Square Holes

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• I had the need to make some square holes in plate steel and was trying to figure out the easiest way to accomplish the task. I m sure there are a number of
Message 1 of 8 , Apr 4, 2012
I had the need to make some square holes in plate steel and was trying to figure out the easiest way to accomplish the task. I'm sure there are a number of methods including a rotary broach but I don't currently have any of these tools. What I came up with was a way to get an almost square hole (limited by the radius of the end mill) using the bolt-hole function of my DRO. My DRO requires the center of the circle (center of the hole), the radius of the circle, number of holes (4) and starting angle (45 degrees). I made a calculator in Excel (attached) to determine the radius for the center of the end mill to move. You need to enter the diameter of the hole (drill size) and diameter of the end mill. I drill the hole (maybe one size smaller than actual), replace with the small end mill, enter the required data into the DRO and starting from the center point move the part the "Distance-to-Go" for the four holes, with the mill set to the appropriate depth. It worked out as I hoped and saved a lot of filing. Anyone else use this method, have comments or have another easy way to make a square hole.

Paul H.
• Paul, I recently had to cut 25 square holes in 3/8” 6061 and used my DRO with a ¼” end mill. My trick was to set up the DRO for zero tool offset. Then I
Message 2 of 8 , Apr 4, 2012

Paul,

I recently had to cut 25 square holes in 3/8” 6061 and used my DRO with a ¼” end mill. My trick was to set up the DRO for zero tool offset. Then I defined my square hole pattern to be 1/8” smaller than the finished hole. In this way I didn’t have to fool with tool offset while making the 4 sided cut.

See

http://rick.sparber.org/sspx.pdf

starting on page 10.

There are a few other tricks for getting square holes. As you found, using an end mill gives rounded corners. If you advance the cutter deeper on each corner and then back out, you will get a void at each corner. That can be better if you are putting in a square peg. Another trick is to mill a slot, turn the stock over, and mill a second slot perpendicular to the first. The resulting hole will have 4 sides that are square, just not all on the same plane. I’ve used that trick to hold HSS cutters and it works well.

Rick

From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On Behalf Of Paul Howell
Sent: Wednesday, April 04, 2012 7:47 AM
To: mill_drill@yahoogroups.com
Subject: [mill_drill] Square Holes [1 Attachment]

[Attachment(s) from Paul Howell included below]

I had the need to make some square holes in plate steel and was trying to figure out the easiest way to accomplish the task. I'm sure there are a number of methods including a rotary broach but I don't currently have any of these tools. What I came up with was a way to get an almost square hole (limited by the radius of the end mill) using the bolt-hole function of my DRO. My DRO requires the center of the circle (center of the hole), the radius of the circle, number of holes (4) and starting angle (45 degrees). I made a calculator in Excel (attached) to determine the radius for the center of the end mill to move. You need to enter the diameter of the hole (drill size) and diameter of the end mill. I drill the hole (maybe one size smaller than actual), replace with the small end mill, enter the required data into the DRO and starting from the center point move the part the "Distance-to-Go" for the four holes, with the mill set to the appropriate depth. It worked out as I hoped and saved a lot of filing. Anyone else use this method, have comments or have another easy way to make a square hole.

Paul H.

Attachment(s) from Paul Howell

1 of 1 File(s)

• ... That s what I do with my CNC when I m not using an automated pocket mill or something. I just have the CAD system add an offset line and tell the cutter
Message 3 of 8 , Apr 4, 2012
On 04/04/2012 08:45 AM, Rick Sparber wrote:
I recently had to cut 25 square holes in 3/8” 6061 and used my DRO with a ¼” end mill. My trick was to set up the DRO for zero tool offset. Then I defined my square hole pattern to be 1/8” smaller than the finished hole. In this way I didn’t have to fool with tool offset while making the 4 sided cut.

That's what I do with my CNC when I'm not using an automated pocket mill or something.  I just have the CAD system add an offset line and tell the cutter to follow the path.
```--
Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
tel: +1 408 356-3886, USA toll free: 1 866 356-3886
Skype:  jerrydurand
```
• Rick - Thanks for another method. It seems especially applicable when making a number of parts as you did. Paul H.
Message 4 of 8 , Apr 5, 2012
Rick - Thanks for another method. It seems especially applicable when making a number of parts as you did.

Paul H.

--- In mill_drill@yahoogroups.com, "Rick Sparber" <rgsparber@...> wrote:
>
> Paul,
>
>
>
> I recently had to cut 25 square holes in 3/8" 6061 and used my DRO with a ¼"
> end mill. My trick was to set up the DRO for zero tool offset. Then I
> defined my square hole pattern to be 1/8" smaller than the finished hole. In
> this way I didn't have to fool with tool offset while making the 4 sided
> cut.
>
>
>
> See
>
>
>
> http://rick.sparber.org/sspx.pdf
>
>
>
> starting on page 10.
>
>
>
> There are a few other tricks for getting square holes. As you found, using
> an end mill gives rounded corners. If you advance the cutter deeper on each
> corner and then back out, you will get a void at each corner. That can be
> better if you are putting in a square peg. Another trick is to mill a slot,
> turn the stock over, and mill a second slot perpendicular to the first. The
> resulting hole will have 4 sides that are square, just not all on the same
> plane. I've used that trick to hold HSS cutters and it works well.
>
>
>
> Rick
>
>
>
> From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On
> Behalf Of Paul Howell
> Sent: Wednesday, April 04, 2012 7:47 AM
> To: mill_drill@yahoogroups.com
> Subject: [mill_drill] Square Holes [1 Attachment]
>
>
>
> [Attachment(s) from Paul Howell included below]
>
>
>
>
> I had the need to make some square holes in plate steel and was trying to
> figure out the easiest way to accomplish the task. I'm sure there are a
> number of methods including a rotary broach but I don't currently have any
> of these tools. What I came up with was a way to get an almost square hole
> (limited by the radius of the end mill) using the bolt-hole function of my
> DRO. My DRO requires the center of the circle (center of the hole), the
> radius of the circle, number of holes (4) and starting angle (45 degrees). I
> made a calculator in Excel (attached) to determine the radius for the center
> of the end mill to move. You need to enter the diameter of the hole (drill
> size) and diameter of the end mill. I drill the hole (maybe one size smaller
> than actual), replace with the small end mill, enter the required data into
> the DRO and starting from the center point move the part the
> "Distance-to-Go" for the four holes, with the mill set to the appropriate
> depth. It worked out as I hoped and saved a lot of filing. Anyone else use
> this method, have comments or have another easy way to make a square hole.
>
>
>
> Paul H.
>
>
>
> Attachment(s) from Paul Howell
>
> 1 of 1 File(s)
>
> <http://l.yimg.com/kq/static/images/yg/img/doc/xls16x16.gif>
>
>
> <http://xa.yimg.com/kq/groups/2632663/564914592/name/Square%20Hole%20Calcula
> tor%2Exls> Square Hole Calculator.xls
>
• Paul, A method for making square and rectangular holes that I am using today is to use square stock and bolt it together. No stress points due to machining
Message 5 of 8 , Apr 5, 2012
Paul,

A method for making square and rectangular holes that I am using today is to
use square stock and bolt it together. No stress points due to machining
sharp corners.

Rick

-----Original Message-----
From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On
Behalf Of Paul
Sent: Thursday, April 05, 2012 4:19 AM
To: mill_drill@yahoogroups.com
Subject: [mill_drill] Re: Square Holes

Rick - Thanks for another method. It seems especially applicable when making
a number of parts as you did.

Paul H.
• Rick, Paul, Take a look at this video. http://www.youtube.com/watch?v=9orX-GmdVoc Carl H ... From: Rick Sparber To: mill_drill@yahoogroups.com Sent: Thursday,
Message 6 of 8 , Apr 5, 2012
Rick, Paul,
Take a look at this video. http://www.youtube.com/watch?v=9orX-GmdVoc

Carl H

----- Original Message -----
Sent: Thursday, April 05, 2012 7:31 AM
Subject: RE: [mill_drill] Re: Square Holes

Paul,

A method for making square and rectangular holes that I am using today is to
use square stock and bolt it together. No stress points due to machining
sharp corners.

Rick

-----Original Message-----
From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On
Behalf Of Paul
Sent: Thursday, April 05, 2012 4:19 AM
To: mill_drill@yahoogroups.com
Subject: [mill_drill] Re: Square Holes

Rick - Thanks for another method. It seems especially applicable when making
a number of parts as you did.

Paul H.

• Carl, I have seen this before. The complexity is in both the cutter and the articulated holder. Way beyond what I could make in my shop... Rick
Message 7 of 8 , Apr 5, 2012
Carl,

I have seen this before. The complexity is in both the cutter and the articulated holder. Way beyond what I could make in my shop...

Rick

On Apr 5, 2012, at 10:03 AM, "Carl Hollopeter" <chollo@...> wrote:

Rick, Paul,
Take a look at this video. http://www.youtube.com/watch?v=9orX-GmdVoc

Carl H

----- Original Message -----
Sent: Thursday, April 05, 2012 7:31 AM
Subject: RE: [mill_drill] Re: Square Holes

Paul,

A method for making square and rectangular holes that I am using today is to
use square stock and bolt it together. No stress points due to machining
sharp corners.

Rick

-----Original Message-----
From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On
Behalf Of Paul
Sent: Thursday, April 05, 2012 4:19 AM
To: mill_drill@yahoogroups.com
Subject: [mill_drill] Re: Square Holes

Rick - Thanks for another method. It seems especially applicable when making
a number of parts as you did.

Paul H.

• I ve seen it too but the holders for rotary broaches are very expensive. LittleMachineShop had the tool holders for less than \$100, but have now discontinued
Message 8 of 8 , Apr 6, 2012
I've seen it too but the holders for rotary broaches are very expensive. LittleMachineShop had the tool holders for less than \$100, but have now discontinued them. They still sell the broaches. They seem to come in common sizes. The following two links describe self made tool holders. The second one doesn't look too complicated, so maybe when I run out of other projects.

http://www.docsmachine.com/projects/rotarybroach/rb01.html

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

Paul H.

--- In mill_drill@yahoogroups.com, Rick Sparber <rgsparber@...> wrote:
>
> Carl,
>
> I have seen this before. The complexity is in both the cutter and the articulated holder. Way beyond what I could make in my shop...
>
> Rick
> rgsparber@...
>
> On Apr 5, 2012, at 10:03 AM, "Carl Hollopeter" <chollo@...> wrote:
>
> >
> >
> > Rick, Paul,
> > Take a look at this video. http://www.youtube.com/watch?v=9orX-GmdVoc
> >
> > Carl H
> >
> > ----- Original Message -----
> > From: Rick Sparber
> > To: mill_drill@yahoogroups.com
> > Sent: Thursday, April 05, 2012 7:31 AM
> > Subject: RE: [mill_drill] Re: Square Holes
> >
> > Paul,
> >
> > A method for making square and rectangular holes that I am using today is to
> > use square stock and bolt it together. No stress points due to machining
> > sharp corners.
> >
> > Rick
> >
> > -----Original Message-----
> > From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On
> > Behalf Of Paul
> > Sent: Thursday, April 05, 2012 4:19 AM
> > To: mill_drill@yahoogroups.com
> > Subject: [mill_drill] Re: Square Holes
> >
> > Rick - Thanks for another method. It seems especially applicable when making
> > a number of parts as you did.
> >
> > Paul H.
> >
> >
> >
> >
> >
>
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