1st Build-OM from scratch and my workbench

Take us through building your guitar step by step. Post pictures and tell us what you're doing.
Post Reply
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: 1st Build-OM from scratch and my workbench

Post by Talladam »

Finished cutting and installing my rosette. I used a herringbone pre-bent rosette from StewMac. It came with inner and outer b/w rings that I intended to use, but the outside ring ended up seeming way too big diameter wise for my OM shaped guitar. So I just went with the inner wide ring. This also helped out with the whole 'keep it simple for my first guitar' thing. I used a circle cutting jig that I recently made (details in the building tools subforum), and it worked very well. Despite the fine setting threads I included in my design, I fussed around to get the right width for my rosette channel. I planed a piece of pine flat and used that as a practice piece for each setting on the router. I had a 1/4" downcut spiral bit in my trim router. In the end I had a channel that fit the ring PERFECTLY. Too perfect, because I got nervous that titebond would swell the spruce to where the rosette would no longer fit. So I ended using some shellac to seal the spruce and gluing the rosette with some thickish CA glue. Worked well. I then planed down the rosette till it was almost level with the soundboard. This was about the most satisfying thing I have ever done, especially since I had just put a nice edge on my plane blade. There is a little scratch in the spruce from the circle jig (something must have got caught under it), but I still have to final sand my top. The rosette came .060" thick and I ended up routing a .040 deep channel. I may go a hair deeper next time, since I had to plane more off than I thought.

I'll finish with a question: I failed to finish sand the scratches from the drum sander out of my top before putting in the rosette. I have enough 'meat' to sand it down now without going to thin, but I am a bit worried that the dust from the black in the herringbone will get stuck in the surrounding wood. Does anyone have an opinion about whether this will be a problem? I could use my card scraper, but people say that they aren't great for softwood.
routing rosette.jpg
planing rosette.jpg
finished rosette.jpg
You do not have the required permissions to view the files attached to this post.
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: 1st Build-OM from scratch and my workbench

Post by Diane Kauffmds »

Very, very nice!
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
ruby@magpage.com
Posts: 1564
Joined: Thu May 24, 2012 8:03 am
Location: Chestertown Maryland

Re: 1st Build-OM from scratch and my workbench

Post by ruby@magpage.com »

Don't you love the cool shavings you get when you plane or scrape the rosette or purfling? Looks great - nice piece of wood

Ed
Ed M
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: 1st Build-OM from scratch and my workbench

Post by Talladam »

Time for an update! This one may be a it wordy, so fair warning. I've been trying to make some progress so I can get the box closed up before the humidity goes up. Right now my basement is at 40%. Since last post I got a go bar deck up and running (see my post in the tools thread). It works great so far, I love it. Before I could start on braces I had to get my top to somewhere close to the desired thickness and get rid of some of the scratches from the thickness sander. I bought some high quality discs for my ROS and smoothed out the outside. I was worried that sanding the rosette would spread black bits everywhere, but it came out fine. I then set up a ghetto deflection tester and started taking down the thickness of the top. People seem to all have their own personal deflection testing procedure, so there doesn't seem to be many hard and fast guidelines for how stiff a top should be. The only reference I could find was a .25" deflection over an 18" span with 5lbs of weight. By the time I got there, my top averaged around .110" thick (its a bit thinner at the edge and a bit thicker in the middle. I wasn't trying to do this, but it seems like a good way for it to be graduated). I thought I was going to be making a blind choice on the top thickness, but I actually feel like I've got it pretty close to correct. Only thing is I'm aware that many people thin down OMs a bit more than dreads, but I didn't want to push my luck. Just for the hell of it I measured the density of my top. It came out at 479 kg/m3. The average listed online is 425 for spruce so I guess its a bit denser than average.


I cut out all my braces on the bandsaw. I would have liked to split them to check for runout, but the blank I bought is only 3/4" thick and once in awhile I want to keep things simple for this first one so I just sawed them a bit thick and handplaned them to thickness. This was super pleasant work. Kinkead calls for 5/16" x braces, but I went 9/32 in an effort to avoid an overbuilt guitar. I was gung-ho to start gluing braces, but my bandsaw started making a loud noise on startup and tripping the breaker. Maybe only one in 5 times I started the saw, but it was bothering me so I dealt with it. I was positive that the centrifugal switch in the motor was at fault, so I pulled the saw apart and cracked open the motor. I couldn't get the fan off the shaft, so I really couldn't access the switch. In doing all of this I noticed that the belt pulley was loose on the shaft, and made a note to tighten it, but I was convinced that wasn't the problem. In putting the saw back together I secured the pulley and made sure the motor pulley aligned with the saw pulley. I also realized that the previous owner of the saw was using the lowest speed setting, so I changed it to the proper speed. Somehow, magically, the saw runs like a dream now and I also got rid of a bunch of vibration. I still don't see how the pulley could cause the problems I was having, but fixed is fixed. This whole experience killed a bit of guitar building time.

Finally I started sizing up my braces. The only problem I had was that my x brace joint was so tight that when I put glue on and jammed it together, there was a little ledge on the radiused part. I sanded it in my dish and glued it down, but I still have a little 1/2 inch spot where the glue didn't squeeze out as nice as the rest. Oddly this spot is not right at the x intersection. I really wanted to carve everything off and make it perfect, but in the end I decided to leave it be. It may have just rolled a bit on the dish and is contacting fine except at the edge I can see. Oh and I almost glued the UTB on the wrong line. Luckily I realized and moved it. Just a little glue mess was the result.

Recently I have been carving braces. This is another place where I feel like I am blindly guessing. I was going to get a guitar builder to have a look, but I'm taking a trip to San Diego in a week, and I don't want to leave the plate out to change shape while I soak up some sun! So my solution was to look at a ton of bracing threads and watch the Dana Bourgois voicing video on YouTube repetitively and try to figure it out. Now my guitar should sound just like one of his! (joking) Anyway, that is where I am now. Have a look at my bracing and let me know if you think I'm in an ok place. I think I may shave down the bottom tone bar a bit.
deflection.jpg
rough braces 2.jpg
rough carved braces.jpg
You do not have the required permissions to view the files attached to this post.
Danl8
Posts: 733
Joined: Mon Jul 28, 2014 7:50 am
Location: Chadds Ford, PA

Re: 1st Build-OM from scratch and my workbench

Post by Danl8 »

Based on looks the top is ok. You will have to determine based on tapping whether the right mix of fundamental and overtones are there. Too heavy and the top will be tight and too light, the top might not withstand the string tension or give the wrong balance of sound. I did my first kit maybe a bit too heavy, but after changing the strings to higher tension, it opened up and sounded ok. There are a lot of variables to consider. IMHO, it's better to make more instruments learning along the way. :-)
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: 1st Build-OM from scratch and my workbench

Post by Diane Kauffmds »

The top looks fine. I hate to venture a guess on how much to take off of the braces, based on photos. I voice my tops; not everyone does. It's important to compare the tap of the top vs. the back; they should sound different to prevent wolf notes.

Just be careful when voicing. It's very easy to go past the point of eventual structural integrity.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: 1st Build-OM from scratch and my workbench

Post by Talladam »

Here is a picture of the braces as they will be when I glue the top to the sides. I took some off the tone bars and finger braces, contoured the utb a little and took some of the fat 'shoulders' off in various places. Then sanded smooth. It's amazing how much nicer the braces look up close after some work with a sanding stick.
finished braces 2.jpg
You do not have the required permissions to view the files attached to this post.
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: 1st Build-OM from scratch and my workbench

Post by Talladam »

Top is on!
top attached.jpg
top attached 2.jpg
You do not have the required permissions to view the files attached to this post.
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: 1st Build-OM from scratch and my workbench

Post by Diane Kauffmds »

Good job.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: 1st Build-OM from scratch and my workbench

Post by Talladam »

I got out the rosewood for my guitar and set to getting rid of the grooves from the drum sander. Man, they were DEEP. I tried to use a scraper, but it was going very slowly. I tried a handplane, (the plate was still pretty thick) but the blade needed some time with the sharpening stones. So I broke out the random orbital sander. With the vacuum hooked up it works amazing actually. The back got smooth in no time, but taking the thickness down would have been a long effort. I figured I'd deal with it on the inside of the back and decided to start routing the backstrip. Fortunately the strip was just a hair bigger than .25" and I have a .25" spiral downcut bit. So I set up two straightedges and cut the slot in a couple of passes. Then I put tape on one straightedge and widened the slot a bit. I went far enough until I didn't have to force the strip in. Then glued it down with go bars and a caul.

The next day I planed down the backstrip (FUN!) and gave the outside a quick sanding. Looked great! No gaps. I cut out the shape of the guitar on the bandsaw leaving 3/16" extra. I then figured I'd sharpen everything up and figure out how to thin the back some. I stuck the back down to flat piece of MDF with masking tape and superglue (from a Ben Crowe video on youtube) and tried my #4 tenatively. No good, it skipped and bit in a strange way. That thing is temperamental. When it works I love it, but it has good days and bad. So I tried my little apron plane and while it dug in along the grain it worked like a charm across the grain. I don't know if that is the low angle or i just managed to get that sucker sharper, but it was great. I thicknessed the back to around .100", hit it with my freshly sharpened scraper and smoothed everything with the sander. Looks nice now! On to the back braces.
routing back strip.jpg
planing back strip.jpg
back plate.jpg
You do not have the required permissions to view the files attached to this post.
Post Reply