Wheel Building

[Cyborg]

Thank you for measuring those flanges. I have 5 here and they range from 0.460 to 0.479, oddly enough the thin one is painted and looks like it’s new.
A learned fellow from Australia measured a couple. One was 0.472 and the other was 0.548. The narrower one would not allow him to slip spokes between the flange and drum, but the 0.548 would.

Timetraveller, do you have an orphan drum and a Vincent spoke… if so, could you hold the flange against the drum and see if you can slip a spoke in there?

I received a response from Bushannon and it reads as follows:

“We can not make the head diameter of the 8-10gauge spokes any smaller since the heads are hammered on. The head diameter on the 8gauge spoke is roughly .290”. What we can do is make a 9-10gage spoke which would have a head diameter of roughly .270” like the spokes on the front wheel. We really don’t recommend the 9gauge spokes for the rear wheel unless the bike is not ridden that much.”

 

[timetraveller]

Yes,it slips in there very easiy with a lot of clearance. That is on a Rap, Knight or Comet drum.

 

[Cyborg]

How critical is the size of the spoke head…. Isn’t it just there to keep the spoke located firmly in the flange. Most of the force is applied to the shank of the spoke where it passes through the flange Y/N? So… if I was determined to have spokes that would fit between the flange and drum, part of the equation could be turning the heads of the stainless spokes in a lathe. Easy enough to make a jig. My 4 jaw chuck has T slots which provide a place for the spoke to hide at the correct angle. A couple of custom HSS cutters along with a ridiculous amount of time and Bob’s your uncle. I say part of the equation because the bends in the last set of spokes weren’t quite right and different/ modified flanges would reduce the amount of material that would need to be removed from the stainless spoke heads. I would prefer turning the heads rather than grinding them to get clearance for the neighbouring spoke.

No spacers required….

 

[Magnetoman]

His drawing of the right angled edge to the hole through the flange did not look rignt

Sorry for any confusion, but at this point the rear wheel is still assembled so my access to the flange to make measurements is limited. The point of that drawing is to show relative sizes. "Subtleties," like tapered edges, will have to await disassemble.

 

[vibrac]

I have mentioned this before, there is another way to build a wheel without spinning it round on a truing stand. Pop 'taveners' in the search box above
its building a new wheel from an existing one with a jig I was told that reputedly all BSA wheels were built like this during the war 'unskilled' workers did it

 

[Magnetoman]

With heights from 0.460" to 0.548" there are still two other important variables that need to be reported, that determine whether spokes can be inserted: the thicknesses of the flanges, and the recesses of the drums.

At a minimum we need to know the thicknesses since what matters is the inside dimensions of the flanges, and what are reported are the outside dimensions. In principle, the 0.460" and 0.548" could have identical inside dimensions if their thicknesses differed by 0.088". Or, instead of the outside dimension and thickness, just report the inside dimension, i.e. from the flat table to the bottom of the flange.

 

[Magnetoman]

If I understand correctly, the values like 0.460" and 0.548" are the distances to the top of the spoke flange, corresponding to the green arrow in the following schematic, where I've represented the possibly-variable thicknesses of the spoke flanges by red and yellow.

Leaving aside the possibly-variable tapers of the brake drums to which the flanges will be bolted, what determines whether or not a spoke head can be withdrawn is the dimension to the bottom of the spoke flange, shown by the magenta arrow.

 

[Robert Watson]

OK So I finally got off my butt and went and measured a few things. This is all off /1997 which has been in one family, in pieces since 1956 and I truly believe from what I have seen that it is as original as you will find.

Here is what I have found.

The height magnetoman is looking for above, the magenta arrow, on the 4 spoke flanges from this bike varies between .280 to .285 On a surface plate with a height gauge but eyeballed for level.

Next I laid out the spokes. So this bike has a 19" front and an 18" rear.

Front spokes are 9 gauge and appear within reason to be all bent at the same angle. The head dia varies (measured across the width that has to go between the flange and the drum) from .248 to .258 and some would not go in behind but some would

The spokes in the rear wheel are butted 8/10 and do appear to have different angles. I know, people say they are too light for a rear wheel but they are going back in all cleaned and re-plated. The heads on these are .278 - .285 and don't really want to go in between the flange and the drum.

That's all today!

 

[Magnetoman]

could be turning the heads of the stainless spokes in a lathe.

Don't think for a second that you're fooling me. You wrote this just to make me feel bad that your lathe is bigger than mine. Mine doesn't have the swing for an 8"-long spoke. On second thought, I'll machine half the head in my lathe, stop the motor, flip the spoke by 180°, and machine the other half. That'll show you...

Based on everything that has been written so far, and assuming when I make more measurements of my assembled hub I don't find a problem with the idea, my present plan is to machine a jig to allow me to press the "wings" of my spoke flanges a further ~0.065" (i.e. an additional 6%) to allow the heads of the spokes to pass through.

 

[Magnetoman]

I spent some quality time with my rear hub today. The measurements that are relevant for this current thread are below.

I was able to remove four spokes from the hub on one side of the wheel despite the gap between the spoke flange and hub being smaller than the diameter of the head. The reason this was possible is shown in the next photograph.

The head is too large to go straight into those four slots, but it was no problem inserting them at an angle and rotating as I pushed them into place. No force was used. However, it wasn't possible to slide neighboring spokes to the place where I was able to remove them because the clearance was too tight. So, I decided to measure the relevant gap at all 20 spoke slots. For this my sacrificial Chinese gage block set was ideal.

As shown in the next photograph, using the 0.200" and 0.250" gage blocks, along with a feeler gage, it was possible to measure the relevant gaps through which a spoke would have to pass.

Note that the gage block is pushed in further than the feeler gage, which only measures the gap at the edge of the slot closest to the outside.

The next chart shows all 20 measurements for both sides of the hub, with both sets of ten recorded on the same chart for simplicity.

Both sides of the wheel are recorded on the same chart for convenience, but there is no relationship between the orientations on the two sides. As can be seen, because of the twisting motion, spoke heads of diameter ~0.280" could be removed through gaps as small as 0.255".

The other feature of note is how much the gaps vary on both sides of the hub. However, how much of this is due to variations in the spoke flanges, and how much is due to variations in the faces of the brake hubs, will have to await me removing the spoke flanges and measuring them on the surface plate (keeping track of which brake drum each goes with, as well as how the holes are indexed with respect to each other.