FWIW - the very first link that googling for "cotter pin press" brings up is to http://bikesmithdesign.com/CotterPress/ - a readily available cotter pin press by Mark Stonich - which I for one can heartily recommend.
Monday, December 1, 2008, 8:16:28 PM, Greg Thies wrote:
> It's fair to recount that "necessity is the mother of invention." However,
> these cotters, especially if they've been in position for a couple of
> decades, can be pretty stubborn, even after a couple of days soaking in
> penetrating oil. I tried improvising with a socket wrench and a very stout
> "C" clamp and found that under the tremendous force required to break the
> pin free, my makeshift press was just too unstable and kept breaking free
> before the job was done. I believe a press is still available, but not from
> Park. Also, in my Google search for presses, apparently some have had luck
> improvising with certain automotive tools that are readily available and
> inexpensive. According to Barnett's manual, the pin is to be clean and free
> of grease and oil when pressed in.
> Greg Thies
> Vienna, Virginia
> Date: Mon, 1 Dec 2008 10:16:38 -0800 (PST)
> From: email@example.com (donald gillies)
> To: firstname.lastname@example.org
> Subject: [CR]Re: Worn cotter pins?
> Message-ID: <20081201181638.8DEB519D8D@ug6.ece.ubc.ca>
> Precedence: list
> Message: 14
> I have two bikes with cottered cranks and I think I will face the
> cotterpin reinstallation issue fairly soon.
> It occurs to me that with a tall stack of washers, or a piece of pipe
> tubing of the right diameter that's fairly thick, plus a hobby vise or
> unmounted vise, you could probably create a makeshift cotterpin press.
> You just need to stack the washers or pipe on the crank arm around the
> cotter pin threads, and then attach the vise to the crank arm. Make
> sure to use some sheet-copper or brass to shield the cotter and/or
> pipe from scratching. Put one jaw on the cotter head, and the other
> jaw on the washers or pipe. Then, crank the vise closed to press in
> the (greased) pin.
> This depends upon being able to find washers or pipe with an inside
> diameter of 10mm+, and a fairly narrow outside diameter so as not to
> hit the crankarm spider.
> Best wishes and good luck,
> - Don Gillies
> San Diego, CA, USA