Proper Use Of Templates For Multiple Passes

[bluesy]

In all my reading and watching tutorials, there's something I am not sure about concerning the use of templates.

I have a 1/2" straight cutter with 1/2" bearings on it's shaft to follow the template. The bit cuts 1" deep max. My question concerns the need/desire to make multiple passes, going a little deeper each time. In fact, the problem starts on the first shallow cut. How do you do this?

Let me explain so you might see where I am going wrong. If the router is set to only take a shallow cut, and the template is stuck to the guitar surface, the follower bearing is way above the template. To get the bearing down to the template level, the bit is cutting the full 1" into the guitar.

My (difficult) solution has been to pack the template up with 3 bits of 5mm MDF and clamp it. I remove one bit of MDF for each pass or so. This is time consuming, plus the clamps end up in the way of the router base.

The only thing I have thought of, might be to make very thick template, but commercial templates I see for sale don't look very thick. So, what am I missing, or what's the trick?

[jmrentis]

I usually try to use 3/4" MDF for my templates. Sometimes I might start with a thinner template and use that to transfer to the 3/4" MDF. If need be you could still space it with something as you were talking about, but usually you'd be alright. I would mention also that I have some template bits with a shallower cut as well, maybe 1/2" depth in cut. It can be useful to have them for certain jobs like angled neck pockets or when cutting the ledge for the electronics cavity cover. With that shallow depth in cut, I can use my 3/4" MDF templates and route for the cavity cover easily. So, really you have a couple options, grab a shallower cutting template bit or transfer your templates to some 3/4" MDF. Honestly I'd do both since those bits work well for certain jobs anyways. Hope that helps some. I'm sure there are other ways as well. Best of luck. J

[bluesy]

I usually try to use 3/4" MDF for my templates. Sometimes I might start with a thinner template and use that to transfer to the 3/4" MDF. If need be you could still space it with something as you were talking about, but usually you'd be alright. I would mention also that I have some template bits with a shallower cut as well, maybe 1/2" depth in cut. It can be useful to have them for certain jobs like angled neck pockets or when cutting the ledge for the electronics cavity cover. With that shallow depth in cut, I can use my 3/4" MDF templates and route for the cavity cover easily. So, really you have a couple options, grab a shallower cutting template bit or transfer your templates to some 3/4" MDF. Honestly I'd do both since those bits work well for certain jobs anyways. Hope that helps some. I'm sure there are other ways as well. Best of luck. J

3/4" templates? Yes, I see how that would work, especially with a half inch depth bit. thanks

[Prostheta]

Kill two birds with one stone - put a layer of 3/4" or 1" MDF between your template and your workpiece:

Cut the MDF close to the finished size. Screw through your top template into an area on the workpiece itself that will be routed out, such as pickup cavities, neck pocket etc. Enough so the template and the MDF are very very secure (4-6 screws). Then rout the MDF and your workpiece. You'll end up with a nice thick copy of the original template, plus you'll have a good start in the real workpiece. Remember your dust mask and as much extraction as you have on hand with the MDF however!

[stereordinary]

Are you using a bandsaw to cut as much of the excess wood off, before you even attach the template and router it? When "depth of cut" is said, in that case it's not the up/down depth. It's how close to the edge of your template the bearing is. I hope I'm making sense. I use the same cutter/bit and 3/4" plywood templates, but I get that bit down as low as it can safely go. Then I start to router, but I don't push the bit into the wood (read: against the template) until the last couple of passes.

[bluesy]

Are you using a bandsaw to cut as much of the excess wood off, before you even attach the template and router it? When "depth of cut" is said, in that case it's not the up/down depth. It's how close to the edge of your template the bearing is.

No, I meant vertically, as in when I am cutting the pickup holes or the neck pocket. Depending on the wood, the full depth in one cut may be hard on the router bit, so recommendations are to take the hole down a bit deeper each time and use 2 or 3 passes.

[bluesy]

Kill two birds with one stone - put a layer of 3/4" or 1" MDF between your template and your workpiece:

Cut the MDF close to the finished size. Screw through your top template into an area on the workpiece itself that will be routed out, such as pickup cavities, neck pocket etc. Enough so the template and the MDF are very very secure (4-6 screws). Then rout the MDF and your workpiece. You'll end up with a nice thick copy of the original template, plus you'll have a good start in the real workpiece. Remember your dust mask and as much extraction as you have on hand with the MDF however!

At first I thought "What a smart idea!" But then I realised I'd be taking a 1" deep cut in one go. Is mdf very much softer and easier on the bits than real wood, or would the advice on taking multiple passes still apply? If the latter, then we have the same problem, how to do the early shallow passes.

But if the mdf is soft on bits, then this will work out brilliantly.

[Prostheta]

MDF is much much softer, plus it has no grain direction so you'll be good. Don't hog it though, because it tears.

I would consider purchasing a shallower bit for future use plus adding a second bearing to the shank as long as the shank has sufficient length to accommodate one.

[bluesy]

MDF is much much softer, plus it has no grain direction so you'll be good. Don't hog it though, because it tears.

I would consider purchasing a shallower bit for future use plus adding a second bearing to the shank as long as the shank has sufficient length to accommodate one.

Yep, I'll be getting a shallow bit for sure. I do already have 2 bearings, I may get a third, however having 2 didn't help because it is getting the first bearing down to ride the template that was the problem. However, with the shallower bit, then the 2nd and 3rd bearings may come into play.

[Prostheta]

Three may be too many, but is okay as long as you have a safe amount of shank in the collet.

[Supernova9]

You shouldn't need more than 2 bearings at most, or really 1. If you do you're doing something wrong.

[Prostheta]

Two is a better number on the basis that if one of the bearings seizes, it isn't going to burn into your template and more importantly, it's not going to ruin the workpiece!

[pinefd]

I use these shorter router bits for shallower cuts: http://www.stewmac.com/shop/Tools/Special_...outer_Bits.html

Also, sometimes, I'll make multiple identical 1/4" thick MDF templates (which is easy to do); then, use double sided tape to tape them together and onto the workpiece...start with two or three templates taped together, and remove one at a time until you get to the desired depth.