vins0010

I seem a little late to the party, but I, like others, made a headset press a few years ago and used it on three bikes. It was pretty cheap to make and worked well. I used the optional copper flange pieces to help center and push the headset on. They were the most expensive part of the set-up (but not expensive), but I think they helped a lot with keeping things centered and just pushing things on well....and soft enough where they weren't going to damage anything. So, the copper pieces fit in the headset to be pushed in. On top of them are flat, big, fender washers, and then nylon washers on top of that, then the nuts. I found the copper flange pieces (not sure what they are really called) in the plumbing section of my local big box store. I haven't used the headset press since.

The roller bearing headset I really wanted at the time still works great (pictured). The Velo Orange Grand Cru headset I put on my wife's bike is a little sharper looking though.

SquidPuppet

My bikes are razor straight because I use space age alignment technology and tools. Nuts, bolts, washers, rulers, straight edges, string, and 2x4s.

Captain Kludge to infinity....and beyond.

Lazyass

Put headset cups in the freezer for awhile. Take them out. Use heat gun on both ends of headtube to expand it. Lightly tap in cups using rubber handle of chain whip laying across the cup and hammer. Done.

himespau 

I've used a similar setup to respace 120mm rear triangle to 130 mm. Big enough rear washers (supported by increasingly smaller ones held in place by nuts on both sides of the dropouts) kept dropouts more or less aligned on a mixte frame with stamped dropouts. Ended up never using the frame (it still sits with a single coat of poorly applied primer), but I'm pretty sure I used my hanger alignment tool (once I finally got one a couple years later) to check and the alignment was pretty tight.

msl109

Have used a homemade one just like this on over a dozen headsets with no issues. I find lubing the threaded rod makes things easier. Check Sheldon Brown site - there's a description of what I made there.

ksisler

Squid - Nice. The string and ruler method is what I started out using for tandem builds (in the mid-1970's) to check alignments before tacking the joints. If the line is pulled very tight around the headtube it can be amazingly accurate. It is still one of the most practical final checks for any frame build (I always put a washer and nut on the outside of the dropout, followed by a another washer and nut to force the cord in tight to the inner nut). The method is also very useful to avoid a lemon when buying a used bike or frame off Craigslist, etc., where many crashed/re-forked bikes are for sell as "like new".

Redshift96

Excellent tip. Two caveats though:

Be sure to check the headtube seat inside diameters first to be sure that the interference fit is within spec. Good practice to check the outside diameter of the races too, though they should be within spec from the supplier if new. The risk is that if for some reason the interference is greater than recommended (seats in need of reaming), freezing the races before installing them raises the possibility that the race could be squeezed in despite being "oversized", then could deform upon warming to room temp, potentially leading to a non-uniform race for the bearings to ride on. {NOTE: I have not experienced this first hand on headsets, but in other machining contexts.}

Don't EVER use a heat gun on a carbon frame bike. The epoxy is subject to soften at lower temps than you might imagine. I'm not sure I'd even use a hair dryer unless on a very low setting. And even then, I sure wouldn't risk it myself. I just really hate ruining things.

veganbikes

Not terrible points necessarily but this thread has been dormant since 2017 and it is now 2022 I think this discussion was over. You might want to use that excellent knowledge on more current threads it will be more helpful.