Monterey... you got me to thinking about this and I realized that many folks, including me, are pretty careless with our terms. So, I went to the books, i.e. I googled archery terms and came up with a number of lists of archery terms defined, from which I gleaned the following:
- Backset -- A longbow design where unbraced limbs angle backward,
- String follow, also known as 'set' -- a term used by bowyers to describe the amount a bow stays curved after it's unbraced (unstrung).
Deflex bow (equipment) - A form of bow in which the entire length of the handle and arms curve toward the archer
Reflex bow (equipment) - A form of bow in which the entire length of the handle and arms curve away from the archer
I did not find "pre-stress" defined anywhere
OK… with those definitions up front, a few comments…
Obviously, for our purposes, we are concerned with Hill style longbows. Recurves and R/D bows are another whole school and I won't argue terminology with them (though my own definition of R/D are shy recurves, or "recurves in drag").
Some time ago, I used the term string follow to refer to a laminated Hill style bow while talking with JD Berry. He kind of took me to task about the careless way bow styles were referred to nowadays and explained that in the old days, "set" or "string follow" were terms used only to refer to wood bows. Laminated bows with the same quality built in were "backset". Laminated bows with the opposite condition built in were "pre-stressed". However, per the definitions above, in more current terminology they would be called "deflexed" or "reflexed". However, at least in my own opinion, under no circumstances on a Hill style bow would they change direction once they set out on their course, as an R/D or D/R bow does.
In general discussions today, it seems the term string follow is used very generally to refer to laminated bows as well as wood bows, though set would logically be a term more common to self bow builders, where it can be a condition that can occur, rather than a feature designed in.
Now, in my own carelessness, I have generally referred to all Hill style bows, whether reflexed or deflexed by design and layup, as "straight longbows", meaning that the limb orientation does not change direction. I guess this has become my way of keeping Hill styles differentiated from R/D's. I, and, I think, most other folks, also generally refer to any Hill style with back set as having string follow. (Sorry, JD.)
Get's confusing, doesn't it?
Getting back to Howard's bow, where we started, it is strongly relfexed, or, in JD's terms, pre-stressed.
I've heard the term pre-stressed used quite a bit in reference to a lot of bows, including recurves and R/D's, to indicate that the draw weight is loaded to the beginning of the draw. The RATE of increase in draw weight per inch then tapers down. This is a speed feature, and one of the reasons I can't shoot most modern recurves, which tend to be heavily pre-stressed to get the speeds everyone seems to demand today. The extra load that I'm pulling from the beginning of the draw (see the power curve charts on any modern bow) means that by the time I get to full draw, I've actually drawn more accumulated weight than I would with the same bow without pre-stress, regardless of the draw weight at the end of the stated draw. In effect, the pre-stress acts as if the draw had been lengthened, as compared to a bow that has an even progression inch by inch from beginning of draw to end.
So, again returning to Howard's bow, it is pre-stressed by 1 1/4", i.e. if you put the bow on a table, back down, the tips are on the table, the riser is 1 1/4" off of the table. I build some of my bows with fairly extreme string follow (or deflex) of 1 1/2" and if I put the bow on a table, belly down, the riser is 1 1/2" off of the table.
The line of the limbs on Howard's bow is a smooth curve, carried through the riser. I have a form that lays up this way but with only 1" of reflex. Until I started using power lams, it was kind of a bear to build to, because I had to make a riser with a curved back to match the form. Now, I calculate the gap between the form and a straight riser and fill said gap with the power lams… much easier!
Just to confuse you further, here is a picture of my dual form… both sides are curved. It builds a reflexed Hill style one one surface and a deflexed Hill style on the other. Of course, if I go to a forward riser design, each side reverses!
Sorry to ramble on so long, but it helped me get my own thoughts in order. I hope it helped more than it confused, though I'm sure it did a bit of the latter...