guitarjunkie28

the 320 didn't leave pits, the 400 did, but the 320 seemed to be a little rough.



i haven't tried the 220 grit, but i'd assume since the 320 was too rough for my taste, it'd be worse. but maybe that has something to do with materials. i have a really cheap DA, and i couldn't find silicone carbide paper, so i used aluminum oxide. do you think that would make a big difference?



the iron definately has a very nice appearance to it now, though. kinda dull and very, very smooth to the touch. from 5 feet back, it looks like a professional job :P

Speedworks

Don't flame me here but what's a DA?

diabolical1

i can answer that. it's a pneumatic orbital sander ... not sure if it stands for something though.

Lynn E. Hanover

DA was a popular brand of air powered random orbital sander. Now a generic term for orbital sanders like Kleenex tissues. When mom says give me a Kleenex when the box says Puffs or some other brand.

A habit of old people.



If you flood the iron with kerosene while running the "random orbital sander" with the 220 or finer wet or dry paper, the finish will be clean and bright. Do not sand the bridge on a bridgeported engine. The idea is to clean the iron and apply an oil holding finish (the little circles), and in some cases to save a damaged iron that has a lot of porting time in it. Not to change the shape of anything, or cure a warped iron. If you don't like the idea, don't do it. Make yourself happy.





Flame free comunication for 64 years.



Lynn E. Hanover

Lynn E. Hanover

The big box stores (Lowes) have wet or dry paper in the paint department. Or an outlet for automotive paint.



The astounding finishes you see on custom cars is not possible without wet sanding for hours. Even after the last coat of clear, there is still wet sanding to do before polishing. Good shops use warm water to flood the area being wet sanded. The water keeps the area shiny to help you see the surface and carry away the removed paint. Use 600 to 1000 grit on paint.



I love silicone carbide paper. Get a thick piece of flat glass for your cleaning tank and some silicone carbide and shorten your oil pump body to the minimum spec, for more idle oil pressure. Wet the glass with solvent, and smooth the paper onto the glass.

keep the paper flooded with solvent while doing the figure eight pattern (Lapping) with the piece being repaired. Dead flat surfaces, and good looking too. The 400 grit is a good all around paper for this work.



Lynn E. Hanover

guitarjunkie28

are you cutting the paper out yourself? i got some adhesive backed paper for it. i suppose i could cut the silicone carbide paper out and give it a whirl.



thanks a lot for the help.

Lynn E. Hanover

Yes you cut it yourself. Use a plain pad and old style pad glue. From the auto body supply shop. Glue up the pad, and stick in the corner of a new sheet of silicone carbid. Then trim around the pad with a box knife.





Lynn E. Hanover

Lynn E. Hanover

Getting an iron out of parallel on a lapping machine would be diffcult. Depending on the grit being used, it takes a good long time to remove any metal at all. If the irons are warn deep enough to need lapping, then it would be quicker to grind first to remove material to the depth of the wear mark and then lap briefly to get the correct finish overal.



A well run grinding operation will also provide good results, but it depends on many things that must be thought through. First is the wheel size for chatter free performance (on nitrideed iron) and to reduce cupping. Also feed speed, coolant, operator experience and more. The method used to hod the piece is a problem. Magnetic? old style clamps? no clamping? So the chance for a out of parallel iron resulting from lapping is very low, while a trainee on a grinder can do it in a few seconds.



The low production rate of rotary engines allows for a better level of quality than would ever be found in a piston engine. Also the numbers favor the rotary. Two housings vice 8 cylinders. Plus there are so many things to go wrong in the machining of a piston engine.



With the exception of the racing engine manufacturers there is not one good piston engine produced anywhere for anything. Honda and Toyota may be as close to really good as is possible to get and stay in business.



A typical V-8 will not have a single bore center parrellel with any others. The crank bore centerlines will be high and or canted on one end. The decks will be high and canted on one end. The cam bores can be anywhere. I have seen casting errors that should have rejected the block or head in running engines.



All of that machine work that hot rodders do is to get the block into the condition it should have been in when it left the factory. OEM quality my ***. I kept a Chevy V-8 connecting rod on my desk at the government. It had hopped out of the forging die, and on the last strike, a good portion of the big end had shifted sideways. This rod went right on through the machining process with no problem. It ran 80,000 miles in my friends tow van when it swallowed a valve (an OEM valve) and required a rebuild and head. He threw the odd looking rod in the trash and bought another. I rescued it and used it for years to offend the OEM quality fans.



In reacent years, the level of quality has improved in the big three, but it may have come too late to save them.



Piston engines are also much more suseptable to power loss from mis-machined bores and surfaces.



So long as there are no major falts on the iron surfaces the rotary will run fine. This is not to say that perfection is not the goal, but there is also no such thing.





Lynn E. Hanover

banzaitoyota

DA stands for DUAL ACTION IIRC.



We used to amuse ourselves on the sub with the lapping plate, since we couldnt play with the latch underway

guitarjunkie28

lynn is just a wealth of knowledge. i gotta get that guy drunk and talk **** with him some day