Why not just buy a Chris King Devolution headset?

http://www.chrisking.com/headsets/hds_devo.html

Here is a link that will give you some information.

http://www.chrisking.com/specs/headsets_all.html

Also check this one.  Sheldon is a wealth of information

http://www.sheldonbrown.com/bicycle-links.html

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.

Here is some more information of Chris King's website on bore sizing.

Bore Sizing:
Head Tube Bore Size
1" Standard 30.1mm
1" BMX 32.7mm
1-1/8" 33.9mm
1-1/4" 36.9mm

Most reamers are .2mm under the nominal cup size while we recommend that the head tube bore be cut to .1mm under. The use of these reamers will produce varying finished bore sizes depending on the properties of the material being cut, and how much reaming is performed. With many materials you may net the correct bore size, however, on materials such as titanium or hard aluminum, the reamer may cut a clean bore in its exact size or smaller. On the other hand, if you face a lot of material with the reamer in the bore, the reamed bore may become oversized. Because the equipment necessary to determine exact bore sizes is not commonly found in most bicycle shops, attentively pressing the cups is the most practical test. It shouldnít be necessary to ìreef" on the press. An exceedingly difficult cup press is an indication that the head tube bore is undersized. If the bore is still undersized after reaming, it may be necessary to use another method to achieve the proper size. One trick we have used is to first press cheap steel headset cups to smooth and stretch the bore slightly. Then, remove and press our cups.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.

I didn't know that this product was out there.  I knew that you can buy reducers which is what I am trying to make.  I can get the reducers made on a Mazak at work for nothing.

Just make sure the spacers have a shoulder on them that will register on the headtube.  That way they will not shift under operational loads.  Also, make sure you have your tolerances figured out so their is no slop in the assembly otherwise you will be asking for problems.

heckelr do youwork for a bike company