Is there benefit in going ILF

[dbeaver]

Am currently making one piece long bows using other craftsmans design.  I eventually want to mess around with the 3 piece construction(possibly and eventually an adjustable aluminum riser) to start a reverse engineering process on future one piece designs.   If I'm going to be learning the 3 piece steps anyway is there a direct benefit to learning the ILF specific process?

[Kirkll]

Getting your limb shape or geometry down and then using an adjustable riser to adjust limb pad angles and different string lengths to fine tune the preload is an excellent way to get the most out of your limb design. I highly recommend that approach for prototyping.

Getting into building ILF limbs require using a std length format of shorts, medium and long lengths that measure 23”,24” and 25” , and riser lengths are most commonly 17”, 19”, and 21” lengths . These combos will give you std AMO bow lengths…. 

With that being said… I would get your prototypes established and dialed in with bolt down limbs with std wedges first. Then build an ILF form with the back of the limb as your bottom form, and then figure out how to mill those funky rocker wedges.

Personally I never cared for the results I got from those short funky wedges on my limb design, so I opted to use toggle plates made from G-10 that I add to the bottom of my limb for the rocker adjustments and use my standard long lean wedges.


ILF systems are predominantly used by target and competition archers that like the ability to fine tune their limbs for string walking and using different types of elevated adjustable arrow rests. There are too many adjustments and tinkering involved to make these popular as hunting bows. But many archers love tinkering with adjustments as much as shooting, so they are quite popular.     .02 cents worth.    Kirk

[Stagmitis]

That sums it up really well Kirk. Good post!

[Kirkll]

A short and sweet answer to your question “Is there any benefit to learning ILF specific format ?”   As a bowyer just getting started with 3 pc TD bows , I’d have to say no…

You should get your limb designs dialed in first and learn the importance of limb alignment and find a good system for mounting your limbs straight and a location pin arrangement so you can build two sets of limbs for the same riser first….

Then if ya want to start into ILF you’ll have the basics down and find that’s it’s a whole different rabbit hole….  Kirk

[dbeaver]

Kirk that was a well informed and thorough response.  I can be sure that I'm not interested nor really want to do it so much as wondering it's viability.  I get the sense of your explanation.  Thanks brother, cheers.

[Kirkll]

Well i'm glad i could help. I've been doing this awhile and have been down a few of these rabbit holes pretty deep on occasion.

When it comes to prototyping limb designs, i have always found that doing my prototyping on TD limbs the most practical approach. Then reverse engineering to a one piece if i want to build them. i used to offer all my designs as a one piece option, but have got away from it over the years. 90% of my bow orders are 3 pc TD , and many have multiple sets of limbs for the same riser. 

What i think is ideal is to try and base a limb design for both a hybrid long bow and RC limb using a  12-15 degree limb pad angle so you can mount both style limbs on the same riser. That comes in real hand if a customer wants both, or comes back to you later and wants heavier or lighter limbs built.

But it sounds to me like you need to get some basics established just getting started on 3 pc TD. There are a lot of little tricks to make this go easier, and the type of tools and jigs you use to build them make a huge difference in the difficulty factor. 

The first big hurdle to get over is coming up with a a good limb mounting system that allows you to drill location pins to hold the limbs straight , and still have the bolt holes line up for your limb bolt. I recommend a two location pin system with a slightly over sized bolt hole in your limbs. you can locate the pins one above and one below your limb bolt, or two pins below the bolt if you prefer.... There are many different ways to do your drilling accurately and find a lot of threads here discussing limb mounting procedures and boring guides that are used by a lot of guys that work pretty well.  I use a vertical milling machine myself.

But..... A lot of guys get their feet wet using self centering drill jigs or just measure center and bore their bolt holes first and get the limbs mounted. THEN straighten the limbs and drill through the limb into the riser limb pads for your location pin 2" below the bolt and 1/2" above.  Of course you limb buts will need overlays to cover the holes. This works pretty well for beginners for getting started with a straight limb mount why they work though all the other intricate details of the trade.

 But.... the first time you miss your draw weight, and want to try mounting another set of limbs on that same riser you will appreciate the precise drill guides and milling machines most bowyers use.... even using a precise milling machine it's real easy to get your limbs mounted out of alignment a bit.... 

Good luck on your adventure!  This can be a lot of fun, and a seriously challenging at times....   Feel free to ask lots of questions...............Kirk

[Robertfishes]

As a Hobby bowyer I found the ILF platform perfect for me. I could build limbs and buy already made risers..Kirk is a mad scientist and really puts a lot of time, money, blood, sweat and tears into his bow designs. He has skills and a strong desire to build the best preforming bows. Kirk and Crooked stic were both nice and very helpful to me when I first started glass bows in 2009 and KennyM when I started building longbows.
I built one ILF Recurve form that would work for short, medium and long limbs and I was Happy with it.. I did experiment with tapers and wedge lengths. I only built 2 sets of Short limbs, zero medium and maybe 16 sets of long limbs before I was injured in 2016 and had to take a break from the bow shop.

[Kirkll]

How are ya doing Robert? Haven’t seen you posting in a long time. Are ya back in the shop again?  Doing any fishing?    Kirk

[Robertfishes]

Kirk, Long story.. I got rear ended at a red light in 2016 and had some issues with my brain, neck and right arm. Had neck surgery but still do not feel like I should be using a band saw.
In 2018 I got a 19ft project boat from TG member "gnome" and slowly got it back on the water. Local lakes only..mostly brim fishing and Speckled Perch (Crappie) fishing with fiberglass cane poles.
After the collision I seem to have lost a lot of desire for things I used to enjoy.

[Robertfishes]

For me Benefits include..Flexibility... Adjustable risers for draw weight and tiller... You can have multiple lengths of risers for your limbs. I have at least 8 risers from 15" up to 21" long, my wife has a 25" riser for her Olympic and bare bow shooting. I have at least 8 sets of limbs and can put them on any of the risers for different draw weights and bow lengths As long as I have the correct string Length,. I hope to shoot a few times today at a 3D shoot. Today I think it will be a 19 inch riser and a set of limbs with Olive Ash Burl veneers under clear glass. But I will take a Back up bow with a 17 inch riser and 45 lb zebrawood veneer limbs.

[Kirkll]

Well it's good to hear from you again Robert. That accident sounds like it messed you up pretty badly. i'm sorry to hear about that, but really glad to hear you are up and shooting again.

We bought our project boat in 2020 about the time covid messed everything up. It's a 19' Bluewater boat with a 4.3 V6 inboard and a full cuddy cabin. BIG boat...LOL   Of course i took it from being a day cruiser / water skiing boat to something a bit more fishy looking with a kicker motor, rod holders and huge anchor system i can use in the mighty Columbia river. dad burn thing weights 40#   But.... we do a lot of salmon fishing and hit the bays for crabbing quite often. I've even slipped out over the bar into the ocean on calm days a few times. The deep V hull does well in 6-7' swells, but scares the hell out of my wife. So I don't do that with the Admiral on board any more.

I'm actually going to the mouth of the columbia tomorrow to go fish the Buoy 10 fishery on another guys boat for a couple days. That is what they call "the Super Bowl of salmon fishing". It can be magical when those fish come in thick. Nothing like hooking 20-30# King salmon fresh out of the ocean.

Kirk