For making mortices I see spiral cut bits are preferred for less chatter/cleaner cuts. But, for making deeper mortices, in my case almost 1.75 inches deep, what is the best option?
I am assuming a double flute straight bit is probably the best or perhaps only option. Any other suggestions? Are there any spiral cut bits that are that long? Most seem to max out at about 1.25 inches or so.
thanks, Jake
Replies
Are your mortices blind or through? If they're through, cut them from both sides. It's safer (with less bit exposed), and your error is reduced, since any deviation will be greater with a longer exposed bit (as long as your measurment around the piece is accurate). With a deep mortice, you'll want a spiral upcut bit to help clear the chips, and help keep the router on the work. Whiteside makes a 1/2" upcut with a 2" cutting length. Others probably do, too.
If you're using a hand held router, make sure you have adequate bearing surface for the base, especially if the pieces are less than the width of the base. Use a platform jig with a fence or hole to limit the router travel, since it's hard to be steady with that much bit cutting wood (at least it is for me). At the very least, clamp scraps to the piece to give a wider bearing surface. FWW had an article a year or two ago on this.
Holy high priced carbide Batman!
It seems that there are plenty of 2" long (cutting surface) spiral bits. I think the price must have blinded me or put me into denial.
Which changes my question a bit (no pun intended); I can't afford a $100 bit right now, so if I drill out a lot of the waste, will a double flute bit pose any danger from chatter or grabbing the wood, etc? It will be in cedar for shutters. I did some practice cuts w/ a 3/8 x 1" bit and got pretty good results.
BTW, these are blind and will be pegged (stiles and rails).
thanks again, Jake
Edited 7/18/2005 12:27 pm ET by flamedmaple
$100? Wow, I just knew they existed, didn't know how much.
Part of the beauty of a spiral cutter is that the cutting surface is always in contact with the wood, which makes it much smoother and less grabby than a straight fluted bit, where the whole cutting edge whacks the work at once.
The deepest mortises I've done are about 3.25 - 3.5" through mortises for the maple base of my workbench. Drilling them out first is optional, since a spiral bit can plunge cut, but if you got good results with your practice parts, go for it.
Also, with a pegged joint, you could get by with a little shorter tenon. Just put the peg close to the shoulder (but not too close) to minimize issues with expansion and contraction of the stiles.
Flamed, try, http://www.pricecutters.com. They have a 1/2" dia 2" cut depth solid carbide spiral bits for $45.00 Maybe not the best bits, but it is solid carbide and a lot cheaper than $100.We are the people our parents warned us about. J. Buffett
The biggest advantage of an upspiral for deep mortises is chip ejection. If you remove most of the material with a drill you will virtually eliminate that advantage and a two flute straight should do a fine job.
Charles M
Freud America, Inc.
Rockler is having a sale on router bits through 7/24:
10% off on one bit20% off on two bits30% off on three or more-Jazzdogg-
"Don't ask youself what the world needs. Ask yourself what makes you come alive, and go do that, because what the world needs is people who have come alive." Gil Bailie
Here's an option:
I recently bought a Whiteside spiral upcut carbide bit, (1/2in dia). On the package it said 1.5 inches cutting length. After installing the bit with the shaft set into the collet as far as it would go, the cutting length was 55mm which is over 2 inches.
pk
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