This tutorial covers modifying the HL 850 Angle Stop or Fence to allow it to be used for back-beveling. The text and pictures were provided by Mark at Festool and sent to us by Christian O at Bob Marino's request. With their permission, I converted and posted this as a FOG tutorial.
Regards,
Dan.
----
The Festool HL 850 fence comes factory set at 90 degrees. In order to use the HL850 for door hanging it is necessary to modify the fence for back-beveling.
The following is a brief description on how that can be achieved.
You will note that on the HL 850 Angle Stop base -- the part that attaches to the HL 850 -- there is a set screw which is factory set at ninety degrees. The first thing that you must do is back this screw out:
You will need a Torx15 driver to do so, one that has a shaft which is long enough to reach the screw head which is located down the circular shaft of the base:
I used a Torx 15 bit with a five inch shaft to reach the adjustment screw. You will need all of that to get to it. If you cannot find a cordless bit long enough, Torx hand drivers are fairly common. I back it out till it is just flush with the edge of the base plate:
Next you will need to relieve material from the support arm or brace on the angle stop. You do not want to remove too much as this will compromise its strength. I mark the amount I want to remove with a permanent marker, which is about half the thickness of the material at the end:
Here is what it should look like when completed. The modified support arm is on the right:
I use a Dremel-like tool with a tungsten-carbide cutter which is a carving and engraving bit. You will want to turn the speed down to about half way. You can also use a structured-tooth tungsten carbide cutter. I followed up with one of these to smooth the edges of my cut. Check for sharp edges and finish with a file if necessary. Remember that the metal on the support arm is soft, so take your time, and avoid costly mistakes:
Next apply a slick strip along the fence to reduce friction and prevent the fence from marring the edge of the door. The slick strip that I use is three-inch wide adhesive-backed plastic film that fits perfectly. I place it flush along the top edge, so that all I have to do is trim the bottom. This can be done with a sharp pocket knife or utility knife:
Now you are ready to Use your HL 850 as a door planer. You will see from the photo that with the modifications we have made you can achieve a back bevel of greater than five degrees. I generally back bevel two degrees. You can use a gauge block cut accurately on a miter saw to set your bevel:
Regards,
Dan.
----
The Festool HL 850 fence comes factory set at 90 degrees. In order to use the HL850 for door hanging it is necessary to modify the fence for back-beveling.
The following is a brief description on how that can be achieved.
You will note that on the HL 850 Angle Stop base -- the part that attaches to the HL 850 -- there is a set screw which is factory set at ninety degrees. The first thing that you must do is back this screw out:

You will need a Torx15 driver to do so, one that has a shaft which is long enough to reach the screw head which is located down the circular shaft of the base:

I used a Torx 15 bit with a five inch shaft to reach the adjustment screw. You will need all of that to get to it. If you cannot find a cordless bit long enough, Torx hand drivers are fairly common. I back it out till it is just flush with the edge of the base plate:

Next you will need to relieve material from the support arm or brace on the angle stop. You do not want to remove too much as this will compromise its strength. I mark the amount I want to remove with a permanent marker, which is about half the thickness of the material at the end:

Here is what it should look like when completed. The modified support arm is on the right:

I use a Dremel-like tool with a tungsten-carbide cutter which is a carving and engraving bit. You will want to turn the speed down to about half way. You can also use a structured-tooth tungsten carbide cutter. I followed up with one of these to smooth the edges of my cut. Check for sharp edges and finish with a file if necessary. Remember that the metal on the support arm is soft, so take your time, and avoid costly mistakes:

Next apply a slick strip along the fence to reduce friction and prevent the fence from marring the edge of the door. The slick strip that I use is three-inch wide adhesive-backed plastic film that fits perfectly. I place it flush along the top edge, so that all I have to do is trim the bottom. This can be done with a sharp pocket knife or utility knife:

Now you are ready to Use your HL 850 as a door planer. You will see from the photo that with the modifications we have made you can achieve a back bevel of greater than five degrees. I generally back bevel two degrees. You can use a gauge block cut accurately on a miter saw to set your bevel:
