Need help understanding how a back fence works

[Richard McComas]

A back fence AKA outboard or trap fence. As I understand it you attach a straight fence to the shaper table on the opposite side of the cutter and run the stock between the fence and the cutter. I understand you must use a power feeder. What I don't understand is, do you also use the factory fence so the stock is trapped between the two fences? Pictures would be great.

[Rod Sheridan]

Hi Richard, no the wood doesn't touch the factory fence, it's spaced back.

The only reason the factory fence is used is because it's attached to the hood.

Regards, Rod.

[Steve Jenkins]

One major advantage to using the back fence is you are running a jointed edge against the fence and dimensioning on the opposite edge so you have a continuous fence not a split one that you have to offset.

[Peter Quinn]

Don't EVER do it with a hand feed. Did I mention NEVER? Yup, its prime function is to dimension stock, possibly at the same time you shape or profile it. The stock fence acts as chip collection via its hood. You can allow the stock fence plates to touch the stock and even run a split fence which helps hold narrow pieces in place. Take a close look at the weaver shaper site or the Aigner fences on the Martin site. They have a nice back fence which has pressure plates on the regular fence pushing the stock to the back fence. Not a bad idea, but not essential for stock wider than 1 1/2" or so. Think finger board in reverse, sort of.

Pictures? Picture a piece of stock 1/8" thinner than the stock you are shaping, 4-6" wide, PSA sandpaper on the bottom, two stout clamps holding it to the table. Simple picture no? A circle (i.e. shaper cutter) can intersect a line (i.e. back fence) at only one point, so simply loosen one clamp and tap the back fence forward or back for precise alignment, then set the hood parallel to the back fence if desired, and set the infeed fence setback using the stock you will be processing, set the out feed fence to the final dimension.

Think of it as a Jedi level shaping technique.. "Richard, use the back fence. Harness the true power of the shaper. Know it is not a router table. Usr the power feeder, Richard!"

[Chip Lindley]

=Peter Quinn;1469917]Don't EVER do it with a hand feed.

Stock feeders are perferred, but a back fence can be used quite well with proper a proper way of holding stock firmly against it, with downward pressure against the table. (always use a push stick to finish the cut)

This is the very principle of the Weaver stile jig. I used this one quite well for 20 years without incident, until I was blessed with several stock feeders. The infeed fence is spring-loaded to hold stock against the outboard fence. I found it advantageous to set up the outfeed half of the shaper fence to a sliding fit to "trap" the finished piece as it emerges from the cutter, preventing any snipe at the trailing end.

A very usable shop-made version could be easily made, if a stock feeder is not in the budget yet.

http://i822.photobucket.com/albums/zz142/zzarus/Weaverstilejigsml.jpg

[Richard McComas]

Thanks for the advice guys. Thanks for the picture. I have a 1 hp PF and will use it.

[Peter Quinn]

I've always wondered with a hand feed on a back fence set up, once you have the hood fences acting as pressure bars, and significant down pressure directly in front of the cutter head to prevent snipe, and significant hold downs before and after the cutter to keep things smooth, with all those hold downs how the heck are you supposed to feed the stock at a smooth and consistent rate, and how would you get your push block past all that mess anyway? Now I'm being facetious, I can see it being done, but that's a very tricky set up and I thank god I don't have to try it. Many guys like to or have to climb cut certain problem species using a back fence and in those case you really must use a stock feeder.

Sorry I don't have a picture, but it is really a simple thing. I hope you will check out that Matin web site for the Aigner fences. They are awful expensive but you can learn a lot from their designs that may be incorporated into shop made solutions.