TIG welded construction

[Plum Hill]

To me it appears TIG welded frames just use mitered tubes butt welded to each other. Correct?
Asking out of curiosity to add EPS to a TIG welded frame. I assume there are no openings from the bottom bracket area to the ST, DT, and chain stays.

[David Kirk]

It depends.

There is no industry standard but typically there are some small holes to allow for hot gases to move around during welding and to allow air exchange once the frame is built - this reduces condensation inside the frame.

These holes do not have a standard size and one would need to look into the BB to see what the builder used. I would say most would fall in the 1/4" range which is enough to pull a wire through but not enough to stuff a box up into the down tube.

Hope that helps -

dave

[oldpotatoe]

It depends.

There is no industry standard but typically there are some small holes to allow for hot gases to move around during welding and to allow air exchange once the frame is built - this reduces condensation inside the frame.

These holes do not have a standard size and one would need to look into the BB to see what the builder used. I would say most would fall in the 1/4" range which is enough to pull a wire through but not enough to stuff a box up into the down tube.

Hope that helps -

dave

Need 5/16 for EPS connectors. 7mm....

[zank]

It depends on the builder. I use decent sized 5/16" vent holes on all intersections because I backpurge with argon. The larger holes help with the gas flow. Other builders drill a tiny hole in the tube itself to allow for the gas expansion during welding and then seal the hole with a dab of silver rod after. Those bikes had no holes in the BB shell. Fat Chance and early IFs were done that way. And then there is everwhere in between. As Dave said, there is no standard. Best to just pull the BB out and have a look in the shell.

[Plum Hill]

Since this got the attention of two frame builders, what are you opinions on drilling a steel frame for EPS use?
Frame in question has a hole to ST that might take connectors, small one to DT.
It would require hole in DT near HT and possible enlargement of drain hole in BB. Also one for front d駻ailleur.
Poster very mechanically inclined but would probably defer work to frame builder in Wisconsin (gives me an excuse for a vacation).

[oldpotatoe]

Since this got the attention of two frame builders, what are you opinions on drilling a steel frame for EPS use?
Frame in question has a hole to ST that might take connectors, small one to DT.
It would require hole in DT near HT and possible enlargement of drain hole in BB. Also one for front d駻ailleur.
Poster very mechanically inclined but would probably defer work to frame builder in Wisconsin (gives me an excuse for a vacation).

I did this very thing on a kinda knackered MXLeader, EPS, v1 battery behind lower bottle cage. Hole by front der, one on down tube just forward of LH shifter boss, another in RH Chainstay. Double 5/16 hole under down tube bottle cage for battery wires. Been riding it for almost 2 years w/o issue. Got the idea from a guy who did it to a SL Ciocc.

But I will add I am NOT a frame builder and you drill holes in your frame potentially at your peril.

[David Kirk]

Since this got the attention of two frame builders, what are you opinions on drilling a steel frame for EPS use?
Frame in question has a hole to ST that might take connectors, small one to DT.
It would require hole in DT near HT and possible enlargement of drain hole in BB. Also one for front d駻ailleur.
Poster very mechanically inclined but would probably defer work to frame builder in Wisconsin (gives me an excuse for a vacation).

That's a tough one to answer in a real way. Again.....it depends. I think with most tubes it would be fine if the hole isn't placed right at the thin end of the tube butt and if the hole has a reinforcement plate put over it.

I personally would not recommend just drilling some holes and seeing how it works. I'd want to put on the plates which will toast the paint and then you are into it for a paint job too.

All that said - it might be fine, it might not. Whether you do it or not might depend on how risk averse you are.

dave

[Plum Hill]

Dave,
Could you explain 'plates'?
Is that a drilling guide?
Could they be padded to avoid drinking the paint?

[David Kirk]

The plate is a way to reinforce the tube around the big hole you just drilled into it to keep it from being a weak spot. It would need to be brazed on which will of course ruin the paint.

dave

[Plum Hill]

Thanks.