# Bosch Colt Cutting 3/4" Plywood



## harpone (Feb 6, 2013)

Is the Colt up to cutting 6" - 15" circles out of 3/4" cabinet-grade plywood?


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## Cherryville Chuck (Sep 28, 2010)

It will but a bigger router would be better suited. You are going to be working that one pretty hard. Most of the members here would suggest that you cut close to the size circle you want on a bandsaw or with a jigsaw first.

The other issue you will have is starting the circle (I`m assuming you mean the disc and not the hole). This is a job for a plunge router to do it cleanly and safely unless you precut and use a template to guide you around the disc. If you want to cut the circle out with a router the most depth of cut you should take per pass is a quarter inch since you can only use a quarter inch bit.

How were you thinking of doing it Dave?


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## JFPNCM (Dec 13, 2009)

Cherryville Chuck said:


> It will but a bigger router would be better suited. You are going to be working that one pretty hard. Most of the members here would suggest that you cut close to the size circle you want on a bandsaw or with a jigsaw first.
> 
> The other issue you will have is starting the circle (I`m assuming you mean the disc and not the hole). This is a job for a plunge router to do it cleanly and safely unless you precut and use a template to guide you around the disc. If you want to cut the circle out with a router the most depth of cut you should take per pass is a quarter inch since you can only use a quarter inch bit.
> 
> How were you thinking of doing it Dave?


I've used that Bosch to route out circles up to 17" in diameter in 2" cedar using the Rockler circle jig. I took very small cuts, 1/8" or less, an up cut spiral bit and moved the router slowly. No issues, but on the next round I'm moving up to bigger router. 

The band saw, jigsaw is an excellent suggestion as well and then finish the edge with the router.


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## Mike (Nov 22, 2004)

Shouldn't be a problem David. The PRO12 dust collection adapter works well.


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## 4DThinker (Feb 16, 2014)

It'll do it. Just take small passes, replace bits often, and the best advice already given is to pre-cut using a band saw. Stay within 1/16" or so of the line freehand, or use a simple jig if you can affix the center point to spin the piece through the blade. 

Colts are often used on small CNCs. I've replaced brushes after using one for a couple of years and run it for another two years before the bearings went. Good little work horse. Plywood varies though, and most flavors are hard on bits.

4D


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## Stick486 (Jan 4, 2013)

@Mike..

don'ja you ever use your stuff ???...
all it always looks so virgin...


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## Mike (Nov 22, 2004)

Stick, I'll let you in on a secret: I take the photos before I use the tools for future reference. I do my best to keep them clean after use. I have posted many times that I use compressed air after each use to blow the dust off and out of my tools. I also use dust collection when ever possible. It really helps that they don't travel to job sites.

Here is an example: these photos were taken of the Sjobergs Smart Vise before any work was done with it. The same is true of the Portamate 3-1/4 hp router motor for use in router lifts.

Wait, did Mike say router lift??? The plot thickens! Tune in next week, same bat time... same bat channel! :surprise:


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## harpone (Feb 6, 2013)

*Undecided*

Chuck -
I was thinking of using Jon's method, circle jig & router. After reading all the replies I wonder whether the bandsaw/router method might be easier. I have made several circles on my small bandsaw and was looking for a better, faster way. I have never routed plywood; what kind of edge finish should I expect?
Dave



Cherryville Chuck said:


> It will but a bigger router would be better suited. You are going to be working that one pretty hard. Most of the members here would suggest that you cut close to the size circle you want on a bandsaw or with a jigsaw first.
> 
> The other issue you will have is starting the circle (I`m assuming you mean the disc and not the hole). This is a job for a plunge router to do it cleanly and safely unless you precut and use a template to guide you around the disc. If you want to cut the circle out with a router the most depth of cut you should take per pass is a quarter inch since you can only use a quarter inch bit.
> 
> How were you thinking of doing it Dave?


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## Cherryville Chuck (Sep 28, 2010)

David the problem using a circle jig without a plunge router is starting the hole. The jigs are meant to be used with a plunge. Many of the members here will tell you that if you only have one router it should be a plunge because it can do anything a fixed base can but the opposite is not true. In your case you should be considering using a template type jig with either template guides or a pattern bit so that you can advance the bit into the cut safely. 

Finish is based on a few variables the most important of which is the sharpness of the bit. You can get straight bits that have a shear cut angle on them or a spiral bit. A bit with spiral or shear angle will leave one edge smooth and the other rough. A compression type spiral will leave both edges smooth but the bits are quite a bit more costly. All panel boards (ply, mdf, etc) are harder on bits than wood is.

As mentioned, you should only be routing 1/8 to 1/4" if you are using the bit for cutout purposes so this isn't going to be any faster than the bandsaw method and much harder on the router and bits and router bits are more costly per inch of cut than bandsaw blades are.


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## jschaben (Jun 21, 2009)

I agree with Chuck... cutting plywood or MDF or most any of the man made stuff is tough on tooling. I have done a few jobs where I went all the way through 3/4 ply but was also using 1/2" compression spiral or chip breaker bits. 
My inclination in taking on that job with a Colt would be to use a 1/4" spiral bit and cut the circle approximately 1/4" deep. Then use a band or jig saw to cut the circle staying within the 1/4" wide router cut groove. Then use a flush trim bit on the router table to finish the cut. 
Takes a bit longer but much easier on the equipment. JMHO


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## hawkeye10 (Jul 28, 2015)

David the longer it takes you the more fun you will have. :laugh2:

If you have a lot of them to cut out I agree with others you need a bigger router. Go to this link. They have good prices fast shipping and no sales tax for most. Don't be afraid of their reconditioned tools. I read a very positive report on this forum about their recon. tools.

Routers and Trimmers | CPO Outlets


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## JFPNCM (Dec 13, 2009)

David:


Just as an update, the attached was routed with the same techniques I described above re the Bosch Colt and up cut spiral bit. The final edge was done on the router table however.


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