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General control line discussion => Open Forum => Topic started by: Wynn Robins on June 04, 2008, 02:32:16 PM

Title: How do you cut a hole like this?
Post by: Wynn Robins on June 04, 2008, 02:32:16 PM

I have tried all sorts of ways to try and get a nice round hole like this one (pic stolen from Walters PT-19 thread)
he only circle/hole cutter I can find is for tradesman and has really course teeth - so how can I do this????

Title: Re: How do you cut a hole like this?
Post by: Ralph Wenzel (d) on June 04, 2008, 02:56:30 PM

I can offer three ways to cut this. Either a scrollsaw or bandsaw will work, but for the enclosed circle, a bandsaw will require breaking and rewelding the blade after inserting the blade through a "starter" hole.

A simpler, probably a better, way is to use a Forstner bit of the correct diameter. The Forstner bit is guided by the edge of the cut hole rather than by a pilot point, and is able to cut almost any portion of a hole. The sides of the hole will be extremely straight and smooth.  A Drill Press is almost mandatory. For an example of a Forstner bit, see: http://www.leevalley.com/wood/page.aspx?c=2&p=45533&cat=1,180,42240

Title: Re: How do you cut a hole like this?
Post by: Tom Perry on June 04, 2008, 03:01:19 PM

Wynn,

I saw that Ralph answered about the same time I did.  So I canceled my original post.  I thought you might like to read this article on the Forstner bit:

http://en.wikipedia.org/wiki/Benjamin_Forstner   #^

Title: Re: How do you cut a hole like this?
Post by: Randy Powell on June 04, 2008, 03:11:15 PM

I would just use a piece of sharpened tubing on balsa. I have a stack of collected pieces of tubing with the end sharpend to make round holes like this.

Title: Re: How do you cut a hole like this?
Post by: Wynn Robins on June 04, 2008, 03:13:56 PM

thanks all - I will go and get a couple of those Forstner bits

Randy - the hole I need to cut is 1 1/2 inches - dont want to use a tube to do that!

Title: Re: How do you cut a hole like this?
Post by: Randy Powell on June 04, 2008, 04:44:35 PM

Wynn,

Hmmm. I do. But everyone has their own techniques. A really sharp Forstner should do the trick.

Title: Re: How do you cut a hole like this?
Post by: chuck snyder on June 05, 2008, 02:48:20 PM

I have a set of hole saws, very old, they belonged to my GrandMother, that do an acceptable job on balsa and ply even though they have coarse teeth. I do use forstner bits up to 1" diameter. My first set of forstner bits were the inexpensive ones.  HB~>
Chuck

Title: Re: How do you cut a hole like this?
Post by: Bill Little on June 05, 2008, 08:17:46 PM

Haven't looked for the *answer*..............

I have some sanding drums that I bought REAL CHEAP at the hardware.  They are 3/4" or 1" diameter and I bought a bunch of sleeves in different grits.  I have a circle template, and I use the drums to get to the finished size.  You can turn them with your hand, you don't have to have a drill for the final fitting.  Scroll saw to about 3/32nds from the line, then sand.

Title: Re: How do you cut a hole like this?
Post by: George on June 09, 2008, 11:19:04 AM

Doesn't anybody use a DREMEL any more?

George

Title: Re: How do you cut a hole like this?
Post by: Keith Spriggs on June 09, 2008, 01:51:53 PM

If You have a drill press put a piece of wood on the table then the work piece followed by another piece of scrap wood on the top clamp everything to the table. You can then use a regular hole saw and drill through the top scrap through the work piece and in to the bottom piece. Run the drill press as fast as possible. The top piece of wood should be something as hard as pine and at leas 1/4 inch thick.