jig making

[DerHammer]

I was wondering if any of you experienced fabricators out there could give me any advice on the best way to create a jig for a production run. Heres the story, its kinda long. I have a part, which will take about 4 or 5 different tool changes to create but I don't want to be forced to run through each stage one full part at a time (obviously because its slow, and will probably ware out my already much too old draw bar). Instead I would prefer to cut say... 10 parts, then change tools and recycle them though and repeat for the next tool and so on. Also, I'm working with aluminum plate about an inch thick to help visualize this.

What I have discovered so far is how difficult it is to remove a part half way though its creation and then put it back for the next stage say to within 2 or 3 thousandths of where it began in both the X and Y directions. I keep thinking that I should go with rails to keep everything aligned, but my parts require outer profiling, which means my outer dimensions change. Since this is the case, its pretty much is forcing me to bolt down through the part since I cant profile through clamps very well right. This is all fine and dandy but heres the real problem. Even with the exact same hole pattern drilled in my jig exactly matching the pattern of my part, drilled with the same drill bit dia, It still aligns sloppy. It looks real close to the naked eye but I'm not convinced its exact because I can wiggle the part while on the jig even when pinned together with the drill bit used to drill them both.

I know I'm not the first person to attempt this , so if anybody has any good tip to create a system like this, where one can take a part out at any stage of the run and throw it right back in at the exact same position (within reason of course) it would be greatly appreciated.

[laka]

You could maybe try reaming some holes and use dowel pins.

[djr76]

What about milling out soft jaws to the profile of the part. Do first operation like your doing and run all parts. Then mill out soft jaws to contour, then do second operation. If you have multiple vises and running this on a machining center, you can even set it up in multiple stages on one setup to machine from raw material->finish part in one cycle.

[rounsy222]

I personlly would create a subplate that you can position dowel pins and clamps as needed for each step. Depending on the size of the part and your machine you could possibly do multiple steps and zero points on the fixture at the same time with just one tool chucked up. Utilize any holes or finished sides you have. Best of luck.

[bbrreid]

I agree with rounsy222 , if the job comes around again you have the complete setup with the subplate

[DerHammer]

thanks for the input. Since posting this, I found out that my vice is indeed large enough to hold the part because I never realized that my vice jaws were movable. Now, I'm trying to figure out a way to utilize the vice since its so much faster vs bolting in and out. My plate blanks will be around 12"x12", so their fairly large. I'm thinking a good work stop and edge finder might actually be the best solution but I'm kinda on the fence, what do you guy think?