All I really did this week was to tune up my lathe a bit, like I said I would, and decided what part to make next. The engine has a mounting plate that looks like a good, quick job for the mill. Depending on how pretty I want to make it.
This is a rendering of the CAD model I made from the drawings that the designer sells. The long dimension is 6.00 inches, the short side is 2.00 and the height is 1.00. I've rough cut a piece of 6" wide by 1" thick plate that will be my starting point.
You might not have noticed at first glance that it's not symmetrical left to right. That big hole is not centered 3.00" inches from either side. It's a little farther to the right than on the centerline (3.057"). Since what the designer is selling is the information needed to make these, I think it violates fair use to show detailed drawings, but just like I wiped most of the dimensions off the drawings of the crankshaft, I've wiped most of them off this part.
Just as the overall part is left/right asymmetric, that means those two angled top faces aren't the same angles on the left and the right. The right side in this view is about 0.5 degree steeper than the left.
I could run that through my CAM program to make tool paths to cut it and I'm sure it would do that, but those flat faces would be full of stair steps. If I was doing this manually, I think I'd put the raw stock on a sine bar so that I just cut the part sticking up away. Since I don't have a sine bar, I used the concept behind the sine bar while doing the CNC conversion to my mill and showed the setup here.
This piece has a smaller square that had one side cut off already screwed to it, but note the bigger rectangle that the square piece is attached to. With that piece tilted 16 degrees up, the blue Sharpie mark on the right is parallel to the table, and "all you gotta do" is make a straight cut along that line to cut the back piece to the angle. In this case, the mill was fully manual and I just turned the X-axis crank to cut it. I cut most of the rough stock off on the bandsaw, leaving the mill just to get the final surface.
I could put this blank at an angle like that, one side on the table (or on a spacer as in the photo) the other clamped in the vise, and just enter CNC moves of the X axis.
In addition to those two angled faces, there's a recessed area on the bottom of the drawing (see the dimensioned drawing). Those things are the puzzles in this part. The marked radius on the recessed portion, 0.313" is 5/16", which means it gets cut with something that has diameter of twice 5/16 or 5/8". I don't have a way to cut a 2" deep hole that's 5/8" diameter. I could get a ball end cutter and cut this on the bottom of the piece along the 2" dimension, but without checking, I'm betting a 5/8" diameter ball end mill is more $$ than I would prefer to spend. On the other hand, it's not an important surface; it's never seen during use. This is a place where stair steps on a cut approximated by the CAM program wouldn't bother me. Much. Probably.
Or, since this is just a mount, you could have it in an hour by using your 3D printer...
ReplyDeleteI have to admit it never crossed my mind. Strange as that may seem. The first step to making it either way is to create the solid model I show at the top. The second step is to save it in .STL format, which I have also done. Might be worth spending some filament on.
DeleteJust to see if it works.
I haven't bought a 3D printer...yet. The phase I am in has me looking at everything to find stuff I could make with one. So far, there hasn't been enough suggesting itself to justify the cost. This thing you show here seems readymade for plastic, though.
DeleteThe easy answer is to say walk through a Walmart and look at what's made of plastic. You can print any of it, with considerations to size, and other design details. Maybe you could take a tour of Thingiverse where people post things they've designed as open source designs. Download and print.
Deletehttps://www.thingiverse.com/
Of course, designing your own plastic stuff is an option.
Then there's "lost PLA casting" which makes metal parts from 3D prints if you're handy with torches and various casting techniques. I'm seeing lots of that on the forums.
Completely off topic. SiG, you once gave a formulation of common household chemicals that effectively removes rust. I have an axe that has been setting in storage for a few years that developed a nice coat of rust. Yes, I could wire brush it off but chemicals should get down in any scratches doing the removal much better. If you remember the post you put that in, I would appreciate a link to it.
ReplyDeleteI remember it vividly because of how surprised I was. The recipe was common white vinegar, the couple of dollars/gallon kind, with salt in it. It was a tool steel cylinder about 2" thick. The posting is from the flywheel for my previous engine. It contains a link to Wiki How, but it's pretty widely available. I did it on another piece of steel for the 1 by 1, and it worked on that alloy, too.
Delete