Making the Most out of the Robert O'brien Mortise and Tenon Jig
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- Опубликовано: 29 авг 2024
- This video is about a jig that I absolutely love! The Robert O'brien Mortise and Tenon Jig (AKA Neck Angle Jig).
There are alot of things about using this jig, however, that trip alot of people up. So with this video, I'm going to walk through my process for using the jig, and address some of the common problems that people have. I will also show you how to hook up a shopvac to the jig so you don't get wood chips thrown at your face!
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Nice video Eric. Have been struggling with a lot of the issues that you have addressed with your mods to the original.. I'm in the process of re-building my jig and I'm making it somewhat more rigid to reduce the flexing. I will incorporate the other ideas to keep everything square and aligned that you have shared here as well.
instablaster.
That was 5 years ago. Now, he is using a different more expensive jig but he didn't say why and didn't respond to that question on a more current video.
On a positive note, Eric's explanation of the process is much better than Robert's.
Robert, this may not be the right video to comment but you are the go-to luthier. Neck angle: we know the strings ride between the nut and bridge, and we want a consistent space between the strings and the fretboard. As we raise or lower the bridge height we need to adjust the neck angle accordingly. I’m your opinion does a steeper angle ( and higher bridge) result in a higher tension and better transfer of vibration to the sound board? Can you recommend some reading material on neck angle, string height, bridge, saddle relationships…or I can just follow the instructions…haha. Thanks for being such a great resource. As a kid, before computers, about the only resource was a copy of Sloan’s in the public library and the old Russian luthier who worked at the Blue guitar
I've just bought Robbie's plans and am about to embark on building this jig. Totally onboard with these suggestions, and I will aim to build them in from the outset. I'm wondering too about clamping. Maybe secure it on some sort of base accessible from both sides? I'm guessing the increased mass of the whole resulting structure will help to negate the ability of the whole thing to flex under pressure, affecting the final neck angle?
Now That was a Cool Video ! ,,, Very informative !
Eric, thanks for the detailed use of the jig. I have tried to find this jig with LMI but they don’t seem to carry it anymore. Do you know where I can get some plans for this jig. I appreciate your help. thanks.
Thanks for making a detailed instructional video. Love your material man! I have one question. What's the significance of the 9/64" when lining up the straight edge with the neck and the body? Is that the usual thickness of the bridge? So you still have room for action adjustment?
Great tips, Eric, thanks for producing this.
I've got a question and one suggestion:
Snugging up the neck blank to the bottom of the tenon template: I understand that the end of the tenon will not bottom out in the mortise, so the end angle of the tenon is not *ultimately* important when finally attached. But when setting up the cut doesn't the butt end of the blank need to be flush to the bottom of the tenon template to ensure that the shoulder of the tenon hits your 14th fret layout line? The end of the tenon can be trimmed off, but only *after* you set the depth of your bit. In other words, in Robbie's layout sequence the nut position is the fixed reference, then the 14th fret line is located from the nut, then the end of tenon line is made exactly 7/8" further from that and the neck blank is cut off at that line. Unless I'm missing something, the end-of-tenon line is your exact index point to properly set the shoulder of the tenon at the 14th fret line. The reason I'm bringing all this up is that if you sand the end of the blank carelessly you might lose your reference point and the neck won't meet the body exactly at the 14th fret. This happened to me, though again there might be something I'm missing.
My observation: I think Robbie's jig is great, but clamping it solidly is still an issue. Eric, even though you made provisions for your clamps I can still see that your jig has quite a bit of rock in it. I was holding my breath every time you used the plunge router, especially since you were so careful to consider the weight of the router and attachments. Locking down the jig a little more is the only suggestion I could make to your very useful video.
Thank you, Jeff. Good question, and a good suggestion.
Snugging up the neck blank to the bottom of the tenon template:
If I am understanding you correctly, here is what you are missing... The bit is bottomed out against the end of the blank before you set the depth of the bit. That way, no matter how far the neck is from the template, the depth of cut is still 7/8" from the end of the blank, and not from the template itself.
In other words, before I set the depth, I plunge the router bit down with the router turned off) until it hits the neck blank and I lock it in place. NOW I set the depth to 7/8. Does that make sense? I think that's what you were referring to. Let me know if I'm missing your point entirely.
Thanks for the suggestion. I agree that it needs more support. I think some way of connecting the leading edge (where the tenon template is) of the router bearing surface to the workbench itself would do it. I imagine something like 2 support beams coming down from the corners to meet the workbench surface to eliminate flex. Whatever way you support it, however, it has to not get in the way of the other functions and moving parts of the system, which is a bit difficult, but not insurmountable.
In lieu of all that though, checking measurements with the weight of everything considered really does produce predictable results when you make the actual cut. You are right though. It would be nice to not have to worry about that in the first place.
Hi Eric. I would like to purchase a router for this operation as I don't have one. I am thinking mid to high quality router. What router would you recommend? I would also need a plunge base for this as well. Thanks so much for your awesome videos. Cheers from Toronto, Canada.
Eric. I noticed that you do not use the nut with the guide bushing to secure it to the router plate. Is there a reason for this?
thank you Eric . question please why not use a dove tail ? as opposed to mortise and tenon ? is there any difference in the strength between the 2 of em ?
I'm gonna use bolt on necks for my guitars, just need sum barrel nuts and 3 bolts. I think that way is better cause u can take it off anytime u need 2
Thanks for the vid. So do you think the weight of the perspex and shop vac hose is causing the jig deform causing the difference in measurement that you talked about (about 20 minutes in)? If so do you think a more slid construction would remove this variance?
"solid construction" e.g thicker ply wood
The Simpson jig !!!!!!!!!!!!!!!!!!!!!
If I cant build a jig......no way I can build a guitar! doh
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