ILF longbow limbs - First Attempt

[grouse11]

So before anybody says anything, I know I am going about this completely backwards lol. But I like to make my life difficult and figured what do I have to lose!

I have never built a bow, an entire bow that is. I know most people start off by buying a binghams kit and building the cookie cutter bow that is guaranteed to shoot and looks pretty good to boot. I'm not smart enough to do that apparently haha. I have made a few ilf risers, two pretty simple and one a little more intricate, that have been a success. With that said, my goal was to complete one of them with a set of limbs so that I can call the bow my own.

I decided to try my hand at building a set of ilf longbow limbs as I already have a recurve set and figured getting longbow limbs to align correctly would be easier. Anyway, gathered the pieces and began working on it yesterday.

Here is the form, I used a piece of mdf and a piece of plywood. I know most everybody uses only plywood but I also know that it can be difficult figuring out how to get your exact width. Plywood runs a little small and mdf runs a little big, which turned out to give me exactly 1.5"! I bought a 4' piece of quarter inch steel strapping and cut it into 4 12" pieces. Drilled holes to fit 5/16 bolts. For the top bolt I used an allen head bolt for easier top removal. Used 1/4 inch plywood to space out the straps away from the form.

Here is where I am at, everything is pretty standard other than making my own brackets.

   

   

Tomorrow my plan is to glue on the formica strip and build a small hotbox. Shooting for 45-50 pounds and as you can see it is pretty pronounced.

Anyways, just thought I'd get this thread started and I'll hopefully be gluing up some limbs by early next week! If anybody sees anything alarming or has any suggestions I am all ears.

[jsweka]

Looking good Mark!

You might be doing it backwards but you're headed in the right direction    

[Trux Turning]

Good start- looking forward to seeing the finished limbs.

[monterey]

Dang, I'd like to see how you did the ilf riser.

Three suggestions:  first, give your form a severe pressure test in the oven just in case the MDF/plywood may have strength issues.  Second, think about using some system to block the lams at each end of the form to keep them from squiggling your under pressure.  Third, some system to do the same on the sides of the form.  As it is there is 1/4" of space on each side that could end up reducing your limb width considerably.

[grouse11]

Monterey, good idea on the pressure test, I'll do that as soon as I get the oven done tomorrow, to test the form and the oven.  as for the blocking system, my limb wedges for the ilf system are actually about 1.5" longer on the butt end than they need to be, my plan is to drill through the entire stack and screw it to the form. I am also going to add a few washers along the edges to keep the rest from sliding. I'm hoping that'll be enough.

and here is the latest riser I made, shot my buck with it this year! It's all wood, mahogany, rosewood i-beams and limb pads, and a mystery wood in the flares. been going strong for over a year. Current limbs pull about 50@28.  These limbs are going on this riser, brown glass should go good with it I think.

 

[monterey]

Nice riser.

Looks like your form is going to work out fine.

[BenBow]

Are you doing anything with your new limb to compensate for the limb pad angle used with a recurve limb. You could end up with your string laying on your limbs or an extremely high brace height.

[grouse11]

BenBow, I have not made any adjustments to the limb to compensate for the angle. the angle is actually not too severe compared to many bolt on recurves. ILF limbs are made to be easily swapped so I'm thinking the only thing I can do is adjust lam geometry. I may get lcy this first time but it will most likely be a trial and error thing.

Now for an update:

Got the hotbox done today, also added the formica strip and washers to my form. everything is coming together almost too well which makes me a little concerned haha. Did a dry run and there seems to be no gaps in the limb, may glue one up tonight!

 

 

[BenBow]

Good luck! Looking forward to see it finished. The experimentation is a lot of fun but filled with frustration too.

[grouse11]

decided to glue a limb up last night, just a might as well go for it kind of thing....and it was a success!!!

pulled it out this morning ad cleaned it up. the glue lines look perfect and it appears to be perfectly straight.

here it is after cleanup still full length
 

and here it is cut to length and pretty much how it will lay on the riser, looks like it has a twist but it really doesn't.
 

I do need to get a string for it because it should come out to 60 inches. I need to start making my own strings but for now i'll need to order one. won't be able to work on it again until monday, although I do have the other limb in the oven now so I should get that done today.

Thanks to everyone that has been following along!!

[ron w]

That's looking real good.......Can't wait to see it braced.

[grouse11]

okay, back at it today and got a lot done. I apologize for the large gap in photos, I basically worked non-stop on it today and took photos when I remembered.

But! I got both limbs finished t the point where I could string it up for the first time. I had to put them on my 13" riser and use my 58" string which is still a little short but I got it strung. And it looks good! Draws smooth and feels about 45#. It should be about the same on my 15" riser because of the difference in limb pad angles.

Here she is before limb shaping on my 15" riser.
 

and here she is strung on my 13" riser. I'll try and get the limbs completely finished by thursday and I'll get some better pics when I get a string.

 

[jsweka]

Looking Good Mark!  But I do agree that it looks like you need a longer string.

If it's about 45# on your 13" riser, it will probably be a about 5# less on your 15" riser.

If you took good notes on everything, you'll now be able to hit whatever draw weight you want with that design on either a 13" or 15" riser.

[grouse11]

Thanks John! brace height there is about 9.25 which is way to high. It was the best I could do at the time, just making sure the limbs weren't going to collapse on themselves.

As per the draw weight, I have a set of medium ******** 40# limbs that I thought pulled 45ish on this riser. But wen we measured them on my other riser it was 51# if I remember correctly. I think that has to do with the limb pad angle. it is either 15 or 17 degrees on the 13" riser and 10 or 12 degrees on the 15" riser. Either way I am elated at making a set of working limbs and like you said, I now have a base to make adjustments to and perfect!

[BenBow]

Looking good

[ron w]

 Look'n good

[LittleBen]

Nice job! Looking really good!

[grouse11]

Okay, so my string came in and I got her strung up on my 15" riser.

 

Braced at about 8" seems to be the quietest and shoot the best. Let me know what you think and any improvements I could make on the next one. If requested I can get a full draw pic.

[Trux Turning]

Nice- it looks like you nailed it!! Lets see a full draw picture.

[BenBow]

Definitely a full draw pic