Drill Press Variable Angle Appliance2

 

I need a new shop built appliance...I need to drill angled holes along a sight line to achieve resultant angles on the new drill press.

The previous variable angle appliance will be used as a model and perhaps offer up some parts.
Design Ideas and Requirements
Design must fix these issues that were evident in appliance1, the  previous shop built appliance: 
  • it must be smaller, easier to handle
  • it needs to be easy to mount on the Nova drill press
  • mount location is to the OEM metal table
  • must mount securely
  •  must enable a range of ~5 to 30
  • must allow clearance under the drill bit
  • at the hinge point, it must allow longer stock to rest off the front edge of device and table
Appliance1...too large and too long to be effective for the task.
When changing the orientation from left-right to front-back it was clear that it would not allow for the angles desired.
So the new design (appliance2)  will downsize from appliance1...the most important factor is to shorten the base.
Making some general calculations...the Nova drill press table surface is ~8 inches from the bottom of the Forstner bit...it is also ~8" from the pillar to the bit...the table is 12.5 x 12.5...the front edge of the table is ~14.25 from the pillar.

So the first change would be to make the bottom plate 16 inches long...this will extend it out over the front of the table...and 13 inches wide...extends slightly over both side edges of the table.
I used appliance1 to get a feel for how the angles would work...the red tape on the bottom plate is at 16 inches.
The slant plate is supported by some scraps to achieve approximate angles.

I used an arbitrary 33 as the high end requirement...
The approximate center of the bit on the slant plate is the X on the long red tape.
The working length allows the target angle with clearance for the drill bit.
This allows me to move to digital design.

Digital Designing
First Sketchup vision of the device...using MatchFit dovetail grooves, clamps, and hardware.
Terms...
The dovetail groove on the underside of the bottom plate will allow two MatchFit clamps to secure the appliance to the Nova OEM metal table.
The two dovetail grooves on the topside of the bottom plate will provide tracks for the MatchFit knobs to secure the wedge assembly.
After playing with some variations...here is the Sketchup with the slant plate at a 33 tilt...




Materials and Build
Hardware: Piano hinge, 7.5 inches...ordered.

Wood selected was walnut plywood, gifted by Tom D.

The underside of the bottom plate was dovetail grooved so that the appliance is securely held to OEM metal table with MatchFit clamps.

Great hold...easy to put on and take off.
The top surface of the bottom plate was dual dovetail grooved to provide tracking for the wedge assembly...using MatchFit knobs.
The wedge assembly was borrowed from appliance1...the maple assembly just needed two new holes to align with the tracks.
The wedge and the assembly base are  held together with Dominoes...dry fit with friction hold.  This will allow alternate wedges as needed.
Test run was done by holding the slant plate in place because the piano hinge is not in...the wedge assembly was moved far forward and with ample room to spare with Forstner bit, this setup allowed and angle of greater than 30.
Piano hinge hardware arrived...screws were overly small...replaced them with #4 square drive x 5/8"...and installed the 90 stop hinges.
With the slant plate installed the effective angle was tested...
with the wedge at the rear the angle was ~13
.
With the slant plate as high as it will go and still be under the Forstner bit...
angle is ~31
.
 
If the wedge is removed from the assembly the lowest angle is ~5 ...in theory, with the flat plate removed the lowest angle could be ~1.
To do...angle test

To do...resultant angle along sightline test...

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