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View Full Version : Need to ream a hole .002" larger in Aluminum..best way??



Mueller
08-06-2003, 02:11 AM
I'm installing new lifters in an engine and the new lifters require the old bore to be opened up from .945 to .947 (.002")

Is is possible to use an expandable reamer for this and still achieve good results.

The length of the bore is about 3 inches.
Would a boring bar be my best bet?

Thanks

G.A. Ewen
08-06-2003, 07:34 AM
For me it would be worth the time and expence to have a .9531 decimal chucking reamer "sharpened down" to .947.

dnsbss
08-06-2003, 10:33 AM
If you use an adjustable reamer, try it in some aluminum scrap to adjust it. What about an adjustable boring head in a mill?

DR
08-06-2003, 10:35 AM
I would expect better results by using a reamer with a pilot on the front so it follows the old bore. Aren't such reamers available? If not, any grinding shop could make one from a larger size reamer.

The pilot reamer would be doubly important if you're doing this operation freehand.

If the old bore is not perfect then boring would be needed, but will need a very accurate setup to remove only .001" per side.

Not an easy task no matter how it's done.

spope14
08-06-2003, 10:37 AM
Boring bar would do well. More on the expandable reamer below.

Is this a total "do it yourself" job? Sometimes, though us HSM people do not want to admit it, it is worth the time, money, and such to take a tight automotive machining job to an automotive machinist. Especially if you have multiple holes to do. They have the general set-ups already in place, the proper tooling already bought for the job, and the chance of "screw up" is much less. Just an observation. Cost is probably more, but in the long run, the cost in comparrison to potential error, the possibility of not quite right tooling, and the time involved being less by the auto machinist may be worth it in the long run.... Besides, you pay money for the expertise of the auto machinist, the same thing we as machinists expect from the "non machinist" asking us to do a job....

BUT, then again, there is something to be said for the "I did it myself" factor, I know this because I do many things that take more time, yah de yah......

Expandable Reamers have worked well for me in some of these situations, but work them in slow from my experience, maybe .0005 at a time.

To best answer this question to determine bore bar vs. reamer, what is the possible "set-up" and machine for the bore bar?

Mueller
08-06-2003, 12:44 PM
Thanks for the replys....

I do have a "professional" shop I can take it to and cost would be minimal, if nothing at all (my job uses this shop and they do me little "favors" now and then) http://bbs.homeshopmachinist.net//smile.gif


But being the DIY type, I'd like to tackle this myself since it does seem to be within my scope.

Machine used would be my 3-n-1 Sloptask
(CNC w/ballscrews, converted by me)

Enco has a sale right now with free shipping, I think I'll order a set of adjustable reamers and give it a shot with some of the advide given (.0005 at a time removal along with making sure I have a good pilot)

Thanks


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Ragarsed Raglan
08-06-2003, 12:50 PM
Mueller,

You don't say in your post whether you already have a 0.945" reamer - which sounds like the standard lifter size.

If you have got a 0.945" reamer and you just want it to cut a couple thou's larger - then slip a piece of newspaper down one of the flutes so that it covers one of the cutting edges. If this only cuts 0.001" oversize use the paper either doubled or covering two cutting edges. Old trick ....... works well!

RR

Mueller
08-06-2003, 12:57 PM
Wow, neat trick !!!

Currently, i have no reamers at all, I am pretty new to this and I am still adding tools as I need or can afford them http://bbs.homeshopmachinist.net//smile.gif

SGW
08-06-2003, 02:48 PM
...or, you can buy virtually any decimal-size reamer from places like MSC www.mscdirect.com (http://www.mscdirect.com)

spope14
08-06-2003, 03:13 PM
I have used the paper trick, but instead of paper, I use a match stick jammed into a flute - Machinist Bedside reader trick.

I will have to tru the paper idea, see if it works the same.

Doc Nickel
08-06-2003, 05:07 PM
Two thou in aluminum? Why not try a bar-hone like for brake cylinders?

Doc.

Peter S
08-06-2003, 08:17 PM
Mueller,

My advice is to get some standard size lifters. The bores don't wear normally (unless grit has been in the oil). If they are hydraulic lifters, then any form of longitudinal chatter mark in the bore, or bell-mouthing will allow oil to escape. I would rather have the standard bore than one reamed or bored...I see trouble ahead...

I have a vague idea some engines (eg Dodge, 1960's) had warnings in the service manual that some blocks had oversize lifters (or was it some bearing) fitted, presumably to use blocks that would have otherwise been scrapped. These blocks were marked in some way.

Boring is out of the question as far as I can see - trying to clock up a hole and remove .002" is difficult, trying to do this to a whole lot of holes on a strange-shaped engine part is dreaming.

Reamers can be tricky things, easy to get chatter marks, especially on a big one like this. Be sure to practice on something else, or risk a ruined block.

Mueller
08-06-2003, 08:52 PM
As luck would have it for me, these lifters are only available oversized for this application.

They are ceramic (Silicon Nitride), not your "average" lifter http://bbs.homeshopmachinist.net//smile.gif

I might try to do this on a spare block of mine, if the results are not satisfactory, I'll be paying the one shop back East that I know does this for other customers...I'm just trying save some money http://bbs.homeshopmachinist.net//smile.gif

Thanks,

Mike

wierdscience
08-06-2003, 10:02 PM
A small Sunnen adjustable hone and a flood of coolant will work fine,but you could use a spiral adjustable reamer,don't use the straight blade reamers they suck mainly because they chatter,if you where to do this regular I would invest in a custom sized lefthand spiral right hand cut reamer,they cut real slick,which is what you need in a lifter bore anyway right?
To bad it ain't a nominal size,if it were you could get a shinny new ball bearing,grease up the bore and press it through.

Thrud
08-06-2003, 10:42 PM
Mike
Don't bother.

As these are not common lifters (SiN4) spend the money on a pro doing it or your money might be a tosser on the block and lifters.