Group Project: Dividing Head - The Build

Thanks to my wife, Lena, I finally got all the bases squared up today. Floor is still covered in a layer of tiny knives. It took quite a lot of manipulating to get the setup right and rigid enough that I can lay a square on it and get even light through all the way across.

Unfortunately, I am not going to be able to hold the dimension of .720" on the wall thickness. By the time I get it cleaned up and then square, I'm down to less than .700" on several of the pieces, and I still have the inside face to clean up. I'll most definitely keep the dimension between the inside faces of the two sides, and the Auxiliary base doesn't need to be cleaned up at all. I think the only change this is going to necessitate is that the shoulder on the trunnion on the main base side be only .600" thick. Maybe .575" for good measure. Not sure how thin we can make it and still have room for the register holes.

Other than that, the pace should be picking up now. I've got the tools made, and spent the last week getting the mill dial in much better. Used the grinding wheel to the table flatter, and trammed it better. Getting the outside faces square is going to be the hardest part of the whole process, I think. I have something to register on for all the other cuts.
 
I got two of the main bases cleaned up on both sides of the vertical part. One is .644", and the other is .646" thick. I would have got them all done tonight, but . . . you know. . . honeydew. I should be able to get all the rest of them to that point tomorrow, and will probably get started on the last cleanup passes on the bottom. Like I said, it's going fast now because I have clean, square surfaces to register against. I've even set the down-stop on the mill so that I get them all the same thickness. It's the first time I've ever used the down-stop, 'cause it is the first time I've ever made 8 of the same thing.
 
It sucks when you're too clever by half.

I dialed the vice in, then got it and the parallels perfectly clean. Ran the dial indicator across the top, and it was off by .0005". I know. I've got a bit aluminum foil right here. I'll slide that under the low end, and I'll have it perfectly flat. I'll be a hero.

Get it set up, and face off one of the Main Base and then take a measurement. Another ten thou to hit my mark. Just on a lark, I measured the other side. Weird. It was off by .005". Measured again. It was still off. Grabbed another set of calipers. Still off by .005". I literally pulled out the micrometer, and, believe it or not, it didn't change anything, either.

What followed was a couple hours of trying to determine what was wrong with my mill. Finally, I just gave up and came inside, when it hit me to try turning the piece around in the vice and face it off in the opposite direction. I hadn't release the quill lock, so it was in the exact same place. Took a pass, and it only cut on one side. The side with the foil.

Hmm? It was in tight. Both parallels were snug. So, I took the piece out and ran my indicator across the top of the parallels. It slowly climbed about .005" as I neared the foil side. Turns out, aluminum foil isn't .0005" like I thought. Especially when it is crinkled. And doubled over. And, it won't correct a low spot when you put it under the high spot. I guess if you're going to go stupid, there is no point in going halfway.

I thought I was going to face off the rest of the Main Bases tonight. Instead, I went to class. I learned to check my setup after the setup is COMPLETE. And if I make a change to it, check the setup again.
 
I’ve been messing around with getting the trunions made. Planning on doing it all in one go. Only thing holding me up at the moment is the engraving.

I’m having trouble with getting suitable tools paths but I think I have a way figured out.

As far as the indexing plates go I need to just drop the money on material seems like it’s going to be somewhat expensive.
 
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Can the plates be made of aluminum?

I just took a batch of old computer hard disks apart. The platters are perfectly flat. I mean they have to just about need to be pried from a surface plate. They'd make perfect indexing plates if enough could be had.
 
Shotgun said:
Can the plates be made of aluminum?

I just took a batch of old computer hard disks apart. The platters are perfectly flat. I mean they have to just about need to be pried from a surface plate. They'd make perfect indexing plates if enough could be had.
Click to expand...
What are HD discs made of?
Robert
 
The ones I have are 3.5" and are made of aluminum. I only have about 10 of them, though.
 
Diameter of the index plates is 5.0". There is a guy on eBay who sells 5" discs. I will ask him about a volume discount.
Robert
 
rwm said:
Diameter of the index plates is 5.0". There is a guy on eBay who sells 5" discs. I will ask him about a volume discount.
Robert
Click to expand...

If they have a 1/2 thick plate that would be easier for me to get it nice and flat.

I can hold on to just a little and face then clean up the outside then flip it and face away the excess to get a nice looking plate and then drill the holes
 
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