My "new" coping sled

[Cyrus Brewster 7]

Hello everyone,

This is my first post here on the creek. Before I go further, I would like to say thanks for the help you all have given me this past year or 2 in setting up my shop.

I generally only buy tools as I need them for projects (or of course, if I find a good deal on CL). I was at a point when I had to make 6 custom window sills. I realized I needed a second router table because I had to make two seperate cuts to shape the face of the sill. So an extension went on my TS. The question then cropped up of how to cope the ends. Since one of the sills was 6 feet long, the simple miter gauge method would not do.

After looking around for commercial jigs in addition to others' homemade jigs, I decided to build my own. Well, I am guessing you can see where my inspiration came from. I came to the conclusion that this was by far the best design I had seen. Although it looks complicated it is truly simple and a joy to use. My cuts came out perfectly.

BTW, it cost me less than $40 and five hours to make. Other than the Incra track and knobs, I had everything else. I will be switching out the part that rides on the fence to lexan when I get my hands on some.

I look forward to future posts.

[Peter Quinn]

Hi Cyrus, and welcome. That sled looks like a beauty. I always find it invigorating to see how different wood workers specifically solve the same challenges in unique ways.

I could be wrong, but from your pics and descriptions, it looks like you are making a STOOL, not a SILL. The sill is the part on the outside that the sash and jamb legs land on, its pitched to shed water and generally extends a bit past the siding. That thing on the inside which forms a draft stop and gives the trim a convenient place to stop is called the stool. I apologize for interjecting this information into your first post but I am on a one man mission to send stool discrimination!

Soooo, beautiful stool Cyrus! Enjoy that sled.

[JohnT Fitzgerald]

Nice jig! Well done.

[Cyrus Brewster 7]

Peter, a stool it is. Thanks for the correction.

[David Thompson 27577]

Seems to be very well done, and very functional.

And, FWIW, it looks a lot like the sled I recently bought for about $140. Mine is the Woodpeckers brand sled, and it has already proved quite useful.

[Cyrus Brewster 7]

David, I guess you figured out where my inspiration came from. After looking at several different ones (including the infinity), the Woodpeckers seemed to make the most sense. The general idea behind both is the same, but I think the Woopeckers executes it better and simpler - the way the clamping bar can be centered over the work piece.

Anyway, mine does work quite well. I think I will get a lot of use from it.

[pat warner]

Cold water? Indeed, but worth knowing nonetheless.
End/cope-cuttings, to be precise, have to fixtured to stuff that is flat, & flat whilst under load.
Your work clamps are good for ~150 pounds/each.
Paper phenolic (3/8" - 1/2" thick, yours?), with a couple hundred localized pounds on it, wiil bend with the lever you have.
An imposed cup, twist or bow on your fixture will present the work to the cutter in an unpredictable way.
I've put 300 pounds on 3/4" MDF and rendered it way out of flatness, e.g.. An 1/8th or more of clamp induced bend/fold is ordinary.

I use paper phenolic as jig substrate too but not with just hold down clamps set to very modest loads.
Isolation of the work with stops & fences is key. A work piece has 12 degrees of slip, slide and twist. & so do the components on that jig!
(in/out/, up/down, left/right and 3 rotational options both CC & CCW).
So for more predictable (quality cuts) routing, isolate & fix the work from its ends and edges too.

[David Thompson 27577]

>>"End/cope-cuttings, to be precise, have to fixtured to stuff that is flat, & flat whilst under load."<<

Well, end copes have to be done while the workpiece is held flat to the table or fixture, and perpendicular to the path of travel.

>>"Your work clamps are good for ~150 pounds/each.
Paper phenolic (3/8" - 1/2" thick, yours?), with a couple hundred localized pounds on it, wiil bend with the lever you have.">>

Although those clamps might be capable of that much pressure, they are also capable of much less --depending on operator training and input. The design of the sled does not require lots of pressure. It only requires that the workpiece can't lift off of the base. Two or three pounds of pressure is all that is required for that.

>>"I've put 300 pounds [of clamping pressure] on 3/4" MDF and rendered it way out of flatness, e.g.. An 1/8th or more of clamp induced bend/fold is ordinary.">>

Why'd you do that? Why not use the amount of pressure that is neede, instead of the excess force?

>>"I use paper phenolic as jig substrate too but not with just hold down clamps set to very modest loads.
Isolation of the work with stops & fences is key. A work piece has 12 degrees of slip, slide and twist. & so do the components on that jig!
(in/out/, up/down, left/right and 3 rotational options both CC & CCW).
So for more predictable (quality cuts) routing, isolate & fix the work from its ends and edges too.">>

And if you look carefully at the photos in the original post, that is what the maker of the fixture did. The workpiece is supported on its bottom, its back, and its front sides. It is held in place with gentle pressure from its top side.

That's four out of the six sides of the workpiece. The fifth side can't be supported, since it will be getting routed. And the sixth side is of little consequence, since the workpiece is held tight to the fixture and can't move.

I have a commercially made version of this same fixture. I've used it numerous times, and have had none of the problems of which you speak.

[pat warner]

Thank you Mr. Thompson.
You're right, in my haste, I missed the fixed fence. Moreover, the
rotational components are also accounted for, my poor judgement to be
sure.
I would emphasize, however, that is doesn't take much to bend paper
phenolic. Even 25-50 pounds (squat with those clamp-knobs) will punch a
hi-center in the middle of that substrate and cup it.
And, in my view, 15-50 pounds or more are required to control the
fixture against the cutter and fence (if one is in play), whilst cutting
end grain. Those forces are enough to dislocate the work on that
slippery substrate with only modest down clamp forces.
I'd paste some #220 paper down for some tooth. You can get away with a
lot less up/down clamp pressure if you do.
Given some stock clamped in for tearout, things can get a little more
slippery, but somewhat tempered with an abrasive under the work.
Not looking for a fight here, just hoping the readers might catch a few
hints on work confinement, routing dynamics, & what to look for when
designing jigs.

[Cyrus Brewster 7]

I was planning on putting some #220 on the surface and also rubber feet on the bottom of the clamps - I am also concerned with the work piece slipping. As for tearout stock making things more slippery, I use clamps fixed to the fence.

I get what you are saying about the edges needing to be clamped, and on wide stock this may be neccessary. It really depends on how much force is needed to hold the work piece in place. So far, because I take several small passes, keep my bits sharp and do not force the work, I have not had to tighten to the point that I have had any deflection - this without the snad paper and the rubber feet. But, I have also not used the sled with anything over 3.5 inches. I will have to test it out.

I do appreciate the criticism. Since you have brought it up, I may actually put a removable clamp on the sliding piece that jambs the work piece into the fence. This will definitely help with any deflection on wide stock. And maybe replace the phenolic with an aluminum base should I get my hands on one. In the end however, anything can become over engineered; and I would eventually like to get to work with wood.

BTW, I do enjoy your web site. Thanks.