Fences for the Drum Sander

[sehast]

This is a continuation of my previous post regarding a Drum Sander build for the Shopsmith.
http://www.shopsmith.com/ss_forum/viewt ... 5&p=216409
Fences for the drum sander serve four basic purposes: 1) provides a stable horizontal support for passing stock over the drum, 2) provides a perpendicular surface to allow stock edges to be sanded square with the face, similar to a jointer, 3) provides infeed and outfeed vertical support for long stock and 4) holds the stock firmly down on the table as it passes over the drum. Using these requirements I choose to make two different fences, one for each side of the table where both would be used to support wide panels. On the right side I built a classical fence that has a solid perpendicular surface. Its primary part is a 2”x 4” x 36” piece of extruded aluminum offered by 8020 Inc.
http://www.ebay.com/itm/80-20-Inc-10-Se ... Swv-NWad~C
It is kind of expensive but offers very solid and square surfaces with T slots on all sides giving it a huge amount of flexibility. I used ¾” MDF and two magnetic switches to hold it down on the steel table. The Magswitches worked great and provide a very solid hold even on a highly waxed surface.
https://www.amazon.com/dp/B01B58UPXW?psc=1
The last parts are the two 3/8”x 5” x 10” aluminum plates used to provide infeed and out feed support for long boards. Actually I bought a 10”x 10” remnant and sawed it in two.
http://www.ebay.com/itm/3-8-375-Aluminu ... XQS6pRx1mb
I drilled holes in the plates and attached them to the bottom T slots on the fence so they can be adjusted. In the closed position they provide a full 18” of support at both the infeed and outfeed, 36” total. Fully extended they provide 24-26”, 52” total. That’s good enough for at least 6 foot long stock.
Lastly I repurposed the Jessem stock guides I have been using on my router table to firmly hold stock down on the table as it passes over the drum. They can be easily shared between my router and sander now. Pictures of the finished fence is shown below. The first one shows the support plates extended.

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For the second fence on the right side all I needed was a simple but solid form of support. I choose to make it out of MDF but with ¾” x ¾” x 36” steel angle stock fixed to the business edge of the MDF. I employed the Magswitches and aluminum plates similar to the other fence. For the hold downs I repurposed the Board Buddies I use for my table saw. A picture of the finished fence is shown below.

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A picture below shows both fences mounted for normal operation on the sander.

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With this configuration up to a 23” wide panel up to 6 feet long could be sanded in a single pass. Using two passes, just one fence and flipping between passes up to 46” widths could be accommodated but you would have to use the Shopsmith extension and floating tables for support.
I could have gotten by with using just MDF, T-tracks and simple clamps for both fences and still functionally met all of my requirements for a lot less money but I was out to build a first class system. I guess it was the same reason I spent two days leveling the table to .002”. Besides I needed a better fence for my 18” bandsaw and these fences can easily be shared. I am still well below the price they want for a new Sand Flee.
Now that the sander is complete my next post will be about using it.

[BuckeyeDennis]

Very slick!

I had a similiar infeed/outfeed support idea, based on attaching a long auxiliary fence to the 520 fence. It would totally eliminate worries about adjusting the I/O supports to match table height and tilt. But I was thinking of building it from wood. Your implementation is much better. Your 8020 extrusion looks like just the ticket, if someone can figure out a good way to attach it to the 520 fence.

BTW, does your sander have a way to adjust the height of the table relative to the drum? I think of these things as big sander-versions of a hand plane, and of course the blade depth is always adjustable on those.

[masonsailor2]

Very nice ! Is that an 80/20 extrusion ?
Paul

[rpd]

BTW, does your sander have a way to adjust the height of the table relative to the drum? I think of these things as big sander-versions of a hand plane, and of course the blade depth is always adjustable on those.

On this type of sander the table height is set just above the and paper, when it is running the paper expands out on the velcro so that the paper touches the wood but there is a layer of air between the paper and the drum.
That way there is no heat build up. To take a deeper cut you use a courser grit.

[BuckeyeDennis]

BTW, does your sander have a way to adjust the height of the table relative to the drum? I think of these things as big sander-versions of a hand plane, and of course the blade depth is always adjustable on those.

On this type of sander the table height is set just above the and paper, when it is running the paper expands out on the velcro so that the paper touches the wood but there is a layer of air between the paper and the drum.
That way there is no heat build up. To take a deeper cut you use a courser grit.

Hmmm. Thanks for the info. I need to ponder on that for a bit.

[rpd]

Hmmm. Thanks for the info. I need to ponder on that for a bit.

Here is a couple of videos by Paul Moore demonstrating the Flatmaster, he explaines it than I can.
[youtube]https://www.youtube.com/watch?v=lgPLOnXCmdU[/youtube]
[youtube]https://www.youtube.com/watch?v=ca2a_IDMkuk[/youtube]

[BuckeyeDennis]

It certainly does seem to work well. As far as having "air behind the sandpaper", my first thought was that air is a good thermal insulator, and so it would tend to trap heat in the sandpaper. So I think the key must be that the arrangement gives nice even light pressure of the sandpaper on the workpiece. If your workpiece is reasonably flat to start with, there is no way that you can make it "bear down" on the sandpaper and generate too much heat, or clog the "valleys" between grit particles, or do whatever it is that makes sandpaper load up.

Now that I think about it, sandpaper has to be somewhat like a saw blade, which needs enough space in its gullets to hold the sawdust until the teeth clear the workpiece.

So now one of those is on my wish list. Meanwhile, I'll try to avoid applying too much pressure when I sand, and see if that gives me better paper life.

[sehast]

Very slick!

I had a similiar infeed/outfeed support idea, based on attaching a long auxiliary fence to the 520 fence. It would totally eliminate worries about adjusting the I/O supports to match table height and tilt. But I was thinking of building it from wood. Your implementation is much better. Your 8020 extrusion looks like just the ticket, if someone can figure out a good way to attach it to the 520 fence.

BTW, does your sander have a way to adjust the height of the table relative to the drum? I think of these things as big sander-versions of a hand plane, and of course the blade depth is always adjustable on those.

Attachment to the 520 fence should not be difficult. I plan to just slip off the MDF base and use a fixture on top of the 520 fence that attaches to the top track on the 8020.
The sander is set one time for the lowest grit paper you plan to use. Adjustment screws are under the table base on the near side.