Beginner's Mistake(s); Trying to Learn Here......

Mr. Neutron

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Hey, All!!!

I'm trying to transition from a guitar "assembler" to a "builder" of sorts. I'm in the process of playing with some plywood, and some 30+ yr. old fir left in my barn from the previous owner of my house. I sandwiched the fir between 2 pieces of 1/4" plywood. Again, I'm using inexpensive materials here to learn with, and had a mishap when routing the outer profile. I got some pretty major tear-out at BOTH of the "horns" on my Tele project. Try to post pics.

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I routed this using a 2" long 1/2" dia template router bit. I left more excess than I should've, so I circled the periphery 3 times, each time getting about a 1/16" closer to where the bearing eventually touched the template. Sorta like freehand cutting, til it got to where I had about 1/16" left for the money cut. The last 2 passes gave me the tear-out you can see in the pics. Interesting thing to me was that the majority of the plywood on the bottom and top remained in good shape; it was mostly the fir piece in the middle that chunked out on the wanna-be body.

I'm now wondering if I'd been better off to use a shorter template bit, say, around 1" long. Route as much as I could with that, then remove the template and finish the rest using the previously routed part as the template.

Or are these 2 areas the kind of areas you leave "heavy" with excess, and use the belt sander to get it to size?

Anyone have any ideas where my technique here was sucko?

Again, this whole deal is for me to learn on, so it's not the end of the world if it doesn't make a guitar. The whole thing has been an experiment, really. I hand planed the jointed edges of the fir for the glue up of the main body. Made and used a router sled to flatten both sides of the glued up 2 X 6s, which kinda made the need for plywood (or other wood) on both the top and bottom. I was going to use 1/4" maple that I flattened with the router sled for the bottom and top, but the maple wound up having a lot of bug tunnels in it....... Decided to try chambebring a body. I had plans of using maple for the top and bottom but the maple given to me from a friend had I'd rather make my mistakes on the cheap stuff so I don't butcher a chunk of wood I really would like to use. And eventually, I do plan on taking a stab at making a neck, once I figure out a way to try that without investing a small fortune in tools I may use only a handful of times...... Just trying to learn here.

Thanks in advance,
Jimmie
 
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dsutton24

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In all honesty, that's not too bad. You should be able to sand it out.

Some woods tear out more than others. A sharp bit and taking veeeeery shallow cuts help a lot. The direction of your passes also makes a big difference. I just kiss the surface I'm cutting, and don't keep the router bit in contact with the wood I'm cutting for more than a second or so, just kind of nibbling away on it. Don't get in a hurry. You're using the router to perfect the shape, not create it.

I've never used a 2" long bit, so I can't say for sure that it is a contributing factor. If the router is bogging at all you're being too aggressive.

Somewhere here there is a drawing by an experienced builder that shows what direction your passes should go on the various contours of a body. I can't find it at the moment, surely some kind soul will be along and post it for you.
 

Mr. Neutron

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Thanks, @dsutton24 !!!

For cutting direction, I reverted back to my experiences as a milling machine operator and did it with "conventional" cutting, not what we called "climb milling".

I probably did take too heavy of a cut in retrospect, and there was indeed a bit of "bogging down" the router at times, even though I tried not to do that.

And in the interest of continual learning, I figured out I should learn how to patch up my mistakes. The body is sitting with a mixture of wood glue, sawdust, and unfortunately, some of my border heeler's hair mashed into the tear-out area like Bondo. (the Shop Vac, where I get my sawdust, also serves to vacuum out the back seat in my truck where the dog rides. That gives me the added bonus of fibers in my putty......)
 
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Mr. Neutron

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I dunno why this fairly recent thread didn't show up when I did my "SEARCH" earlier. Guess I didn't use the right combination of words.......


This thread seems to be full of great help. Will spend some quality time reading it more thoroughly......

Also, I'm kinda thinking that I left way too much excess on there for the router to remove, even after making 3 passes around the body. I do have a small Ryobi band saw, and probably should have tried to cut "a bit closer to the line" with that before using the router.
 
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richiek65

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Thanks, @dsutton24 !!!

For cutting direction, I reverted back to my experiences as a milling machine operator and did it with "conventional" cutting, not what we called "climb milling".

I probably did take too heavy of a cut in retrospect, and there was indeed a bit of "bogging down" the router at times, even though I tried not to do that.

And in the interest of continual learning, I figured out I should learn how to patch up my mistakes. the body is sitting with a mixture of wood glue, sawdust, and unfortunatly, some of my border heeler's hair mashed into the tear-out area like Bondo. (the Shop Vac, where I get my sawdust, also serves to vacuum out the back seat in my truck where the dog rides. That gives me the added bonus of fibers in my putty......)
Another (ex) metal machinist here, have always wondered about the merits of climb vs conventional milling on timber (have yet to dip my toe in the water)
 
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Old Verle Miller

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End grain tear outs are a reality of life for almost all woods being exposed to cutting tools.

Personally, I'm a fan of a very fine-toothed band saw and a vertical drum sander for this kind of shaping. YMMV.
 

guitarbuilder

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You won't have tear out if you cut outside the line and then sand to the line. That's how people had to do it before pattern bits were available to DIYers. If you read the various build threads by new builders, you'll see that they generally do exactly what you are doing. They experience the same tear out where the grain direction changes.


You'd be wise to lay off the videos and concentrate on build threads here, as you'll see what has happened to the hundreds of members making guitar bodies and necks. You'll eventually learn what not to do. A good place to start are the older Challenge Archive threads on the Home Depot Main Page.

It sounds like you are using the wrong template bit for such a thick piece of material. You may want to investigate a spiral bit or a shorter one like the stewmac bit that won't take as deep a bite at one time. The template bits really should only remove as little wood as possible to clean up the work. Spiral bits can send your work across the room just as much as the template bit used incorrectly too. Read up on these things so you know what and what not to do to keep your body parts intact. As always YMMV...


 
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peterg

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+1 for sanding to the line. I used to use template bits starting with 1/2” then 3/4”, 1” and 1 1/2” dropping down 3/16” with each pass. I’d still get tear out and need to sand anyways.
 

Jim_in_PA

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The lesson here is that in many cases, particularly with open grain woods and softwoods, one cannot just flush trim by going all the way around the workpiece. The whole process has to be broken down so that the tooling rotation direction isn't biting into the wood "uphill" which can grab chunks. This is easiest when one uses tooling that has both top and bottom bearing so you can flip the workpiece to insure every short cut is in the best direction to avoid tear-out.

Or, as has been suggested, sand to the line using an oscillating spindle/belt sander to avoid almost all risk of tearout.
 

oldunc

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A downcut spiral bit will give much better results, as will climb cutting the final pass (it will have to be a very light pass cutting through that much depth). Spiral bits in carbide are expensive (they're solid carbide, not a chip) but a worthwhile investment. If you use template guides rather than a ball bearing bit you can do the depth in stages without using a super thick template.
A large diameter bit is also helpful- the shapers used for commercial production have bits several inches in diameter so they're cutting nearly parallel to the edge of the workpiece.
 
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gb Custom Shop

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I had this same problem on my current build with a mahogany body, and I was using the beastly Whiteside upcut spiral bit (one of the best bits out there). My lesson learned is even the best router bits do not compensate for poor practices. For future reference, sand as close to the line as you can!

Now I'm curious to see how you'll deal with this? I imagine that tear out goes ~1/8" into the body, possibly even more on the horn. I suppose your plan of action will depend on what final finish you wish to achieve.

You may wish to sand that out if you want to maintain a natural finish, but you'd be re-profiling a bit at that point. You could also fill the void, and do a burst, or a full opaque finish.

I know setbacks like this can be disheartening, but they're also blessings in disguise. These situations account for the best learning opportunities. Good luck!
 

schmee

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That very deep tearout would be unacceptable to me.
Very sharp carbide bits, slow going, minimal material removal on each pass can help on soft wood like Fir.
I likely wouldn't use a 2" cut either unless it's a hefty diameter bit so it doesnt flex and chatter.. Maybe two passes with 1" then a clean up pass with the 2"?
Assuming you are using a table router, yeah climb cutting should help...
 

Mr. Neutron

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I had this same problem on my current build with a mahogany body, and I was using the beastly Whiteside upcut spiral bit (one of the best bits out there). My lesson learned is even the best router bits do not compensate for poor practices. For future reference, sand as close to the line as you can!

Now I'm curious to see how you'll deal with this? I imagine that tear out goes ~1/8" into the body, possibly even more on the horn. I suppose your plan of action will depend on what final finish you wish to achieve.

You may wish to sand that out if you want to maintain a natural finish, but you'd be re-profiling a bit at that point. You could also fill the void, and do a burst, or a full opaque finish.

I know setbacks like this can be disheartening, but they're also blessings in disguise. These situations account for the best learning opportunities. Good luck!
Bummer about it happening to your Mahogony body. Bummer that it ever happens to anyone at all, actually........

Whether the body I'm performing "scientific research" on ever becomes a guitar or firewood doesn't really matter. Several things have been learned here, and that's what I consider important. I do plan to keep finishing it as if it were going to be a for real body. I've got some putty blobbed into the torn out areas, made of Tite-Bond and sawdust, mostly. I can learn how to fix that, now. The divots are around a 1/16" deep in points, so I can either accept that as-is after filling and sanding, or "re-profile" the thing to remove the bad naughty parts by sanding it all away.

I like the grain on the middle section of Fir or Pine (not certain which it is; I "inherited" the wood with the house & barn). For those types of wood, it seems to have nice, tight, straight grain. Nothing like what you'd find at a Lowe's or Home Depot nowdays. The 2x6 it came from has sat in the barn for probably over 30+ years. I had planned on leaving it visible with a poly or similar clear finish, but it might be a Bondo & paint kinda deal now, which no doubt will bring me more learning opportunities, hee hee.......
 

Ronkirn

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when using a wood that's subject to tear-out... First I cut the rough on a band saw leaving about 1/16th inch (1.5mm) then I use an old resharpened several times bit for the initial cuts... I do this becasue resharpeming ity makes the cutting edge slightly smaller than the guide bearing, leaving a little more wood than ya want...

ONce that is done... I come back with a fresh bit that removes the slight overage bring it down to nominal...

also I hold the work firmly, and move slowly , , it's easier to take care of a little burning by the bit than it is to fix a tear out like that..

On woods that will do what ya see above.. I make sure there is minimal wood to remove, every time..
 

Freeman Keller

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I know this is controversial but I route a lot of long grained soft woods that are subject to tear out - namely spruce and cedar . I always paint some sealer - either shellac or vinyl lacquer - on the edge to be routed, then do the "climbing cut" going around the wood clockwise as viewed from above if I'm using a hand held router. I then go counter clockwise all the way around the body to clean up the route. I try to saw the body or top to as close as I can get it before routing, I use a router table when I can (flat instrument) and I can honestly say I've never had a problem. I do the route in steps gradually taking deeper cuts. I've not done a pine body but I built five douglas fir tele style guitars and they routed cleanly. I use a random oscillating sander to clean up but most of the wood is removed with the router. If routing from the top I clamp the body firmly to my work bench and go very slowly.
 
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guitarbuilder

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And somebody should probably mention to the OP that climb milling is opposite of normal safe routing. People here recommend it all the time.

Router safety rules state that moving the router against the direction of cutter rotation, whether on a router table or by hand is the correct method. There are folks here who have shot their bodies across the room doing this. Climb milling can grab the wood and scare the crap out of you. You take a risk when you climb mill. You should know that in advance.










23. DIRECTION OF FEED. Feed work into a blade or cutter against the
direction of rotation of the blade or cutter only.
 
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Ronkirn

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You take a risk when you climb mill. You should know that in advance.
Yep. I'm with Marty on that one... even today, after more than a half a century of making sawdust, it still gives me goose bumps to move that thing in the wrong direction... I've seen what a 3.5 hp router can do to a 4 pound piece of wood, and how far it can throw it when it has an attitude...

Just bre careful.. and practice on junk wood...
 

Mr. Neutron

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Leave it in and call it a Telegasher.
I love that!!!

As for climb milling vs conventional milling:
I retired from Boeing as a machinist. Not saying I know everything about machining (and especially routing! ), but I have seen airplane parts fly across the shop WITHOUT the rest of an airplane, hee hee. Actually, from conventional and climb milling........
 

Freeman Keller

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I said climb cutting is controversial and I mostly only use it routing thin woods like the top and back of an acoustic guitar. When I'm routing a solid hunk of wood I either use my router table or clamp the wood to the bench and take very small cuts. Routers scare the hell out of me.
 




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