by gofaster » Tue Aug 28, 2007 7:31 pm
I tried it, at first it was difficult to do intake seats without chatter. It will work ok once you get the hang of it.
First and foremost, you have to set it up so the head is mounted solidly, and you need to have the pilot aligned in the guide so it doesn't feel like it has loose or tight spots as you rotate the cutting head. To solidly mount the heads, I made an aluminum fixture plate that holds two Evo or TC heads. The fixture mounts the heads with the intakes on one side and the exhaust seats on the other, with four slots in it for pilot clearance, locating dowels for the two alignment holes in the top of the head, and bolt holes lined up with the rocker box bolt pattern. This helped reduce set-up time and made it easier to keep seat depths equal.
When cutting, it is important to make sure that your "Body English" doesn't influence cutting pressures or you will have concentricity issues. I always used Serdi carbide pilots.
Standard three angle cuts are the easiest to master. When you move on to advanced profiles with 4 or more angles, and radius bowl and combustion chamber blends, it gets tricky. In those cases, it's best to make your basic seat cuts with a simple single or three angle cutter, then finish with the advanced cutter. Some high performance cutters go fairly deep into the bowl. Those cuts should be preceeded by a pass with a 75 or 82 degree cutter. The idea is to do what you can to make all of your cuts light. Deep cuts will want to chatter, and once a seat has chatter marks, it is difficult to get it back under control, to the extent that you may have to dress it out with a stone and start over. This introduces the additional problem of excessive seat depth/stem protrusion. In other words, if it goes wrong it doesn't take much to reach the point where the seat will need to be replaced and you'll have to start over. Harley, Rowe, KPMI and some others offer shorter stem valves to help get around this, but the idea is to do it right so one of these band aids is not needed.
I used a Serdi Micro 2000 for a couple of years, and once I learned to work within it's limitations, I did a lot of nice work with it, BUT... as soon as I was able, I bought a new Serdi 1.0 AD. That's the way to go! Air float on the head, sphere, and table, plus a powerful spindle drive, and rock solid rigidity. I made a fixture plate for it, too. It bolts directly to the rollover fixture, holds 2 heads.
MY OPINION and nothing more: If you are buying the Micro to do your own heads and maybe some moonlight work for your buddies, it's ok. For a busy professional shop doing a lot of head work, it's too time consuming. If you have a shop and motorcycle heads are your primary business get a 1.0 AD, and if your shop does motorcycle and automotive heads get a 1.1. (or an equivalent machine from Sunnen, Newen, etc.)
[I]
Jim