How to make this cut?

[Sean McCurdy]

Some feedback:

When cleaning up the worm-rotted surface that you can now see in the pic what I did was a full depth circ saw pass about an inch in from the face, then took it over to the bandsaw. My experience there was not particularly great. Wresting a 80 lb beam around on the bandsaw wasn't great, and my 1/2" 3 tpi blade struggled with the cut. It's a 1hp 3 phase motor, the problem was the belt drive would just slip. The old growth stuff is just that tough. It also had tracking issues, so I'm not thrilled about the ideas of slicing off a face then re-glueing it.

Lee, I wish I knew someone with a sizeable end mill, but no luck there. Otherwise, a great idea. I'm wondering if this is something I'd want to try on my mortising machine now...

At the moment my most likely plan is to cut the lines with a plunged circ saw (yikes indeed) then follow up with a forstner for additional depth.

[Matt Day]

Just thinking out loud, but how handy are you with chainsaw? Seriously, with a small saw you could hog most of it out and clean up with your mode of choice.

[Jesse Busenitz]

Just thinking out loud, but how handy are you with chainsaw? Seriously, with a small saw you could hog most of it out and clean up with your mode of choice.

This would be my choice as well, but I've logged a few hours on a saw before (no pun intended).

[lowell holmes]

I would route it and square the ends with a chisel.

[Tim Bueler]

Depending on what tools you have available... I would cut just inside the line w/ a circ saw. You can come at it from all directions. Then I'd alternate between a OMT and a heavy blade chisel to hog out the majority of the waste. Set up a router guide to follow your cut line. If you have a pattern cutting bit you can do your first cut with a guide, then use that cut as the guide for the next cut. It shouldn't take too much to chisel or OMT whatever waste is left. I've used a similar approach several times notching newel posts around various obstacles and always tried to make a cabinet grade cut even when it didn't count so I was practiced when it did count. It'll be fun!

On your circ saw plunge cut keep the blade moving forward, it doesn't take much, as you plunge will help avoid the back end of the blade from grabbing. On a piece that large you could even set up a guide for the saw foot if it makes you feel more comfortable. One less thing to watch.

[Sean McCurdy]

All,

Just a quick update. I did complete this this weekend successfully. Well, mostly.

Results:
mantle.jpg

Method:
Ran the circ saw down the lines, and again with overlapping cuts; for a total of 5 plunged rips. Unfortunately, this only freed the one corner. The rest stayed put, even with some considerable prybar application.
So, we turned to the drill press. Chucked up a 1 1/2" Forstner bit and an extension so the chuck wouldn't hit the work. I was hoping to use my cheap-o Ryobi set, but it doesn't have the depth needed without the extension. So instead I used my nice Colt Maxi-cuts.

Running two 6 foot rows of overlapping holes resulted in approx. 150 bores of 4-6" depth each. This took a lot of time, as I'd have to pause every 4 holes to let the bit cool down. Despite that precaution, I still managed to overheat the bit. And sieze it in the extension. Looks like I have another project.

About 2/3 of the way through I did resort to resharpening the bit with a fine file, but since the edge had been overheated this didn't last very long. Roughly a $40 mistake.

[Tim Bueler]

Way to go Sean! Where there's a will there's a way. Knowing what you now know, just think how much easier it'll be next time.