Group Project: Dividing Head - The Build

[rwm]

Line boring is a great idea and might be less work than making the adapter for the boring bar? Still the boring bar might be easier to adjust to hit the number.
Robert

 

[ErichKeane]

Line boring is a great idea and might be less work than making the adapter for the boring bar? Still the boring bar might be easier to adjust to hit the number.
Robert

I still can't envision the intent here that wouldn't end up hitting somewhere, but I trust Shotgun knows what he's doing there

 

[Shotgun]

Thanks for the video, @ErichKeane

The advantage of the line boring seems to be that you'll have support on both ends to enhance rigidity (?)

I've got a solid 3" of MT3 buried in the headstock, that transitions into just under 2.5" stock. Do you guys think it can get much more rigid than that? It would seem to me that a floating support on ball bearings (or a cap nut in my case) would be less rigid.

 

[ErichKeane]

Thanks for the video, @ErichKeane

The advantage of the line boring seems to be that you'll have support on both ends to enhance rigidity (?)

I've got a solid 3" of MT3 buried in the headstock, that transitions into just under 2.5" stock. Do you guys think it can get much more rigid than that? It would seem to me that a floating support on ball bearings (or a cap nut in my case) would be less rigid.

It IS the enhanced rigidity, though the biggest advantage is the length/depth of cut. It would be insane to try a 1/2" deep drill operation 20" long, but with an appropriate length line-boring setup, thats no big deal.

I don't have a good idea of what you mean by the adapter for the boring head... I just can't visualize what it looks like in a way that you don't have clearance issues.

Also, line boring is cooler than normal boring

 

[Shotgun]

I still can't envision the intent here that wouldn't end up hitting somewhere, but I trust Shotgun knows what he's doing there

Look back at the last pictures I posted. The "shank" is smaller that the hole saw, which is the intended size of the hole. The base is 5" across. I have about 8" between the tip of the saw teeth to the headstock. I bolt the base down to my cross slide (1), indicate it square (2), and feed it toward the headstock. Then I put a large flycutter in and face the side of the base (3).

1 - I have yet to cut a mounting plate
2 - The bottom will be squared up on the mill before this step
3 - The mounting plate will be indicated in, so the facing operation should make the base square enough that it'll be usable as an angle plate.

 

[Shotgun]

I don't have a good idea of what you mean by the adapter for the boring head... I just can't visualize what it looks like in a way that you don't have clearance issues.

My boring head is threaded. Something like 7/8"x16, I think. I'd just need to thread a part that would bolt up the end of the shaft I pictured earlier in place of the hole saw.

 

[ErichKeane]

Then I put a large flycutter in and face the side of the base (3).

Ah, I think this is the part I was missing. A little tough to dial your final dimension in, but would work. I thought you were going to use a boring head, where the 'shank' of the tools are often as wide as the cutter when you get far enough out. The heads themselves are necessarily 'wider' than the cutter can go out, so I would expect that is the limiting factor...

 

[Shotgun]

Ah, I think this is the part I was missing. A little tough to dial your final dimension in, but would work. I thought you were going to use a boring head, where the 'shank' of the tools are often as wide as the cutter when you get far enough out. The heads themselves are necessarily 'wider' than the cutter can go out, so I would expect that is the limiting factor...

I think the plan now is to do the finish cut with boring head mounted on the shaft I made for the hole saw. I'll put the boring bar in the hole that comes out the side of the boring head. I have a small (2") boring head, so it'll be able to pass through the rough cut hole, and need less than 1/4" of boring bar sticking out. I think I'd need to buy a larger lathe or mill to get more rigid.

 

[ErichKeane]

I think the plan now is to do the finish cut with boring head mounted on the shaft I made for the hole saw. I'll put the boring bar in the hole that comes out the side of the boring head. I have a small (2") boring head, so it'll be able to pass through the rough cut hole, and need less than 1/4" of boring bar sticking out. I think I'd need to buy a larger lathe or mill to get more rigid.

AHHAH! That is what I was missing! I had forgotten boring heads had that out the side functionality. I see how it could work now. Thanks for being patient with my brain-farts

 

[rwm]

That sounds like a good plan. Just curious why you wouldn't face the side of the base on the mill?
Robert