Author Topic: Another self made tool: the square broach  (Read 3686 times)

Offline Florian Eberhard

  • Full Member
  • ****
  • Posts: 437
Another self made tool: the square broach
« on: October 22, 2016, 10:05:18 PM »
Good Evening Eveyone

Well - I have been making another tool myself (because this time you can't even buy it in this size)

A Square broach.
I hade the inspiration from the video that was uploaded on youtube by Chris (Clickspring):
https://www.youtube.com/watch?v=MYI1slVGziU

I however chose a different approach on making it. I didn't have any square tool steel and picked a 3mm round bar i had around.
The broach shall finally produce 1.6mm square holes!

I started with machining the square form of the teeth. The tooth pitch is 2,5mm and i machined 2mm wide slots into the bar. The Idea is that I can move the bar out of the collet tooth by tooth and each "flange" still supports the unfinished broach when machining the teeth.
If you look at the support of the bar - that is just a square brass piece with a reamed hole in it. Then put into a small vice and clamped down on the table at the right position. Works pretty good when you do not have a dividing head tailstock!

The next step was executed on the lathe. I first pull out the workpiece (the grooving tool works as an end stop so I pull it out exactly the amount required). Then I machine the groove.
After that, I change the tool and machine the clearance angle on the back of each tooth. I chose 4° (that is how the top slide of the lathe is adjusted). Every tooth has 0.04mm more diameter than the one before. That gives 0.02mm depth of cut per tooth (since the depth of cut is in the radius)
Picture no. 5 shows how the unfinished broach looks when you take it out of the lathe, with the two last "flanges" left.
After finishing on the lathe, I hardened the broach using a reducing flame (in order not to get too much scale) and sharpened it on a fine honing stone.

And of course I also tested it (the picture is a little blurry  :embarassed: ):

It works great. The hole on the left has been drilled slightly too big, the one on the right seemed to be quite right.
I will definitely make other size broaches (2mm, 2.5mm, 3mm or so) - I could have used them several times before!
« Last Edit: July 23, 2017, 09:10:51 PM by Florian Eberhard »

Offline philjoe5

  • Full Member
  • ****
  • Posts: 1012
Re: Another self made tool: the square broach
« Reply #1 on: October 22, 2016, 10:52:47 PM »
Nice work and congratulations on making a tool that's very useful.  :ThumbsUp: I think many of us have had the need to make a square hole.

Cheers,
Phil
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

Offline 90LX_Notch

  • Full Member
  • ****
  • Posts: 1613
  • North Eastern Pennsylvania USA
    • YouTube Channel
Re: Another self made tool: the square broach
« Reply #2 on: October 22, 2016, 11:18:21 PM »
Well done Florian.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 4693
  • Boise, Idaho USA
    • Photo Bucket
Re: Another self made tool: the square broach
« Reply #3 on: October 23, 2016, 12:05:50 AM »
Very nice!

Dave

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13860
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Another self made tool: the square broach
« Reply #4 on: October 23, 2016, 12:50:55 AM »
Works as good as it looks too Florian. Well done.

Bill

Offline jeff l

  • Full Member
  • ****
  • Posts: 234
Re: Another self made tool: the square broach
« Reply #5 on: October 23, 2016, 02:27:15 AM »
Well Done :ThumbsUp:

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15294
  • Hampshire, england.
Re: Another self made tool: the square broach
« Reply #6 on: October 23, 2016, 08:21:19 AM »
Nice  :)

Florian are you using it as a pull or a push broach?

I wonder if a little flat on the part of the broach that initially goes in the hole would help squaring it up  :thinking:

Jo
Enjoyment is more important than achievement.

Offline Florian Eberhard

  • Full Member
  • ****
  • Posts: 437
Re: Another self made tool: the square broach
« Reply #7 on: October 23, 2016, 09:39:05 AM »
Good Morning Jo

I use it as a push broach. I didnt really care about which orientation the broach has, tahts why the square holes are just somehow not parallel with the material sides. But if it had to be oriented to something, I think i would do it optically by clamping something straight to the finishing teeth of the broach. You could of course machine a D-shape on top of the broach (or like chris machine a square on the top)

Florian

Offline Perry

  • Full Member
  • ****
  • Posts: 194
Re: Another self made tool: the square broach
« Reply #8 on: October 23, 2016, 12:52:12 PM »
Hello Florian, thanks for sharing, an use full tool indeed. What will be the first project for it? I like your projects, aspecialy the Stuart steam pump.
Regards

Offline Florian Eberhard

  • Full Member
  • ****
  • Posts: 437
Re: Another self made tool: the square broach
« Reply #9 on: July 23, 2017, 09:14:23 PM »
Hi Perry

Im sorry for not responding! (Just restored the pictures in this thread and finally saw your unanswererd question)
I used it for the cochrane boiler - you can see it in reply #114 on page 8 of the cochrane thread.

Cheers Florian

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal