Bound in roller nut

Greetings all,
I was recently looking at pictures of late gothic crossbows and a lot of them have bound in roller nuts. Does any one have experience in this process and how does it work? Thanks in advance for your reply.
jds6

Good morning.

Experts are still kind of argueing what side effekts the thread could have, beginning with just security reason to prevent the nut from falling out or slightly decellerating its rotation after firing. (I have built two of them the second way and have no problems with this)

The big pro for a bound in nut is the nut itself is the axle (and a pretty big one). So it is better to dirstibute the power of a strong bow on a big axle instead of a smaller one from steel for example where you need to reinforce the sides. A con is, your nut and bearing must be made very precise and from best material.

Another pro is the nut rotation will be much softer after firing so you won´t be shaken too much from the rotating weight of a heavy nut.

For my next build I made a reinforced antler nut with antler bearings which will be bound into the tiller.

Still don´t need to say bound in nuts are my favorite.

Greetings Rizzar

Thanks Rizzar,

What kind of material is used, sinew or hemp to bind on the roller nut?
Do you have any pics of what you have done? Would like to see how they are tied without becoming loose!

jds6

JDS,

I use waxed linen thread to bind the nut. As Rizzar says, it is not serving as an axle, so it does not have to be especially robust. By the time you pass the thread six or eight times through the nut, it does not much matter how you tie the thread off. I just tie the ends together with a square knot on the underside of the tiller.

I have always drilled my holes in the sides of the tiller to be coaxial with the nut. This makes "sewing" the nut in easy. It looks like some bows have the binding holes angled up from below. Perhaps this is to but a bit of downward pressure on the nut to help keep it from clattering about in its socket.

Mac

Hey JDS, waxed linen or Hemp would work fine for the binding.
I have in mind somebody told me for securing factor they originally used horsehair, but i´d rather prefer good natural thread.

As mac mentioned, you do not need to care much about loosening, there shouldn´t be so much tension to open a knotif the bearing is proper made.


first one with a little groove


a second quick made one


current work in progress


Rizzar

Nice, thanks guys for the info. So the nut must fit the socket tight with no play ?

jds6

You are welcome.

Let´s say it should run smoothly without too much play, but not too tight.
Hard to describe^^

Rizzar ,

I think I understand what you are saying. It needs to be tight enough so it doesn't wobble in the socket but not too tight that it causes a lot of friction and slows down speed of the release?

jds6

Exactly!
Yo will know it when you build one^^

Thanks Rizzar for the info and the pics. I'm sure it well help.

jds6

Rizzar wrote:

first one with a little groove


a second quick made one


current work in progress


Rizzar

Rizzar,

You have really nailed the shape of the nut in your last pic.

Are you going to set the bearing assembly in from the side, or inlet the whole package from the top?

Mac

In fact this picture was made a couple of weeks ago.

I didn´t have the opportunity to make pics from the current status: right now this whole assembly is inletted from the top and glued into the tiller. The sear hole was milled out afterwards from underneath with the mechanic housing (if there was no mill i would have done it before).

Rizzar

Rizzar,

I look forward to seeing pics when you can.

Mac

Thanks,

and I am really looking forward to showing you some pictures, but it is not the right time yet.

erhaps later a little peek ...

Nice work, Rizzar. My own approach to the latest project is similar. This is a heavy crossbow, and I used 1/8" steel and tapped and screwed the bone bearing blocks for added security and piece of mind. I may also rivet or pin them in from the top into the tiller, but not certain yet there. There is so much force happening in this area that I wanted to build this like a tank. This is designed to be dropped into a mortise chiseled in the tiller from above. In the picture, the clearance for the sear is still in process, and is already done. I purchased an entire moose antler at a swap meet on Cape Cod, in Wellfleet, this past summer, so I get really big pieces of antler to work with. It was funny...the guy who sold it to me almost wouldn't when I told him I was cutting it up for projects. Note that the bearing blocks were still in progress here.


Dane

Really impressive !!! Can you use bone as reinforcement in the socket, or is too weak?

jds6

Yes, bound-in roller-nuts work very well. The cord doesn't bear the load, the socket does. Cord just keeps the nut from oscillating when rolling. And it can't fall out.
I have found moose-antler about the best bone/antler for roller-nuts and reinforcing blocks, but dense bone should work about as well. You'll still need a chunk of iron or steel for a sear.
Geezer.

jds6 wrote:Really impressive !!! Can you use bone as reinforcement in the socket, or is too weak?

jds6

It depends on the bone. The porous stuff won't do; it has to be very dense. In general, the ends of a bone are denser than the shaft.

Mac

Where's the best source for bone/antler. Can it be purchased online?
Found a sight on the net that sells bone slabs but I think it for knife handles etc... Thanks in advance!

jds6

The bone slabs from origindia are very good for bone tops and detail work. For roller-nuts and reinforcing blocks, try Moscow Hide and Fur. (Moscow Idaho, USA) They have an online store, do a web search.
Geezer

Thanks Geezer got the info, will do!

jds6

Tiller is in absolute raw mode to make milling easier.

Rizzar

jds, please keep in mind that working with bone and antler is both stinky (really bad, take a long shower after working with it, trust me), and breating bone dust can potentially be lethal. I assume antler is similar, but not sure. Lots of studies of bone workers in India, and TB is just one hazard. Mad cow (Bovine spongiform encephalopathy) is another if you work with fresh bone apparently, but not sure about that. In any case, I probably already have it, as do all military personnel who were stationed in Germany during my active duty period. Non-curble and you can never donate blood again, even if a loved one needs it and will die otherwise. Shame too since I have O-.

In any case, any risk is too much. Try to ventilate the area you work in, and at a minimum, wear a respirator - not just a dust mask. You will feel like a post-apocalyptic character, but it is far better than breating this shit.

Dane

PS some tropical and other woods can be toxic too, such as yew. Just be careful in shop, and not just with sharp tools and power saws.

Regarding sourcing, you can find stuft at swap meets, antique fairs, and dont forget slaughter houses, too. I dont know if any place commercially slaughters moose, but getting friendly with local hunters and taxidermists may lead to some finds. Moscow Hide and Fur is a great company, fast and good prices, too. Sometimes you can find bone and antler through Native American craft suppliers, as well.

Dane,
Thanks for the heads up! Good to know these things, had no idea it was toxic!!! My wife would be pissed if I where to get something caused from working in the shop! Lol.

jds6