewoods to luthiers and guitar factories; wholesale source for guitar, ukulele, Weissenborn and other string instrument makers.
-
Finding the resonant frequencies is not that difficult, and well worth your time and $ investment. You will need a computer, some software, and a measurement microphone. I recommend you start by watching Guiliano’s first video on this site regarding testing.
For measurement, the UMIK-1 works (USB connection) and costs about $130 or so. The Behringer ECM 8000 also works well, but will require a preamp. It is on sale right now at Sweetwater for $20 with free shipping. I have used both and both work well.
There are several free software options. Guiliano likes REW which works fine. https://www.roomeqwizard.com/. Trevor Gore likes Visual Analyzer 9.0.6 (not the later versions). https://www.sillanumsoft.org/download.htm. A third option is Guitar Tap. https://github.com/dwsdolce/guitar_tap. All these do is take the tap signal and do FFT (fast Fourier transform) on it to get the resonant frequencies.
You will first need to make sure your top panels are planed, not just rough sanded at 80 grit (the smashed rough sanded wood fibers add mass but do not contribute to stiffness). Cut the panels to true rectangular. Then measure dimensions, thickness, and mass.
There are three different tap tests to measure the elastic properties of the wood. We will need these three numbers.
The first is the long grain Young’s Modulus. Hold a plate at 22.4% of length downwards, and tap in the middle. The tap frequency will give the long grain Young’s modulus. Write this down. I haven’t tested Mahogany, but for Spruce this number is generally around 60-70 Hz.
Second is cross grain YM. Measure 22.4% along the width of the wood and hold at 22.4% in from edge about 40% down the length of the wood. Write down that tap tone frequency. As above, I don’t know the likely range for Mahogany, but for Spruce typically around 100-110 Hz.
Third is shear/diagonal YM. Hold along the length at node (about 50% down) and tap in lower corner. Put microphone directly behind the tap area in lower corner. Write that one down too. It will be about 40 Hz and is sometimes hard to get (and not all that critical for the formula). With larger plates it can be lower and really hard to get.
If you decide to do the testing, report back with the data points (x/y dimensions of plate, thickness, mass, and the 3 resonant frequencies) and I’ll do the math for you and get you a suggested top thickness.
Best,
Michael Minton
-
A bit hard to tell from your description, but is what you are describing as an oscillation a beat frequency? If so, it is possible you have multiples of two resonant frequencies that are nearly colliding there.
2800 is about an F7. Do you have and FFT analysis that shows T(1,1)1, T(1,1)2 and T(1,1)3 data for your top? We could start there (although there are higher resonances that could be a possibility as well).
-
It is probably too late to ask this question, but you never know what might still be in the trash can.
Have you checked the tape for the ripped out remnants? If you still have them, you may just be able to glue them back in.
Another possibility is creating a patch from a 3D model of the area. Jerry Lynn did a presentation on that (search the Looth Group videos). He inspired me to get an HP David scanner, and I am learning the process. There are other more affordable scanners (e.g., Revopoint) as well. Obviously, you would need access to a scanner and CNC. I don’t know where you are, but if you are close to Pensacola you could do it in my shop.
-
What is the height of the existing bridge?
-
it is sad to hear there are quality problems with JJ tubes. I’ve used them (haven’t bought any in a decade though) and found them to be good quality. JJ’s a Slovakian tube. EH owns the factory in Saratov Russia that makes Svetlana, Sovtek, Mullard (the reissue), and Tung Sol. I’ve never really had much of a quality issue with any of them, but boy have they gotten expensive in the past few years. Preamp tubes that I bought in quantity 20 years ago for 7 or 8 bucks are now approaching $25-30. ShuGang, in China, makes all kinds of tubes, but I had a bad experience years ago with a lot of Chinese tubes I purchased and never went back. New Sensor (the EH outfit) used to give better prices if you were a dealer, and you didn’t have to buy all that many in order to qualify.
-
I solved all of my air line contamination issues with this rig. First step is a basic moisture and oil trap, second is a desiccant based moisture remover, third stage is a high end (very small particle size) filter (Deltech SPXFlow). Latter is pretty expensive, but worth the expenditure.
Surface preparation is also critical. I wipe every surface to be sprayed with alcohol, then with WaxWash.
-
I don’t know. If you went cross grain, aren’t you risking splitting the top because the woods will expand/contract at different rates because of the different grain orientation?
-
There are two things that come to mind.
First, you want the grain orientation of the neck to be the same as the body, because wood moves differently (i.e., in differing amounts) depending on the grain direction. Most wood is pretty stable longitudinally. As humidity changes (or as wood dries out initially) the biggest change is across the grain (tangent to the growth rings–think you are looking down in the direction of the annual rings). Green lumber can shrink as much as 8-10% in this direction. Across the growth rings, wood will shrink about half that much. Obviously, if you are working with properly dried wood, you don’t have to worry about the initial shrinkage, shrinkage/expansion becomes a question about how well the finish will resist humidity changes.
Second, optimally, you would choose woods that have similar shrinkage characteristics. The online wood database has information on many woods regarding this.
