Two Point Mandolin

[talladam]

The wife has been studying for a big exam so I've had a bunch of time to work on my mandolin!


I've got the back looking pretty smooth. Scraped and sanded to 120 grit. I chased bumps around for quite awhile and eventually you have to decided to stop! My arches come pretty close to matching Adrian's plans but It seems like for me to get them to fit perfectly I would have to make the recurve shallower than the dimension shown on the drawing. You would think maybe I started with too thin of a piece, but the high part of my plate is still the correct thickness. I don't think it matters too much, I'm only off by a millemeter or so and I have nice smooth looking arches. I'm going to try to be very accurate with the thickness graduations. I tried to take pictures of the arches of my plate but it is tricky to get a good shot.

[talladam]

I spent some time getting my drill press ready for depth indicator holes. I glued a little bit of leather to the dowel to try to avoid dents. I also made a little wedge to help me measure.

[mikeyb2]

Just a little tip which might seem obvious but nevertheless worth mentioning. Have a firm grip on your plates when drilling them using your drill press set up, otherwise it's quite easy for the plate to ride up the drill bit and cause havoc. Maintain a steady downward pressure against the stop. Mike

[talladam]

Thanks for the tip Mike. Good timing. I'm just about where I am going to drill my holes. I am also worried about the stop on my drill press slipping so I did a little preventative maintenance on them as well.

[talladam]

Time for another update.

I drilled depth holes in the back. The little measuring wedge worked great! Also, nothing went wrong with my drill press and the back didn't ride up the bit. I had purchased a nice sharp new 1/8" twist drill from Lee Valley so that probably helps. I drilled to 2mm thicker than final dimensions.

The depth holes helped allow me to gouge out the back without worrying too much. As before, this took some time but wasn't as hard as I had thought. When I started worrying about going too far I started with my finger plane.

At this point I realized that I would need to draw my 'topo' lines way too many times to not have some kind of a template. Experienced people probably don't worry about the lines after the initial roughing but I want to sneak up on things. I cut a template for each topo line from 1/4" plywood. I didn't fuss too much with them, just using them straight from the bandsaw. They reference of the 15th fret location and the centerline. As I continue to work I'm very happy I did this.

At this point I'm within 1-2 mm of what I am thinking will be my dimensions. The top is getting more flexible, especially around the edges. The area towards the neck is quite stiff still. Having no experience with how stiff things should be, I'm still flexing it and trying to magically figure it out. I'm going to leave it for tonight. I'll look at it and flex it a few times and think about how I want to proceed. I will definitely go thinner, I just think it is a good point to stop for now.

[HoGo]

Best method to chase bumps on arching is use of low directed light in a darkened room like a small torch laying on your table next to the plate. You will clearly see shadows of the tiniest bumps.
For final check I use my thickness caliper but I replace the dial gauge with a pencil (semi hard to hard but not too sharp not to mar the surfaces). You can make simple U frame out of plywood and drill hole for pencil and add a pillow block against the tip. I set it to desired arch height (don't go for exact thickness as even tiny difference in pencil setting will show in position of the lines you'll draw) and carefully mark where the height is achieved, the lines should follow the map you aim for. Even tiniest bumps will be magnified as distortion in the lines.
I use wedge that looks just like yours but I generally add only 0.5mm for safety. I prefer using drillbit grinded to more acute angle than standard bit (which actually has obtuse angle). That puts less pressure on the other side of plate while drilling. You can use sharpened pin instead of drillbit and use the drillpress like the "stradivari punch" for fine tuning your graduations.
Instead of templates I mark the inside just by eye. I have a copy of drawings on the wall and just eyeball it. For marking outside arching topo lines I use simple thin plastic sheet with punched holes along the lines. I pin it to the plate and mark the plates either with an awl or sharp hard (mason's) pencil. Flip it and do the other side.
Keep up the work!

[talladam]

Thanks Adrian. I spent an hour or two after I posted the picture of my back arching trying to chase out all the bumps. I was thinking I should have drilled my holes a bit deeper but I’ve read a few threads where people leave a couple of mm. I’m ok with doing things the slow way for my first.

[talladam]

Here's another update on where I am with this project.

I continued with the back graduations until I got to where the plate felt like it had the 'correct' flex and 'bong' when tapped. Of course, this is a guess. My graduations are a bit thicker than the ones on my plans, but I'm using Bigleaf Maple so I figure it is likely I will end up a hair thicker than if I were carving different maple. This decision is still rolling around in my brain and there is a chance I will go back and change the thicknesses, but my instincts (probably not to be trusted at this point) have told me to stop. I will attach a pic that shows where I am right now. One thing that I discovered is that I shouldn't have carved right up to where the kerfed linings will sit. While sanding and scraping it was very difficult any time I was up close to my boundary line because any tiny bit of material removed beyond the line would make for a poor glue surface. On my top I think I will give myself 1/8 or 1/4" and I can relax a bit when I'm refining things. Is there a 'standard' practice for this? Do you guys leave yourself a bit of room?

My wife went back to Calgary for a week to visit friends and go to an equestrian symposium so I've had more time than usual to work on the top. For the top I decided to drill depth holes for shaping the outside as well as the inside. I made a cardstock template and poked holes through it with an awl (as suggested by Hogo in a previous post). This time I left myself 1mm extra and I ended up wishing I had left .5mm. The final thickness is decided by the interior carving, so if you go too far on the outside surface, you can just adjust your arching. In this case I ended up with a smooth arch that I liked that was 1mm too thick and I had to go back and rework things. While I was getting all this ready and drilling the holes I was thinking that as I gained experience I would probably dispense with this step to save time, but it was so nice to have those depth guides during my carving that I can't imagine not doing it next time. The roughing really went faster. It helped especially to convince me to carve further along the edge where the recurve goes. It is surprising how far the top stays 'flat' before starting to increase in thickness.

Before carving the top I happened to watch a video of Ken Parker carving a top for an archtop on Youtube. Seach 'Ken Parker Achtoppery' if you are curious. There are seven videos I think and he doesn't really cut much out of the process so it is a bit long and boring, but there are some really interesting ideas and I feel like there aren't many other examples of a start to finish carve that have the same amount of detail. In the video, Ken establishes the 'long arch' first by using gouges and planes straight across the plate. He then carves from the edge towards the center with a gouge and proceeds to smooth things out with a spokeshave and planes. I tried carving my plate in this order and I think it was an improvement from my 'random beaver chewing' method that I applied to the back. I also had some success smoothing my carving out with a scraper this time. On the back the scraper seemed to just leave things lumpy. This time I got much closer to a smooth surface with the scraper. I'm not sure what the difference is except that maybe I just didn't persist long enough on the harder maple before resorting to sandpaper.

My biggest challenge was the recurve. I haven't figured out how to carve a recurve that doesn't end up uneven. I started with the fingerplane with a toothed blade (because of all the grain direction problems) and tried to continue with a custom sanding block with the correct curve shaped into it. Towards the end I had some success scooping with my gouge from the outside edge to the bottom of the curve and then coming from the other side in the same way. In the end there was a prolonged session with 80 grit and various round implements and it does look fairly good now but it was a struggle. The curved scraper doesn't seem to get rid of the waviness. Next time I do one I'll have to figure something else out, maybe I'll watch some violin making videos? Those guys don't even touch the sandpaper.

I've got the top smoothed out fairly nicely. Despite my success with the scraper I still needed to go back with sandpaper and chase lumps. It's looking good now, but I suspect if I go back and look in different light I may need to continue the endless task of chasing the last lumps out. I know that when a glossy finish goes on, any unevenness will be very visible.

[talladam]

A few more pictures:

[talladam]

Here is the top at the moment. I carved into a bit of a dark streak. It will just be a bit at the edge. I could cover this with a burst, but I was hoping that if I didn't have too many sins to cover I could save myself the complication of a hand rubbed sunburst until a different build. This one is for me and I don't think it will bother me if I decide to leave a little character.

[talladam]

I carved the inside of the top in the same way I did the back. I set the depth of my drill bit so that I had a bit less leeway after my experience with the back. I think I left an extra 1mm extra. As I thinned the top I noticed that one side was noticeably stiffer than the other. Somehow one side is more off-quarter than the other. While I was carving and flexing I ended up a bit thinner on the stiffer side than I intended to go. It is still stiffer than the other side even though it is thinner. This section is near the f-hole and I have a good thickness all the way down the string path so at this point I am intending to go forward rather than start a new top.

The next step was the tone bars. I decided to cut a piece off the stock I purchased for the tone bars to see what the runout was like. It turned out that the piece ran out very quickly. I ended up visiting a local luthier who was kind enough to donate a piece of bracewood that was much more suitable. To fit the tone bars I used a method that came from Ken Parker's 'Archtoppery' series of videos. I ended up putting in 'leftie' tone bars in a 'righty' instrument by mistake. It ended up that this layout put a tone bar closer to the most flexible side of my top so maybe it was a happy accident.

I shaped the tone bars as closely as I could to my plans. I decided to do this by first trimming them down to height, then putting a peak on them with a finger plane and chisel and finally tapering the ends before rounding things out with sandpaper. It is interesting trying to work with the grain in such a strangely shaped piece of wood. I think they turned out well.

I cut out the f-holes with my fret saw. This wasn't nearly as easy as I thought. Maybe I used the wrong blade. I trimmed to the final outline with a sharp knife. This was an enjoyable thing to do, but again the grain direction took a lot of concentration. I finalized the shape with sanding sticks and files.

Next task is making some spool clamps so I can get the top glued on. I have to cut across my top at the 15th fret as well.

[talladam]

[Madphingers]

I recently embarked upon my first Mandola build, a two-point as well. Enjoying seeing your progress!

[talladam]

Looks like my last post was just after the f-holes were finished. I had to try to get the top and the rib assembly super flat so the glue joint was tight. I should have done a better job on the top plate before putting on the tone bars because they were in the way. The only thing is I figure the top might move a tiny bit when the bars are glued on. I used a level with sandpaper on one end and tape on the other.

Vancouver Island has been very dry so I was thinking the humidity would be low, but right as I was getting ready to glue on the top, humidity rose to above 60%. I had to haul out the dehumidifier and I put the mandolin and dehumidifier in the shower in a rarely used bathroom and closed the door. Good thing my wife is patient. My understanding is that gluing the top on is one of the times you really want the humidity correct or you might get cracks as the top shrinks across the grain.

I made up a whole bunch of spool clamps in preparation to glue the top on. On a tip from someone on an internet forum I purchased wooden wheels from an online hobby supplier and then glued sheet cork on them. In the end I decided I wanted the mandolin in the mold while the top got glued on so after all the effort to make spool clamps I ended up using my gobar deck to glue the top on. I used a cork sheet 'halo' to pad where the rods pressed on the top. The glue-up went smoothly and when it was dry I used a chisel, knife, and rasp to carefully get the top close to flush with the sides. Next time I'll leave less extra, I'm sure the maple for a back plate would be a pain to do this way.

After thinking about it a bit, I realized that the next step was probably the binding ledge, since it would be harder to do after the neck riser was attached. I was hoping to put this off until later because it is an easy place to screw up, but I sucked it up and got my binding jig ready. I have a very basic jig based on a makeshift router table and using spool clamps to hold the mandolin body level. Getting it set up perfectly took ages but the cut went smoothly. I tried to climb cut a bit in spots to avoid splitting out the grain, but it was a bit scary with such a small body so I mostly routed the 'correct' way. My bit is a spiral bit so maybe that's why it didn't chip out too badly. I chickened out and didn't rout all the way to the points, thinking they might chip off the top.

I figured the last little bit would be easy with my home-made gramil, but in the tight curves near the point things were not easy. I came close to really screwing up the binding channels here but managed to save things with a bit of careful filing and exacto knife work. At this point I was really glad I decided not to try an F5 because the scroll binding ledge must be a real trick to do properly. I'm thinking I might use the router all the way around on the back (well, maybe not the button) and hope the points stay on.

I've never used celluloid binding before and I have to say that using celluloid and Weld-On 16 is SO much easier than the wooden binding I put on my guitar. I used cotton twill tape to put a bit of extra force on the binding at the waist to pull it tight. In the end I think it will all look fairly good. I really want to scrape the binding, but I'm waiting a bit in case it shrinks a bit from the glue. I had a tiny little gap between the binding and the sides that I put some 'goo' in from melting some binding in acetone. The tortoise binding came out looking a bit 'louder' than I thought it would, I think because it had light coloured wood behind it. On a D18 it looks way darker.

[talladam]

[talladam]

It's been awhile since my last post! It seems like I left off with the binding. All in all the binding turned out very well. I still need to do some final scraping but I think things are going to look pretty nice. I added the neck riser and 15th fret crosspiece. The crosspiece was a couple of thin pieces of ebony to match the point protectors. Then I proceeded to the scary part: the neck .

The first part was fairly straightforward, involving some careful squaring of the blank with the handplane and cutting out the angles on the bandsaw. I tried to cut a round bottomed slot for my two way trussrod but my bit didn't end up deep enough. I ended up really wishing I had just gone with a square slot, but everything ended up fine. Something I didn't think about was that my rod ended up shallower in the neck then is typical so it comes out of the headstock closer to the nut. This will mean that my trussrod cover will be in a different spot than on the plans. Not a big worry for me but it would be annoying if you wanted a traditional look.

I went with a dovetail joint. I did one with my guitar and I really enjoy the self locking aspect of it. If I'm being honest I enjoy the idea of getting better at something that is quite difficult too. I cut the mortise with my hand saw and chisel. The next time I do this I think I will use the bandsaw. I got into tilting the bed of my saw for the neck so next time I would cut the mortise and tenon at the same time and the angles should match perfectly. As it went, the mortise is shifted to one side of the joint a bit. I shifted the tenon over to match, so everything should end up centered, but it made things a bit more complicated. After some struggle with the cuts on the body I did the cuts on the neck tenon on the bandsaw and this went much smoother.

Fitting the neck joint was a big challenge. I had things fit perfectly and then realized my bridge height would be very low. Getting the neck tipped back opens up a can of worms and I've spent the better part of a week trying to finesse things into place. I now have it fitting tight and at the correct angle, but all the messing around has led to a few consequences. I've burned through some length in the neck so the 15th fret will miss the crosspiece by little bit. The button on the neck is going to be a bit small. I ended up somehow making the neck heel a bit narrower than I was planning on so instead of the 1 1/8 nut width I was planning on I think I will have to go with something a bit smaller. I considered starting a new neck, but aside from the nut width, these things are cosmetic and fairly minor in the grand scheme of things. My current mando has a 1 5/64ths nut and I actually like it quite a lot. I just wanted to try the wider neck but that may have to wait for number 2. One more strange thing I realized was that the way I measured out the neck, the nut will be on the angled peghead instead of the flat part of the neck (like a Martin guitar). Again not a big deal to me, but a miscalculation.

In the last couple of days I thinned the peghead to a slight taper per the plans (easier than I thought with just a handplane and saw-rasp) and glued on a black veneer to the back of the peghead.

[talladam]

[talladam]

[talladam]

I got a bit busy over Christmas and not much got done on the Mandolin. The formwork for our new barn is done and the slab will get poured Tuesday so that will be a milestone. I also created a customized box for a Christmas gift for my parents. It holds the cards and coins that are needed for a game called "Nickles" that they love. I used leftover bits of wood from my mandolin and I think it turned out pretty well. Doing dovetails in 1/4" curly maple was interesting and very different from using thicker stock. I'll post a pic in this post and then do a new post with the progress I've made on the Mandolin.

[talladam]

Some more progress has been made on the Mandolin. I realized the peghead would be too thick once I added the plate on the front so I had to very carefully thin it down. I cut the fretboard to the correct taper and thicknessed it to 3/16". This allowed me to get a better idea of the neck angle and I realized that the bridge was still going to end up too low! Honestly, this neck joint has taken me weeks of futzing to get to where I feel it is acceptable. Someone will probably tell me I should have used the Siminoff joint for my first and maybe that is correct in hindsight, but I really do think the dovetail is a super cool thing so I'd like to figure it out. Looking at Sunburst and Hogo's pictures recently gave me a new appreciation for the work they do. I went through the cycle again and got the angle to where I'm convinced it is correct. I double stick taped the fretboard to the neck because I thought it would help with neck shaping. I cut out my headstock using my version of 'Arthur' from Sunburst's build.

I also made the little part of the neck riser that cantilevers over the body. This was really fun except I had to be very careful cutting and sanding such a small piece. My oscillating spindle sander was a huge help here. It is still a bit thick so that I can glue it on and take it down to the same angle as the neck plane after the neck is glued on.

The next step is neck shaping! I think I'm going to get it very close but leave a tiny bit of meat because I think I'll have to pull the taped on fingerboard off, glue the neck on, make sure everything is on the same plane and glue the fingerboard on. I feel like I may need to do a tiny bit of sanding after that to make the neck and fingerboard feel like one piece.

I couldn't resist doing a mockup. I like the way it's looking. I'm not sure about the tailpiece, it is a cheapo Chinese cloud style one. I love the cloud tailpieces, but I wish I could buy a better one. Any of the ones from the states come with a pretty hefty import duty and shipping cost that makes me hesitant to purchase one. I really think the Prucha ones are great (they are not clouds), but I looked into getting one shipped here and it is just silly. Maybe I'll start a side hustle importing mando bridges and reselling them! I could make tens of dollars!

[talladam]

A shot that shows the peghead shape I went with.

[talladam]

Well, the mandolin is pretty much done! I knew I was going to the Georgia Straights Music Camp at the beginning of June so I pushed hard to get it done. We can't skip straight to the end though!

After all the trouble the neck gave me, the actual shaping was a pleasure. I ended up using carpet tape to tape the pre-shaped fretboard in place. This is so I could shape the neck before gluing it in. I did most of the carving with a Shinto Saw Rasp, as well as every other file, rasp, and sanding stick I have or could make. The bit around the heel is quite fiddly. I enjoyed shaping the area of the backstrap gradually until it came to a nice point. I made cutouts of the neck profiles on my drawings so I suppose I have a 'Loar' neck profile with a few minor differences. Once it was shaped (with a tiny bit left on the sides for final shaping) I pulled the fretboard off and glued the neck in. This way the neck could slide in however deep it wanted and I could trim the heel afterwards. I then leveled the fretboard extension to match the neck plane and glued the fingerboard on. I radiused the fretboard after it was glued and used a sanding beam to get it spot-on level.

It's surprising how hard it is to decide when you're happy with the neck shape. I took a little off here and there and compared to my Eastman to try to get a feel for what I wanted. I rounded off the 'riser block'. This is when I discovered what a pain ebony next to maple and spruce is. The ebony dust gets into the pores and scratches of the light wood. This was a PIA all the way up through finish sanding. The neck always seemed like it was a little dirty and it wasn't until the very end that I carefully scraped and sanded until things looked clean. Its enough to make a guy use some other kind of wood. Richlite?

I used a 'pin drilling' type of jig to drill the tuner holes. I have to say this worked amazingly. You can be super careful with your jig, make a test headstock, put in the bushings, and if the tuners fit, you can be confident when you drill your real headstock. I drilled all the way through with the drillbit sized just a tiny bit smaller than the bushings. When I installed the bushings, I ended up wrapping a rat tail file with some 120 grit sandpaper and just turning a few times until the bushings were an easy press in. The tuners fit in the holes beautifully and this is when I realized that I'd made a mistake! My test headstock had the outline cut at 90 degrees to the front and the tuner plates fit perfectly. The actual headstock gets cut at an angle (90 degrees to the neck plane I guess) and one of my tuner plates just pokes a little too far towards the neck. I got all worked up and ready to plug the holes, redrill, touch up etc, and then decided to take a break. The next day I decided that this would be one of the mistakes that stayed on my mandolin. At some point you just have to keep building. After living with it for a bit, I actually don't really notice it and lord knows there are other mistakes that will be visible.

[talladam]

Here is a photo of the tools I used to shape the neck riser.



I forgot to include the fact that I installed a JJB piezo pickup before closing up the back. Every time I go to an open mic, the host looks at me like I'm crazy to want to mic my mandolin. I also figured if the mandolin sounded bad, at least I'd have something I could plug in. I cut a guitar cable end off and tied a piece of dental floss to it. I plugged the jack into the endpin jack and used painter's tape to tape closed the f-holes. The dental floss was trapped by the tape. This is a twoodford trick (ish) from youtube. It worked great, but it was annoying to have the jack rattling around in there until the very end.



I used spool clamps to clamp on the back. I think this worked well. I had a couple of other clamps over top of the neck block that aren't in the photo.

[talladam]

I dislike routing binding channels and this is the first time that it actually went really sideways. I was flush trimming the back to the sides and was very carefully climb cutting when the bit caught and ripped a inch and a half long section near the end pin. It looked really bad after it happened and I should have taken a pic but I didn't (maybe I just didn't want to look at it). All the routing after that was 'conventional' and not climb cutting. I knew to be very careful about climb cutting and my hands were nowhere near the bit, but I didn't think it would chip out like that. The rest went fine, and by the time the binding channel was done, more of the damage was gone than I'd initially thought. In hindsight, the biggest thing I did was try to take a bit too much off at first. After considering wider binding, purfling, etc, I decided to fill in the tiny remaining gaps with dust and glue. I put a bit of water in the glue and made the mixture mostly dust. Maybe it's because of the flame disguising the fix, but it is very very hard to see in the end. I can't imagine anyone would ever notice unless I pointed it out, and even I'd have to look for a bit to find it. I preshaped the binding a bit with boiling water, which was easy and enjoyable:



Cutting the binding ledge by hand around the neck heel was a pain. I think I'll trim my back smaller there next time. It's mostly end grain and I gave myself a little cut on the finger with an exacto knife while I was working on it. I didn't really take many pictures of the binding process for some reason. I glued most of the binding with Weld on 16 (messy, but it worked great) and glued the little piece on the neck heel with super glue. I held it in place and shot it with accelerator. I don't know how you'd clamp or tape it on there otherwise.