MadModder

Gallery, Projects and General => Neat Stuff => Topic started by: andyf on September 21, 2011, 08:19:25 AM

Title: Make your own Allen screws.
Post by: andyf on September 21, 2011, 08:19:25 AM

My inventive pal Mike - he of the swing-up toolholder - has developed a tool for rotary broaching of triangular, square, pentagonal, hexagonal etc holes in the lathe. Simple and cheap; we like cheap, don't we?  :thumbup:

 http://mikesworkshop.weebly.com/rotary-broaching.html

Andy

Title: Re: Make your own Allen screws.
Post by: Bernd on September 21, 2011, 08:37:37 AM

Thanks for the link Andy.  :thumbup:

I remember doing hex broach work at the place I used to work at. Only difference was we used large turret lathes and under power.

Bernd

Title: Re: Make your own Allen screws.
Post by: andyf on September 21, 2011, 09:01:29 AM

Just for clarification, Bernd, Mike's broach is for use under power, with the spindle turning. Contact with the workpiece causes the cutter to rotate in its holder. As the tool is at a very slight angle, each successive corner takes a little peck at the workpiece as it rolls into contact. You will have worked that out for yourself, but responses on another forum seem to show some folk thinkinking the tool is simply being rammed into a stationary workpiece, gouging out the corners as it goes in

I must ask Mike whether he feeds the tool in under power, or cranks the carriage along by hand.

Andy
 

Title: Re: Make your own Allen screws.
Post by: AdeV on September 21, 2011, 10:02:47 AM

From the description, it sounds like he hand-feeds the carriage in (using the tailstock for extra "push" if required).

I like the way he used his toolpost holder as both a toolholder AND a jig to make the cutters. Clever stuff!  :smart:

Title: Re: Make your own Allen screws.
Post by: Bernd on September 21, 2011, 02:31:47 PM

Andy,

The turret lathes I worked on had 50hp motors on them. There was two ways of doing the broach. One being using the power feed on the turret or using the weight of the turret to broach manually. So both ways were used, power and manual. There were also speical holders the let the broach sort of wobble. Same effect as you mentioned by being off center slightly.

Bernd

Title: Re: Make your own Allen screws.
Post by: dickda1 on September 21, 2011, 02:57:10 PM

I like the idea, but wonder about the strength of these fasteners.
-Dick

Title: Re: Make your own Allen screws.
Post by: Rob.Wilson on September 21, 2011, 04:21:21 PM

 :thumbup: Nice one  :clap: :clap: :clap:

I had a play at making at tailstock mounted rota broach a few months ago ,,,,,,,,,, needs a bit of refinement  :smart:  worked ok on mild steel ,ally and brass ,,,,,, no good for stainless  :doh:
(http://www.nam-engineering.com/cm/albums/userpics/10002/normal_Rotary%20Broaching%20Head2.jpg)
(http://www.nam-engineering.com/cm/albums/userpics/10002/normal_Rotary%20Broaching%20Head.jpg)

Rob

Title: Re: Make your own Allen screws.
Post by: andyf on September 28, 2011, 05:12:38 PM

 :update: for anyone interested in the rotary broach:

Mike has added refinements to his device as shown on his web page
 http://mikesworkshop.weebly.com/rotary-broaching.html , at the bottom of which is a link to a video of it in action.

Andy