Hi all,
I have been a carpenter for a very long time, but have little experience with timber framing. A project I'm working on requires me to create a pocket in a 6x8 douglas fir post that is 1/2"x4" and 24" deep through the center of one end. The purpose for this is the insertion of a steel plate that will then be through bolted as per engineer's spec. Technically, I suppose this would be a blind mortise.

I try to refrain from referring to it as a mortise as the depth is simply off the scale. My problem is that I can't find any tool capable of removing the material to that depth with any degree of accuracy. Any suggestions would be appreciated.

Thanks,

Lowell Shaw

what about cutting a 1/2" wide groove deeper than the plate width. Glue in a 1/2" piece of DF to hide the groove after. Done well this would be almost invisible.

Without buying or borrowing a slotting tool such as this
http://www.timbertools.com/Products/SwissPRO-Horizontal-Slotter-SG-400.html (and it only goes 18" in) or plunging it with a chainsaw (not recommended as it takes a perrfectly tuned saw , tremendous skill and years of heavy chainsaw use to be able to do that accurately) you'll have to do as Ray said and cut an open slot down the face of the post and then fill it in after the post is installed. Depending on your tooling and the orientation of the slot in the 6x8, you may need to cut the slot from both sides of the post and then fill both faces. Check with the engineer to verify that this is ok.

Ask the Engineer how he/she would normally do this.
They can't just go around making shit up without having a way to do it. I'm sure there is a better way to do this.(Head shaking)

I agree with the idea of cutting a particularly long mortise and then blocking off part of it to hide it. If the plate is throught bolted this shouldn't have much affect anyway.

Also, this seems strange. Did the engineer have a little much to drink?

The guy who did this:



Used a chain saw but he had a bracket to mount it to the timber and then slide on a square steel tube to hold the chain saw at the exact position to plunge cut the base of the post.

It can be done.

Unfortunately right after I took this picture my camera lens motor broke and I couldn't focus the camera any more.

I did take some pictures of him cutting one but you can't see anything as the pictures are too blurry.

Jim Rogers

Thanks Thane, you made my day(and summed up my current job site).

It can be done, and the tool to do it with would be a chainsaw, with some sort of guide, even if its just a jig to hold the bar level. Plunge cutting is one of the more dangerous cuts.

I make plunge cuts all the time when felling large trees. Sometimes this normally dangerous cut is really the safest way to go about it. It's a must when the tree has a risk of splitting, or you suspect it may be hollow or otherwise rotten inside, or if it has a heavy lean.

The key is to go in with the right part of the nose, start the plunge with the lower half of the tip and once your in a good ways I actually will turn the saw a bit and lead with the top of the tip because in this case it gives me better control of the cut. The chain needs to be good and sharp too.

DLB

If the engineer needs the steel for a connection you may want to look into timberlinx connectors. They are easy to install and ares structurally tested and certified.

Thanks for all the input! I've got a meeting in the AM to see if I can make any mods to the specs. I'm hoping to shorten the plate to the max depth of the longest chain mortiser we can find. We already have the Makita, but it's plunge is way too shallow and the clamp system wouldn't work well on a post end.

I have made some dicey chainsaw plunges in the past and been successful, but this one is just too close to the dimensions of the bar to avoid a hell of a fight.

L Shaw