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Routing Neck Shape Help


jay5
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OK, so here is my deal. I am trying to get my first neck off the ground and have run into a problem. I am using a template and flush trim bit to rout out the neck shape. I have a 2 flute Whiteside flush trim bit that is realitively new and a MDF template for my telecaster neck. The problem is that when I attempt to use the bit to rout the neck shape the bit tears out huge splinters of wood, especially along the edges of the fretboard area. It has also tore off a good portion of the headstock as well. I practiced on a piece of pine and this happened. I just figured it was due to the nature of the wood. When I proceded to my 3/4" maple blank (from Warmoth) the exact same thing happened. It was ruined almost immedieately. My question is, what the h@!! am I doing wrong? I know that alot of people use this method with no issues. I made sure that after I rough cut the neck shape I sanded it down to no more than 1/32" outside of the final shape so I know that Im not trying to take off too much material. Also, my bit is good quality and is realitively new. I have used it on MDF and 1/4" acrylic and thats it.

I have gotten a new router since my last attempt (Bosch 1617) and have decided that maybe I should try a brand new bit this time. Whiteside offers two bits that I am looking at; 3 flute flush trim and Helix flush trim. I am looking into the 2" cutting length and 3/4" diameter bits. The 3 flute bit SHOULD provide a smoother cut. The helix bit is interesting as it has a downward shear, similar to a spiral bit. It would be cutting upward in my router table, Im not sure if that would be an issue. So anyway, can anyone provide we with some advice on which bit you would opt for or if I should try a different brand (CMT maybe?). Could I have gotten bad neck blanks? Any insight into why am am destroying wood like I am wpould be much appreciated. Thanks guys!

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I have used it on MDF and 1/4" acrylic and thats it.

MDF dulls cutting edges pretty quickly. Also, look at the grain where the tearout occurred. You will probably notice that it is leading in to the edge where the bit is cutting. As long as you are down to 1/32 of trim, try carefully running the router right to left in areas where the grain is running this way. Make sure the piece is held securely, and just do about a half inch at a time, working from left to right, but running the router right to left. Hope I explained that OK. :D If you are working on a router table, you'll have to flip that explanation upside-down, but you get the idea, right?

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Make sure everything is really secured. The blank needs to be tight as a tick to your work surface. The bit needs to be tightly seated.

Those long cutting edge bits tend to vibrate a lot. Use the shortest bit that will do the job!!

If you're down to 1/16 or less back routing is the way to go. slowly cut from right to left. The router will have a tendency to run away and to dig in and bite.

What I do is cut a starter slot about two inches from the start with the router. Then I reverse cut to it. Then another slot the rout to that, etc.

There are quite a bunch of good books on router tips and techniques, Check Taunton Press. They also publish Fine Woodworking, which has a lot of how to do it tips in their archives.

Patience, hand strength, and a sharp router bit, grasshopper.

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I never thought back-routing would be very effective, but if it's a recommended technique, I should give it another go.

I have to say, even though I have very little experience, it sounds an awful lot like either your router bit wasn't aligned in the collet properly, or the bit itself wasn't as sharp as it first appeared.

Greg

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I'm not totally understanding this. Are you recomending that I feed the wood against the spin of the bit or go with it? I always thought that going against the turn was the right way. I imagine that running a board with the spin could be somewhat precarious. Am I right?

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Generally, you should feed the wood AGAINST the spin. This is the first time I've read that feeding it with the spin can be effective, but if a lot of woodworkers recommend it for when you're down to a wee bit left, then it's worth considering at least.

Another thing is to not try to use the whole depth of your bit at once. Not sure if you tried this, but I found I had to make passes of about 3 different depths when I was doing my body. Haven't done my neck yet.

Greg

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Jay,

I had the same problem when I made my neck.Totally stuffed the first one up by breaking the headstock out.

The second one,

I cut the headstock shape with a bandsaw,run the router up and down the sides slowly ,and a bit at a time,then I made a "Robo" sander which is a drum sander with a template guide on it (Stewmac sell them know) and stood infront of the drill press for about 1/2 hr and sanded it to shape.

It came out good.Better than stuffing up the neck and I had some control over how much i took off.

It is the "Gutless" way to do it I suppose.

Greg W

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I had a problem like this before, and I found out that I was going to fast and cutting too much in the same pass, so I started placing the template on the piece to be cut, outlining it, and then using a scrollsaw or bandsaw, cutting it as close as Ican get to the line, leaving more or less 1/8 extra. then just rout it slowly. This should do it.

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I really like the Robo Sander for necks simply because of the tearout issue you can have with router bits, but then again if done properly a router bit works great. I basically have came up with a 3 step method of cutting the neck out now, but I never use a router on the headstock part though.

1. Bandsaw as close as possible.

2. Robo-Sand it even closer but not complete down to template.

3. Flush trim router the neck taper and end.

But this is just the way I do it.

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On the back routing: No, you don't want to do the whole thing in one pass this way, the router would take off and make an awful cut.

Here's an example: Picture at the neck blank. It is tapered, so the grain runs out at the sides, right? On the treble side, you can rout the regular way (heel to nut) no problem, the fibers are simply sheared off. On the bass side, you are going from the nut to the heel, and thus, into the grain. Imagine running a chisel this way, and you can picture what happens. The same thing happens at different parts of the head and heel profiles. Anytime you can see that the bit will be cutting into the grain like this, pull out, bring the router about a half inch or so to the right, and rout back to where you stopped. Repeat this until you are out of that area.

Bigger operations actually have machines and cutters set up to run in reverse to handle this, but us mere mortals just have to take our time and pay attention. :D

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Thats right org, running the spinning bit INTO the grain, ie. cutting tip is contacting end grain of curves head on, spells disaster. It happened to me when I knocked a chunk out of the first curve of my tele headstock. Glued it back on but you can see where the damage occurred. The proper way was to come in from the other side with the spinning blade hitting the wood ACROSS the grain. Also, if your router has more than one speed the best results are at the highest setting. Travel slow, but not lingering long enough to burn the wood, although that can easily be sanded out.

Here is what I'm referring to:

router8ff.jpg

Assuming you have rough cut the shape with a bandsaw or jigsaw and want to "fine tune" the shape with a router.

Edited by Southpa
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Wow Org, you are exactly right. I totally see what was happening now. Thanks alot. Guitarfrenzy, I was thinking of trying to use a robosander but I was wondering, how good of a "cut" do you get with it? I imagine that a sanding drum isnt as accurate as a good routerbit. How much cleanup did you have to do?

So, does anyone have a suggestion on which of the two bits I linked to would be a better choice?

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Whitesides are good quality industrail bits.

You need to use the 1/2" shank bits for this stuff.

I use 2 flute bits. The helical bits are primarily designed for trimming laminate. They "push down as they cut and have less tendency to chip the plastic. If you're routing a body with a "cap" of another wood you may want to use a spiral bit.

Again, I get good results with a 2 flute. I rout everything from walnut to Corion with only an occasional tearout.

Once you get the hang of back routing you'll be okay. It does take a little while to figure out how big a bite to take each time. And, unfortunately, figured maple is about the worst wood to try to do pattern routing on. Wacko grain, hard, brittle, nothing worse.

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I have gone through Matts's tutorial several times and it is obvious he had good results. I will probably get a 3 flute bit and use it in conjuction with the robo-sander as matt suggested. I found two decent maple neck blanks I had from a while back that I plan on practicing on. Well see if I can get a hang of back routing without tearing too much stuff up. I am tempted to order one of these, but $75 is a bit steep. I imagine that this would be the ideal bit for the sitaution though. We'll see.

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Here is technique that ca be used in some situations, use a template bit when it will not cut into the grain- if you get to an area where it will cut into the grain, then flip over your piece (or your router) and switch to a flush trim bit- in essence you are reversing the spin direction of the cutter in relationship to the wood grain.

edit- for the record, I only use my routers when absolutely neccessary. I plan on using a robo sander setup when I eventually decide to spend some bucks on a big and solid drill press.

Edited by bassman
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if you get to an area where it will cut into the grain, then flip over your piece (or your router) and switch to a flush trim bit- in essence you are reversing the spin direction of the cutter in relationship to the wood grain.

great idea -- i did that with my maple V wings by switching the 'template' onto the other face of the body, then flipping it over. but that was easy with V wings, since the template was just a straight edge. your method lets you flip the body without having to align a second template.

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A buddy of mine showed me a great tip too.. Nefore you route, do some planning.. take a pencil and draw direction arrows in areas where you need to be careful.. Then while you're routing you don't have to think.. Just go slow and follow the arrow. Always start at the end of an arrow and move till the tip.. then pick up and move to the begining of another arrow. Silly but for a minute of pre-planning it will save a lot of headache.

I can't figure out why your board was splitting on the long end unless you had really bad grain runout or something. I've wasted 2 necks with tearout on the very tip of the peghead.. but never in the straight part.

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The helix bit is interesting as it has a downward shear, similar to a spiral bit. It would be cutting upward in my router table, Im not sure if that would be an issue.

i just noticed this comment of yours. yes, using a Downcut bit on a router table will put Upward pressure on your workpiece and is a VERY BAD idea. the force will tend to lift the workpiece up off the table -- you can imagine how disaster would then occur. most helix and spiral bits are also availible in an Upcut version. those bits will tend to pull the work against the router table, which is good.

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