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Old 12-05-2007, 09:47 AM
thrytis thrytis is offline
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Reducing blowout while routing end grain

I've been having problems with blowout while doing some flush trimming on hard maple end grain:



To prevent it, i've tried:
  • Switching between a 3/4" template bit and a 3/4" shear angle flush cut bit based on grain direction (when not perfectly 90 degrees to grain) and proximity to corner
  • reduce router speed a notch or two
  • trim as close as possible with jig saw first
  • use multiple light passes
  • use climb cuts

but i still hit it. I have a lot of flush trimming to do on this project and i'm getting tired of fixing blowouts and short on time. Any other suggestions for reducing blowouts? I think i may try picking up a spiral flush trim bit next. Do these eliminate blowouts completely, just reduce the chance of them, or not do a whole lot for the situation?

Thanks!
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Old 12-05-2007, 10:06 AM
crokett crokett is offline
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I would cut with a spiral bit. I have a spiral upcut (not flush trim) that I use for timming endgrain and it helps. I also use a backer board.
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Old 12-05-2007, 10:19 AM
SARGE..g-47
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I used to do it with an over-head bearing template bit. I would cut to within 1mm of the line and take the final mm with the bit and backer boards as Crockett mentioned. I never had a problem as long as the bit was sharp?

I still cut to within 1 mm... but I use a low angle block plane to make the final two passes at this point. From the sounds of it you need them pronto and probably don't have time to develope skill with that method. If you are in a major hurry, you might consider purchasing a 90 tooth blade to get a slick cut and then a little light sanding at that point would get you to the finish line.

Just curious if you had this happen on other species also for future reference?
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Old 12-05-2007, 10:49 AM
thrytis thrytis is offline
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Quote:
Originally Posted by SARGE..g-47 View Post
I used to do it with an over-head bearing template bit. I would cut to within 1mm of the line and take the final mm with the bit and backer boards as Crockett mentioned. I never had a problem as long as the bit was sharp?

I still cut to within 1 mm... but I use a low angle block plane to make the final two passes at this point. From the sounds of it you need them pronto and probably don't have time to develope skill with that method. If you are in a major hurry, you might consider purchasing a 90 tooth blade to get a slick cut and then a little light sanding at that point would get you to the finish line.

Just curious if you had this happen on other species also for future reference?
Thanks.

I think instead of the backer board i can alternate between the router and the jigsaw - cut one side of the corner with the jigsaw leaving a large overhang, flush trim it, cut the other side, cut the other side with the jigsaw, then flush trim it.

The block plane and 90 tooth blade won't work for most of the cases. This particular cut was straight, but the majority of the project is curved.
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Old 12-05-2007, 10:52 AM
thrytis thrytis is offline
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Quote:
Originally Posted by SARGE..g-47 View Post
Just curious if you had this happen on other species also for future reference?
I had problems with walnut too on the same project.
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Old 12-05-2007, 10:55 AM
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JR JR is offline
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Did you try flipping the piece over to get the grain going in the opposite direction?

Other than that, I got nuthin'.

JR
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Old 12-05-2007, 10:56 AM
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LarryG LarryG is offline
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Are you routing hand-held, or on a table? Bit choice and grain characteristics aside, I get better results with better control feeding the relatively lightweight workpiece into the spinning bit on a table than trying to finesse a heavier and bulkier hand-held router into the correct position when making a delicate cut like this.
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Old 12-05-2007, 10:58 AM
thrytis thrytis is offline
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Quote:
Originally Posted by JR View Post
Did you try flipping the piece over to get the grain going in the opposite direction?
Yes, that was why i was using both a template bit and a flush trim, so i could flip it over and change directions. I finally figured out the purpose of top and bottom bearings on the same bit!
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Old 12-05-2007, 11:04 AM
thrytis thrytis is offline
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Quote:
Originally Posted by LarryG View Post
Are you routing hand-held, or on a table? Bit choice and grain characteristics aside, I get better results with better control feeding the relatively lightweight workpiece into the spinning bit on a table than trying to finesse a heavier and bulkier hand-held router into the correct position when making a delicate cut like this.
I'm routing on a table, though some of the pieces would be big enough that they could be clamped down and route hand-held.
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Old 12-05-2007, 11:47 AM
cabinetman cabinetman is offline
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You might try changing the feed direction. IOW run it backwards on the bit before your final pass.
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