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Gallery, Projects and General => How to's => Topic started by: ieezitin on February 05, 2017, 09:36:34 AM

Title: MAKING A SQUARE BROACH
Post by: ieezitin on February 05, 2017, 09:36:34 AM
Lads

My needs dictate a 3/16 square broach for a project my Personality dictates I am cheap I refuse to pay $70 for a broach Itís a case of making one or probably multiple while I have a set up.

I have been thinking out the machining steps and the two major ones I think are the angled relief behind the cutting edge and the taper angle from the pilot start down to the last cut edge, Having both a lathe and a mill I have choice on what machine to use as both will do the job yet both are equal in set up.

I am curious has anyone made broaches and how did they do it?

Anthony


Title: Re: MAKING A SQUARE BROACH
Post by: wheeltapper on February 05, 2017, 10:01:15 AM
Hi
Clickspring made one here.


hope this helps.
Roy.
Title: Re: MAKING A SQUARE BROACH
Post by: ieezitin on February 05, 2017, 10:13:01 AM
Yeah i have watched this excellent video...... if you notice he uses a Sherline lathe which is capable of rotating the headstock he set it 3 deg horizontally a nice feature to say the least, this angled cut would have to be done differently on a conventional set up.

Thanks for posting..

Anthony.
Title: Re: MAKING A SQUARE BROACH
Post by: philf on February 05, 2017, 11:38:54 AM
Hi Anthony,

How deep a 3/16" hole do you need?

I've made hex holes in steel by simply using a piece of an Allen key with a cutting edge made in the lathe with a carbide tool set about 5 degrees from perpendicular. No side relief at all. I've pressed the tool in with the bench vice. I drill the hole about 0.1 - 0.2mm bigger than the a/f size and a shallow guide hole the across corners size.  It tends to make the hole tight on the key but if you repeat the operation turning the key 1/6 turn at a time it works fine.

I made a clock key in brass recently using a tool simply made by milling a square on a piece of silver steel with a small relief angle and the cutting edge turned on the lathe.

The method I'd like to try is http://mikesworkshop.weebly.com/rotary-broaching.html (http://mikesworkshop.weebly.com/rotary-broaching.html)

Phil.

Title: Re: MAKING A SQUARE BROACH
Post by: ieezitin on February 06, 2017, 07:43:03 PM
Phil..

Nice work..

Your thread has given me room for thought about making a rotary broach seams quite simple.

my depth will be around 9/16 on this project and its in an 3/8ths round stock at an angle of 30 deg but there is room to put a champher on in fact its a mini boring bar i am designing ..

Anthony.
Title: Re: MAKING A SQUARE BROACH
Post by: mattinker on February 07, 2017, 04:46:37 AM
Phil..

Nice work..

Your thread has given me room for thought about making a rotary broach seams quite simple.

my depth will be around 9/16 on this project and its in an 3/8ths round stock at an angle of 30 deg but there is room to put a champher on in fact its a mini boring bar i am designing ..

Anthony.

I may be a bit of a killjoy, if it's only a 9/16" deep in 3/8" stock, a 3/163 square is easy to file! Much less work than making either a rotary or a standard broach!

All the best, Matthew
Title: Re: MAKING A SQUARE BROACH
Post by: ieezitin on February 07, 2017, 08:09:06 PM
Mathew

I actually own a diefiler and i with this machine filed into shape the square hole to size from the pilot hole took me 20 minuets to get it into shape. I want a straight action a broach gives, If I make 20 boring bars the investment of making a rotary broach will be a pay-off , also the tool will service me on other projects for square hole broaching...

Anthony