# Another rotary broach project



## melsdad (Jan 24, 2014)

I am in the process of making my own rotary broaching tool. There have been a few threads recently on the subject and that was my motivation to get this project going. 

All the parts of made of S7 tool steel right out of the scrap bin. Once I am sure all works well and no tuning needs to be done I will heat treat all the parts and they will last forever! The broaches I make will be made of M2 or M4 material. The tool will also accommodate broaches from other sources with a .500" shank. 

First project up will be a pentagon shape with an I.C. of .745". 

Sorry I didn't get any pictures of the parts being machined in the lathe. I know how everyone loves those photos. I will be sure to take some action photos of the milling operations though.

*The body of the tool that houses the bearings and the broach nest.*





*The broach nest*





sent from my hand held hickymajig


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## melsdad (Jan 24, 2014)

_*The tail piece that will have the 1° angle milled on the face.*_


_*All the pieces.*_


_*This is basically what it will look like when complete. *_




_*That is a 12mm hex broach in the nest.....

Stay tuned for the milling!
*_


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## Calibre (Jan 24, 2014)

I have been wanting to build one of these for years. Will be eagerly awaiting further updates!

Please include dimensions and part numbers.


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## markknx (Jan 24, 2014)

melsdad,How are you using this? In the mill or lathe? If in the lathe how are you holding it?Thanks,Mark


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## melsdad (Jan 24, 2014)

It will be able to be used in both the mill and lathe. The tail is .750" diameter to fit in the mill, and large drill chuck in the lathe tailstock

sent from my hand held hickymajig


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## melsdad (Jan 24, 2014)

Calibre I will post drawings and part numbers for the bearings.

sent from my hand held hickymajig


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## lotechman (Jan 24, 2014)

Great to see.  I was given several thrust bearing assemblies from a bottling line thirty years ago.   I now have a use for them:')


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## melsdad (Jan 27, 2014)

I just got a 10" bison 3 jaw chuck for my troyke 15" rotary table off of ebay. Once i get that delivered and set-up I will continue on this project. I am still on the look out for a tail stock for the table just to have for future projects.


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## Kevinb71 (Jan 27, 2014)

Nice Looking work Brian! Looking forward to The diagrams. What registers the tailpiece with the broach holder bearing housing?


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## melsdad (Jan 27, 2014)

The only real duty of the tail piece is retain the broach nest in the body. There is only .005 linear movement of the nest between the thrust washer and the retaining washer of the nest. The two roller bearings hold the nest concentric within the body. 

Hopefully this assembly drawing will clear things up. Wish I could print in color

View attachment Rotary Broach Assembly.pdf


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## melsdad (Jan 27, 2014)

McMaster Carr bearing part numbers.

Roller bearings:   2342K188    2 required

Thrust bearings:  5909K12     1 required

Thrust bearing washers:  5909K84     2 required


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## markknx (Jan 27, 2014)

I'm starting to get how it goes together the thrust bearing goes in then the two roller bearing sit on the lip, next adding the broach nest, and secure all that in with retaining screw and washer. did I get that part right?What I am not getting is how the main body attaches to the tail end. Is that what the holes in the Drawing are for? The gap is just to illistrate the slight slope of the tail ends face?ThanksMark


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## melsdad (Jan 28, 2014)

I just realized there are 2 pdf files posted in the link above. Use the one that is just text and not in the window. I have parts of the assembly called out there.

If someone can help me delete the 123 k.b. file that would be great!


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## Calibre (Jan 28, 2014)

Melsdad,
I do ever so much appreciate you giving out the prints to your project. It helps us guys that don't have a lot of time for R&D!

Thanks!


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## melsdad (Jan 28, 2014)

markknx said:


> I'm starting to get how it goes together the thrust bearing goes in then the two roller bearing sit on the lip, next adding the broach nest, and secure all that in with retaining screw and washer. did I get that part right?What I am not getting is how the main body attaches to the tail end. Is that what the holes in the Drawing are for? The gap is just to illistrate the slight slope of the tail ends face?ThanksMark



Sorry for the late response Mark, don't know how I missed it. 

There will be threaded studs attached to the tail and nuts and washers holding the nest body in place. The 10-32 tapped holes that leed into these bolt holes are for adjusting concentricity.


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## markknx (Jan 29, 2014)

Thanks Brian, Look foward to hearing/seeing more. I made a simple broach for my mill But do not have one for the mill. this could be the way to go.Mark


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## melsdad (Jan 29, 2014)

Calibre said:


> Melsdad,
> I do ever so much appreciate you giving out the prints to your project. It helps us guys that don't have a lot of time for R&D!
> 
> Thanks!



Your very welcome calibre! I am going over the individual part drawings and will post them soon.

sent from my hand held hickymajig


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## rgallus (Jan 30, 2014)

A very nice project Brian.  I started to make a broach for my lathe but never completed it.  I like you design that will work in both the mill and lathe.  I will be waiting to see future updates and a dimensioned drawing.

Thank you for your hard work.


Rick


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