Slab o' plastic (about ¼" thick-a lexan type--acrylic, I think--would
be better than a brittle plastic, like polystyrene--I'm not too good
on plastics). You could also use Baltic birch.
Stick o' UHMW for a fence. Screw to plastic. Make sure it is
absolutely square to the side of the sled that will bear against the
router table fence. You could also use Baltic birch.
Toggle clamp. De-Sta-Co is the original, I think, but there are
others. Screw to UHMW.
Has to be just about the easiest accessory to build. No need for
ANY square block that can ride against the router fence will do, of course.
Nice thing about blocks is that they also gain the profile of the cut on the
first pass, and aid in preventing chipout on subsequent. You can do the
holding if you like, after adhering a bit of sandpaper to the edge of the
block. Don't put it where the bit's going, obviously!
You can make full rig for a a set of hold-downs if you want, then elevate
the bit to clear the base of the sled. Just make sure, on anything you
make, that you allow for a replaceable backer to get best advantage.
Start here and work toward your design. http://www.oak-park.com/usa12.html
That way you'll have a miter fence, too.
The sled's fence needs to be perpendicular to the miter gauge slot if
one is being used. Since the miter gauge slot and the router table fence
are almost never used together, and since the router table fence is
usually adjustable, it could be a coincidence if the fence and the slot
are ever parallel.
If there is no miter slot, it might be better to guide the sled with the
front edge of the router table (if it is suitable) than with the fence.
Once the sled fence is made perpendicular to the table front face, it
will always be so. When an adjustable fence is used, perpendicularity of
the sled fence to the router table fence has to be checked/adjusted
whenever the fence is adjusted.
However, if a miter gauge slot is available, it is usually much better
that a coping sled be guided by it, rather than by the router table
fence. The main reason is that the cutter is prevented from pushing the
work away, which is often seen in coping operations.
Sorry to be so wordy.
[top posted for your convenience]
You must have missed the other thread. My counsel is not to have a
miter slot, and the need for the sled is based on that premise. One of
the arguments against the slot is the need for parallelism between it
and the fence. If there is no slot there is no parallism issue.
By counseling for the front edge as the guide you bring back the issue
of parallelism. Why complicate things? If the fence is the sole
guiding part of the table you never have to worry about any other
guiding apparatus' relationship to it.
Your assertion of needing to "adjust" the fence must be in reference
to a split, jointer type of fence (one used when a full profile is
routed off the material). In reality, only a small percentage of
operations need that capability and having a split fence for all the
rest is a waste of engineering and time wasted on a fussy apparatus.
This is likely to start up another thread on router table design
Sorry. I did miss the earlier thread. I still do not understand the need
for parallelism between the miter slot and the fence. Just as with a
table saw, it is most unusual to use both the fence and the miter slot
simultaneously (unless the fence is used as a cutoff stop a la Unifence,
rather than as a fence). Can you provide an example of where this
parallelism is necessary or advisable?
If there is no slot there is no parallism issue.
And even with a slot there should be none.
Not complicated at all. The sled fence must be perpendicular to whatever
guides the sled in its travel. That can be the router table fence, the
miter slot, or the edge of the router table. But only two of those
options will never change. And of course, the orientation of the sled
fence relative to sled travel is advisedly fixed also.
Well, a split type of fence would present a problem. But many non-split
router table fences can be adjusted to make various angles with respect
to the sides of the router table. The angle such a fence makes with
either the front of the table or the miter slot is 180 degrees only by
coincidence, unless it is set that way. It is a little disturbing that
my comment has been turned into advocacy for split fences!
That might be useful, unless, of course, the final words have already
Actually, I made no recommendations with regard to router table design
or fence design. My comments were directed at the OP's request for info
on coping sled design, taking cognizance of the overwhelming
preponderance of commercial router tables with miter slots.
Keep in mind that some of us might use coping sleds guided be either the
miter slot or the front of the table, your apparent counsel to the
contrary notwithstanding. In those cases, making the sled fence
perpendicular to the router table fence is inappropriate advice for the
reasons I have offered.
I also advised that, if available, a mitre slot-guided coping sled
offers the advantage of preventing movement of the work away from the
cutter. While a clamp on the sled discourages movement of the work
relative to the sled's fence, it does nothing to prevent movement of the
sled itself away from the router table fence. The operator must provide
this function with his hands. I've found it to be far more pleasant to
cope on either a shaper or a router table when the only control I had to
provide was the feed rate and a slight downward force on the sled.
It can be left to the reader to judge whether that is persuasive.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.