Bass Edge & Routing

[Bassatronic]

A repost after I posted in the DB section.

HI! I'm just working on my 3rd Bass build and over last couple of goes I've become a bit frightened of my router! I made a simple routing table with a hole and the router underneath. Which did some good round over edges but I always take a chunk or two out of the body. Which is forgivable if your painting the body a solid colour I guess.
This time around I'm wanting a natural finish, so I want to get the edges right this time!!!

About the bass/wood. I'm using Mahogany for a Neck through section and figured camphor laurel for the wings.

So some things I am trying to work out are:

Do I need to break the edge first? Not sure what that is.

Should I be changing direction or just do one pass all the way round?
Is a wider or thinner round over saver to use?

 

[Matt Liebenau]

Are you trying to get the full depth of the roundover in one pass? I make 2 or 3 passes around the body lowering the bit each time until I get to the desired depth of the roundover. I go continuously around the body, as long as you’re taking small bites you should be good.

 

[Bruce Johnson]

A repost after I posted in the DB section.

HI! I'm just working on my 3rd Bass build and over last couple of goes I've become a bit frightened of my router! I made a simple routing table with a hole and the router underneath. Which did some good round over edges but I always take a chunk or two out of the body. Which is forgivable if your painting the body a solid colour I guess.
This time around I'm wanting a natural finish, so I want to get the edges right this time!!!

About the bass/wood. I'm using Mahogany for a Neck through section and figured camphor laurel for the wings.

So some things I am trying to work out are:

Do I need to break the edge first? Not sure what that is.

Should I be changing direction or just do one pass all the way round?
Is a wider or thinner round over saver to use?

Like Matt said, The way to avoid tearout is to make multiple shallow cuts, rather than one big cut. If you are making a roundover cut on a body edge using a router in a table, do it in 4 or 5 passes. Start with the bit lowered down into the table maybe 1/4" below the final height. So it takes a small shallow cut. Then make 4 more passes, raising the bit 1/16" with each.

This also makes the router safer and less frightening! With light shallow cuts, it won't tend to grab and pull the wood. And this is true for all types of routing, including cutting cavities. Multiple light shallow passes.

 

[Bassatronic]

Hi Bruce and Matt. Thanks for your replies.

Oh OK! I haven't tried doing shallow runs and adjusting the depth as I go. But it makes sense now you say it.
I have been trying to do it in 1 or 2 passes as the same level. Just going for it.

Thanks guys. I'll do some practice runs with this method and see how I go.

 

[Thumpin6string]

I've done mine in a single pass, but not with a table mounted router. I take it slow and use a quality, sharp bit.

 

[BuddhaFingas]

Should I be changing direction or just do one pass all the way round?

Like most cutting tools, router bits are directional. You always want to feed 'into' the workpiece.

"Changing direction" can cause tearouts or chatter, and is dangerous... it can make you lose control of the workpiece.

The blade should push toward the piece, not pull it.

 

[ctmullins]

Like most cutting tools, router bits are directional. You always want to feed 'into' the workpiece.

"Changing direction" can cause tearouts or chatter, and is dangerous... it can make you lose control of the workpiece.

The blade should push toward the piece, not pull it.

Yep.

On the other hand, pushing into the cutting direction can cause tear out when the grain is opposing. This is why “climb cutting” is sometimes mentioned. But only climb cut when 90% of the waste has been removed, then the climb cut is a very shallow “finishing” pass. And always with complete mental and physical focus.

 

[scuzzy]

I haven't seen it mentioned, but I was having issues similar to you because I was running it too slow. I sped up the RPM and it was much cleaner. The LC helped me with that as well.

 

[Beej]

I'll add that routers are not ideal for removing lots of material without tearout, so I also cut the piece very close to the line so that the router does not have to do much work. I aim for 1/16" or so as anything wider has more potential for tearout.

 

[Plain Old Barry]

Like CTMullins mentioned, understand grain direction.

"Climb cutting" against the grain will cause problems, even with a new super sharp bit. If you must rout uphill, you need to take shallow, downhill bites. You can finish with a very shallow pass in one direction, but you MUST remove the bulk by not climbing the grain.

 

[Bassatronic]

I haven't seen it mentioned, but I was having issues similar to you because I was running it too slow. I sped up the RPM and it was much cleaner. The LC helped me with that as well.

Hi scuzzy, yeah I am just setting mine at halfway.

 

[Bruce Johnson]

Hi scuzzy, yeah I am just setting mine at halfway.

The speed that you run a router is mostly related to the diameter of the router bit. For safety. The general rule is that router bits under 1" diameter can run at full speed, usually 21K rpm. Bits in the 1" to 1 1/2" dia range should run slower, like 17K rpm. Bits 1 1/2" to 2" should be 14K, over 2" should be 10K rpm.

In general, you shouldn't be using a bit over 1 1/2" dia in a medium size (1 to 1 3/4 hp) router. Particularly if it's not variable speed.

 

[Gilmourisgod]

I still use a router for a lot of stuff, but due to some tearout tragedies on figured ($$) wood, I’ve mostly settled on using my Robosander to pattern route to final lines. It’s slow as hell, but…. No tearout. I still use either 5/8” or 3/4” dia bits for round overs though. Even small increments can singe the wood a little sometimes if you run it too slow.

 

[Bruce Johnson]

Even small increments can singe the wood a little sometimes if you run it too slow.

Yes, that's an important thing to know about routing wood: The optimal feed rate is a narrow range. If you go too fast, you get kick and tearout. Too slow, and you scorch and burn the wood. With experience using a router, you learn to feed smoothly, paying attention to the sound of the motor (to judge its speed and load), and how the chips are flying off. Adjust the feed rate so it's cutting clean and easily, not struggling. Keep the feed rate smooth, don't let it pull itself in, and don't slow down or stop.

It takes some skill and physical strength to operate a router. Like any handheld power tool. You have to hold onto it with strength, and be able to accurately control its movement with your arms and shoulders. There's some significant force involved when it's cutting.

And you always have to have an escape path to instantly stop the cutting, while keeping both hands firmly on the router. Some direction that you can go in to get the bit away from the wood. Lifting straight up, tilting up, or moving sideways, away from the edge. Don't go plowing into a deep groove that you can't get out of. That's when the danger starts.

 

[tr4252]

A lot of good advice here. I too am respectful of routers, and my lawn mower, table saw, etc. Anything that can do physical harm needs to be handled with appropriate care. Sometimes I'll just ponder a while, while I'm setting up a job to give myself every advantage I can think of.

I once worked with a guy who turned on a router, and it jumped out of his hand and skittered across his right foot. Bone, tendons, and suffering were the result, I can say no more. I was standing about 6 feet away when this happened. Yes, he was wearing safety steel toed boots. Root cause was his loose grip on the router when he turned it on. You should always have complete control of power tools. Always be aware of how seriously they can hurt you.

On a happier note, as an industrial guy, I've had access to a lot of different machine tools and methods. One handy thing I discovered is that solid carbide end mills generally cut better and last longer than many router bits I've used. I use both plain and ball end. There is a huge variety of types, and they aren't too pricy. I have found that most of the useful ones can be had with 1/4" shanks.

Good luck

Tom

 

[Gilmourisgod]

I have lost control of a router when it caught in the wood and jumped, luckily away from me, so no injuries, just a ruined piece of wood. I try to use my router table whenever possible, I'm always a little nervous freehand. The accident was entirely my fault, tried to take off too much at once, I got lucky.

 

[Bruce Johnson]

I have lost control of a router when it caught in the wood and jumped, luckily away from me, so no injuries, just a ruined piece of wood. I try to use my router table whenever possible, I'm always a little nervous freehand. The accident was entirely my fault, tried to take off too much at once, I got lucky.

The same rules apply if the router is in a table, and in a big pin router. You are still controlling the feed rate and direction with your hands. You have to set it up to limit the possible depth of cut, and to have an escape path.

 

[ctmullins]

​

I have lost control of a body when it caught in the router table and jumped, luckily away from me, so no injuries, just a ruined piece of wood. I try to avoid my router table whenever possible, I'm always more in control freehand. The accident was entirely my fault, tried to take off too much at once, I got lucky.

 

[Gilmourisgod]

I've never had an issue with it, but when cutting something that unavoidably "captures" the bit, like a truss rod slot, doesn't seem like there is any viable "escape route", other than up (or down) and out. I use an upcut spiral bit on my router table, piece face down, with marks for start/stop cuts. So far, so good, and I have yet to see the router table jump out of or off anything. More than one way to skin a cat, I guess.

 

[tr4252]

The problem with routers is that there's no easy way to guard them.

My approach is to make the job as easy as possible, and I use as much prep as necessary. I always use templates, whether inside or outside cuts (the idea being to have the template protecting the part you want to save, and exposed wood in the areas that will be scrap). The template must be attached to your blank in a way that you can trust it not to loosen. I don't trust double sided tape. I know that many do, successfully, but it's a personal rule (don't ask how I know). Templates can be secured with screws or clamps, as long as you keep them out of the way of the tool path. In some cases this can be a pain in the ass. I attach the workpiece to a bench or my ancient Workmate stand. When I'm finally ready to make some chips, I cut scrap until I feel everything is set up right.

I make dry runs with the router turned off, to see if I'll run into anything I hadn't thought of, if the cord gets in the way in awkward spots, how comfortable I am while making passes along the tool path, add a light for better visibility, etc. One of those little 1 gallon shop vacs is always handy for the mountains of chips I'll be producing. Don't try to vacuum while the router is running.

Doing the job itself, a good sharp tool, slow feed and shallow passes are the rule for me. I don't care if it takes an extra hour because I make little .075" depth adjustments. I do it because it's easy on the tools and easy on me. Besides, the guitar body or whatever may outlive me by decades; I want my Journeyman's papers in order when I get to Valhalla.

Safety glasses, hearing protection, and work boots if you have them. Allow no distractions like conversations, loud music, poor lighting, etc.

I've seen several industrial accidents in 40+ years and picked up a few scars myself. I evolved a pitch I always include when training, lecturing, or just bull sessions. In a nutshell, it involves asking the trainees what would they pay to replace a lost eye, compared to the cost of double checking safety gear, etc. In practice, it's a lot more detailed and graphic than that.

So, stay safe.

Tom