Rounding over edge of thin hardwood strip

[blueman]

I am trying to round over the edge of a 4ft long 1.5" x 3/8" strip of hardwood using a 3/8" round-over bit.

Since the wood is so thin (3/8"), I am using my router table for otherwise the bearing would extend below the wood (and in fact the roundover diamter is the same as the thickness of the wood).

The problem is that I am having trouble doing so without causing jumps & gouges in the edge.

The problem is particularly bad near the tail end where I get a rather big jump when the strip leaves the infeed guide. I believe the problem is due to the fact that when the entire edge is rounded over, only the very bottom edge of the strip is touching the guide which makes alignment very difficult.

So, I am looking for a reliable way of rounding over the entire edge of a thin strip of wood as above.

Are there any tricks? (such as maybe temporarily attaching it to another piece of wood)

[Nova]

Round the edge of a thick strip and then make it a thin strip.

[blueman]

Unfortunately, I already cut the strips (and it's from white oak so expensive)...

[blueman]

I'm thinking of doing the following: Use my TS dado head to carve out a rabbit in 3/4" MDF to precisely fit the hardwood strips.

Then use double stick tape to secure the strips to the MDF board

Then use the router free-hand (no router table) with the plate resting securely on the MDF board side and the bearing along the MDF board edge.

Any better suggestions?

Thanks, Jeff

[Leon]

If the wood is thin and you having the most problems at the end be sure to support the wood all the way through to the end. If the wood vibrates or slightly pushes away from the fence the blade can gouge and chip the surface. Keep the wood pushed firmly against the fence and close the gap on the fence at the bit. Additionally take slow and shallower cuts.

[Lew Hodgett]

As compared to a trip to the E/R when you F**K UP?

Lew

[DJ Delorie]

Having done this before....

Get a steel ruler.

Rotate the bit so that the cutter that cuts the least (on my bit, that's the part nearest the bearing) is at the "peak" of it's swing (i.e. deepest into the wood).

Position the ruler along the fence so that it crosses the bit right at that part of the bit's cutting edge.

If the bit sticks out too far, the ruler will "rock" a little, tapping first the infeed then outfeed parts of the fence.

If the bit is too far in, the ruler won't touch the cutting edge.

I have an incra fence, so I just micro-adjust it from "rocks" to just barely "doesn't rock" and then I know that the fence will support the wood after it's cut without interfering with the shape of the cut.

[Dave Balderstone]

Grind/shape a cabinet scraper to the profile you want, and do it by hand. Safe, and you have complete control. It's only four feet, after all.

[B A R R Y]

Use a bull nose bit instead of the round over. You'll need to shim the outfeed fence to make up for removed material.

I've made miles of beading to wrap around door trim this way.

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[Roger King]

I've never had a lot of trust in double sided tape... My fingers are more valuable than a little time. If this was me, I'd tack glue the piece to a more substantial back-up piece and then route the round over, then cut the pieces back apart.

[blueman]

Good point, I'll try hot melt glue

[blueman]

largest piece is about 4ft which is why I mentioned that number).

[Dave Balderstone]

I'd still look at the scraper, myself. For speed, you could chamfer the edge with a hand plane first.

By the time you do all the other futzing about to begin using the router, you could be finished.

Your call, of course.

[B A R R Y]

Having noticed that the OP is doing the entire roundover from ONE side, scratch my bullnose suggestion and listen to DJ!

I have a typical clamp-down fence (Rousseau), adjusted with mallet taps, and can vouch for similar accuracy. So even if the OP has any sort of "average" fence, lacking a high-end version, DJ's method should work well.

This is the same method I use for bullnoses, triple beads, etc... where there is no bearing to guide the bit. A shim behind the outfeed side of the fence will probably be necessary if the OP does not have a fence as adjustable as an Incra. I've used sheet styrene (from a hobby shop .005-.010-.020-.040-.080 thicknesses from a $2-3 assortment pack), beverage can stock, laminate scraps, sheets of paper, masking tape, and my dado shims, to set the outfeed fence at one time or the other.

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[blueman]

Did it today as above (but instead of double stick tape just used blue painter's tape across the top -- plenty of strength since the tape ran down the whole length of the strip).

Took about 15 min to make the MDF jig (mostly just setting up my dado head).

Worked really well!

Thanks all for the advice and help!