ILF Bolts and Dovetails

dvd8n

Supporter
Supporter
Quick question - in an ILF limb fitment is the root of the limb / thrust from the limb meant to bear on the dovetail or on the bolt?
 


geoffretired

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Supporter
It's like trying to lever the lid off a tin of paint with a screwdriver, or lever.
The tip of the lever is pushing up on the underside of the lid and the pivot point of the lever is pushing down on the lip of the tin.
So the tip of the limb is pushing up on the underside of the head of the limb bolt trying to pull it out of the riser. while the bit that fits into the dovetail is pushing that down into the riser.
 


dvd8n

Supporter
Supporter
Can you explain that differently please?
The ILF fitting has a dovetail connection (with the retention detent in the middle) and a bolt (commonly referred to as the tiller bolt). I was wondering which actually takes the longitudinal thrust along the line of the riser. I.E. When you slot the limb into the riser which bottoms out first - the dovetail or the bolt.
 


dvd8n

Supporter
Supporter
It's like trying to lever the lid off a tin of paint with a screwdriver, or lever.
The tip of the lever is pushing up on the underside of the lid and the pivot point of the lever is pushing down on the lip of the tin.
So the tip of the limb is pushing up on the underside of the head of the limb bolt trying to pull it out of the riser. while the bit that fits into the dovetail is pushing that down into the riser.
So you reckon that the dovetail takes the longitudinal thrust along the line of the riser and the tiller bolts ttake the torsional forces?
 


Mufti

Member
Yes, the dovetail takes the load - it is a precision made metal whereas the limb U shape is made of a softer, less accurately made material.
 


Rik

Supporter
Supporter
When you look at the fitting in various different limbs, you can see that the "U" of the slot doesn't contact the bolt. I guess it kind of has to be that way, since you can adjust the angle, and the detent clicks into a fixed place. So the bearing in that direction has to be on the dovetail (and slot end). The main load bearing, on the other hand, is on the bolt and the contact point between the limb butt and riser pocket.
 


geoffretired

Supporter
Supporter
Hi dvd8n, I totally got wrong what you wanted to know. I was explaining how the limbs put stress on the tiller bolts and dovetail when the bow is drawn, or even just strung.
The answer to your question, now that I see what you mean, is that the dovetail , in order to work , will jam tight. If the tiller bolt stopped the movement first, the dovetail would still have slack in it and the limbs could move side to side.
It is no good, however ,having the dovetail fitting tightly if the butt end is loose at the tiller bolt. The slot in the limb at that end is parallel so it should be a snug fit in all positions, with no side to side movement. The depth of the slot should be sufficient that the slot doesn't bottom out on the bolt.
 


jerryRTD

Active member
Not what I call a doves tail. The picture shows slot that the location lug passes through on the way to the brass limb alignment adjustment piece where the limb lug is located. There is no way that is shaped like a 'doves tail' The sides of the slot are parallel whereas the doves tail has sides that are fanned out. After the limb is correctly located this slot's function is over. So, no dove tails. The limb is held by the 'U' shape cut in to the end of the limb and the limb bolt and the lug locating in the brass alignment adjustment piece in the riser.
 


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geoffretired

Supporter
Supporter
Dovetails have two parts, the tail and the slot it fits into. The slot has to be fanned out to accommodate the dovetail that fits inside.
 


Rik

Supporter
Supporter
And terminologically, whether or not the slot is a strict "dove tail", that's what that part of the riser/limb fitting is called...
 


geoffretired

Supporter
Supporter
The problem with things like this is we don't know who is sending the right information.
Who determines what is the correct terminology? Even the idea of what's in common use, breaks down in some regions.
Perhaps we need an archery dictionary.
I remember changing my Berger button for a nice new pressure button. Sounded much more "professional"..... worked better ,too!!
 


jerryRTD

Active member
Ok so there are in fact two dovetails at each end of the riser, the limb pocket and limb that that fit together form one, keeping the U slot in the limb clear of the limb bolt (as Rik said in an earlier post) which the revolution does not have and the slot at the bottom of the limb pocket.
 


Rik

Supporter
Supporter
Ok so there are in fact two dovetails at each end of the riser, the limb pocket and limb that that fit together form one, keeping the U slot in the limb clear of the limb bolt (as Rik said in an earlier post) which the revolution does not have and the slot at the bottom of the limb pocket.
This may be the gap. There is only one dovetail slot on each riser pocket: the one which the revolution also has. The limb has a u shaped notch which fits around the bolt on the riser. The limb also has the dovetail fitting (round with a flaring "dovetail" end) which goes into the slot on the riser. The slot on the riser pocket narrows towards the surface to accept it. This, collectively, is the bit referred to as the dovetail. Strictly it's the bit on the limb that fits into the slot. All "ILF" limbs have them.

A picture may help, this is how the dove tail fitting looks out of the limb:

and a diagram of how it all fits:
 


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