Second Build- In Progress

In the process of my second build, progress moving right along( much easier this time).

Tiller- 2 pieces of 1" maple doweled and glued,
So far I have just laid out and rough shaped tiller.

Here's a few pics of the progress at hand.





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jds6

Looking excellent. I love the curves you are building into this one. How did you do the sear for the rolling nut?

Dane

Thanks Dane for the kind words.
Now for the roller nut, I cheated on this one. I bought it complete from Slo-Bows . On my first build the roller nut is pretty much like the one I purchased . I cut a small grove in the nut, and used a small piece of banding material( from lumber yard). Then I just epoxied in place to keep it secure. With out the epoxy the nut had a tendency to open a bit when pressure was applied from string.

jds6

Looks great so far, jds6? What are the specs on the prod you're using?

Thanks Gnome. I am using a steel prod 28.5", thickness 3/16', 1 3/16" @ center of prod, Draw weight in the range of 110#.

jds6

Thanks for the answer. It makes me wonder about suitable sear materials and how they are fitted into a nut at greater weights, say up to 1,000 lbs. I am guessing that issue you faced with the nut material seperating is because the nut is cut all the way though. Eliminate that (i.e. inlet it into the bottom of the nut but have material on each side of the wedge/sear) and the issue is lessened / resolved. Payne-Gallwey I think talks about a wedge used as the sear.

Geezer here, mouthing off again.... this time about roller-nuts and sears.
Most of the strong medieval bows I have seen use a staghorn roller nut (there are a few that use brass) with an iron (or steel) sear. Payne-gallwey shows the sear-block as a pyramidal piece, fitted in the bottom of the nut. Egon Harmuth ("Die Armbrust, 1986") has radiographs that show a roughly pyramidal lower section, but usually the top of the sear-block is more or less cylindrical, and extends up through the top of the roller, to show a round spot between the lugs. Some very strong bows were fitted with slender iron/steel pins to reinforce the lugs... according to radiographs, those pins go almost through the roller to the bottom.
Later, multi-axle nuts have an iron/steel block fitted in the BACK of the roller-nut, rather than the bottom. That means the trigger system locks the nut from the back, rather than the bottom, which reduces the strain on the top edges of the nut-socket.
I have determined, after much experimentation, that moving the sear-plug back from dead-center bottom, about 1/4 inch substantially reduces nut-socket load. Of course that makes the geometry of the release a bit trickier.
Most of the roller-nuts I have seen range from a minimum of 30 mm to a maximum of perhaps 45 mm in diameter and an inch to two-inches in width (the Padre Island bow is the smallest lock I have seen, just a hair over 1 inch in diameter and the same in width)
If you anticipate going over 1000 lb draw, I suggest using brass with a steel sear, or possibly just machining the whole roller from steel. Medieval armbrusters generally didn't have the tools for that, but I'd say better safe than sorry. Needless to say, really strong bows will also need a strongly reinforced nut-socket for the roller to run in. Payne-Gallwey illustrates a strong steel socket used in later Flemish target bows. Again, that'll probably have to be machined.
Have fun stormin' da castle! Geezer.

Good info. Later I will begin a special thread, but I am now building a crossbow with a prod made by Jens Sensfelder. This prod's spec are:

Braced hight: 65mm / 2.559”

Spanned: 150mm / 6.102”, Weight: 367 kg / 807.4 lbs.

Spanned: 160mm / 6.299”, Weight: 403kg / 886.6 lbs.

Bow Weight: 1908g / 4 lb. 3 oz.



This is quite a challenge, but a wonderful opportunity to make something very powerful. More details to follow later. I just finished making the tickler, and am going to have a smith case harden the sear engagment point and the sear. I'm debating how to go about that detail.



Dane

Say Dane this second build/special thread sounds right up my alley. Do you have any idea when you will start posting/and photos to. Happy Easter Dane and also HAPPY EASTER TO EVERYBODY IN THE SITE. Mike.

Pretty soon, Mike. I just want enough intial material to start a good and useful thread

Good Morning: Its O- early hours here in Southeastern Wis. Question for you sir! I used Cat Gut some years back to secure my roller nut to it's housing and then around the stock several times. Now I just notice that the cat gut is starting to give way.. What type of glue should I use to fasten the cat gut back down again . Do you have a favorite (Brand name Please ) Until Later. Mike PS. I like this little guys

Looks nice...

Because I'm based in Europe... I find that maple really unique...