Framebuilders - Milling Down a Headtube?

Hey all, I have nowhere else to ask this question, so I figured this section of the forum would be best.

Anyway, I have a steel 29er frame that fits me perfectly except for the fact that I can't seem to get low enough on the front end. I know, the easiest step is to get the next size down, but having ridden that size, I feel overly cramped which is something I definitely DO NOT want while racing XC.

So, there's about, oh, I'd say a good usable centimeter of steel on the top of the head tube before I would even consider it being an issue of interfering with the weld to the top tube.

I know most frame building shops have a lathe with a headtube cutter used more for facing than milling, but I figured I could pay for the cutter to be sharpened after anyway.

After that incredibly long, rambling into, I'm just curious if there are foreseen structural issues with milling down my headtube? I know milling from the bottom can alter the steering angle, but I can't figure out any other downsides to taking the headtube down 5mm on top.

Could be done, probably best though to just carefully cut off most of the excess tube (hacksaw) and then use a file and finally the facer to clean up the cut, rather than milling all the tube down in one single operation. If there is any sort of re-inforcement band on lug around top of the TT, you shouldt obliterate it.

How about first going to a stem with less rise (or flip a stem for negative rise like a road stem).

Did you already try a -17 stem and flatbars?

I'm currently running a -17degree stem with flatbars. Too high.

GrayJay - there is a reinforcement band on the top - how much should I leave? Measures about 1.5cm in height.

Additionally, does anybody know of a lower stack stem than a Thomson X4? It's what I wanted to buy when all was said and done.

What about a track stem?? Do you think a super low x2 thomson stem could do it? It might be cheaper than dealing with the frame.

GrayJay - there is a reinforcement band on the top - how much should I leave? Measures about 1.5cm in height.

I would be hesitant to remove any more than 1/2 the reinforcement band (leaving .75cm band).
Looks a bit odd, but you could always use a high-rise stem of more than 17° flipped to angle the bars down further.
Have you tried a stem that is longer than your current stem? A bit of additional extension might substitute for the low height. If you have a shock fork, lower travel setting would also help to bring the front end down.

If the bars are noticeably high, the 5mm or less removed from the headtube isn't gonna make much difference. Move saddle- change/flip stems- different stem- headset with less stackheight- remove headset spacers- different bars, etc are more logical solutions.

How about a profile view of the bike?