Alternative approach to cutting tenons

[Jim Becker]

The mill clearly does nice work, albeit not at moon rocket speed. And using all the tools available for whatever they do best isn't a horrible thing. Machines and all those beautiful hand tools on your wall can and should coexist very nicely together; they each have their advantages and compliment the other. IMHO.

[Brian Holcombe]

Thanks Jim! I’m finding it handy to tool up the mill. I agree totally that the two coexist nicely. There are many things where it is effective to work by hand and others where it is very handy to be able to make very accurate and repeatable cuts.

[Chris Parks]

I have seen a Bridgeport used to cut box joints many years ago.

[Derek Cohen]

Brian, words fail me! That is some machine. I know that it was set up for fun, but how much time would it actually take to do from scratch if for real?

I suspect that this post was partly, if not unconsciously, a response to my post on WoodCentral, where I showed my set up for using power tools to make M&T joints. I did not post it here as I am in awe of the machinery that is so often on display. My default is still to return to hand tools, although I have used power tools for at least three decades. Anyway, I cannot link to the WC post, so offer an abridged (as opposed to Bridgeport) version of my quick route to tenon cutting.

It uses the tablesaw for shoulders, and the a spacer on the bandsaw for the cheeks. The mortice was first routed out. I work with reference sides, rather than exact centering, so exact positioning is not important.

First the shoulders are defined on the tablesaw .....





The bandsaw is set up to saw the cheek furthest from the fence. The reference side faces the fence.





This spacer is for a 8mm or 5/16" wide tenon/mortice (in the current build). The measurement is the width plus the width of the bandsaw blade kerf.




Place the spacer against the fence, and saw the other cheek without moving the fence ...





You can see that the beauty ends of the tenon still need to be removed.

Regards from Perth

Derek

[Chris Parks]

I reckon the router table with memory will top the lot but I can't link it here so look in the Oz forums/router tables for the build.

[Brian Holcombe]

Derek, Hah, no that was a serious job. I'm building chairs currently and so the process is often short production runs. I'm finding that as I build a lot of them I prefer exact duplicate parts rather than hand-fitting each joint. The more accurate and hefty the machine, the more often those parts are actually identical.

I save the handwork for the shaping and so forth which is time consuming but it is very necessary for the finished product.

I have a variety of methods which I employ; Bandsaw, router table, handsaw and now also Bridgeport mill. Really what I would like to be doing is cutting these with a shaper or tenoner. The trouble with a bandsaw, router table method is that it's multi-step and so more time consuming than the bridgeport even though the Bridgeport feeds stock slowly, but it can be quite accurate, nearly as accurate as the bridgeport if the work is done carefully. The minor things which effect accuracy on the router table do not on the bridgeport. IE when work is clamped into a milling machine vise it doesn't move out of position but work held into position against a stop can move on a rare occasion. Those occasions tend to happen enough to be annoying when you're doing a five-step cutout with multiple setups.

I can also do things to turn up the rate of progress on the bridgeport.

Truth be told I did not have that thread in mind, specifically, but I suppose I've been thinking about it more now that the thread is going.

[Chris Parks]

When I saw Derek showing how the spacer works the lights came on and I thought it was a terrific idea. The router with the fence I have an issue with but it is my own personal dislike of hand held routers with the factory fence used in a similar fashion, I just can't get past how easy it is not to be accurate but if it works for Derek so be it.

[Brian Holcombe]

I hesitate to reference to the length of part when setting stops, at times, it introduces another place for error to accumulate. Unless the stop is perfectly square and contacts the entire face of the part there will be a good chance that the referred length will be slightly different as the part is turned because the stop is contacting the part differently as it is turned unless both faces or one face is perfectly square.

When I've cut tenons with simple tooling (router table) I've gotten the most accurate parts by cutting one joint using the fence as a stop, then cutting the opposing side using a stop which contacts the tenon shoulder. This resulted in parts which had totally square shoulders and which repeated their lengths precisely.

Ideally, one clamping should result in the entire cutout, but that's impossible with most of my tooling.

This is the result when using the router table, I'm pretty happy with this. These are double tenons, fully shouldered.

[Brian Holcombe]

When I saw Derek showing how the spacer works the lights came on and I thought it was a terrific idea. The router with the fence I have an issue with but it is my own personal dislike of hand held routers with the factory fence used in a similar fashion, I just can't get past how easy it is not to be accurate but if it works for Derek so be it.

The spacer is a slick way to do it, beats resetting the fence. I actually had not been thinking of that which is why I'm glad when these discussions come up as these sort of things pop-up.

[Chris Parks]

I don't know why but I find stops not to be as accurate as they should in theory be and I wonder if it is because they are made of wood, don't ask me why but I wonder if they were made of a harder material such as aluminium or a solid plastic they might give a better result.

[Mike King]

If you like repeatability and accuracy, a shaper would might be an improvement in function. And quicker.

[Van Huskey]

Is there some kinda weird supermoon or is Mars in retrograde? Brian and Derek both over here using electric pixies. I am afraid to go to the Neander forum, a bunch of machine guys may have crossed over and be there in a cat fight over bevel angles and chip breakers.

[Brian Holcombe]

There is a good chip breaker thread getting started over there, hehe.

Chris, it's likely due to what I mentioned above, that end grain slightly out of square has a consequence in how it translates to the cut. As you rotate the length is effectively different and that shows up in the shoulder.

Mike, I agree, I'm on the hunt. I just missed a Hofmann shaper and have been kicking myself. I'll probably end up getting a Minimax TW55ES.

[John Goodin]

Maybe I will show this to my wife and say I need a machine like that but will settle for a better drill press.

[Matt Mattingley]

I don't know why but I find stops not to be as accurate as they should in theory be and I wonder if it is because they are made of wood, don't ask me why but I wonder if they were made of a harder material such as aluminium or a solid plastic they might give a better result.

Sometimes I use gauge blocks or gauge pins. Sometimes when you’re looking for a specified size, the blocks and pins will be your friend. If there are odd size blocks or pins, you just surface grind or cyl grind to suit your needs and add it to your arsenal of fixtures.

I might measure the size of a hole or pocket very differently then Jim, John or Ed. To each his own.