Resurfacing Aluminum Cylinder Heads on a Bport Mill? 50Ra surface?

[triumph406]

I would think 8.25 would be a tad undersized.
Given that you want only one side to cut that adds a lot to table travel.
Any cross cut or hatch is usually bad here so a very tiny tilt is used.
In production the often rule is if the ass end of the cutter touches or leaves a mark the tools need need to be changed out.
Yes this means a dish. Which is why on a 8 inch surface one wants a 14 to 20 inch cutter body.
There is not only a dish but a dive/raise as one goes goes across full load and then the lighter Z load as you cross the big holes.

I guess I was illustrating if you used a 8.25 dia flycutter you would need 18.25" of travel, 14" dia would require 24" travel etc etc. Either way it's problematic.

If all I had was a BP i'd do it on a glass plate.

 

[triumph406]

Modern head gaskets do not want a smooth surface. They want a surface that is "just right" for the sealing materials and technology applicable.

We may note that 50Ra is very coarse indeed. and that is my experience. Lapping, as we may think of it, is strictly OUT unless you are running the work over Black Beauty blasting slag.

I'm sure a BP could do the job. Motorized table feed for controlled rate. Better might be a Blanchard.

ETA

Consider, It will be the TRAILING cut that produces the surface finish when using a fly cutter or face mill.

Entirely depends on how well you tram the head. You could tram in the middle of the table, get it perfect, go 10" in each direction and it'll be off. Over 18" of travel my BP would cut leading edge of cutter at one end, perfect in the middle and trailing edge at the other end.

I'm sure I've had a flycutter cut entirely with the leading edge, trailing edge and in between.

 

[gbent]

Surfacing such a small head should not be a problem.

A HSS fly cutter will work just fine for aluminum. If it is a couple of inches larger than the head it will be ok, 4" larger would be better. If the head is trammed heavy on the leading edge by .001 or .002 you won't need to travel the cutter off the end of the head completely. Put a nice radius on the cutter, more flat on the bottom and plenty of polished rake. Ra of 8 microinch is easily doable. A power feed is necessary.

If the knee is rocking, tighten the gib until it stops.

And for you purists, I could tilt the head .005 on a 10" cutter and you will never find the concavity, even with a surface plate and indicator.

 

[GregSY]

My opinion is you can do it - but you can't do it with repeatability and reliability.

I would think by now a dedicated head cutter-machine would be fairly easy to buy, and not too costly. That's because so many people have gotten out of the engine rebuilding business.

If you had multiple attempts at getting it right, using a BP would be tolerable. But when you're working on a customer's head and your own time is of value, you need a machine that you can count on to set up fast and know what the result will be when you push the start button.


As for cylinder head gaskets...Cometic seems to be at the cutting edge of the industry. FelPro? I like them but I think they are yesterday's news.

There are a few schools of thought on profile. Some say you need 'tooth' to prevent the head from squirming around. Some say you need a mirror smooth finish to allow the head to squirm around. I guess I'd talk to Cometic (if they sell Subaru gaskets) and follow their advice.

 

[michiganbuck]

High chance of loading a wheel and so marring the finish grinding aluminum, but yes it would take a very good condition BP to surface heads.

 

[eKretz]

Surface grinder will work but it's not optimal in terms of throughput. I'd look for a dedicated machine if she wants to make money. These were done for a buddy on a surface grinder with a silicon carbide wheel.

 

[GregSY]

Cometic Gasket - Sealed Under Extreme Pressure

 

[turnworks]

Been out of the car scene for awhile but I remember more than a couple rebuild shops using wide belt horizontal sander for surfacing aluminum heads.

One guy I watched got the sander going then tilted/layed the head onto the belt then added some weight and looked at his watch. 8-12 seconds later pulled it off and did another.

Shocked the crap out of me but he said it works great with the right grit and weight on the head. Impressively fast process.

 

[GregSY]

On some engines you can get away with murder. On other engines, not so much. I generally think any of the 4 cylinder aluminum headed engines...not so much. They're designed on the edge to begin with.

I'd wager the European engines are the worst...German, Italian, etc.

 

[turnworks]

^^^^ IME, belt sanders always round the start and end of the part it's doing?
So not flat, but obviously "good enough".....

Not a clue if the sander was purpose built. Thinking out load with good flat platen under the belt and some brackets for the head to rest against that puts the head away from the platen edges it could be pretty flat after.

I think there is a difference between processes that are correct and processes that work.

Good luck on helping them out and let us know what route you had them take please.

 

[cg285]

Been out of the car scene for awhile but I remember more than a couple rebuild shops using wide belt horizontal sander for surfacing aluminum heads.

One guy I watched got the sander going then tilted/layed the head onto the belt then added some weight and looked at his watch. 8-12 seconds later pulled it off and did another.

Shocked the crap out of me but he said it works great with the right grit and weight on the head. Impressively fast process.

i have one of those machines i bought new that could be available

 

[alphonso]

Kristi,
Does Bre have a junk head she could bring/send me to play with? If I can make her happy with the surface, I'd be willing to do that for her in batches 4 or more.

 

[CarbideBob]

GM did the belt sander thing once in the Lansing engine plant.
Life results on that motor not good.

I once designed a cutter for the Flint plant making SBCs. Absolutely gorgeous finishes and flatness. Way,way pass the spec. all day long.
Everyone involved was so happy and proud.
Then they began to fail on the high mileage dyno tests.
Over 3000 heads per day for a month built already. 60,000+ 350 chevy heads went into the dumpsters.
I learned some bite is good and too good of a finish is a real thing.
At this time there was not a min. spec on the print as no one had hit it in a long run.
Bob

 

[triumph406]

Surfacing such a small head should not be a problem.

A HSS fly cutter will work just fine for aluminum. If it is a couple of inches larger than the head it will be ok, 4" larger would be better. If the head is trammed heavy on the leading edge by .001 or .002 you won't need to travel the cutter off the end of the head completely. Put a nice radius on the cutter, more flat on the bottom and plenty of polished rake. Ra of 8 microinch is easily doable. A power feed is necessary.

If the knee is rocking, tighten the gib until it stops.

And for you purists, I could tilt the head .005 on a 10" cutter and you will never find the concavity, even with a surface plate and indicator.

..

Total BS, you could put a 12" scale across that and see daylight underneath the center. I'm wondering if you've ever trammed a head or used a BP

 

[CarbideBob]

..

Total BS, you could put a 12" scale across that and see daylight underneath the center. I'm wondering if you've ever trammed a head or used a BP

Oh this should be good.
One should remember that the cutter and machine deflects under load so static tilt checks are not real world cutting.
On a machine easy 10 times the size and HP of a B-port with mega dollar spindles one puts in .004/.005 tilt on a 14 inch cutter to clear the back end by tenths.
The bigger problem milling heads and blocks is the full cut vs two tiny cuts as we go across the holes. This is long term wave due to axially loading the system and hard to measure but a pain.
The car makers have huge dollar stuff for this.

On a rebuild one can get away with a lot here. I have done all the most terrible things and been fine. Hell, I've done sheets of sandpaper on the surface plate.
Bob

 

[CITIZEN F16]

Anybody else remember when damn near every independent auto parts store had a machine shop in back? I wonder what the percentage of those is compared to now from 40 years ago?

 

[gbent]

..

Total BS, you could put a 12" scale across that and see daylight underneath the center. I'm wondering if you've ever trammed a head or used a BP

Why don't you do the math and tell us exactly how much concavity is in the part.

 

[Overland]

I remember, back in the day, we used to broach the top deck of 4 cylinder cast iron cylinder blocks, OEM of course.
Quick cycle times !

 

[john.k]

I remember the ring wheel grinders too,had a biggie where I was that could have operators both sides sliding heads thru.....1970s......from what Ive been told by those who do heads,its a different game with ally heads and MLS gaskets.....The finish must be perfect for the sealant on the steel shim.All the new heads I see have a mirror finish.....not exactly mirror,more a "DVD"finish...

 

[slowmotion]

All those parts store shops from the 60's and 70's are folding like a cheap lawn chair. They never updated their equipment and all of a sudden one day it's all worn out. Those that are still using that equipment can't get an MLS finish on aluminum, it requires CBN or better yet PCD, I have both. I've seen so many botch jobs using a belt sander, it's even worse than an old carbide machine. it hogs out material in thin areas like between cylinders, and the front and rear. Don't even get me going on bottom end equipment.