Building a Single-Core Fiberglass Longbow — The Full Tillering Process
10 Video Views·Feb 27, 2026
Follow the complete tillering process of a single-core fiberglass longbow, from removing the bow from the form to reaching safe, controlled full draw. This video demonstrates essential techniques every beginner bowyer should understand, including floor tillering, long string tillering, reading limb bend, and making precise material adjustments. You’ll see how a fiberglass laminated bow transitions from a stiff blank into a balanced, functional traditional bow.
Single-core fiberglass bows require careful attention because the limb structure depends entirely on one wood core for tiller and performance. If you are learning how to tiller a fiberglass bow, build your first laminated longbow, or improve your bow making skills, this video provides a clear, real-world look at the process used by experienced bowyers.
Building Your Own Bow?
Let's see how this turns out. I mean it's certainly hunting weight. Go ahead and get this guy out,
see what we ended up with. I've taken the bindings off of the one side of the glue up here
and you can see that this limb actually pulled away from the mold by probably half an inch or so
and that is what I think is caused by the fact that we did a single
uh core lamb in there. All right so we are free from the mold and ready to start shaping this
bow out but I can tell like when you scratch on it like this you know you're getting a good
reverberation on that. There's no there's no hollow sound to it. Means I mean initially that
would indicate that we got good solid glue up through all of our parts. Ground this guy down
on the sander out there and got really good glue lines. Hopefully you can see that
so everything seemed to go together pretty well at those termination points. Very very small gaps
even better actually than I anticipated so pretty happy with that. The
tips have been cut down to size. We're in almost a net zero reflex and or deflex so it's like flat
even with all of the deflex and reflex in the design itself. The bow is net zero from grip
to tips. I've put a little bit of a taper into these limbs now so not only cleaning up these
sides but then putting just an ever so slight taper probably an eighth of an inch outside of
my pencil line that was on the tape here. So you know starting wide it's just like any any work
with a bow you can take material off but you can't put it back on so we work up to this slowly.
You will notice with the tiller on this bow now or at least the floor tiller notice how the limbs
they straighten out. All right we are set up on the tillering tree here.
I don't even have the scale turned on because it's really useless information when we're
dealing with a long string tillering operation. Really what we're looking for is initial bends
in those limbs. I'll leave it on long string tillering until I get to brace height
and then we'll go to a short string tillering process from there. But here's what I'm looking
for very specifically is that these limbs come straight. All right these limbs are straight
right here. You'll notice that it looks when you take a look at this it looks like we're like
bending heavy in the early thirds or the first thirds of the limb. I'm going to challenge you
to watch this bow exercise so watch how much this bends right here when I let it back down.
It stays put. You see there that part of the limb is not moving. We are not we are not hinging
we're not hinging at the fades. We are unfurling along the length of those limbs.
These limbs are simply straightening out from their reflex. That's exactly what I'm looking for
in this bow. Strung to a brace height now of about five and three-eighths inches
and shown still basically even bend on each limb at least even gap here. We haven't done any
tillering really to this bow. We've let it sit strung for a little while and as an update we do
not have any string follow or set really that has taken place in this design. At the
18 inch mark right here you see we're running right at about 29 pounds of draw weight.
So 29 pounds of draw weight at 18 inches and I've had it pulled to that length
several times before I measured the set and any kind of string follow associated with it
and there's none. We pull this thing on to we're just going to check it at 20 inches
uh 33 pounds. All right so we're picking up about two pounds per inch at those lengths.
If you figure 30 pounds at 18 inches and we got another 10 inches yet to go
to get to full draw and it's a pretty safe assumption to be getting about two pounds per
inch in that scenario then we are right there in the 50 pound range. Exactly where I want to
be with this bow. I'm going to trust that everybody can see the same things that I can see.
It's it's very subtle but it's it it is there. All right so like right here in this section you
can see how it bends like this. The tip remains kind of stiff but up in here it's it's still
retaining like some reflex. All right so we got issues right here where it's not bending enough
here where it's bending too much and then our tips are just out here where the tips are.
All right so what we're going to have to do to rectify this is just like you would on the
We're going to mark off the areas here that need to be thinned down. We do not want anything
happening along in here. This is already bending. We're going to leave our tips alone until the end
as much as possible anyway but I've got this side marked out. I'm going to draw
lines across the back here so that I can then transfer those lines to the other side.
Now I'm going to do this practice with both of these limbs because they're actually both
behaving in a similar manner. As it stands right now I am able to get this bow pulled out to 26
inches and I could certainly take it on out to 28 but I don't want to continue drawing out
for as long as I have some tillering opportunities. So I'm going to get this guy
pegged off at 24 inches and just kind of give it a quick appraisal before I take any permanent kind
of set. You can see we're getting a little whip ended right here. We've got a little bit of a hinge
and it resides on both sides a little bit. It looks like it's bending really hard out of the
fades but that is just a trick of the eye given the deflex nature of the limbs. This right here
is my stiff spot. Now I have taken material off of the sides right to do some side tillering
and it's still relatively wide but basically I'm running out of room. What it's saying is that I
am not experiencing any extreme limb strain on this bow and we have had it pulled to 26 repeatedly
and on to 27 a couple times just to register some tillering changes. So I do not foresee
really any set in this bow like I was anticipating with the single core limb design.
I went ahead and took off just a little bit more on the side tiller here
to see if I could just affect a little bit more change and I think it was just what I needed
at least to get close enough. I'm going to peg this off again at 26 inches
or 24 inches rather and we're starting to get a good bend along the whole length of these limbs.
So I did that little bit of tillering on the belly and it gave just enough
rounded out nature to those limbs. They look good. I'm feeling good about that bend,
really good about that bend. Here we go we're taking this bow actually to 29 inches here a
couple times but at 28 inches, oops that was 29, at 28 inches we're pulling just over 47 pounds
almost 48 and at 29 inches we want to go that far for 49 pounds right about 50. So
looking good. So we are at full tiller tillered to full draw and I'm feeling good about those
bends. So you're 47 pounds at 28 inches and 50 pounds at 29. So it has been pulled to full draw
and potentially passed and just unstrung. I'm still set back still set back on those limb tips
so no I'm going to claim it right here no set in these limbs whatsoever.
47 and a half at 28, 50 even at 29.