Characteristics of a Compression endmill

I am trying to find a compression endmill as I plan to do a lot of through cutting on plywood. I am in Japan, and I am not sure what the equivalent of compression endmill is in Japanese terms so I can’t do an online search, so I am looking to see what the essential characteristics of a compression endmill is so I can identify one by site. Is it obvious just by seeing the endmill?

This maybe helpful crew. Might be difficult to identify by sight but worth a try I guess.

Wouldn’t mind trying them myself. I’m in Australia by the way - same time zone.

https://tools.toolstoday.com/search?w=compression&ts=custom

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You can tell that it is a compression end mill because the spiraling flutes will change direction.

The top half or more of the end mill is down cutting, so the flutes will be right hand spiraling. And the bottom section of the end mill is up cutting, so the flutes will be left hand spiraling.

When you see one in person it is easy to distinguish because you see where the flutes change from up cutting to down cutting. The link that @patonclover shared shows some good examples of what to look for.

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FWIW I cut a fair amount of plywood and my favorite bit is a 1/4" single flute straight router bit. I have tried upcut, and downcut, but not compression bits, but I honestly don’t see what could be improved over the straight single flute bit, it makes a really clean cut. Just another option.

Dan

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Courtesy of Harvey Tool (note change of flute direction as @Plumshades mentions) :

And courtesy of Winston Moy (@wmoy):

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Thanks. I actually used a single flute straight bit, but had lots of delamination. Could it be an issue other than the type of bit, such as some factor of the feed rate?

Thanks. The site seems buggy if I change the shipping location. Good reference though!

I did a feed and plunge both at 48ipm and set RPMs at 18153, although I tweaked that up a bit higher to kill a bad resonate sound I was getting at that RPM, so maybe 20,000. Pass depth was 0.125" and stepover was 40%. I have been cutting 3/4" thick maple ply with these settings and it comes out pretty clean. This ply is the better stuff at the big box store, has very few voids. Have not tried it on different varieties. Bit is a 1/4" single straight flute from Inventables.

Dan

Thanks. I will try those settings. My bit is a 6mm one though ( I changed collets)

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