Shopsmith Forums

I have a 15" x 15" x 3/4" board, I need to put two dado's/grooves 1/2" wide by 1/2" deep on the diagonals from corner to corner.

The picture below is the best I have to show the diagonals I want to cut. The parts shown in the groves are T-Tracks and are actually 4 separate pieces that don't meet in the middle.

[ATTACH]17058[/ATTACH]

I have a Shopsmith 520, a router table and a handheld router and none of these seem like the obvious tool. I am not even sure how to lay out the sides of the cuts so they are exactly in the correct spot.

520, dado blade set to groove width, miter gauge set to 45° with an extra block or stop on a long fence.
Make dado cuts before cutting center hole.

Another way would be to use your hand-held router and 1/2" straight or spiral router bit. Draw diagonal lines from corner to corner. Measure from the center of the router to the edge of the sub-base. (A Porter Cable 690 router has a 5 3/4" sub-base, so this measurement is 2 7/8" for the 690.) Draw two additional lines that are parallel to and 2 7/8" from your original corner-to-corner lines. Now place a straight edge on one of the new lines and tack it in place . Now route the first groove using the straight edge as a guide for the edge of the router base. Reset the fence and cut the second groove.

If you have a guide bushing set, you could tack a straight edge 3/8" away from the first set of diagonal lines and use a 3/4" guide bushing with the 1/2" bit to achieve the same thing.

I was thinking of a "V" jig like a crosscut sled and cutting them on the 520. Even without a dado blade, it should be pretty quick to make multiple passes, rotating the piece in the jig 4 times before resetting the cut.

I'm with fiatben - make a jig - here's just the sort:

http://www.youtube.com/watch?v=uygTzLpoStk

Use a piece of 1/4" plywood and attach a piece of 1X2 for a guide for a router.
Cut the plywood so that the distance from the 1X2 is a little larger than the distance from the router base to the edge of the cutter you will use on the router to make the cuts. Then trim the plywood using the router with the cutter you will use and the edge of the plywood will be the cutting limit of the bit. Place the plywood edge along the dado cut line. If you use a 3/4" bit to make the jig only one pass will be required to make a 3/4" dado.
Mark the edge of the router with a magic marker and keep that mark against the jig fence when cutting to maintain the distance and make up for an out of round router plate.
Bill V

This is the jig I was trying to explain.

[ATTACH]17080[/ATTACH]

The router is placed to the right of the fence and the plywood to the left of the fence is used as the area to clamp the guide. Feeding from bottom to top as indicated aids in keeping the router against the fence. Line up the right side of the jig along the cut line and route
Bill V

I did a quick drawing in sketchup late last night but I guess I forgot to post it.

I'd go with a jig that rides against the rip fence and that you have a notch cut into for the workpiece to set in. You need to use a push block to feed with but it should be just two dado blade cuts as seen below.

[ATTACH]17081[/ATTACH]

Ed

I have posted a SketchUp model here, for the lathe steady rest. After reading many replies here and elsewhere the solution I came up with was different then what many suggested and wasted some wood but was very easy to do. I started with a piece of left over 3/4" laminated counter-top 22" x 22". I cut the dado in the middle of the piece using the rip fence as a guide, then rotated the board 90 degrees and cut the second dado. Then I used my track-saw to cut between the dadoes at 45 degrees. This is shown in the attached file.

I will post pictures of the completed steady rest next week once I finish my caster upgrade and remount the rest.

paulmcohen wrote:I have posted a SketchUp model here, for the lathe steady rest. After reading many replies here and elsewhere the solution I came up with was different then what many suggested and wasted some wood but was very easy to do. I started with a piece of left over 3/4" laminated counter-top 22" x 22". I cut the dado in the middle of the piece using the rip fence as a guide, then rotated the board 90 degrees and cut the second dado. Then I used my track-saw to cut between the dadoes at 45 degrees. This is shown in the attached file.

I will post pictures of the completed steady rest next week once I finish my caster upgrade and remount the rest.

I have looked at your post. Seems to be a neat solution.

Is it adjustable or is this a specialized jig?

Do you clamp it to the ways?