Router mishap

[56nortondomy]

I had one of those router events today. I was cutting the binding channel on the top of the archtop i'm building and because of the shape i had the router bit as low as i could get it in the router so i could make the cut. All the way around i was thinking it's going to slip down,and sure enough about 100mm from the end it did, and of course it was in the hardest to get at part of the guitar. As soon as i realised there was way more chips spitting out than should be i turned it off, i had a section about 40mm long where it chewed out. I've made a repair and finished the channels, so hopefully it'll be nearly invisible under a finish. I guess the moral is don't take shortcuts, after that happened i modified my jig so i could have more bite on the bit and it worked fine. I hope this post will help stop it happening to someone else.
Wayne

[demonx]

I opened the post half expecting to read about mince meat fingers or something, so in comparison your post is good news! From the pics your repair does look invisible.

Must be the day for it. I had a router height whoops today myself. Started with the rosette ring and when it lifted up it tripped out a limit, when it continued it was out by a couple millimeters and cut the outer purf channel straight through the top!

Just like you I moved on and dealt with it. When I get to the bracing I'll maybe add a ring or something around that area for extra support. I've seen this done in some guitars as standard anyway instead of the linear sound hole reinforcements

[56nortondomy]

Must be router f%&$ up day.
Wayne

[kiwigeo]

No router stuff ups but half an hour ago the head came off my log splitter just as I had it above my head ready to split a large log in half...luckily the head missed my head...and my foot.

[56nortondomy]

Sounds as if you weren't wearing your PPE Martin, i'm sure on the rigs you get it drummed into you. Funny how when we get home all that safety goes by the wayside.
Wayne

[Dave M]

Man those router gremlins were busy everywhere today.

I obviously tried to take too big a bite with my pattern following routing. It is also an illustration of just how soft the 'cedrela', probably a mahogany (?) that is sold for necks in the UK.

I spent ages getting the geometry right on the mortice and tenon joint so no way am I ditching this neck. I guess I can split the scarf joint and replace the headstock piece.

I've got to find a way of reducing the risk of this. Maybe roughing out to much closer to the pattern. Maybe burying the router cutter in a fence so it can't take a deep cut...?

Seriously cross Dave

[demonx]

I've got to find a way of reducing the risk of this. Maybe roughing out to much closer to the pattern. Maybe burying the router cutter in a fence so it can't take a deep cut...?

Seriously cross Dave

By the look of it, your first mistake is trying to take it all out in one pass. That is asking for trouble.

Try this: get a router bit machined back to 5 or 6mm for this type of cut. Instead of doing one pass, do about four passes to cut through the headstock thickness. Much, much safer.

Use your template for the first pass, then remove the template and use your first pass as the new cutting template. This removes the risk of the template moving and it also helps get the short cutting bit to the depth you need.

[Dave M]

Allan of course you are right. I know this technique, just forgot in the heat of the moment.

I was in too much of a hurry. I was so keen to get some strings on. Will not do that again.

Dave

[56nortondomy]

That's a real bummer Dave, i hope you can save it somehow, you'll really have your work cut out doing that.
Wayne

[kiwigeo]

I obviously tried to take too big a bite with my pattern following routing. It is also an illustration of just how soft the 'cedrela', probably a mahogany (?) that is sold for necks in the UK.

Look at the bright side...you've verified that that neck wood is nicely quartered

[kiwigeo]

Sounds as if you weren't wearing your PPE Martin, i'm sure on the rigs you get it drummed into you. Funny how when we get home all that safety goes by the wayside.
Wayne

Well I had on everything except a hard hat......I usually don't worry about head gear as there arent any dirty big derricks with nuts and bolts falling off same.

[needsmorecowbel]

could you use a forsner bit to hog out the majority of the headstock channels? Then get the rest with a router or is that asking for trouble?

Stu

[kiwigeo]

could you use a forsner bit to hog out the majority of the headstock channels? Then get the rest with a router or is that asking for trouble?

Stu

That's what I do.......I hog out with a forstener and then trim to the pattern on the router table.

[simso]

Wow,

The rosette came up a treat.

Shame about that headstock, but it happens to the best of us once or twice

I almost lost fingers taking too big of a bite when I was profile shaping a guitar neck, I usually bandsaw and grind down to within a mm or two, once I left a good 4mm on, 21mm depth, exploded the neck blank, my fingers clipped the roller bearing on the router bit and I almost went home to change my pants , that was scary.....

[kiwigeo]

I tend to use a small diameter cutter also when trimming headstock slots to a template.....it takes out less wood in one bite than a bigger cutter.

[Dave M]

Well I decided that I wasn't sure I could retrieve the neck with the broken headstock so decided to start again.
It's all good practice yes...?

And indeed the new neck didn't take too long to build. Having more confidence in the process I am willing to cut closer to final dimensions rather that leaving lots of spare wood which then takes a long time to pare off.

I took all the advice offered. Note that the damage occurred routing the outside of the top of the head where it is really vulnerable on that corner.

I took the rough cutting pretty close to the line so there was not too much material left to cut with the router. I doubled up on the template so I wasn't cutting the full depth on the first pass, removing the second layer to complete. And I nibbled at it in thin passes.

Martin yes a thinner cutter looks right. I am going through the catalogues.

Steve you're dead right it is a slightly dodgy technique. Although if all is going well your hands are reasonably far from the cutter, if things go drastically wrong as they did with me, and obviously with your experience, then there is the chance of going into the cutter.

Anyway on he upside I now have a decent neck that has the right angles in both dimensions to the body, with the headstock cut correctly. I also glued the fretboard today so final shaping of the neck and fretting should happen soon.

Dave

[kiwigeo]

A 1/4" shaft flush trim cutter with bearings at both ends is what I use. It allows use with pattern on top or bottom of the work.

[demonx]

Martin yes a thinner cutter looks right. I am going through the catalogues.

I was never able to find one I was happy with, so I bought the closest thing to it and had the tool shop machine it back to 5mm cutting depth. Costs only $80 (ish) for the bit and labor, but you get a router bit that is purposed for the job. Them you can move onto the longer bits to get the depth after the first couple of passes.

[kiwigeo]

Martin yes a thinner cutter looks right. I am going through the catalogues.

I was never able to find one I was happy with, so I bought the closest thing to it and had the tool shop machine it back to 5mm cutting depth. Costs only $80 (ish) for the bit and labor, but you get a router bit that is purposed for the job. Them you can move onto the longer bits to get the depth after the first couple of passes.

Ive got 3 of them...the CMT is the better of the bunch. I use them in a router table....

[demonx]

I finally remembered to snap a pic of the router bits I was talking about. These are both 1" bits, however one of them I had machined no 5mm long. Very handy.