automotive engine boring on a mill

I want to get into the hobby of machinist;automotive machinery to be
exact. I have six kids so I am on a really tight budget. My question
is, can I bore automotive engine blocks on a large grizzly mill? I
have read alot of posts that discourage against this but how difficult
could it be? I am not sure of what particular modle to purchase but it
will be pretty heavy-duty. I can buy a very stirdy jig to hold a
engine block from one of the many companies which now sell machines
which are similuar to a mill. The only problem I can see, is what type
of boring bit to use and how to attach it? Is a R8 end holder sturdy
engough? It must be sturdy enough to bore hole up to six inches. Any
coments?
Reply to
nattydreadlocks
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Sounds like a troll, but I'll bite either way.
Aren't most engines rough bored then honed? I'd think that with enough hone action, you might be able to bore it on a lathe. :)
Reply to
Joe
Dont waste your time on this idea- automotive boring machines are very specialized- your best bet is to cruise around various automotive machine shops and try to find a used portable boring bar- these clamp to the block surface to do 1 hole at a time and can even bore a hole with the block in the car. Then you need a hone ( not a glaze breaker) For hobby work you might get the basics for under 1000.00 to get started.
Reply to
Ahernwill
snipped-for-privacy@yahoo.com (nattydreadlocks) wrote in news: snipped-for-privacy@posting.google.com:
Hehe...not a chance in hell... Ya...you *can* do it.....but the bore will be absolute junk, quality- wise. R8 doesn't have the ridgity needed to bore the block to the quality requirements needed for an engine. As for the other poster on the hone...junk bore to start with on a hone....junk bore after honing...
Reply to
Anthony
"Anthony" > As for the other poster on the hone...junk bore to start with on a
????????
Reply to
Ahernwill
Honing isn't exactly a "high rate of material removal" process. Nasty boring jobs usually leave reasonably deep grooves in the bore that I wouldn't want to try to remove with a real (Sunnen) honing machine, especially on a 6" diameter cylinder. Of course, I've never done it so I could be wrong.
Regards,
Robin
Reply to
Robin S.
IF you want to do boring get a horizontal mill, the bigger the better. They are all over the place for practically nothing. I would look for one with a 50 taper since tooling is easy to come by. If your lucky you will find a horizontal with a nuckle head, or two axis swivel head that will give you vertical capabilities too, and all those mills have automatic feed.
John
Reply to
john
When I was a kid I bored both single cylinder Briggs & Stratton and four cylinder Crosleys on my Dad's 11" South Bend. It was quite an exercise as the boring bar he had was simply a big stout boring bar with not calibrations. You adjusted the bar by loosening the tool and tapping it gently then made a test cut. Usually took a couple of evenings to do a Crosley to +/-.0005. I have some Crosley engines to do right now and you can bet I will be doing them on a Bridgeport type mill. They don't work well with the standard automotive boring bars as they have nondetachable heads and you have to have a rigid downstop. BTW: To the fellow that suggested you use a boring bar sysem that locates on the top deck of the engine, NO WAY! Good boring machines locate on the crankshaft centerline. To answer the original poster's question; a vertical mill is not the machine to bore engines on. Leigh at MarMachine
Reply to
Leigh Knudson
Remember the guy is a low budget hobbyist- every automotive machine shop has the deck mount boring bars for special jobs and for any production automotive work they are fine- Indexing off the crank is only necessary for high performance engines- Don't forget that most mills dont have a table designed to hold a block and the required accessories, not to mention the difficulty of lifting the block into place- specialized machines have large non- moveable tables and open fronts so blocks can be slid into position from rolling carts. This is all in relation to automotive engines- lawn mowers, go carts and little stuff like Crosleys are a different story.
To the guy who posted the gibberish about honing, you always rough bore and hone to fit.
"Leigh Knudson"
Reply to
Ahernwill
I'm not aware of any normal boring machine that locates on a crank centreline. Either the block stands on its sump face on the machine table or the machine bolts to the top of the block. V engines can sometimes be tricky to jig up if there is no readily available flat face to mount on so they can need a jig that bolts into the crank saddles. That isn't a function of the boring machine though. It's a function of the jig that bolts to the machine table that is hopefully true to the boring head.
Provided either of those faces is as true to the crank centreline as needed then both methods work fine. I always put a light skim on the head gasket face before using my bolt-on boring machine to make sure the head face is true. There's no guarantee that a sump face will be true either though.
However it's a crock of shit to think that tiny errors in the bore's perpendicularity or centrality to the crank make any real difference to an engine's power output. In fact if the error in the original bore was very big you'd never be able to correct it anyway without going to a very large overbore size.
Reply to
Dave Baker
Do you know Dodge Reidy? He's local engine builder (San Francisco Bay Area)that's done a lot with Crosleys, especially with vintage race motors. I suspect the Crossley world is pretty small.
Peter
Reply to
Peter Grey
Naw, not I. I'm not in to Crossleys. I was just glad to hear Leigh say that vertical mills are suitable for engine boring, etc.
Bob Swinney
He's local engine builder (San Francisco Bay
Reply to
Robert Swinney
snipped-for-privacy@aol.comNoEmails (Dave Baker) wrote in news: snipped-for-privacy@mb-m29.aol.com:
Sure...but what *quality* of bore do you have? What is the roundness and straightness? Yes....it might work....but for how long? What kind of blowby and ring wear are you going to see? A hone, to some extent, is going to follow the bore that exists. This is true of most any finishing operation. The quality of the previous operations will almost always influence the quality of the finish operations, to some degree. It is a matter of to what precision you wish to measure, and how accurate you wish the final product to be.
Reply to
Anthony
This is about the minimum you are going to be looking for:
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If you can't afford the right equipment, I can *assure* you that you won't be able to compensate people for the scrap blocks...
Reply to
Gene Kearns
In addition to the other drawbacks to using a BP clone that have been mentioned, one other BIG drawback is that most BP clones only have 5" of travel to the spindle.
Mike
Reply to
The Davenport's
The whole point of rigid stone honing is that it doesn't follow imperfections in the original bore. The most it follows is the general direction of that bore. A good honing machine removes all taper, ovality and lack of straightness. Provided sufficient material is left in place to allow a perfect cylinder to be created after the original boring operation it makes no difference what quality that boring operation was done to.
As for measuring equipment, my own bore gauge is a Mercer dial bore gauge reading to 0.0001". Most commercial engine reconditioning operations use 0.001" gauges which are adequate for the general -0/+0.001" tolerance on piston fitment. My work needs to be infinitely more precise, and is!
I have two honing systems. A Snap-On 5" stone system which is best for achieving perfect bore straightness because the stones are longer and a Delapena 4" stone system which is better for removing taper from the bottom of bores where the crank saddles prevent you "through honing" as far as you would ideally like. Choice of stone grit and speed and feed then lead to the perfect surface finish and cross hatch angle.
I have to conclude that if you think that honing can't create a perfect bore regardless of imperfections in the boring operation then this isn't an area of machining that you have actually been involved in. In fact I'll ask. Have you ever actually used a professional rigid stone engine cylinder honing system?
Reply to
Dave Baker
Buzz. No.
Dave. You need to be careful as you are walking a fine line here. Some of us actually make mass produced cars, pieces of mass produced cars, or the things that make the mass produced cars.
To scratch the surface of your statement above, your Mercer dial bore gauge is as accurate as is required to measure a bore who's diameter (in only one plane) needs to be within .001". If you wanted to make the bore to within .0001", your bore gauge would not be accurate enough. Also, your bore gauge is _incapable_ of telling you if your bore is *correct*.
GD&T and process capability (Cp and Cpk) come into play big time, just off the top of my head.
Buzz. That word doesn't exist in automotive manufacturing (and if it did, I'd be walking to work).
Regards,
Robin
Reply to
Robin S.
Holy cow, you have some Hot-shots? The stamped ones, or cast?
We've got to see some photos of this, Leigh. I saw drawings from the early '20s of some pretty interesting setups with a 4-cyl. engine clamped to a slotted cross-slide, and I've always wanted to see someone do it.
Ed Huntress
Reply to
Ed Huntress

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