Suggestion for 12mm router bit. Upcut, down cut or Compression

[FOGNewbie]

I am looking for a 12mm in diameter router bit. It can be Upcut, down cut or Compression. I would like to make a template like Big Rock did in his kitchen cabinet video, but I am having trouble finding a 12mm, in diameter, router bit. I have a OF 1400, so the shank can be 1/4", 8mm, or 1/2" Any suggestions. I could use a Forstner bit and my drill, but I think using a router would be better.  

** Slow of thought today(Okay, most days...). I noticed in the comments section of the YouTube video it is mentioned that the undersized plywood bit was used. I was thinking of going that route already as a temporary fix. Going to experiment with the MFS for an alternate jig solution since my router templates are metric.

 

[fdengel]

Going to the Woodcraft site and searching for "12mm router bit" immediately returned several hits.

Amazon.com does the same.

 

[FOGNewbie]

Going to the Woodcraft site and searching for "12mm router bit" immediately returned several hits.

Amazon.com does the same.

Thanks! I wanted to use an up, down cut or compression bit, but it may not matter if I use a straight bit since the plunge shouldn't be that deep. I am going to try the undersized plywood bit, before I order a CMT, or Infinity bit.

 

[fdengel]

There is at least one upcut bit in the Amazon search results, but it is relatively $$$$....

An "undersized plywood bit" is just a normal router bit in one of the wierd sizes that is often cited for plywood thicknesses.

Thanks for the mention of compression bits btw... I'd never heard of those before, so I just looked it up and learned something.

 

[martin felder]

I am looking to make some dados in 3/8 plywood.  I did a test cut with a shaper and got a lot of tear out in comparison to a clean cut with poplar. 

I know a dado stack with a table saw is an option, but I am going to go with my Festool router.  I was thinking downcut spiral 1/4 and then a second pass to dial it into a nice fit for the plywood as these downcut spirals to not seem to be made in plywood sizes.  I looked at Rockler and saw at 1/4 inch option with mixed reviews - dulls-burns quickly.  Then I saw this
https://www.toolstoday.com/v-13354-...qD83C9gi_lYA0vP7ZxORDUVXoBVSHrnkaAtS7EALw_wcB

That is an Amana compression bit for a CNC.  I have never used a CNC but my understanding it these compression bits offer the advantages of both uncut (chip clearance) and downcut (clean cut).  It is a bit pricey but cheaper in the long run than an inferior bit that does not last long.

Anyhow, does anyone have any experience using these CNC compression bits on hand held routers?  If all bits were the same price, would this be the top choice for a dado or rabbet cut?  Thanks.

 

[egmiii]

[member=71926]martin felder[/member]

CNC compression bits can be used in a handheld router, but you need to take at least 3/8" or more depth of cut to engage the downcut portion of the spiral. Otherwise you will be using only the upcut portion, resulting in tearout. You could use an upcut bit to hog out 90% of the material, then come back with a downcut bit to perform the finishing pass. A guide rail and fine adjustment would make the job easier.

 

[Jim_in_PA]

[member=71926]martin felder[/member]

CNC compression bits can be used in a handheld router, but you need to take at least 3/8" or more depth of cut to engage the downcut portion of the spiral. Otherwise you will be using only the upcut portion, resulting in tearout.

This is important advice. .375" and .5" (and presumably 12mm) compression tooling tends to have a longer up-cut section at the tip than a .25" compression cutter which often has a .1875-.2" long up-cut section at the tip. Your initial cut must be deeper than that to take advantage of the characteristics of a compression cutter. For those of us using CNC, we often employ compression cutters to do full thickness cutout of sheet goods with clean edges on both sides, but even when used for grooves or pocketing or whatever, that initial depth is important.

If you are intending on cutting grooves and rebates for plywood to fit in, rather than trying to find tooling that "matches" your plywood...which as has been indicated is a moving target...a double cut with a narrower bit to the exact thickness of the material to be inserted into that groove or rebate is a best-practice. Yes, it takes a little more setup, but the end result is going to provide a closer fit than any other method.

 

[Cheese]

I used an Amana solid carbide downcut spiral bit to cut dados in the sides of several cabinets. The material was prefinished maple ply from Menards...so probably not the best quality ply that's available.

The first 2 passes were to establish the depth and the second 2 passes were to establish the width. I used a Micro Fence edge guide and just literally "dialed in" the extra width I needed.

The finished dado and a close up of it.

[attachimg=1]

[attachimg=2]

 

[martin felder]

Great advice!  Thanks.  I will forget about compression bits and go with the downcut spiral.  I was not aware of the need for a certain depth to utilize the downcut. 

 

[Jim_in_PA]

Great advice!  Thanks.  I will forget about compression bits and go with the downcut spiral.  I was not aware of the need for a certain depth to utilize the downcut.

Just remember that with down-cut tooling, you get a clean edge, but you also can get a recess packed with chips as well as extra heat that results in burning, or even flames if you pause too much in a captive groove. Adjust your technique accordingly and if you need to go deep, do it in steps, cleaning out the debris with compressed air and/or tools between the passes.

 

[egmiii]

Great advice!  Thanks.  I will forget about compression bits and go with the downcut spiral.  I was not aware of the need for a certain depth to utilize the downcut.

Just remember that with down-cut tooling, you get a clean edge, but you also can get a recess packed with chips as well as extra heat that results in burning, or even flames if you pause too much in a captive groove. Adjust your technique accordingly and if you need to go deep, do it in steps, cleaning out the debris with compressed air and/or tools between the passes.

For the reasons above, I’d stick with an up cut bit to remove material down to the full depth and 90% width. Use the down cut bit to tweak the width.