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Making my own monofin (progress)

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Merlin

New Member
Feb 28, 2005
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Making my first monofin (progress)

I decided to start with a small monofin to learn the process first and then I will eventually make a bigger one (maybe wilder designs too). So far I have cut the blade, and foot pockets. Everything has been done from scratch. Total cost $12 (lexan blade) + old stereo fins ($??) = $12

Next:
-refine all the edges the edges
-paint it
-attach the blade to the pockets (I am playing around with different ideas right now on how to do this). Any suggestions would be welcome.

Pictures of progess here:
http://community.webshots.com/album/305009928EsCrSv
 
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commonerg

Half Man, Half Chlorine
Jun 3, 2004
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Using the Lexan is a wonderful idea. Searching the board, I don't see any other instances of using lexan for fin making. I'll be excited to try out the finished project. If this works out well, I think you will have made DIY monofins a much easier prospect.
 

Mad Max

New Member
May 21, 2002
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Merlin asked me for my 2 cents.

When I built my first DIY Monofin I also thought of new materials, also Lexan. I also did some experiments with it, but it was too fraguile to handle the force you put on the blade with every finstroke.
So I decided to make the blade of resin and fibreglass like every normal fin. (also most of the carbon blades have a core made of fibreglass and resin).
Of course fibreglass and resin isn't really cheap. A DIY Monofin like this with OMER footpockets have total costs of about 70-100 Euro, depending on which materials you take and how stiff you want your fin.
Then you have about 5-6 hours working time, and the insecurity if the fin really works like you wanted it and if it's worth the effort. So Monofins from Specialfin or Leaderfins which costs 200 Euro (I don't know how much, but you can look on the pages) aren't very expensiv.

For instance, I tried to make a carbon-aramid-glassfibre fin. It was total crap. It looks great but what a crap. The bending was not good, and too hard. 70 Euros for a nice looking blade with no purpose of use. Too much in my mind.

But I find a good way to fix footpockets on the blade. First I tried a two compnents glue specially for rubber, forgett it. And the yellow glue doesn't look nice on the blade. Then I tried superglue (normal superglue from the market) this works, but don't use it economically. Take a lot of glue.
The best is the same resin as I used for the blade.
If you will use OMER pockets use the screws on the downside.

If you would like to know what material I used for my fins look at
www.r-g.de

-epoxy resin L
-hardener EPH 161 (VE 3261)
-EP gel coat colourless (for the last layer on each side of the fin, you can also colour this)
-glass filament fabric 80 g/m2

This you will need for a normal mono. But you also find the other things like Texalium (I used for my second mono, it's a aluminium coated fibre, for metalic surface)
and also the carbon aramid fibre.

The next fin I'd like to make is a glass - aramid fibre fin, for Dynamic (nearly straight with open heel footpockets). extremly lightweight and thin, but the same bending and stifness as my second fin (the Texalium thing), I hope my calculations will be right.

I sure will put some photos and a detailed report on deeper blue, if some are interessted. But you will have to wait one or two month until I will have some time to spent for planning and constructing.
 
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Merlin

New Member
Feb 28, 2005
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Mad Max thanks for the speedy reply. Your experiences on lexan are not encouraging :head being too fragile. I was actually thinking initially it may be too stiff. Well I guess it is all a learning experience :duh I will try to finish it anyway using the lexan and give it a shot and I will use the resin epoxy to glue the foot pockets like you suggested. For now I would like to stay away from OMER pockets because my main thought is to try to make them as inexpensive as possible (although they do look very nice). I would eventually like to try making multiple and more complex designs (dolphin tail).
 
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Mad Max

New Member
May 21, 2002
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Hi. OMER footpockets are good for monofins because it is very stiff. No needless deformation during force transfer, or nearly no deformation. For monofinning it is very important that your feet are very hard fixed to the blade (not to the footpocket), Normaly finswimmers take footpockets that are too small for their feet (2-3 sizenumbers), it must hurt. But thats good, there is no more space for your feet to move in the pocket, and the full force will be transferd to the blade. Thats why I think that footpockets for normal fins wont be the best choose.
But try it, i'm interessted what you think about it, maybe it works for you.

I don't know what Lexan blade you use, there is a variaty of lexan models. But your right, it is very stiff. Maybe too stiff. But try it. The best way to learn is to try.
Another problem of Lexan is that it is the same thickness from the footpocket to the end of the fin. Thats not good for the bending. A laminated fin is from thick (footpocket) to thin (end of the fin), So that most of the bending appears at the last third of the fin. That would be the best, for bending and flexing. I often talked with Herbert about it, and he has the same opinion. (he also likes my fin).

I think this thread is going to be very interessting.

Have a nice evening.
 

DeepThought

Freediving Sloth
Sep 8, 2002
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I have no idea what Laxen is (I know what's a Luxan. :)), but maybe you can sand it to become thinner near the edge...
 

cdavis

Well-Known Member
Jan 21, 2003
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Would it be possible to take a router and taper the blade, thin at the trailing edge and thicker near the foot pocket?

I'm considering doing this to an old set of cressi 2000hfs. Anybody else try something like this?

Connor
 

Merlin

New Member
Feb 28, 2005
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Well, I attached the foot pockets to the blade. The foot pockets are really tight and small so they are good. I ended up stiching them into the blade literally with a strong nylon string. The epoxy did not work because the pockets were too stiff and deformed (old cheap fins). However the attachment feels very firm and strong. In the future I will stich it even more around the entire foot but for now I think it is good. Another thing I should mention is that this is a relatively small fin. I gave it a very messy blue paint job with black rubber foot pockets (better paint coming in the future). I will also add in the future a rubber lip to the sides like you did Mad Max (looks very nice) and I want to add a small flush lip on the bottom of the blade to hid the nylon string. I am going to the pool tomorrow to try it out (cross fingers), just hoping it works somewhat.

pictures
http://community.webshots.com/album/305009928EsCrSv
 
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Merlin

New Member
Feb 28, 2005
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cdavis said:
Would it be possible to take a router and taper the blade, thin at the trailing edge and thicker near the foot pocket?

I'm considering doing this to an old set of cressi 2000hfs. Anybody else try something like this?

Connor
It would take an artist, a lot of patience, and a lot of work to be able to taper it down. For taper it is probably better to use a different material.

This website mentions a way to taper the blade by removing various layer thicknesses from foot to tip and then sanding the discontinuities but this will not work with lexan. In fact I do not believe they even mention which material to use for the blade to do this technique.
http://www.geocities.com/colosseum/bench/8586/equipment.html
 

immerlustig

BlueSkunk
Aug 17, 2002
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hi

don't know if this might be of use for anyone, but my girlfriend sanded her ww down ( about half the blade)to make it more flexible/softer near the edge because it was too stiff. she used it like that the whole last season without any problems whatsoever. she is very pleased with the result.

i was wondering how fiberglass blades (like ww) are tapered, what is the mechanical process??? can anyone tell me??


roland
 

Merlin

New Member
Feb 28, 2005
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immerlustig said:
hi

don't know if this might be of use for anyone, but my girlfriend sanded her ww down ( about half the blade)to make it more flexible/softer near the edge because it was too stiff. she used it like that the whole last season without any problems whatsoever. she is very pleased with the result.

roland

Roland, pardon the ignorance but what does "ww" stand for? And did she just do it by hand or did she used some kind of power sander?
 

Merlin

New Member
Feb 28, 2005
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Well guys, I just came back from the pool and I am VERY happy with the way it performed. It was not too stiff not too soft (definitely not a sprinting fin), it also did not put stress on my legs at all. The stroke felt amazingly natural and smooth.

The bad part is .... that the knot in one of the stitches came loose when I tried sprinting. This however is not a problem at all and should be easily fixed soon! The final veredict will come once Greg tries them since he is way more experienced with monofins (it broke before he got to the pool). I would like to get a video of it in action once it is finished (Greg *hint* *hint* :eek: ) to show.

Thanks to everyone who helped especially Mad Max!
 
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Mad Max

New Member
May 21, 2002
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Great. A video would be very interessting, to see the bending. I looked at your pictures. Fin looks good.
It's good that you are happy with your work.
I hope that our "cooperation" will continue.
 

Merlin

New Member
Feb 28, 2005
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Well a few cuts, a trip to the emergency room, and a few stitches later :duh ..... I finally fixed the fin and even made a second monofin with footpockets that Greg donated to me. :friday Testing begins tomorrow.
 
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Merlin

New Member
Feb 28, 2005
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Well I got them in the pool and they seemed to work very well. I only did a few 50m since I had no dive buddy today. Pretty happy with them. If I invest some more money I could make them more professional looking but for now these will do.
 

laminar

Well-Known Member
Aug 13, 2001
1,129
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Hi Merlin and Mad Max,

After going a whole year without finding a monofin that I like, I am trying to make my own monofin as well, and I have a few questions.

1. Instead of making the fin yourself from scratch, why not buy a 2mm thick sheet of fiberglass and cut it down? Any reason why you did not do this?

2. Is the finish on your fins smooth or rough?

3. What were the specific challenges in mixing the resins and binders and all that? Mad Max, can you share a step by step account of how you made your fins?

4. I have an older custom Waterway fin (my favourite fin - but cracked) that curves gently in the same plane as the font of the wearer's body. This turns out to be an important feature. I wonder if cutting away layers has this effect, or perhaps it's the sanding. On this particular fin, the top is sanded unusually smooth and the bottom has all the usual WW cut away channels. Also, the fin is a darker yellow/orange. Waterway no longer makes fins this way. They are all flat and pale yellow. :(

5. What thicknesses are your fins and what are the corresponding relative stiffnesses?

Lexan snaps fairly easily if stressed. How are the Lexan fins working out Merlin?

I'm glad someone is sharing their experiences with making fins...

Thanks!

Pete
 

derelictp

Freediver
Oct 16, 2001
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Pete,

I also have an old WW with the curve. Seems like the models over the years differ...

The thickness should be 1,5--1,8mm for glassfibre, otherwise it will probably be to stiff. (I suppose your footpockets will be tight)

I design my own footpockets and blades, take a look at www.nordicapnea.com/fins.html

Are you going to make your own footpockets?

The blade is pretty hard to get right because it's important that the blade has the right bending line, which means that the blade must have the best stiffness at every part of the blade, takes many many blades to figure out...

I have made 6 blades and the last one is very near perfect and my dynamic apnea is better (much better) than ever...
 

derelictp

Freediver
Oct 16, 2001
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Mad Max,

When you use the glue you mentioned, did'nt the stiffness of the blade change under the footpocket??

I use superglue (that You also mentioned.)

It's important that the whole blade flexes, even under the foot...
 

ajwaverider

New Member
Jan 3, 2004
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I had thought about making a monofin using fiberglass sheet also.Is it better to have a
fullfoot finpocket or finpocket with just straps? thanks AJ
 
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