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Thread: Pattern routing problems

  1. #1

    Pattern routing problems

    Hi everyone

    I was trying to make a bunch of small cutting boards using a board that I made in 7th grade as a pattern. It is in the shape of a pig, so there are lots of turns etc and the pattern crosses the grain at different angles in the project.

    Used double sticky tape to attach the blank to the pattern. I had cut it roughly to shape, about 1/8" larger than the original. I used a straight flush cut bit in my router table. Lots of tear out and a near accident, I wasn't holding down hard enough on a push pad and the router bit grabbed the piece and threw the whole thing off the table. Fortunately using the push pad kept my fingers out of the way.

    No luck on the second one either, they both are in the trash. I can't find anything in my books that tells me what I'm doing wrong. Should I slow down the router speed? Should I be using a spiral bit?

    Thanks for the help.

  2. #2
    Join Date
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    Sounds like, at different times, you were going with grain, cross grain and against grain, possibly with different woods too. The tear-out would have given me pause. Without being there to watch. I believe I would have gone to a quarter round bit, put the board on a non-slip pad and used the router instead of shaper. Glad you weren't injured.
    "Folks is funny critters."

    Think for yourselves and let others enjoy the privilege to do so, too. ~Voltaire

  3. #3
    Join Date
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    Jay,

    These are really pricey but I think that they would be your best bet: http://www.infinitytools.com/productscs.asp?dept=1340

    Less expensive but gives a good cut that might solve your problem: http://www.infinitytools.com/products.asp?dept=1336 You could try both pattern above and below to see which gives you the best cut.

    I hate to pay the Infinity prices but have not been disappointed yet.

    I do not think that slowing down the speed is the answer.

    Good Luck! Allen
    Last edited by Allen Bookout; 04-21-2007 at 06:59 PM.

  4. #4
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    The bit in Allen's second link would work well for what you need to do. I haven't got one of those but I've had good success by cutting what I can with a bit with a bearing on the end (flush trim) and then switching to a pattern trimming bit to finish up. It's a slower way to do it but it gets the job done.
    Irony: The opposite of Wrinkly

  5. #5
    Thanks guys

    I'm a bit confused! What is the difference between a pattern bit and a flush cut bit? The two bearings instead of one? Angled cutting surface rather than straight?

    Dave -- Why to you go over the surface twice? I would think that the pattern cutting bit would create a part that was the same dimension as the pattern. So, what does going over with the flush bit add to the process?

    Not going to play with that puppy today! I have to admit that I was surprised by how fast that wood was grabbed out of my hands, and so thankful that I wasn't holding it without a pusher pad on top. So, I'm cleaning up stuff and playing on the net until my hands stop shaking!

    Jay

  6. #6
    I've had small work "blow up" on my shaper...not an unexpected thing when shaping muntin bars for circular and elliptical windows. The spiral bits should help with this problem, but still make sure to keep your hands in a safe place. The spiral will cut with a shearing action rather than the blunt approach of a straight bit, kind of like slicing a turkey with a knife as opposed to going at it with an axe

  7. #7
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    Jay, I don't go ove the surface twice. I cut what I can cut without getting chipout with one bit--those areas where I'll be cutting without lifting the grain. Then I flip the work and template over, change the bit to the one with the bearing on the opposite end of the cutter and finish up those areas I didn't do the first time.
    Irony: The opposite of Wrinkly

  8. #8
    Join Date
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    Jay,

    My inexpensive flush trim bits have the cutter straight down the shaft. The Infinity double bearing pattern bit has the cutter slanted down the shaft. I do not know if it is how the bit is designed or if it is mainly the quality but the pattern bit sure cuts a lot better. I will mail mine over to you if you want to give it a try.

    I think that the best of all worlds for a pattern bit in a table would be the downcut spiral flush trim bit which in a table would seem to be an upcut bit. That way, if you could attach the pattern tight against the workpiece, such as small nails, it would not splinter the non pattern side and the pattern would help it not splinter on the pattern side. I have not tried that as I do not have one of those bits (next bit to purchase) but I do have a couple of their regular spiral bits and they really cut smooth. Of course any of the top brands should be very good quality but I just happened to get started with the Infinity brand.

    You are right about things happening really fast using a router. Faster than any other tool that I own. I think that is why that I always choose to hold the router instead of the workpiece if possible. Keeps my hands away from the bit. Doing something like a pattern on a table I use the Gripper. If I did a lot of that kind of stuff I would have two Grippers.

    Be careful.

    Allen
    Last edited by Allen Bookout; 04-21-2007 at 09:44 PM.

  9. #9
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    Quote Originally Posted by Jay Knoll View Post
    Hi everyone

    I had cut it roughly to shape, about 1/8" larger than the original. .
    Something no one has mentioned is I would get as close as I could to the pattern because of all the grain problems. The less to cut the cleaner the cut.

  10. #10
    Join Date
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    I ran a test cut with my double bearing pattern bit and the results are below. I double taped a piece of MDF to represent the pattern to a piece of plywood to route the end grain where tearout would be if there was any. Then I set my router to the hightest speed. Made the cut using the starting pin just in case. I fliped the pattern and workpiece over for the first photo. No tearout and no grabbing equals no problem. There is a little tearout and the end of the cut which is to be expected with no backerboard but even at that it is not much, especially with plywood.



    I separated the pattern from the workpiece and flipped over the workpiece. No tearout.



    Here is a picture of the bit in my router and table. The bit's cutting length is two inches. A shorter one might be handier for most things as this is pushing the length of travel for my setup but works.

    Last edited by Allen Bookout; 04-22-2007 at 09:24 PM.

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