Pattern Bit

[Mark Klika]

One of the scarier things to do in the woodshop is use a pattern bit. Invariably, I read the grain wrong and bad things happen. So far the only repercussions were a ruined workpiece. I take shop safety seriously and would like to stay uninjured. Does anyone have advice on router bits, technique they can share with me? The photos attached just happened today. The bit grabbed the wood and chewed it up. It did it with such a force that the red spacer got damaged and popped out of its location. Scary stuff. TIA. MarkIMG_3648.jpgIMG_3647.jpg

[Kevin Jenness]

Rough the workpiece out as close as possible to finished dimension so you aren't taking such a large cut. A substantial jig with handles well away from the bit adds safety. A starting pin can help control the lead-in. A cut like the one pictured will cut cleaner if you use a top-bearing bit in one direction and a bottom-bearing bit opposite so you are always cutting with the grain and avoid blowout at the exit.

What is the diameter of that bit? It may be flexing and chattering with a heavy cut due to its relatively small diameter. The spiral bit you are using will give a cleaner cut on the lower face of the stock but it tends to push the work up and away from the table, so you need to hold it down firmly.

[Jim Becker]

Kevin hit it exactly...for pattern routing, it's a best practice to have the workpiece very close to the finished profile so there is only minimal material being removed. It's even more critical with a small diameter tool like you were using. Pattern routing is to clean a workpiece to the final outline, not to cut it out. Now it's true you still need to pay attention to grain direction and when pattern routing, you may not be just running the cutter around the workpiece in a single, unbroken pass. Some kinds ot profiles on certain wood species still demand you pay attention to the grain direction to avoid tearout. That means flipping the workpiece which in turn may require changing from a top bearing to a bottom bearing, or vice versa unless you use a pattern bit that has both top and bottom bearings.

[Michael Burnside]

That’s also endgrain and looks to be Oak. Two of the worst combinations unless you’re close to final dimensions as posts above indicate.

[Richard Coers]

I switched to a Freud 1 1/4" top bearing bit. It cuts so much better than a 1/2" bit. It's like apples and oranges. Freud 50-126

[Joe Adams]

Trace your pattern onto the board and use a bandsaw or jigsaw to cut outside the line. Ideally, you want to be trimming less than 1/2 the diameter of the pattern bit. You never want it captured or leaving an off cut.

Also, consider buying some 1/8" larger diameter bearings to switch out on the bit before making the initial cut. Afterwards, switch back to the OEM bearings for a finish cut with no burning.

Finally, my experiences with the Whiteside Ultimate Flush Trim Bits have been awesome. Woodpeckers makes them as well (Ultra Shear) but I have no experience with their bits.

[Mark Klika]

Thanks to all who took time to answer! The bit I used is 1/2" in dia. with a 1/2" shank. I don't remember the manufacturer, but I believe it was a Whiteside and not cheap. I knew to get the bandsaw cut as close to the template size as possible. Most of the time I was within 1/8" or less. I thought that would be good enough. If not, what's the use of a template anyway? I just ordered this bit on Amazon. According to Katz-Moses, it's the solution to all template problems. Guess I'll see about that. Thanks again! MarkWhiteside Model UDC9112 Spiral Combination 1/2" SH X 7/8" D X 1-1/8"CL.

[Patrick Varley]

Thanks to all who took time to answer! The bit I used is 1/2" in dia. with a 1/2" shank. I don't remember the manufacturer, but I believe it was a Whiteside and not cheap. I knew to get the bandsaw cut as close to the template size as possible. Most of the time I was within 1/8" or less. I thought that would be good enough. If not, what's the use of a template anyway? I just ordered this bit on Amazon. According to Katz-Moses, it's the solution to all template problems. Guess I'll see about that. Thanks again! MarkWhiteside Model UDC9112 Spiral Combination 1/2" SH X 7/8" D X 1-1/8"CL.

Did he have an Amazon affiliate link in the video with the bit he's calling the " answer"?

[Kevin Jenness]

I knew to get the bandsaw cut as close to the template size as possible. Most of the time I was within 1/8" or less. I thought that would be good enough. If not, what's the use of a template anyway?

With a router you really want to trim off 1/16" or less, that will keep the load on the bit to a manageable level. You can get away with a bigger overcut on a shaper, but why not just cut close to the line? Treat it as if you were going to clean it off by hand or a sander and you will have an easier time. That Whiteside bit looks good and will allow for having your pattern above or below your workpiece, but it won't work well with trimming off a large overage.

[Jim Becker]

Again, with touchy grain, you will have to route from both directions; some areas from one and some areas from the other so you are never cutting into the end-grain. I spoke about this in my previous response. The issue isn't the tooling you're using; it's the nature of the material and the operation.

[Patty Hann]

Trace your pattern onto the board and use a bandsaw or jigsaw to cut outside the line. Ideally, you want to be trimming less than 1/2 the diameter of the pattern bit. You never want it captured or leaving an off cut.

Also, consider buying some 1/8" larger diameter bearings to switch out on the bit before making the initial cut. Afterwards, switch back to the OEM bearings for a finish cut with no burning.

Finally, my experiences with theWhiteside Ultimate Flush Trim Bits have been awesome. Woodpeckers makes them as well (Ultra Shear) but I have no experience with their bits.

Do you have some part/ model numbers you can post? (I use mostly Whiteside bits for other apps) Thanks

[Michael Burnside]

That’s a good bit, I have it as well. Normally you might be ok but with Oak and endgrain and 1/8 that’s quite the task. I’d try to be less than 1/16 along endgrain.

[Mark Klika]

Haha. No, but he had one to Taylor Tools for it. I went the Amazon route to speed up and save on shipping. It's tough resisting the Borg.

[Joe Adams]

Do you have some part/ model numbers you can post? (I use mostly Whiteside bits for other apps) Thanks

I have the Whiteside UDC9112 Ultimate Trim Combination bit.

Expensive but well worth it IMHO.

Nowadays, I generally only buy Whiteside but I also have a bunch of Amana router bits.

I have a few Freud (Italy), CMT (Italy), and older Dewalt (Israel) still in the mix.

[James Jayko]

I like to use a really short pattern bit (like 1/2" cut depth) to establish the shoulder and reduce the required cut depth, after bandsawing as close as you dare. Then work your way through it with a compression bit.