What is the purpose of these holes?
 

This English built frame has drilled holes in each of the bottom bracket shell ports and in each side of the bottom head tube lugs. Look closely at the photo showing the bottom bracket shell; just to the rear of the rear cable guide you will find drilled holes. Look closely at the photo of the head tube; you will find
drilled holes in the bottom of the lug. Is their purpose to minimize condensation in the tubes? BTW, the drilled holes don't go through the tubes. The drilled holes in the drop outs are for lightening I'm sure. The holes that I am speaking of are not to vent gasses, those holes are already there.

Thanks.
Attached Thumbnails

Maybe grease ports? Although I'd expect those to be more on the bb shell itself.

Thanks marqueemoon but the holes are on both sides of the frame. I'm inclined to believe that they are for no real purpose other than to look unusual.

They look like framebuilder drillium to me, an idea supported by the evidence of drillium in the rear dropouts. The frame would appear to be the right vintage too.

They should be decorative, since they only are drilled through the lugs.

Mark I thend to agree with you. As I understand it some British builders of this vintage were quite taken with drillium. Thanks.

Yep, I think you're correct. Thanks.

As I suspected that's a Hilary Stone deal. I bet he'd know if you e-mail him.

Nice looking frame by the way.

OP; Nice frame...

Although I don't see any holes in the one big collage picture you posted (not seeing a set of pictures as mentioned...), but based on how they are described, I would guess that the holes in the lugs are there to aid the builder in getting two things: 1) Better access to the internal joint to more easily add brazing material; 2) to better observe the flow of the brazing material into the joint. At least I know that I do it for those reasons; especially if the lugs are very ornate/thinned and I want to minimize the heat on them or if the lugs are deeply socketed.

If the holes (and I haven't seen them) are small like 1mm to 2mm, then I would guess the lugs had been drilled for a pinned construction and then not used on that build. I know I have several sets of lugs on the shelf that I rejected rather close to the torch phase...for whatever reason.

When I have decided to use pins, I will drill the lugs ahead of time on the drill press and then assemble and align everything before drilling through the tubes using the holes in the lugs to keep the drill bit from wandering around. Basically reduces the total number of broken bits or skin that might get punctured...so to speak.

If this is the case, the builder in the later use of the lugs could have filled the hole in with braze or could have put in a dab of body filler before final paint prep (it looks like you are in for a respray, so a dab of filler would solve it. I certainly would never reheat a joint just to fill a cosmetic hole/flaw).

Hope that helps with your mystery
K

Nice explanation and it brings back memories of a visit I once made to a foundry and noticed various holes in moldings which were used to vent air and gasses when the castings were being poured in order to get a better result with fewer air pockets. Your explanation makes perfect sense! Thanks!

- Wil

Thank you Ksisler. Your explanation is very enlightening! I'm thinking now that those hole have no functional purpose after brazing.

[QUOTE=Wil Davis;15167248]Nice explanation and it brings back memories of a visit I once made to a foundry and noticed various holes in moldings which were used to vent air and gasses when the castings were being poured in order to get a better result with few air pockets. Your explanation makes perfect sense! Thanks!

- Wil[/QUOTe

"Your explanation makes perfect sense! Thanks!" Indeed it does. Thanks.

I did email Hilary but he didn't provide a direct answer to my question. I won't interrupt him a second time. Thanks.

I didn't reply to the mention of Hilary Stone... I actually thought MarqueeMoon was making fun of the peekaboo holes in those lugs by making a subtle illusion to Ms Sharon Stone in Basic Instinct movie and had just boffed the name a bit or had gotten bit by the spell checker... Geez and my apologies should Hilary read this.

The frame arrived today so I got my first in person look at it. Well, firstly it is a very nice frame even better than I expected. Secondly, there are several holes drilled in the lugs. The bottom bracket has three holes top and bottom on each side and the holes are in descending sizes. Same thing with the upper and lower head tube lugs. The holes in the dropouts are countersunk. IMO they look good. I think that we can now say that the whole thing of drilled holes in this frame is purely ornamental.

Thank you very much for your response. I learned something.

sisddwg; I can see the individtual pix today for some reason. Having seen them, I will swing my vote over to those who felt they were simply builder inspired delightful touches vice any specific purpose toward aiding the brazing (although they would do that also).

Regarding your note that the holes in the dropouts being countersunk. Yes this would be the correct way to do it. Coining the edges of almost any material with a sharp edge will significantly reduce the likelihood of a stress crack forming on that edge. In many cases a well place hole may actually strengthen the part or aide in it not bending under stress. If holed-out to an extreme then it will be much weaker and may break along the line of holes. I have most always hesitated to put holes in dropouts for those reasons. Perhaps one of the other posters can provide a more learned discussion or splash up some math to illustrate the points. That wouldn't be me....