1/3 Scale Ford 289 Hi-Po

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Eccentric

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Terry,

All the best during your eye surgery! It will be awesome to be able to see clearly afterwards. Many of us are in the same boat, I need ALOT of light to do most things now. No worries about the scrapped block, it could have come much later in its machining. And I noticed you had a nice long stick of 7075 for another go. (Pretty precious stuff)

take care, Greg
 

mayhugh1

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The three pairs of 6-32 threaded holes that will be used to attach the inner bronze bearings to the block were machined by counter boring, spotting, drilling, and then tapping with a spindle tap holder. These bolt holes need to be carefully located to insure the bearings will repeatably install during fitting.

An extended reach 3/8" ball cutter was used to finish the interior surfaces (excluding those for the bearings). This step probably wasn't necessary since the interior will be hidden by the oil pan, but I'll be looking at it for the next several months. Measurements of the finished webs were used to determine the effective cutting diameter of the end mill which turned out to be a surprising .373". This diameter was used by the CAM software to compile the tool paths for the bearing pockets which were machined in their own operation. The final result was a pair of close-fitting ball bearings.

I was anxious to verify the final sprocket spacing. When I corrected the block design I did so for minimum chain slack based upon measurements using the actual parts rather than the 'sloppy' spacing recommended by my chain calculator. The fit was essentially identical to my target.

The next operation was to machine the bell housing mounting flange on the rear end of the block. This operation's peripheral machining was extended some half inch below the flange in order to produce reference surfaces for the cylinder decks when they're machined later. (The front end machining will be extended similarly.) An additional .010" deck material was added to the CAM model used for this operation to create extra stock for the decks' finishing passes. The pocket for the rear cam bearing was machined in its own operation using the cutter's effective diameter determined from measurements of the finished flange. The result was a light press fit for the ball bearing. - Terry

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dnalot

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close-up vision difficulties I've been having in the shop were diagnosed as cataract related
I have had the surgery to install artificial lenses in both eyes. Painless and life changing. I expected to be able to see better but what really blew me away was the vibrant colors. Old eyes have yellowed lenses that make everything thing drab looking. If your getting new lenses you will be thrilled with the outcome. It's just a little unnerving seeing the knife coming at you end on. Don't blink.

Mark T
 

mayhugh1

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The block's front end was machined similarly to its rear end leaving .010" excess deck material for indicating and later finishing. I'm not sure why I drilled that pair of 7" deep 1/4" diameter coolant holes through the front of the first (scrapped) block. They only needed to be deep enough to penetrate the cooling jackets of the two front cylinders. Since the jackets overlap between cylinders, coolant will flow through the block without those deep holes.

The block's front-end features were roughed-in using 3/8"and 1/4" end mills before being finished with an extended reach 1/4" ball cutter. Most of the front-end's modeling time was spent adapting the full-size engine's filleting to this particular cutter. The organic cavities between the camshaft and distributor bores ended up with fillets stacked upon fillets, and the whole thing was a house of cards ready to fall with any changes to the design. It was this area that drove my decision to correct the timing sprocket error by moving the crankshaft up rather than the camshaft down. Since the fuel pump and dipstick will be later add-ons, the front-end machining is essentially completed.

The original workpiece was carefully machined so its surfaces could be used to indicate the block within its various machining setups. As the workpiece is machined away, work-holding and indicating become more difficult. To fix this, a fixture plate was machined next. It bolts onto the bottom of the block through the oil pan holes and is dowelled to it.

An angle table will be used for the 45 degree and 225 degree setups. The fixture plate will be required in the two 45 degree deck milling operations. The block will have to be flipped over for the two side milling operations which require the 225 degree setups. To keep the setups rigid, the block will be clamped to the angle table with a bar run through the crank bearing webs. On the surface plate this bar indicated true to within a thousandth on all block axes.

The Enco angle table I own is rigid enough, but precision is sorely lacking. Its most frustrating issue is the ground slots which aren't parallel with the table's rotational axis. This error which is nearly .050" at 45 degrees varies with the tilt angle, and changes when clamped down to the mill table. I typically re-machine a portion of the table every time I use it, but this only makes things worse for the next setup.

For this build, the table's 45 degree tilt was indicated on a surface plate using the deck reference surfaces machined on the block's front and rear ends. Custom tee-nuts were machined to allow the workpiece to be shimmed into alignment. Of course, when moved to the mill, all this will have to be re-tweaked.

I'm still working up a machining sequence to make best use of the workpiece during the remaining operations. - Terry

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mayhugh1

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The left and right sides of the block laying between the already finished front and rear surfaces were machined next. Both sides hold bosses for the motor mounts as well as cosmetic freeze plugs, and the driver's side includes a mount for a spin-on oil filter. The most efficient machining orientations were +/- 225 degrees, and so the top surface of the workpiece was mounted against the 45 degree angle table. It was clamped in place using the crankshaft test bar laid through the crank bearings. The bar was indicated and used to reference the workpiece to the mill.

CAM software differentiates between a "part" and its "workpiece" and creates tool paths which remove material from the 'workpiece' until only the 'part' remains. The part is usually defined in CAD, while the CAM software provides a default workpiece or maybe a user defined one based upon a combination of boxes, cylinders, and tubes. The prismatic workpieces presented by the sides were pretty inefficient compared with the default CAM options. Fortunately, my software allows the workpiece to also be created in CAD. This was my first experience with this feature, and although a four hour learning curve was involved, it saved nearly two hours of 'air machining' time. Total machining time for the two sides was some ten hours.

The sides' filleted features were designed to be finished with a 1/4" ball cutter, but a one inch long 1/8" end mill was needed to cleanup the flat areas between a couple closely spaced fillets. The block's reflective surfaces not only make photography difficult, but minor surface defects are tough to see. The eighth inch cutter left some chatter in the surface finish that will have to wait to be cleaned up until after the block is bead blasted to a satin finish.

I recently junked my Trico micro-drop coolant dispensers and replaced them with Fog Busters. The proprietary Trico hoses are ridiculously expensive and require yearly replacement. My coolant of choice for machining aluminum is WD-40, and it worked well in the Trico units, but I could not get the Fog Busters to reliably flow it. I tried every combination of air pressure and unit mounting height and even magnetically stirred the reservoir, but the flow rate knob had to be continuously tweaked while running.

I'm now using Kool Mist which flows well in the Fog Busters, but the sticky surfaces left behind on my machines and tooling is taking some getting used to. Another thing I've noticed on 7075 is splotchy staining that's reminiscent of silver tarnish. It was particularly noticeable on the workpiece surface that was clamped against the cast iron angle table. There's no apparent surface damage, but white Scotch Brite isn't quite abrasive enough to remove it. - Terry


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gbritnell

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Wonderful work Terry! Are you keeping any kind of log on the hours? This of course would include design time. Although I never included oil galleries in part models I could send you a layout of them if you like.
 

mayhugh1

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Wonderful work Terry! Are you keeping any kind of log on the hours? This of course would include design time. Although I never included oil galleries in part models I could send you a layout of them if you like.
George,
I never tracked the hours spent on design, but I have kept tabs on some of the machining times. Yes, I'd like to see your oil passage sketches and could also use your water pump model. Right now, I'm recovering from surgery on my right eye, and everything is pretty blurry. Hopefully that's temporary. - Terry
 
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George,
I never tracked the hours spent on design, but I have kept tabs on some of the machining times. Yes, I'd like to see your oil passage sketches and also use your water pump model. Right now, I'm recovering from surgery on my right eye, and everything is pretty blurry. Hopefully that's temporary. - Terry
Best wishes for a positive and speedy recovery from both of your eye surgeries, Terry!!
 

e.picler

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Congratulations Terry!
Again another extraordinary project.
I wish you have a prompt recovery from your eye problem.

What cutting speed and RPM do you use on your Waterline strategies machining? I use the same CAM as you.

Edi
 

mayhugh1

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Ed,
Thanks. For roughing with a 3/8" flat cutter I use 5000 rpm at 20 ipm. For roughing or finishing with a 1/4" flat cutter I use 5000 rpm at 15 ipm. For finishing with a 1/4" ball cutter I use 5000 rpm at 15 ipm and a scallop height of .0003". - Terry

edit ... I should add that I'm using 4 flute cutters.
 
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mayhugh1

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Workpiece material covering the deck surfaces was faced to within .010" of their finished values in order to improve machining access to the lifter valley. The remaining material will be removed later when the cylinder liners are installed.

I'd been looking forward to the lifter valley machining ever since my modeling-palooza last summer. It soaked up lots of hours of effort, and after several frustrating do-overs I finally had something I could live with. Thanks to my constraint that it had to be machinable with a quarter inch ball cutter, I wound up with yet another amateurish and fragile design that wouldn't tolerate even minor design changes.

Shortly after finishing its CAD, I learned through a correspondence with George that the lifter bores aren't parallel to the cylinder bores as I had assumed. Instead, there's some 3.5 degrees difference between them. Correcting the lifter bosses would have required starting over again. The error didn't sound significant, and so I decided to continue on with what I had. Later, when more of the engine's modeling was complete and I had a virtual assembly, I discovered the lifter angles had been necessary to avoid conflicts between the push rods and rocker arms. My workaround will be to angle the bores in the existing bosses by two degrees and make up the difference with modifications to the heads.

The lifter valley's total machined surface is now probably the most complex thing I've ever machined, and I was relieved when it was finally done. The finishing pass was over 150K blocks of g-code, and for some reason crashed Mach3 with a mysterious 'emergency shutdown detected' error every time it was loaded under my Tormach profile. I still don't understand why since my computer indicated nearly half of its three gigabytes was still available after the code was loaded. Dividing the operation into two half-size overlapping operations seemed to solve the problem though. Somehow it seems a shame to hide that seven hours of machining under the intake manifold.

One of the last steps in the lifter valley machining was to spot drill shallow divots in the tops of the lifter bosses that will used as sanity checks when the angle table is readjusted and the lifter bores drilled. This won't happen for a while though. I just had my first eye surgery, and it looks like it will be several days before its vision returns. - Terry

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johnmcc69

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Very nice! That must have been "Fun" to model it up.

A shaky finger on the "Cycle start" button?

Wishing you a speedy recovery!

John
 

e.picler

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Thanks. For roughing with a 3/8" flat cutter I use 5000 rpm at 20 ipm. For roughing or finishing with a 1/4" flat cutter I use 5000 rpm at 15 ipm. For finishing with a 1/4" ball cutter I use 5000 rpm at 15 ipm and a scallop height of .0003". - Terry
Hi Terry! Thanks for your information. What is the "Scallop Height" My SprutCam is in Portuguese.

Thanks,
Edi
 

mayhugh1

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Hi Terry! Thanks for your information. What is the "Scallop Height" My SprutCam is in Portuguese.

Thanks,
Edi
On the parameters page of the water line operation there is an option for setting the scallop height. When you select this, the software will compute the machining levels of the operation's toolpaths so a 'ridge' no higher than what specified by the 'scallop height' is left in the surface finish. This is an alternative to just specifying the distance between steps which one would likely do for a waterline roughing operation. Setting this height to a tiny value will produce a smooth and shiny surface with a waterline finishing operation. Of course, the disadvantage is a longer machining time. Depending upon the slope angle of the features to be mavhined, .001" can produce a nice finish especially if the surface will be bead blasted. I don't know why I chose .0003". I guess I was trying to see how far I could push things, but more likely I was just showing off :)>) - Terry
 
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Basil

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Hi Terry
I'm working on my big block Chevy program. I would like to know your opinion on flat plane verses cross plane cranks on these engines. I am mainly concerned with the finished sound of the engine as I am sure most of us want to also replicate this. The full size units definitely do sound more like a V8 with a traditional cross plane. What was your plan on the 289? Thanks
 
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mayhugh1

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Basil,
I expect that a manifold that keeps the flow rate up as high as possible would be best in a model engine. I plan on using a single plane manifold though to keep the machining reasonable. I've found the things that affect the engine's sound the most to be the camshaft and the exhaust pipes. Opening up the exhaust valves early can have a significant effect on the loudness. - Terry
 

mayhugh1

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Sorry Terry, we appear to be at crossplanes, lol.
I was referring to the crankshaft configuration.
Cheers
I apologize. I could barely make out your post. A week after my right eye surgery I'm still essentially blind in that eye except for a bright glare that affects my total vision. Reading is such a hassle that I've become a couch potato in front if the tv. Needless to say progress on the 289 has come to a halt.

To answer your actual question, though, I'll be using a cross plane crank, but I don't know enough about the two types to intelligently comment on your question. Regards. - Terry
 

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