|Forum topic by elschaefer||posted 06-05-2011 05:29 AM||10029 views||2 times favorited||8 replies|
06-05-2011 05:29 AM
I’m new to Lumberjocks, but I’ve been reading the forums for a little while, and I’m always amazed at the incredible work I see on here. I’m slowly setting up my own shop in a pretty small space (roughly 12’ square with an opening out onto the driveway) and I’m in the process of outfitting a table saw for the sort of work I do (a lot of theater scenery, some interior shelving/cabinets, event and worship space design and fabrication). I’m used to working in larger shops, so if possible I’d like to duplicate the functionality of the larger spaces in the limited space I have access to. I have an idea for the fence for a table saw that I’m hoping to try out, but i’d love some input from more experienced (and perhaps cautious) minds. If it proves successful it might be a great option for woodworkers in small shops looking to expand their saw’s functionality.
I picked up a Delta Contractor Saw for cheap (probably 10-15 years old), and I’ve been fixing it up to give me the accuracy and capabilities of a large, fixed cabinet saw while keeping it flexible for my small workspace. I acquired a cast-iron wing from a unisaw and an extra contractor saw table-top, which i bolted to the left and ride sides of the saw, respectively. I’m going to build an 8” router table to attach to the right side out of MDF and laminate, and mount an extra Porter Cable 8901 router base under there. I switched out the stock V-belt for a link belt from Harbor Freight, and I put the whole thing on an HTC3000 mobile base from Woodcraft (which already broke a little bit, which I’m not so happy about).
The fence that came on the saw is an aluminum t-slot channel that runs in an aluminum extrusion along the front of the saw. It allows 30” of capacity to the right, but at the moment I have it moved over 6” to the right to give me 36” of capacity. But what I’d really like to have is a full 52” of capacity, but I don’t want to have permanent rails sticking out that far, given my small workspace. The fence also has more play than I’d like, and I’d really prefer to have a biesemeyer style fence, especially when I add that router table.
I just picked up a Powermatic Accu-fence off of ebay (just the fence, no rails) and I’m planning to build rails for it to give me that 52” of capacity to the right of the blade. I’d like to be able to build a sliding 5’ long rail that would give me 30” of capacity most of the time, but expand to 52” of capacity when I need it. Here’s my idea of how i might do that with some steel purchased from my local supplier and a bunch of UHMW. It’s essentially a marrying of the concept of the regular Biesemeyer-type fence design with the sort of design found on higher-end portable table saws (Ridgid, Porter Cable, etc)
For the front rail:
A 4’-8” length of 2” x 3” angle iron bolted to the front of the saw, dropped about 1/2” below the top of the table to clear the miter slots
A 4’-8” length of 2” square box tube (or possibly 2.5”, if the C Channel isn’t beveled on the inside) attached to the 2” x 3” angle iron, either welded or secured with bolts screwed into tapped holes in the box tube
A 5’ length of 3”x 1.5” C Channel to ride on top of the 2” or 2.5” box tube
UHMW in various thicknesses and widths attached with adhesive and/or screws to the 2”/2.5” box tube
Some kind of clamping mechanism that I haven’t figured out yet that will press the C-channel firmly against the box tube.
For the rear rail:
A 4’-8” length of 2” angle iron dropped 1/2” below the table to clear the miter slots
A 4’-8” length of 1.5” angle iron attached to the 2” angle iron
A 5’ length of 1” box tube that rides inside the space between the 2” and 1.5” angle irons
Small 1/4” x 1/2” steel tabs welded to the bottom of the C-channel (or a length of 1/4” x 1/2” steel all the way along the C Channel) to help hold it captive on the box tube (see diagram below for clarification)
UHMW tape to allow the 1” box tube to slide smoothly within the space in the rear rail
I haven’t decided yet whether this should be mounted with the angle iron rightside-up or upside-down, I’ve seen it both ways in current production fences. Any thoughts?
Side spacer bar:
A bar that can be attached to either side of the front and rear rails to help support the fence assembly when it’s moved away from its normal configuration.
I haven’t quite figured out the design for this piece yet, any input would be very much appreciated!
A few diagrams:
A cutaway isometric view of the front and rear rails:
The same, but with the rear rail upside down:
A plan view of the increased rip capacity to the right of the saw:
A plan view of the increased rip capacity to the left of the saw:
The way I envision this working:
For normal rips (up to 30” right, 12” left) the saw functions like any other Bies clone system, and the rails stay locked down and in place.
For far right rips: fence gets clamped down in position on the far right of the rail, and the spreader bar is attached to the right sides of the front and rear rails. Then the entire assembly is slid to the right until the desired measurement is achieved, then it is locked down.
For far left rips: the fence gets clamped down in position on the far left of the rail, the spreader bar is attached to the left side of the front and rear rails. Then the entire assembly is slid to the left to the correct measurement, then it is locked down.
Does anyone currently use the Powermatic Accu-fence? Will 3” (1.5” high) C-channel give me enough clamping surface to allow the fence to lock down correctly?
Is UHMW sufficiently structural to make it a good choice for this application? Are there any other easily available materials that I should be considering instead?
What kind of clamping device would be most effective here? Ideally it’d work to lock down both the front and rear rails at the same time, like the rack and pinion design on the Dewalt portable saws.
Is there anything I’m missing here that is going to make this setup particularly unsafe when it’s extended out? I’m not a structural engineer, so I can’t evaluate the rigidity of the c channel versus 2” x 3” box tube, but based on my practical experience it seems rigid enough for most applications. There shouldn’t be more than normal deflection from the fence, and because it’s a stock Powermatic unit I shouldn’t have issues there. I’m also thinking of clamping down the rear of the fence to the rear rail, so that even if there is flex the fence will move parallel to the blade if it moves at all.
Is there a chance of the clamping force from the fence bowing the C channel inward through repeated use?
If you’ve gotten this far, thanks so much for reading and feel free to add comments, criticisms, questions, warnings, etc. I’m excited about making this work and I really do appreciate any assistance or thoughts.