Router speed
#11
Putting a round over on a table edge and had a decent size blow out. Unfortunately it came off in 2 pieces and I can't glue back. I was using a Ryobi Palm router because I only had a 1/4" shank 1/2" round over bit.
This is a half round table and I only have enough room to cut the shape once more to re- do the edge.
I now have a 1/2" shank bit for my variable speed router.
My thinking was that the palm router was just running too fast causing the tear out?
Should I be slowing the router down this time?
I'm using African mahogany and the tear out was at the very front of the top where there is long grain.
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#12
It's possible that there was a hidden check in the grain, right along the edge, which contributed to the blow out.  Take a couple passes, rather than one heavy cut.  I think that's the safest way to avoid tearout, regardless of shank size, bit speed or which router you use.
If you are going down a river at 2 mph and your canoe loses a wheel, how much pancake mix would you need to shingle your roof?

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#13
Or maybe you should be making this in multiple cuts.  Or the palm router base was too small to keep the router flat on the surface.

To be careful I would take this in multiple smaller cuts.
No animals were injured or killed in the production of this post.
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#14
Definitely multiple cuts, with the last just a skim cut that will shine it up nicely, and get rid of any burn marks.

You didn't have a picture, but I also wondered how you approached the sides. I always do the end grains first, as they WILL blow out, and when satisfied with them go with the grain to finish it off. I really don't think it was speed. The vari speed function is new in the history of routers, and my favorites still are just on, and off, which for most routers is around 23, 000 to 25, 000 RPM. Tell the truth the only time I slow one down is doing really large diameter cutters. For most work I go full out, and don't have much problem. I'd say familiarize yourself with the correct directions for any type of cut. It will be infinitely more important to know for good results, as well as safety, than knowing when to slow down, or speed up.


Attached to this FWW link is a good video with some thought about router tear out


Worst case scenario on your table is you cut just a smidge off the side with the blowout, and redo the edge. Always learning, after doing this stuff over 50 years I still learn new ways to do things all the time.
Worst thing they can do is cook ya and eat ya

GW
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#15
Yes as Steve stated do end sections first . I also am wondering if there was a end grain change somewhere along the line . With a curved top there will always be areas of change . You may start out with the grain , but usuall you will come to end grain as the curve goes around . Those areas do a climb cut . Gary
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#16
Thanks for the replies. Looks like I was way off base with my reasoning.
I'm going to re- cut the curve on the top and carefully route the edge again.
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#17
This is a chart a made from the instructions for my Dewalt 618. It's probably the same idea for any router.

http://www.employees.org/~bstewart/pix/dw618speed.pdf
Phydeaux
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#18
Bob that is a great chart, and I don't see it as router specific as you are addressing the bit sizes versus speed, which is really what is applicable here. Keeper
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Worst thing they can do is cook ya and eat ya

GW
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#19
Definitely always do several light passes. Also you may want to do a climb cut when entering the end grain area.
John T.
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#20
Two most common causes relate to machine and operator.

1. Cutting too deeply
2. Dull bit
3. Cutting too fast
4. Difficult wood

Climb cutting can be necessary if the grain is really gnarly. Not entirely safe and I wouldn't suggest you try this the first time on a project. Practice first. It can be done freehand but it can be scary if you get a catch.

GO SLOW, take multiple passes if needed, and carefully examine grain direction as you go using the climb cut CAREFULLY.

This should solve your issue.
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