[SCCoupe]

I have a Grizzly G1006 mill that I converted to CNC. Is this machine heavy enough to bore engine block cylinders .020" over? If I level the block and secure it heavily, then center a fly cutter correctly over the cylinder bore and then lock the gibs down, can this be done correctly and accurately or is this asking for trouble?

Thanks

Jason

[fizzissist]

You get today's award for being ambitious and optimistic.

I'm going out on a limb here by suggesting a test cut in something a little less expensive than a real block.

[underthetire]

Well, simply because you are trying to use a flycutter to bore cylinders, probably not a good idea.

[SCCoupe]

What would be the correct tool to use for this operation? I have plenty of extra blocks to experiment on, I go though them like fuses.

[wildwestpat]

What is the bore and what are your expectations in terms of performance when done. Car engines are re-bored on a much sturdier machine than yours. They are machined then honed in two separate stages. Take a look at these and others on YouTube [ame=http://www.youtube.com/watch?v=NsF2FRc8UIA]Manek - Vertical Cylinder Boring Machine Model: 300 - YouTube[/ame] [ame=http://www.youtube.com/watch?v=HShR1r0vVl4]Boring.wmv - YouTube[/ame] There are bigger machines these are the babies.

Regards - Pat

[fizzissist]

Not just the tool, but the machine...

cylinder block boring - Bing Videos

http://www.videosurf.com/video/acf-2...omec-126690003

[SCCoupe]

So what i'm hearing is, this machine is in no way capable of performing this task?

[underthetire]

You need a boring head. Blocks have been done on a bridgeport for many years. A bridgeport is a much stronger and larger machine than yours, and it takes pretty much all the bridgeport to do it.

[fizzissist]

You need a boring head. Blocks have been done on a bridgeport for many years. A bridgeport is a much stronger and larger machine than yours, and it takes pretty much all the bridgeport to do it.

what he said.

[brian257]

I can imagine what it would be like trying to indicate the cylinder in three axis on a V-8 block on a Bridgeport. Are there special fixtures to hold the block for this? Doing the boring once it is indicated would be the easy part.

[wildwestpat]

Setting up should be easy as most if not all engines have their bores referenced to the head gasket face. If you must do this on an end mill simply bolt down the inverted block to the bed using multiple parallels and work from the big end cavity. As previously pointed out this is all a question of rigidity and that is naturally related to bore size and expectations on surface finish.

Regards - Pat

[underthetire]

I've seen them just sat on the oil pan flange, and the Bridgeport head moved to indicate in on v8s, 4 cyl usually pretty easy. Seen angle plates with guides to capture the main bearing and indicate around. These were never production shops, more one off motors. It was also common to bolt torque plates where the heads would normally be as to try and keep things same same.

[Kiwi]

Automotive cylinder boring machines have a bar 2.2 inch diameter (larger for 4+ inch bores) which carries the tool holder and extends through the body of the machine.
No morse, R8, BT30/40 taper or the like, which will reduce the rigidity.

[wizard]

So what i'm hearing is, this machine is in no way capable of performing this task?

We don't even know what sort of blocks you are tailing about, nor stroke length or bore size. You talk about going through them like fuses which leads me to think RC aircraft engines. But you could be talking about lawn mowers, dragsters or John Deer tractors.

As to that mill I'm not actually familiar with it but you will need an automatic quil feed plus the quil stroke would need to be longer than the engine stroke, actually longer than the bore length. As such I highly doubt that this machine can handle automobile type engines as i suspect the quil stroke would be too short That doesn't even get into rigidity issues and other machine quality issues. Plus the block actually has to fit on the machine.

After all of that you still need an automatic quil feed something that could be rigged up. Given all of this I suspect that even if you could meet the physical needs of mounting the block you still will have work to do to get the machine even close to attempting such a boring action.

So the simple answer is no, this won't do if you are targeting large auto engines.

[packrat]

Also, good auto cylinder boring machines reference from the main bearing journals, not from another surface on the block.