# WHY Can't I buy a Centering Cone for the Mill?



## GT Mills (Jul 14, 2020)

I use a rotary table for cutting parts for my aircraft Yamaha aircraft engine conversion business far more often than a vise or fastening directly to the table.  I really do need a lathe, but I don't have room for one, I've outgrown the space I'm in long ago as it is.  

A work piece centering cone with, say, a 1/2" or 3/8" shank to fit into a mill collet would be SOOOO useful!  I woudl even buy an expensive R8 centering cone if there was one out there.  

For years I have been making do with a 60° chamfering tool, but that really isn't very good for this, I've actually done some slight damage to the tool using it with steel pieces, and it isn't nearly wide enough for larger parts.  

This seems like the stupidest, simplest thing in the world to me, and yes if I had a lathe I would knock out several in no time at all.  

Why can't I just buy one off the shelf for $20??!?!   Jeez.  Anyone feel like making me one out of 1018?  1/2" shank,  1-1/2" major dia.  & 60° cone.  

Thanks,

GT Mills, owner
Mohawk Aero Craft
Columbia, SC
Info@MohawkAeroCraft.com
www.MohawkAero.com


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## Nogoingback (Jul 14, 2020)

If this is something you need on an ongoing basis for your business, why not just pay a local machinist to make one for you?
It won't be 20 bucks, but it should be an easy job.


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## GT Mills (Jul 14, 2020)

I am old, cantankerous, and a fool.  I only need one.  

Yeah, I can call up Johnny Shop and have him make one for me for $100-$200, but good grief it just seems to me like SOMEBODY out there should have figured this out by now after a century and a half of tool making in the USA, and marketed such an animal on Ebay, MSCDirect, or Amazon for cripes sake. 

I have a 7-axis mill, I could make one myself by tilting the head and spinning a section of 1018 round bar around on the rotary table, but then I'll have to get the head straight again once I'm done.  

Oh, well...guess that's exactly what I'm going to do - after I get my 150HP, 595 lbs, hot rod gyrocopter back in the air again, first!  A man's got to have his priorities straight, after all.  I was workign on it when I came across this problem - AGAIN, for the umpteenth hundredth time.


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## Superburban (Jul 14, 2020)

How about grabbing an NMTB 30 tool holder for 1/2", chuck a 1/2 drill rod in it, and the other end of the rod into a 1/2 holder for your mill, sounds like it would be about what you want.

in other words, Use the NMTB 30 tool holder as a cone.


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## darkzero (Jul 14, 2020)

This centering cone that you want, is for quick centering for the rotary table or workpieces? IMO for centering the RT it may not work that well if the chamfer on the center hole of the RT is not machined accurately or gets boogered. But then again not sure the tolerances you need to keep.

Most RTs either have a straight hole or Morse Taper. I made a centering mandrel for my RT that has a MT center. I use it for quick center & gets me under 1 thou. With the same mandrel I made it so I can quickly center up a chuck on the RT also.

https://www.hobby-machinist.com/threads/rotary-table-quick-centering-mandrel.77392/

I know you said you don't have a lathe but you can do some turning work with your mill. Mount a lathe bit in the vise & the work piece in the spindle. Taper you could cut by tilting the head if your mill can. Not ideal but doable. EDIT: N/M, missed where you said you had a 7 axis mill, etc.


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## GT Mills (Jul 14, 2020)

darkzero said:


> This centering cone that you want, is for quick centering for the rotary table or workpieces? IMO for centering the RT it may not work that well if the chamfer on the center hole of the RT is not machined accurately or gets boogered. But then again not sure the tolerances you need to keep.
> 
> Most RTs either have a straight hole or Morse Taper. I made a centering mandrel for my RT that has a MT center. I use it for quick center & gets me under 1 thou. With the same mandrel I made it so I can quickly center up a chuck on the RT also.
> 
> ...




There's no need to mount a stationary lathe bit to cut a cone.  Tilt the head, turn the work piece on the RT, and make the cut with a standard mill end.  

I am not centering the RT, I am centering the work piece mounted in the RT.

The whole process of centering a workpiece in the RT should take 30 seconds with a cone stuck into the quill or collet, while it takes 30 minutes using a dial gauge.  Like I said, I can do some of these with a 60° chamfering mill end, but it is nor made for that, it is damaging the tool, and the tool is too small to be useful most of the time.  

It is  a terrible waste of time to have to resort to a dial gauge every time I need to center a workpiece when in fact all I need is a cone in the quill to both center it and hold it in place while I snug up the chucks.  A cone does it in one, simple, easy step since in most cases the tolerance does not need to be crazy accurate.  

The question is, "Why hasn't anyone marketed this simple tool - does no one on Earth use this very simple method to center a work piece that already has a hole in the center of it?"

I really can't believe that I need to make, or have made, a "special" $200 custom made tool just to do this.   It is a basic cone with a shaft for heaven's sake.  Why aren't they available for sale?  

We have centering drill ends, why not a simple, basic centering cone that is large enough to be useful up to 1-1/2" or 2", that goes into (A.) the R8 quill directly, or (B.) a collet?  

Does no one out there use a RT on a regular basis and _not _find that they could use one of these things frequently?  I can't believe it.


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## Winegrower (Jul 14, 2020)

Yes, I use a RT often.   I made what you describe on my lathe.


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## dpb (Jul 15, 2020)

Sent you a pm


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## ttabbal (Jul 15, 2020)

I suspect that most people who want one would fire up their lathe and make one. It would take a bit to knock 1" off of the diameter on a smaller lathe, but not so long as all that. It seems like most around here have a lathe as our gateway tool.  

To avoid having to tilt the mill, could you chuck up something like a plumb bob? 

If you want to farm it out, I'm sure someone here would make you one.


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## darkzero (Jul 15, 2020)

GT Mills said:


> The question is, "Why hasn't anyone marketed this simple tool - does no one on Earth use this very simple method to center a work piece that already has a hole in the center of it?"



I've made a couple small ones, 1/2 shank, & have used them for that purpose (not on the RT) but very rarely. Mine just sit there most of the time but they do come in handy sometimes.




They do make em, just not that common. Search for straight shank dead center.

https://www.ebay.com/itm/Small-Lath...234033?hash=item445ecc7631:g:B1QAAOSwrVpfDe2v



https://www.ebay.com/itm/Dead-Cente...824220?hash=item2888fab79c:g:RXQAAOSwkyRdzn3p



https://www.ebay.com/itm/RDGTOOLS-1...051584?hash=item52371e4f80:g:BN8AAOSwrkJe7IGz




Speaking of which, another option is to use a MT dead center with a R8 to MT adapter. Both can be bought for cheap.


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## KMoffett (Jul 15, 2020)

I made these for centering router template bushings. They are tubing finials for custom vehicle frames from Total Metal Innovations. Just added a 1/4" and 1/2" shafts.


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## Choiliefan (Jul 15, 2020)

I've used a coaxial indicator to center rotary table to spindle centerline many times.


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## mcostello (Jul 15, 2020)

Still need one. I made mine out of a used end mill.


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## mickri (Jul 15, 2020)

I got tired of dialing in a swivel base that I mount chucks on.  My swivel base now lives on the left side of the table and the mill vise is on the right.  I spent a goodly amount of time one day getting the swivel  base centered on the quill.  I then wrote down the X & Y coordinates including the direction to move the table to those coordinates and taped the coordinates to the head of the mill.   To center the swivel base to the quill all I have to do is move the table to the coordinates.  Without a chuck on the swivel base anything in the vise clears the swivel base.  And with a chuck on the swivel base anything in the chuck clears the vise.




I know someone is going mention losing everything when I move the head.  If I have to move the head I always use a DI to bring the head back to the same position.


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## Bi11Hudson (Jul 16, 2020)

What you are asking after is a "Bull Nose" center with a straight shank. I have a couple that I've finagled into a live center with a 1/2" tail stock chuck that swivels. Normally used for pipe or tubing, mine are only about 3" diameter for the large one. I don't do large work so don't need anything bigger. I have seen them above 12" in the Pipe Shop but don't know what the shank size was. It should be an "off the shelf" item under the name "Bull Nose Center".

.


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## pstemari (Aug 11, 2020)

Also, check Advanced Innovations in Austin. Joe Pie makes a centering tool for rotary table work that you can use with a DRO.

Sent from my Pixel XL using Tapatalk


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