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I just spent a ton of time making my router template out of MDF...taped it on....and started routing using my bushing template to ride the edge of the template. I took my rough cut baulk and started routing and about one minute later the router jumped up onto to top of the template and took a nice chunk out of the bottom of my guitar shape. I am no good at routing and am not sure how to fix this.

second pic

Andy-
This is the sort of thing that's happened to most of us- though that doesn't bring a lot of consolation, I'm sure.

Fixing the guitar body will be pretty difficult to make 'invisible'. Is the body going to have binding or a contoured/rounded edge profile? Some of the mistake might be in an area that will be removed anyway.
Can you 'move up' on the body blank, or is the other end routed to final shape already?
If it were my project, I'd consider changing the body shape a bit before I'd consider a 'patch' of any kind.

You can repair the template or just make a duplicate template with the original and your router and do the 'mistake' area by hand- same way you made the original. Small dings in templates are a good spot for Bondo, but that one is a bit big.

In the '20-20 hindsight' department:
Making the first cut really light/shallow is always a good idea.
Do you have a good router bit? (sharp?) Spiral bits cut a lot more smoothly and are worth the expense if you are working with decent wood, though they are expensive, and a little hard to find with bearings. Some of those cheap router bits are pretty rough- if the bit is vibrating it will tend to chatter and 'catch' the work.
It sounds like you were hand-holding the router? This can work, but you need to have the workpiece fastened securely to your bench, which can be tricky to organize. (I've done the 'hold it with your elbows' thing, and it is a bad idea....)
Another possibility is to make/improvise a router table of some sort, so that the weight of the guitar body is working to hold it down to the table.

Cheers
John

edit:post removed.

Thanks guys....I just realized that the answer to this fix is to plane off to make the whole rest of the body the depth of my mistake. If I do that it is still 1.5 inches and I'm adding a maple top that is .75 inches....Now I just need to figure out how to plane the whole thing.

My router is pretty cheap but i did have the guitar strapped down securely. I have one of the $69 Ryobi specials from Home Depot. I agree...holding down the router is just not exact at all. I'm especially nervous for when I go to do the the neck pocket and pickup pockets. I'm tempted to do those by hand or make my router into a table like your talking about. The router just catches to fast for me to be able to control it. I'm just glad this won't screw up my whole project if I figure out the planing project. I'm finding out that the more work I do with my band saw on the outside shaping, the easier my life will be.

Don't get down on routers, they are great tools. While the Ryobi IMO is junk, it can still work, a good bit will help, +1 on the spiral suggestion, then it is about going slow with depth of cut, good chip ejection is important too, stuck chips cause the bit to jump. I like to do a routine check through before routing, check all the clamps and router for tightness, review the cut, draw lines to remind me which way to run the router, I also think, heavy hand light hand, which hand is holding the router down, and which is the light hand that guides it.
When you get a better router, that Ryobi will be fine as a dedicated router in a table, truss rod set up?
The MDF template can be repaired with Bondo.
Rob

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hey andy, sorry that happened. yer not the only one.
is that a laminate trimmer you are using?
if so, it's too light and underpowered.
also, you can get one to one pattern bits in many sizes.
the bit will cut exactly what your pattern is.
it's got a bearing on it.
easier tha a collar set-up.
the main thing about routers is to take off a little at a time, and notice which way it is cutting.
if you go backwards, and are not careful, it will want to jump,
even if you are experienced.
be careful!
the lam trimmer will work if you take miniscule passes.
also, with a one to one bit, you can keep lowering it, using what you have already cut as a pattern.

indeed. watch the direction of your cut. a climb cut, moves left to right and will always want to dig in and jump right out of your hand. always cut right to left unless your working against the grain, then wood will tear. in such circumstance, climb cuts are the only way. take off as little as possible and work slow. routers are the shizzle! get agood 1/4" blade on the bandsaw and belt sand it smooth. templates are good for some jobs, pickup cavs and such, but body shapes should in my mind be one of a kind.

If I have your procedure correct, you created a body shape template fromMDF, taped it to the body with acrylic double stick tape, and then are proceeding to cut the shape of the body using the router with a pattern cutting bit, and the router held by hand riding on top. Is this correct?
If so, you may get better results if the router were mounted in a table, with the template on the bottom, It would be more secure that way, I think, less likely to kick up. You have to be careful though, the router bit can grab the body and throw it, or pull your hand into it if you are not careful. Many luthiers make pickguards this way, using beveled router bits.
I use a roundover bit and round the edges of my bodies this way.

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I agree, a router table and a top-mounted bearing. Helps prevent slips like this and also no 'tippage' problems.

I agree...been working on my routing skills and realizing how valuable it is. I did follow the process of taping on my MDF template and routed using the bushing guard. I might attempt to mount it to a table soon but I've been practicing at taking it slow and it seems to work better. I used my router as a planer to get rid of the mistake that I made since I luckily had more than enough thickness on the baulk to reduce it. I have a flamed maple top coming on Tuesday. Does anyone recommend if I should route the maple top and mahogany separately or should I glue the rough cut top on first? Thanks for all the advice! This forum has made my first guitar project a lot easier!

Glue it all together first. Also trim as close as possible so you're only routing away a small amount. You almost always run into trouble when you end up burying the bit too far into wood.

hey andy. i would cut the top about an 1/8" bigger than the body all around, glue it on, then get a trim bit with a bearing on the bottom. it will cut the top exactly with the body, because the bearing and the bit are the same size, otherwise you will have trouble lining everything up, gluing the top, and lining up your template. one to one rocks!

Drill press+chisel=happyness

Don't give up on that router yet. It is one way to thin the body that you want to thin. Check out some router thicknessing jigs that can be very easily and quickly made to do that for you:

http://www.google.com/images?hl=en&q=router%20thicknessing%20jig&um=1&ie=UTF-8&source=og&sa=N&tab=wi

I used a sled similar to some of those pictured to thin some pieces and it worked great.

A Wagner Saftey Planer on a drill press is another option.

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Chuck Kish

Hey guys...completed the routing on the baulk and had some spots of tear out. The baulk is going to be black so I'm hoping i could just smooth those areas with putty and paint over it. Any thoughts on what type of putty or filler I should use?

a couple of pics ....I might actually luck out because this is the pretty much exact spot where I was going to put the jack.

Nevermind i sanded it all out! ....thankfully the guitar won't get any smaller! I think my next project I will start much bigger to allow for more mistakes. Thanks for all the advice guys. I will post pics of my progress in a few days when I glue my top on.

You will be amazed at the difference a good-quality (new) spiral router bit will make. I'd rather work with a cheap router and a good bit versus a good router and a poor bit.

Cheers
John