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- Dec 26, 2015
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I am primarily a woodworker, and needed a way to make square mortise holes in hardwood for a new project coming up. I decided to turn my PM935 mill into a square mortise machine for this project. This is the story of how I designed and made the adapter that would mount the square chisel on the mill.
This is what the chisel looks like - it's basically a precision ground square chisel that's hollow and an auger bit inside that does most of the work:
What I needed was a way to securely hold the square chisel on the nose of the mill. Similar adapters are made for conventional drill press equipment, but none of those would fit or work on a milling machine. I came up with this design:
It's a two piece adapter - one piece clamps onto the nose of the quill, the other is a donut-shaped adapter bored to hold the 19mm OD of the square chisel. The auger component of the chisel would be secured into the spindle with a conventional R8 collet.
I started with two drops of 4041 steel I found on eBay for about $40 delivered:
I then set about machining the two components on the PM1340GT lathe and the PM935 mill. Here are couple shots of how that progressed. Here's the main housing that will attach to the nose of the quill after rough sizing and boring:
Here's the donut-ring after rough sizing and boring:
And a test fit of all the components:
Back to the mill with the rotary table, I machined away large sections of the main housing to essentially produce three fingers to hold the donut-ring:
Then I refined the donut-ring to reduce weight:
And after drilling and tapping for the mounting screws, this is what I ended up with:
And here it is on the PM935 under test.
This was a fun project and the thing works great.
If anyone is interested in the complete build log with lots of video and photos, here's the link: Square Chisel Attachment
Thanks for viewing. Comments/questions welcomed.
`
This is what the chisel looks like - it's basically a precision ground square chisel that's hollow and an auger bit inside that does most of the work:
What I needed was a way to securely hold the square chisel on the nose of the mill. Similar adapters are made for conventional drill press equipment, but none of those would fit or work on a milling machine. I came up with this design:
It's a two piece adapter - one piece clamps onto the nose of the quill, the other is a donut-shaped adapter bored to hold the 19mm OD of the square chisel. The auger component of the chisel would be secured into the spindle with a conventional R8 collet.
I started with two drops of 4041 steel I found on eBay for about $40 delivered:
I then set about machining the two components on the PM1340GT lathe and the PM935 mill. Here are couple shots of how that progressed. Here's the main housing that will attach to the nose of the quill after rough sizing and boring:
Here's the donut-ring after rough sizing and boring:
And a test fit of all the components:
Back to the mill with the rotary table, I machined away large sections of the main housing to essentially produce three fingers to hold the donut-ring:
Then I refined the donut-ring to reduce weight:
And after drilling and tapping for the mounting screws, this is what I ended up with:
And here it is on the PM935 under test.
This was a fun project and the thing works great.
If anyone is interested in the complete build log with lots of video and photos, here's the link: Square Chisel Attachment
Thanks for viewing. Comments/questions welcomed.
`
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