Boring for sleeves on 3axis vmc?

[msomerville]

Like the title says I have a buddy that handed me a V6 . aluminum block that he needs sleeved.
I have been a Mold maker for 11 yrs. so I think I have the ability to do it. The question is if I have the equipment to get it done and I know I don't have the know how yet. The travel on my machine is 40"x30"x24". I think I have enough travel but I dont think that is going to be the issue. This block is out of a Nissan 350Z and if I know him it will be either turbo or supercharged. I need to be right on. This machine has some wear in the ballscrew maybe .002 push pull test, so that is a concern.

In addition to boring what other machining processes are required after the sleeves are intalled?

I know this is a big undertaking, and I want to hear what the pros think.

P.S. The sleeves are Darton Wet Sleeves and are about 5.1" in lenth and have 3 different diameters.

[msomerville]

Sorry just refreshing the topic

[NC Cams]

Boring the holes to get 3 different diameters concentric can be your hardest challenge. Fitting an iron sleeve to an aluminum block is not that difficult as long as you carefully hone the bored cyls to size afterwards. Honing aluminum will pose some challenges.

As far as fitting the sleeves, different people have different preferences. However, back in the old "Vega block" repair days, these were repaired via the installation of thin walled/flanged sleeves. When done properly, they worked fine.

THe first thing you did was bore the block withing a few thousandths of size. "Size" was determinned by measuring the sleeve at 6 places (3 at the top at 120 deg intervals and likewise at the bottom) and then averaged the 6 measurements. You then honed the block to yield enough clearance that you could press the sleeve DRY to within 2/3 to 3/4 of seating the flange (the Vega repair sleeves had a small lip flange that got pinched between the gasket and head). You then either pressed or lightly tapped the sleeve home.

You did NOT want nor need to use glue or loctite - the press/slip fit held it. The thermal differential of hte hot sleeve and colder block caused the sleeve to grow faster and thus "lock" itself into the aluminum bore plenty tight. Adding loctite actually could let the sealer/glue to "ball up" or cook/coke behind the sleeve and cause thermal insulation problems/issues. It could also move around and distort the sleeve over time. SOme folks did it anyway and some had good luck and others bad.

You wanted/needed a smooth/round bore to enhance both fit and heat transfer - a rought bore in the aluminum could actually impede heat transfer. Too much clearance to let the sleeve slip all the way into position typically caused the sleeve to crack at the flange. Too much, too little or an uneven counterbore of the flange mounting surface would also peel off or break the flange.

The key to what you're trying to do will involve a well machined, properly fit flange and/or sleeve to the parent metal block.

Finally and most importantly, what does Darton recomment???????

I dare say that they should/would be able to tell you EXACTLy the best way to mount the sleeve (fits, tolerances, whatever). If they can't, it would make me think twice about using the sleeve.

Relying on 25 year old "Vega" technology might not be the best way to do what you're trying to do. Then again, lacking info to the contrary from the sleeve maker/developer, Vega sage wisdome might be all that you can rely upon.

Good luck.

[greg b]

Nc cams is dead right in fit and finish, i do a lot of resleeving but in a motor cycle industry and it is not to be taken lightly.On both two and four stroke motors the finish has to be very very good,or your heat transference will suffer and seizing can occur,the interfearence fit also must be taken into account,to little and the sleeve also looses heat transference.I normaly give 3to 4 inch cylinders around .005" interfearence fit,but with wet sleeves they are only size on size because the blocks have o'rings machined in them.When i used to do v 4 two stroke sleeving i made a bar that run staight through the crankshaft saddles and made special fixtures to hold them down to the milling table so the bores were in line with the crankshaft anyway i hope some of this gabble has helped regards greg.

[samco]

we have done a few custom sleeving of engines.. We have found that going to your local bottle gas dealer and getting some liquid nitrogen really makes installation easy. heat the block with some heat lamps.. Drop the sleaves into the liquid nitrogen. They slip right in. After everything settles - you may have to press the sleave in the last 1/16 inch (sleeve will grow as it heats back up). But it is better than the whole distance. (for us anyways - we don't have a press big enough to fit an engine.. they where pulled in with a fine treaded rod, large washers and thrust bearings.)

use this info at your own risk

sam

[NC Cams]

One needs to be REAL CAREFUL with the liquid nitrogen trick.

The use of cryogenics has had an overall positive effect on many industries. However, some materials simply can't be dunked in the stuff, shrunk and stuffed into the hole.

Cryogenic treatment does cause the material to shrink but this can also induce a lot of residual compressive stresses into the part. Unless you properly stress relieve the parts afterwards, cracking can occur. Contact a heat treater who does cryo treatment for recommendations - stress relieveing is CRITICAL after freezing some parts!!!!!!

0.005" press is a lot - especially for a thin sleeve in a correspondingly THICK by comparison housing. With REASONABLE fits of 0.001" to 0.002" press, we find that heat lamp/propane torch heating in concert with simple refridgerator freezing of the to be pressed part (with a resonable press) will result in fall together fits that rapidly tighten up when the temps normalize.

Never was this demonstrated better than when I visited a railway locomotive shop. They had this deep freeze filled with "frozen pizza". Why so much pizza at a locomotive shop? Anyway, I was there to observe the guys install some railway traction motor bearings.

The guy takes out a bearing housing roughly 12" in dia. He'd already mike'd it an knew it was round and properly sized. He then take out the mother of all rosebud torches and some tempstick and starts heating. He had the housing on this "lazy susan" that he stole from his wife (I think).

Anyway, when the housing was heated to about 250F, he opens the deep freeze and opens a "pizza box" and shakes out the pre chilled outer ring and I sat in amazement as it literally fell into the housing. He twisted the now seated ring to make sure it was properly seated and walked away. In 20-30 seconds, the ring was locked solid into place and would remain there for another 250,000 miles or so.

Bearing fits are not unlike press fits of sleeves. With the proper fits and finish, you can end up with good performing systems.

I'm not saying that the suggested 0.005" if wrong - I"m only saying that it can be considered to be quite high and perhaps in some cases excessive.

Keep in mind that the SMOOTHER the finish between the parts, the LESS press you can run. A 10-15 micro inch finish would work with say a 0.0005 to 0.0015 press while a 40-60 micro might want a bit more whereas 0.005" might work ok with a 125 micro.

Point being: there's more to fit and finish than simply the amount of interference.

[samco]

^ definatly listen to NC Cams.. We wing it a lot..

sam

[msomerville]

Thanks for the responses.

I have decided to bail on this little project due to the fact I would have to do it in my spare time (which we all know is hard to come by). Although I have the equipment to get it done, I don't have all of the tooling. Buying the tools is not something I am prepared to do right before buying a house. Of course after I buy the house I will have all kinds of spare time

[samco]

Dream on...

Originally Posted by msomerville Of course after I buy the house I will have all kinds of spare time

[msomerville]

I am sure my Honeydo list will grow by leaps and bounds

[bentwings]

I worked in a high performance auto shop for quite a while. For sleeves we had a cylinder boring machine similar to a magnetic drill machine. This used a 3 point expanding head to center the quill on the bore. The base was then clamped to the head surface with the head bolts. A special boring bar tool with a carbide tip was used. There was a sharpening wheel built into the machine for truing the tool. You set the tool against the existing bore and then adjusted for the cut. I had a nice bore gage to the sizing.

For sleeves inthe 3.5 to 4.5 bore size I used about .002-.003 interference. I bored to a step in the bottom of the hole and used a depth gage for the quil.

Back then you could get Freon 12 in 25 pound tanks. We coated the new bore with green lock tite and chilled the sleeve with the Freon. It took 2 people with a coordinated attack to do install the sleeeve quickly. One would chill the sleeve and get it lined up and the other had a wood block and big hammer. Getting it lined up and BAM usually 2 hits and it was home. We didn't miss very often. It just meant boring the sleeve out and re-trying.

We then trimmed the top flush with the block and bored and honed to size as normal.

I did all 8 holes on some blocks and never had any trouble with the sleves. Some blocks we even resleeved when they got burned in the top fuel motors.

I don't know if Freon 24 would get cold enough now. CO2 might work too but we never tried it.

These sleeves worked on daily drivers as well as top fuel cars. I even did a few diesel motors. I don't remember what the wall thickness was but between 1/8 and 3/16 at the most. Some of the 392 Chrysler blocks and flathead Fords had bad core shifts and the walls got pretty thin. The sleeves really helped these motors.

It used to take about an hour to bore, install and hone a sleeve.

[NC Cams]

Bot the Freon and the liquid nitrogen "freezing" processes have been used by they can cause cause some serious problems. Freon fumes ingested can be dangerous and, in the presence of a flame, can create phosgene gas which is highly poisonous. Freon is also NOT something that is or should be vented to atmostphere due to its negative affects on ozone.

Cryogenics (freexing) of parts used to be a done helter skelter. However, with time, it has been learned that the process can result in metallurgical changes to the frozen metal. It can actually result in changes to the metallurgy that can result in the part yielding prematurely. Call it a "negative effect" heat treatment. This is why freezing is properly and carefully followed by a controlled stress relieve heat cycle when done PROPERLY.

I know that "we do it all the time" justifies the continued use of the process in some minds. But consider this: Failure to stress relieve (controlled reheating to reduce the residual stresses in part induced by freezing) the part can lead to cracking during subsequent boring or honing operations.

The "shock" of cold against hot can lead to further shock potential. Combine this with what could be a high presss (0.002" to 0.003" could, not will be high dependiing on the thickness ratio of the sleeve wall to the thickness of parent metal) and you could be setting yourself up for loose or dropped or crached sleeves.

Finally, many "factory install" methods for sleeves do NOT involve the use of loctite. With the proper fit, the mechanical interference of a properly bored and honed bore in which a sleeve is fit DRY will result in many miles of trouble free service. There was a production HD gas engine that ran dry fit sleeves. They were thin wall, dry and were slip fit into the bore with ABSOLUTELY NO sealer or anything.

Yes, guys ignored the dry fit recommendation. Result: they installed them with whatever sealant they felt like using. More often than not, they had troubles. WHy? The sealant can and did migrate as the vibration of combustion took place. It would then "ball up" in areas and literally unevenly shove the sleeve away from the support wall - this alone was enought to cause scuffing/scoring.

Another problem involved "coking". The heat would eventually cook the goop and it would carbon/coke up. THis had an insulative affect that inevitably was NOT equaly. Scuffing, scoring and localized overheating resulted.

The fix? pull sleeve, hone out/remove the goop, install sleeve DRY and proper and problem solved.

Before ANYONE follows my or any other message board recommendations, one should contact the sleeve supplier and see what they recommend FIRST. Unless you have first hand knowledge that the suppliers' recommendations are bogus - they hardly are - that's when you can rely on whatever other method suits your fancy.

For a more detailed "treatise" of fits (sleeve or bearing, the concepts are essentially the same) do a "bearing fit" search on this website. ALthough differering in function, the caveats are essentially the same. My prior bearing tit rants pertain in some way to "sleeve fits" just the same.