Hello All! I have an update on my plate progress. This post is also a little long winded. I get that way sometimes.
As usual, my projects take a LOT more work than I originally imagine. I'm also not used to machining parts this large. In the 30 plus years I've been machining bits and pieces, most of my work has been small precision aluminum parts for some high-tech industry of some form. This project has also pushed the limits of my machines too. I ran out of table travel more than once on the mill. But all is good, I got creative, and I feel the plate is coming out nice. I've definitely got the back broken on this thing anyway. Below are some progress pics.
I drilled some holes to hold the plate down to some tooling blocks. This allowed me to rough off the two faces, and bring the edges to size. I did my facing and edging with a large roughing mill:
Finished milling the sides with a long four flute:
Then I dusted the faces with a single point fly-cutter to make them as flat as possible in preparation for the surface grinder:
Ready for some big holes!:
I used a regular hole saw to blank out the bore holes, then I rough bored each one to 3.95" in diameter. I'll leave the holes small at that rough size for now until I get the faces ground flat and smooth:
The plate as it sits now. Bore holes roughed in, edges to size, and faces almost flat (within a couple thou):
Next up, I'll dust the faces off with the surface grinder to make them nice and flat. The final thickness will end up being very close to 1.86”. I think that's a little thick for a plate, but better too thick than too thin. I'm going to also fab-up a couple handles to mount on the ends. I think it will make the plate much safer and easier to use. I also plan on putting a radius on all outside corners, 3/16” radius perhaps. Once all that's done, I'm going to stop progress on this thing until I get the block home. Here is the reason why:
I preformed very careful measurements of the cylinder heads that I have here, and I came up with what I think is the correct locations of all necessary holes. Originally I was going to measure the heads using the surface plate. Instead, I used the glass scale DRO on the milling machine to do the job. But, something strange came out of my measurements, strange to me anyway. It appears that every measurement I made, ended up being just a couple thou away from a rational number. Excuse my ignorance, but Chrysler seemed to place all bores and bolt hole locations to the nearest fractional inch location. Maybe this is what all the automakers did back in the day?
In the 30 plus years I've been cranking handles, I have very rarely made something to the nearest 16th or 32nd of an inch. I'm feeling like a big chicken about this, so I'm going to wait until I get my block home to measure it, and compare those numbers to my drawing. In the mean time, as promised, I'm including a preliminary drawing of my findings. The drawing below is what I think the dimensions of my torque plate will be, hole locations that is. PLEASE! DO NOT consider this a final drawing until I get a chance to measure my block. If someone here has these dimensions worked out already, I would appreciate it if you can chime in and confirm my findings.
The image below is too small to read the dimensions, but you can click the link to download a much bigger version of the drawing for easier viewing:http://www.uiwriter.com/tmp/platefinal2.jpg
You might have noticed, I included the dowel pin locations as well. I know that dowel pin holes are considered and option on most plates. I'm thinking of putting them in mine while I have it dialed in on the mill for final hole machining. One more thing, my plan is to take the plate bore holes to 4.090" in diameter. That should allow for a safe 0.060" overbore. If someone here thinks I can get away with less, just chime in.
Well, that's it for today. Take care all!
Horsepower determines how fast you hit the wall. Torque determines the size of the hole you make. Holzwarth's Law