# what bit to cut circles



## tennispaul (Jan 6, 2011)

I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


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## bobj3 (Jan 17, 2006)

Hi Paul

Use a standard router bit, it will not plunge but it will cut out the cir. once you start to move it,,Don't use your high end bits on MDF or plywood..plywood is full of junk just like MDF and will dull the bit in a heart beat...

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tennispaul said:


> I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


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## jschaben (Jun 21, 2009)

tennispaul said:


> I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


Hi Paul, welcome to the forum
Since you made the jig I am assuming you accounted for the bit size so your question is about the type of bit.
I prefer a spiral but, as Bj pointed out, plywood and MDF is full of junk and spiral bits are expensive. Just use a straight bit of the appropriate size and "ramp" into the cut. By ramping you plunge to your preset depth as you are moving around the circle. You should reach your preset depth within 3 or 4 inches of travel but it means you will need to go beyond your starting point by that amount to complete the cut. You also need to secure the part of the workpiece that will become the disc with double face tape or something to prevent it kicking out on you at the end of your cut. Don't ask me how I Know this:wacko:


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## Ralph Barker (Dec 15, 2008)

tennispaul said:


> I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


A round one? 

Sorry, couldn't resist.


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## TWheels (May 26, 2006)

tennispaul said:


> I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


Hi Paul, Welcome to the RouterForums.

Can you describe your jig? Is it designed for cutting on the inside edge or the outside edge? Is it designed for hand-held or table mounted router use?

Whatever, I would suggest some type of inexpensive flush trim bit or a bit along with a guide bushing. Inexpensive bit, for exactly the reason Bobj3 and then John mentioned.


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## jw2170 (Jan 24, 2008)

tennispaul said:


> I wish to cut out some circles from MDF and Plywood. I have made a jig, but don't what kind of bit to use? Thanks


G’day Paul

Welcome to the router forum. 

Thank you for joining us


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## tennispaul (Jan 6, 2011)

Thanks guys, I think you have all given me enough info to get started on my project.


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