Hi everyone,
i was looking for some 3d printed tool, tool or anything else to make a “perfect” single concave. I found the trick in my bed.
I used a regular bed slat with sanding paper. If you need more concave, you push on center. If you need less, you push on the end.
Hope it’s uselfull.
Great idea!
for no stringer i can see it. handplane and sandingblocks for me 
i wanted to make a tool like this one but found it’s easyest with bed slat. And less expensive…
The concave still be perfect, better than if i’ve done with planer and sandpaper. I use planer for double concave / spiral V or other work.
That tool has been used by autobody shops at least 50 years .
50 years with a missing bed slat - no wonder those guys always walk like they got a sore back!
If you are shaping a stringered blank; You had better take down the stringer first with a hand plane to your desired depth of concave. Then shape to that.
That’s what I would do, if I was going to do it with his tool: take down the stringer with my planer, then use the sanding tool to blend a nice smooth concave.
Sorry I meant the Vulcan tool , post #4 .
…no doubt that necessity is the Mother of invention but in the case of shaping or sanding there is a protocol actually. If you follow strictly that you always finish with a consistent great fine product.
I watched the videos of Vulcan and what he shows is something that the planer do better; in fact he then pass the hand plane to level the stringer…
If you do not want bumps you need an electric planer and an eye developed to check first the blank to see where the glueing problems occurred or the problems with the plug mould then smooth that out and level the blank (pre shaping)
AFTER that you see where the problem if any, with the bottom you have. putting an straight edge from rail to rail in different parts of the bottom curvature.
If you just are cutting one PS block with hot wire is even more easier to have a nice flow curve from tail to nose; but if you want to put stringer/s is better to glue them at this stage not after the bottom is done.
Anyway; the thing I want to mention is that this is a labor that you can do as the “schedule” like most of us the guys that earn a living doing it do or you can explore different variations; that in most cases conduct to similar results but not better results and more time consuming; but if that is cool in your process, is good too; however, the WEIGHT of the tools are really important (like the electric planer and the angular sander for the sanding stage) and the technique of course. The planer with the shoe dictates the passing and trueing better than all the blocks (remember the weight too)
-In my opinion, we have an almost LOST WAR with the machine but we are winning some small battles but we need to demonstrate that still the handshaping and handbuilding process is not only cool but good; if we finish in raspers, scrappers or back yard shapers without understanding what exactly is finesse, smooth tools; nice fluid curves, eye developtment and basic know how not only in the construction part but in the design part (that actually is more important) we will lose almost all the rest of the battles with the megacorporations (the Man) and the hype (Slater s )
Understand and learn a given labor is not something that you can do in couple of months but is it possible; even more if you have time, but if you are a youngster that wants all now (seems a problem with new kids) you will finish with the machine or doing not so good stuff.
I see this in other activities a plenty with young fellas.
Even me I know that I am not great as some great ones from the past when the stuff was really hard core (like in martial arts, that I practice) because the society changed and now is al “insta” just add water mentality.
So if you focus your mind (have a concept before start to shape the board); have the electric planer ( a must) that actually is not expensive. I mean, this is one of the cheapest professions (a few tools and an space or two for not so much money) ever; follow a protocol and work a lot in the development of your eyes to see details and fluid curves all would be good.
You need to flow with the tools not spot scrap or sand; never do that. You do not need cross passes too; that is a mistake really. Is a not necessary technique and if you want to use it better to be very profficient with the planer and have a really good eye…
You need power of synthesis and that is what the electric planer does. You shape all the board with the planer the other tools is helping in details and getting rid of the marks but not shape anything (except in the tip of the nose of some HPSB that or the planer does not fit or is dangerous to brake the tip–on the deck part—)
Time; you need to put time in a given field but the new guys always ask how much time to be a black belt? That is not the way to think.
Yes, doing this labor as a hobby; alright; you have time; no matter the consistence of the final pieces; no customers etc but having a good cocnept in mind, let you see better results in less time and also contribute to help maintain this labor as something that have some credit; trustworthy.
—I say all that an I started some decades ago without the money and the space, as a kid so I shaped my first board with a file and a tool that I did to hold it in two different manners and laminated it with a tile rounded edge skirting…
I use 2x4 and 2x6 lumber and belt sander media to make long sanding blocks. I have one that was set to have 1/8" inch of inverted “V”, and another with a slight radius to create concaves. I like to use off cuts of foam to make a variety of radius curves for concaves and double concaves. The thicker blocks will maintain a constant curve (doesn’t flex). I also made a hinged tool to sand the crown in decks. I rarely use stringered blanks, so sanding blocks are good enough for shaping. I have 3 small planes for stringers. Use whatever works for you.
I’m a backyard board builder for 28 years, i start planer shaping before CNC surfboard machine, learning from shapers and mag photos, on clark foam blanks, and already eps home made blanks i used for RC planes…
As a mechanical engineer i created tools and process for industrie, at a time i couldn’t use noisy planer so i started playing with hot wires and hand tools on EPS. Take me long time to educated my hand to feel bumps and lumps and to cleanly erase them with “0 pass”. This is what Reverb explain: an electric planer is the efficient tool to take off material with minimal bumps and lumps and feel how to erase them with sanding block need a good eye and a good hand (bad view, low contrast perception for me).
So if you want a perfect concave, cut it accurately with a planer and sand it with a concave flexy block with long pass from start to end and rail to rail at 45° again and again with constant pressure on tool, ended with zero pressure pass. electric planer is faster but if you have time you can use a hand plane the trick is to control depth of pass.
