# 2" short boring head with 15 deg dovetail



## burgermeister (Feb 9, 2015)

A 2" boring head that's a bit shorter than the generally available ones.  It allows the boring bar to sit right below the mounting arbor threads.  Handy on a 5820 without a spacer block!  The downside is the travel is limited since the boring bar and leadscrew cannot occupy the same space at the same time.  I used a 15 degree dovetail angle.


I milled the angles in the head with a 1/4" endmill and the head trammed to 15 deg via tramming tool & sine bar.  I finished the corners with a shopmade cutter that was maybe 15.5 deg.  The boring bar holder was also done with the head trammed, but in this case I used a 1/2" endmill to rough the angle, and then a fly cutter for a final pass.  There are 2 boring bar clamp screws - a short one for the outside hole, and a long one (with a brass insert) for the inside hole.  Locking is via a 3/8" setscrew and a small brass "shoe".  I used 1/4" drill rod to measure the dovetails, flycutting the bar holder to fit the body, and it actually worked - there is no slop at all between the 2 pieces.  Probably just got lucky ...

The leadscrew is a 4-part press fit assembly.  Not sure what to call all of the parts ... the inside bearing goes through the dial all the way to the outside.  The dial is press-fit on.  It's bored on the outside for the head of an allen bolt, also press fit in, and on the inside for a 1/4" rod threaded 40 TPI.

The "keeper" is less than pretty inside.  It was the last piece, and I wanted to get done, which resulted in lots of backlash, some corrective welding & remachining, and a few hours longer.  I keep learning that there are few worthwhile shortcuts in metalworking! 


Overall, I like the result.  Not a lot of parts, easy to clean & disassemble, low space requirements.  If I had to do it again, I'd make the "keeper" taller so it would protect the dial from banging into things.  I'm not terribly comfortable with the unsupported overhang of the dial.


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## randyc (Feb 9, 2015)

That is way cool !  Impressive design and impressive workmanship, thank you for posting it.  How did you mark the dial ?


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## Billh50 (Feb 9, 2015)

Do you have any plans for the boring head?


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## burgermeister (Feb 10, 2015)

Sorry, no plans... I had a rough sketch of where everything would end up with rough dimensions, but I've apparently pitched it.  

The bar holder is 1" at its base, and however high it can be and still have 3/8" boring bar holes drilled in its center.  The dovetail in the body is about 5/8 deep.  Mounting threads are also 5/8 deep, making the head 2" dia. by 1.25 high, maybe a little more.  Leadscrew is 1/4-40, the clamp setscrews are 3/8-16, and the 4 keeper screws are 8-32.  Everything is centered.  There isn't much more to it than that ...

I marked the dial by pressing it on a temporary arbor and sticking it in a tilting dividing head mounted on the mill.  I made an engraving tool, chucked in the spindle, and used the x-axis feed to scribe the lines.


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## randyc (Feb 10, 2015)

And the numbers are stamped in the dividing head ?  I'm very interested in this because I have a project that requires very nice, precise marking.  I've been experimenting with electrolysis etching producing _raised_ lettering with fairly good results but always looking for alternatives.









This is a greatly enlarged photo of a small steel item.  The letters are actually 3/32 high as I recall.  I dunno what's up with that copper tint - it must have been an artifact of the lighting because the part looks like normal steel -


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## burgermeister (Feb 10, 2015)

Oh no, the numbers are just 1/16" number punches used by eyeball in an arbor press.  They're not the most pretty or precise in person - some day I've got to come up with some sort of jig for that.  The dividing head was just for the scribed lines.

For something precise, I'd think some sort of fairly strong pantograph could be used to scribe nice small letters from large computer generated printouts?  That actually sounds neat, I'll have to check if fleabay carries such things at reasonable prices ...

Your electrolysis etching setup looks really cool!


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## compsurge (Feb 10, 2015)

Well done! It looks like a top quality piece when it's all sealed up.

What material did you use?


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## randyc (Feb 10, 2015)

burgermeister said:


> Oh no, the numbers are just 1/16" number punches used by eyeball in an arbor press.  They're not the most pretty or precise in person - some day I've got to come up with some sort of jig for that.  The dividing head was just for the scribed lines.
> 
> For something precise, I'd think some sort of fairly strong pantograph could be used to scribe nice small letters from large computer generated printouts?  That actually sounds neat, I'll have to check if fleabay carries such things at reasonable prices ...
> 
> Your electrolysis etching setup looks really cool!



Thanks for the explanation; I've posed questions regarding precision marking on the internet and most explanations have involved complex setups !  I tried stamps held in the quill of my vertical mill, spacing the letters with the X axis handwheel but the various letters required different stamping pressures.  Didn't come out all that well -

The electrolysis process is stupid simple but creating the letter mask is not easy.  For a young person, no problem, but my hands are too shaky to apply the lettering (transfer letters).


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## Billh50 (Feb 11, 2015)

I saw a lathe mounted jig for punching. I thought it was on here somewhere but not sure. Could have been on one of the other sites I travel. He used a degree wheel mounted on lathe for both skiving the marks and stamping the numbers.


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## Billh50 (Feb 11, 2015)

Randy,
 for sraight line characters in flat metal they make gang stamp sets. I used to use them for marking the plates on slip ring control boxes for tank turrets. Punched all the charactors in a straight line and for location I used a square magnet and shims.


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## John Hasler (Feb 11, 2015)

Billh50 said:


> I saw a lathe mounted jig for punching. I thought it was on here somewhere but not sure. Could have been on one of the other sites I travel. He used a degree wheel mounted on lathe for both skiving the marks and stamping the numbers.



I remember that too.  It was here.


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## iron man (Feb 11, 2015)

randyc said:


> And the numbers are stamped in the dividing head ?  I'm very interested in this because I have a project that requires very nice, precise marking.  I've been experimenting with electrolysis etching producing _raised_ lettering with fairly good results but always looking for alternatives.
> 
> 
> 
> ...



 That is so cool you need to start a new thread on this. Ray


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## Billh50 (Feb 11, 2015)

found the thread with the stamping head.

http://www.hobby-machinist.com/showthread.php/30586-4-inch-manual-rotary-table?highlight=stamping


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## randyc (Feb 11, 2015)

Billh50 said:


> Randy,
> for sraight line characters in flat metal they make gang stamp sets. I used to use them for marking the plates on slip ring control boxes for tank turrets. Punched all the charactors in a straight line and for location I used a square magnet and shims.



Yes, that's exactly what I used, borrowed from a buddy who runs a one-man job shop.  But because each character has a different length of perimeter (the total length of all segments of the character), I found that some letters stamped heavier than others (the stamping holder was set up in a vertical mill).  The result was not appropriate for my application, which I'll post shortly.


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## barnett (Feb 11, 2015)

I would be interested in some more info about the electrolysis etching too, Does it just work on steel ?


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## Billh50 (Feb 11, 2015)

the one I used must have been of better quality because all the characters stamped the same depth.


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## randyc (Feb 11, 2015)

Billh50 said:


> the one I used must have been of better quality because all the characters stamped the same depth.



On pre-hard 4140 ?


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