I want to see if a friend of mine who is a machinist could lap my housings for me he has access to a milling maching to freshen up cylinder heads but is that type of machine whats even used to "lap" a intermediate housing, how much would be cut also if the Irons are good for a rebuild?

 

I think I read somewhere that those used for cylinder heads arent capable of doing the job right(?)
I think it's because the area covered by the normal "milling machine" isnt great enough to lap an intermediate housing with one "swoop" or what-not(?)
I could be totally wrong though. Maybe a guru might chime in on this and let you know.

 

Do a search on "lapping" and you will get some shops that do this.. Racing Beat, Atkins, a place in Phx also.. I had some lapped and they only took off .002.

 

When I had mine done they called it Blanchard. it cost $50 per face.

 

A cylinder head doesn't usually have a super fine finish on it. Chances are its not good enough to "lap" the irons of a rotary engine. The finish needs to be nearly mirror smooth.

 

Some shops don't call it lapping but grinding. Paul Yaw did ginding also.. I'll get more info on this tommorow and post it..

 

I was wondering where the cheapest place would be to send my plates to be lapped.

 

just be careful with the 'mirror smooth' finish. I did quite a bit of research on this. Apparently the problem with the mirror smooth finish is that the oil beads up. The example of this to compare is like when u put water on say a car thats been polished. instead of the water running off in a line, it actually runs off in little droplets. Apparently this is what happens to oil as well which is then bad for the rotor as the oil is not spread evenly.

 

A Blanchard machine is a rotary surface grinder. It is a large surface area grinder.

http://www.fpmiller.com/

I had mine done by Prather Racing in Wakarusa Kansas (Near Topeka).

 

Grinding Lapping and Milling are all different processes.

-Milling uses a metal cutting tool to remove material. It is not suitable for Irons because the surface finish left is not very good.

-Blanchard grinding uses an abrasive wheel to remove small layers of material. The machines are very precise and the right wheel can be used on very hard metals. Many machine shops will not have a grinder big enough to fit a housing on the table.

-Lapping is just rubbing one flat surface against another with abrasive "lapping compound" between them. (can also be done with any matched shape) It produces a very consistant flat and uniform surface. The compound grit will determine the roughness of the surface finish. Lapping alone is not the best because it does not have any means of maintaining a parallel relationship between the faces of each iron. Grinding does because the part is held at a constant height from the cutting wheel. Some surface roughness is necessary for oil retention. I've only heard from others, shiny is bad, matte is good.

I have access to a blanchard grinding machine and I built my own lapping machine from an old drill press. I ground .003" from each face and lapped the surfaces just to achieve the surface finish. When ever you remove material from the irons you will remove the Nitrided (hardened) layer. This layer is much harder than the base material (cast iron) and if left that way it will wear very fast. When I had finished m port work, grinding, and lapping I sent my irons out and had them Ion Nitrided and had them do my stationary gears while they were at it.
After doing all this myself I can say that it is no easy job. If you don't have the equipment it is much cheaper and less headache to just find some good used side housings.

 

I am sendind 8 set of irons to a shop next week to be blanchard ground ,They are charging me $ 40 per face .I have pulled the dowell pins out and the vent tubes .

 

Thanx RXBeetle,that was very informative.