Questions about router mortise cutting

[reible]

I have a new project on the drawing board. It has to do with using the shopsmith in drill press mode and using a router bit to cut a mortise.

I've been working on this for about a month now and have what I think is a pretty good idea what I want to do. Since I normally don't make mortises this way I've not had to work within constraints of the shopsmith. I'd like to change that.

So what I'd like to know from those that do use the machine this way.....

1) What is the maximum length you cut for a mortise? For me I'd say 4".

2) What is the thickness of wood you might want to use? I'd say from 3/4" to about 4"

3) How tall of wood do you cut this way? I'm thinking from 3/4" to again 4" tall.

4) Do you ever use the shopsmith mortising jig to make the end hole square? I haven't but I could see this as a possible.

5) Would a stop device for each end of the cut be useful? I'm inclined to think this would be a big plus.

6) How interested would you be in being able to be able to use this with the OPR? I don't have a new version so I would need someone to work with me to make it compatible, you know someone who owns one.

Sorry I can't release other details as the details are floating too much yet.

Ed

[charlese]

I use the OPR to make all mortises. Don't understand any limitations on wood size.

I use rounded ends on both mortises and tenons. Tenons are thickened by the thickness planer.

[algale]

I used the Shopsmith in drill press mode with a router chuck and down cut bit to make some angled mortises as seen in this thread. http://www.shopsmith.com/ss_forum/viewt ... p?p=181228

Because it was an angled mortise I had to put the work piece between the way tubes and I used the miter gauge with extension as my fence. If you are just cutting a straight mortise then you could use the rip fence.

To answer two of your questions, I did have stops at each end, which is important. I also did not square off the ends. I don't think there is any practical limitation on the width or height or length of stock that you can work on as long as you can set up some extension tables and supports.

[edflorence]

Last week I used the Shopsmith Speed Increaser under the table to rout edge rabbets on 3 foot long 1 x2 pieces. As this operation is pretty similar to cutting mortises, I thought it might be appropriate to post a few thoughts about how it worked out in this thread. First, even with the bit spinning at a bit more than 10,000 rpm, the cleanest cuts came when I kept the passes to just a bit more than 1/16th. I have also found this to be true when using the Shopsmith in drill press mode to rout mortises. What I prefer to do in that case is to not rout the mortises at all, but drill out the waste and trim up with a chisel. However, I could not do that with these long rabbets. The rabbets were stopped at 3/8 of inch from either end of the workpiece, which presented another problem, namely I had no practical way of establishing stops. So I used the method Nick describes in "Woodworking Wisdom", which is to mark the ends of the rabbets on the workpiece and mark the diameter of the bit on a piece of masking tape attached to the table in front of the bit. This works, but requires the last little bit of the cut to be back-routed, which is quite nerve wracking. I would much rather have established stops but could not figure out how to do it with such a long piece. So I think if you are routing mortises along the length of a long workpiece it is going to be difficult to establish stops. If anyone has figured out how to do that, I would be interested in hearing about it. FWIW, if I have to do stopped rabbets on long pieces again, I think I will cut them on the table saw as through rabbets and then glue back in small plug pieces on the ends.

[rjent]

I have made one table (I almost didn't post here ... but what the heck), but I did 16 mortice and tenons doing it. Using the info found here and in the sawdust sessions, I used stop blocks, like demonstrated by Nick and others, and once I had it set up on practice pieces, the rest were extremely repeatable and accurate. The tenons were rounded over with a chisel and sand paper. I was cutting the mortices over 1 inch deep and 1/2 inch wide with a straight router bit in overhead router mode. I took about a 1/4 inch depth at a time.

There is my .02 ....

[jimthej]

Last week I used the Shopsmith Speed Increaser under the table to rout edge rabbets on 3 foot long 1 x2 pieces. As this operation is pretty similar to cutting mortises, I thought it might be appropriate to post a few thoughts about how it worked out in this thread. First, even with the bit spinning at a bit more than 10,000 rpm, the cleanest cuts came when I kept the passes to just a bit more than 1/16th. I have also found this to be true when using the Shopsmith in drill press mode to rout mortises. What I prefer to do in that case is to not rout the mortises at all, but drill out the waste and trim up with a chisel. However, I could not do that with these long rabbets. The rabbets were stopped at 3/8 of inch from either end of the workpiece, which presented another problem, namely I had no practical way of establishing stops. So I used the method Nick describes in "Woodworking Wisdom", which is to mark the ends of the rabbets on the workpiece and mark the diameter of the bit on a piece of masking tape attached to the table in front of the bit. This works, but requires the last little bit of the cut to be back-routed, which is quite nerve wracking. I would much rather have established stops but could not figure out how to do it with such a long piece. So I think if you are routing mortises along the length of a long workpiece it is going to be difficult to establish stops. If anyone has figured out how to do that, I would be interested in hearing about it. FWIW, if I have to do stopped rabbets on long pieces again, I think I will cut them on the table saw as through rabbets and then glue back in small plug pieces on the ends.

I can think of a possibility. Using the "Flip-stops", set one for the beginning, set another for the end. That would be about 3/4" apart on the channel, centered on the bit. Start with the beginning stop down to establish the cut. The end stop would be up. Flip up the beginning stop to move the start past it and flip the end stop down so it drags on the workpiece. When the end stop drops all the way, stop the cut. I haven't tried this, but it should work. Don't know if it would be safer or more accurate than tape on the table.

[edflorence]

I can think of a possibility. Using the "Flip-stops", set one for the beginning, set another for the end. That would be about 3/4" apart on the channel, centered on the bit. Start with the beginning stop down to establish the cut. The end stop would be up. Flip up the beginning stop to move the start past it and flip the end stop down so it drags on the workpiece. When the end stop drops all the way, stop the cut. I haven't tried this, but it should work. Don't know if it would be safer or more accurate than tape on the table.

Now that is a neat idea, I like it. You are essentially using one of the stops like the "fingers" that turners use to determine the thickness of a bead or cove cut. The finger drops off the workpiece when the desired diameter is reached. Very cool. I think that would work really well, but I am not sure how I would mount the stops, though. I am attaching some photos of how the Shopsmith was set up to do the rabbets and you can see that I used the shaper fence with the add-on pieces to hold the vertical feather boards, leaving no way to attach stops that I can see. I wonder if I could have used a regular rip fence with a track that would let me use stops, to which I could have bolted an auxiliary fence of wood with a gap for the bit...hmmm...that might work. Thanks for the ideas.

This shows the fence I used and also the masking tape guide lines:

masking-tape-for-stopped-ra.jpg (66.54 KiB) Viewed 3142 times

And to get back to the original point of this thread, I did recall that a year or two ago I made some cupboard doors that required mortises in long rails and I did use a spiral upcut bit and the SS in drill press mode. It worked great. I had forgotten I had done these mortises this way. I think this was the first time I had cut mortises by routing versus by drilling. I have to say, after remembering this, that it did work fine. I can't recall how many passes I made but the passes were somewhere in the range of 1/8 or so deep each time. Again, the question of how stops could be arranged in this situation comes up...I just marked the ends of each mortise and eyeballed the cut. No big deal when the mortise will be completely covered by the tenoned rail. The stops in the rabbets I cut last week will show, though, so stops for that operation would have been very useful.

mortises-in-a-long-work-pie.jpg (80.75 KiB) Viewed 3142 times

routing-a-mortise.jpg (53.56 KiB) Viewed 3142 times

[JPG]

An advantage of the SS router bits is that they also have the ends sharpened so they cut like an end mill.

That allows one to cut the 'hole' almost to the 'end', then using the quill like a drill press cut the ends of the 'hole' vertically with one pass at each end.

The rest of the 'hole' can be created first without precise regard for the 'ends'(just keep it short)

A piece of tape attached to the fence serves as a 'locator' for the end cuts.(or table, but I do not need to tell ED about that! )

[edflorence]

An advantage of the SS router bits is that they also have the ends sharpened so they cut like an end mill.

That allows one to cut the 'hole' almost to the 'end', then using the quill like a drill press cut the ends of the 'hole' vertically with one pass at each end.

Ah Ha! I didn't know that...seems like that is the way to go...I will have a closer look at Shopsmith's bits...I might vary your suggested procedure a wee bit by drilling the end holes first so they act as stops, then rout out the rest of the mortise. Thanks for the tip, JPG.

[charlese]

And another way to do mortises with a Shopsmith is to use "Horizontal Boring". This holds the board a bit more stable with the face down on the table. Of course you must place the board near the edge of the table, but it's sliding is real easy!