Fashioning Complementary Templates for Tight Control Cavity Covers

[michaelwayneharwood]

I have recently discovered a method for creating for what I call "positive / negative" or "complimentary" templates, though there may well be an actual name for this sort of technique. I am using the technique to create templates for control cavity covers and the associated cavity itself. Here's the basic technique:

1. Create the main cover routing template out of 1/2 inch MDF. This will be used to shape the cover itself.

2. Use the cover template and some Bondo to create a negative of the cover for use in routing the top 1/8" of the cavity where the cover will rest. I am using blue painters tape around the edges of the cover template to keep the bondo from adhering to it, and you can wrap several layers depending on how tight a fit you are aiming for.

3. Use the negative to create a copy of itself as the Bondo mess will be less than helpful when routing.

The results? The cavity cover fits like a glove. You can now use the cavity template and some dowels to create another cavity template. The dowels will create the posts necessary for either screws or magnets.

This technique can also be used for any operation where you want to have a tight fit for two pieces and need a "positive" and "negative" matching template.

 

[mapleglo]

Awesome tip Michael! Thanks! I can imagine that technique would be useful for pickups and neck pockets as well.

 

[michaelwayneharwood]

Awesome tip Michael! Thanks! I can imagine that technique would be useful for pickups and neck pockets as well.

You are very welcome! This technique can be used for anything you want to make a "negative" or complimentary template for. I am pondering the possibilities for tightly fitting off shaped pieces for a top - essentially a large inlay.

 

[Matt Liebenau]

Interesting. Certainly no harder than the test fit, sand, and swear method I usually use. Do you need to wax the edges of the cover template or is the tape enough to be able to easily extract it from the Bondo?

 

[michaelwayneharwood]

Interesting. Certainly no harder than the test fit, sand, and swear method I usually use. Do you need to wax the edges of the cover template or is the tape enough to be able to easily extract it from the Bondo?

*grin* I got tired of the poor results I usually get doing it by "hand".....this is to compensate for lack of skills in shaping.

The tape works just fine without any additional wax, oil, etc.

 

[Gilmourisgod]

Nice! I have seen that done for making a neck pocket template, but hadn't thought of it for cavity covers. I'm trying to find a good method for making a continuous grain cover cut out of the actual back laminate so it reads as unbroken grain pattern, might be possible to adapt this method.

 

[michaelwayneharwood]

One thing to note - when applying finish to a cavity cover you may want to leave more of a gap than this process seems to accommodate. This can easily be remedied by using multiple layers of tape around the template piece used to make the negative image. The more tape you wrap around the piece the more of a gap you will create. I am using blue painters tape, but any tape that will not adhere to the bondo will suffice. For an easy way to add more gap electrical tape would work well.

 

[chinjazz]

One thing to note - when applying finish to a cavity cover you may want to leave more of a gap than this process seems to accommodate. This can easily be remedied by using multiple layers of tape around the template piece used to make the negative image. The more tape you wrap around the piece the more of a gap you will create. I am using blue painters tape, but any tape that will not adhere to the bondo will suffice. For an easy way to add more gap electrical tape would work well.

This is a great tip!
Thanks @michaelwayneharwood!! I needed a better method as I’m at that point in my current build. I did something like this for fittting an already built neck into a new body. I used Plaster of Paris for the mold which held up enough to make the real template. Thanks again!

 

[thisSNsucks]

Nice work!

 

[chinjazz]

Hello All,

I decided to try my hand at it. Was going to go with Plaster of Paris, but found this stuff sitting right next to it (Durham’s Rock hard water putty) - just like PoP. And away I went:

This is after it’s almost dry. Hind sight is my blurry vision -LOL! I needed to plan an effortless removal of the cavity cover template.

Plaster would have cured/dried faster but this can of Durham’s was like a buck fifty. I may have to do this again. Will report back on what happens

 

[Gilmourisgod]

Is that a two part epoxy putty? It seems like plaster would be too fragile if it’s the surface in contact with a template bearing bit. I’ve been trying to work out how to use a similar technique for a set of Ric HB-1 pups, the edge profile is really thin.

 

[chinjazz]

Is that a two part epoxy putty? It seems like plaster would be too fragile if it’s the surface in contact with a template bearing bit. I’ve been trying to work out how to use a similar technique for a set of Ric HB-1 pups, the edge profile is really thin.

This stuff is said to be smoother and harder than plaster of paris. I have used plaster of paris on a neck pocket
I wanted to fit exactly to a pre-built neck, and it was plenty hard enough actually. I wanted to get away
from all the smelly toxic stuff. Minus my issue I'm working out on my removal technique, there's a good surface
area around the edge to give it more stability (I think). I'll report back on how removal went, etc..

Here's the exact small can of it I bought which was the perfect amount for making 2 template fills. I've also done the inner cavity (shelf) template at the same time, but didn't want to drop too many pics in this thread .

Durham's Rock Hard DU-1 1 lb. Water Putty-1#CAN - The Home Depot

 

[Gilmourisgod]

Wow, it’s cheap! Bondo is stupid expensive, let us know how it works out with the Rock Hard putty. I’ve been waiting for Harbor Freight to start selling bondo, no luck so far!

 

[chinjazz]

I went back to P of Paris, and waited about 20 minutes till it was firm enough and scored the top edges and then pried the template out from the bottom and some handles I made from the top. It worked fine and actually removed from the MDF easily. Next time I may try ThermoMorph as it may be easier to work with and most likely hard enough. A few pics of my experience mentioned...

 

[Matt Liebenau]

I posted this over in my thread but just to have it someplace else as well…

I was watching a New Yankee Workshop on the tubes the other day and got reminded of these bits. Norm was using one to make a Dutchman plug for a table or something but I think it might work for cavity covers. Use the same template for the ledge for the cover and the actual cover. Maybe just wrap some tape around the bushing when you cut the cover to make it a tad smaller than the opening.

Taytools Router Inlay Kit Solid Brass 3-Piece Guide Bushing Set | Taylor Tools

Taytools Router Inlay Kit Solid Brass 3-Piece Guide Bushing Set

taytools.com

And how they work.

 

[Beej]

Just one of his many shared learnings for the community. I learned recently that Michael passed away last year. I'm not sure if @Rôckhewer knows, but I know they chatted here. RIP buddy.

Michael W. Harwood Obituary (2023) - Parker, CO - Ponderosa Valley Funeral Services - Parker

View Michael W. Harwood's obituary, send flowers and sign the guestbook.

www.legacy.com

 

[Rôckhewer]

Just one of his many shared learnings for the community. I learned recently that Michael passed away last year. I'm not sure if @Rôckhewer knows, but I know they chatted here. RIP buddy.

Michael W. Harwood Obituary (2023) - Parker, CO - Ponderosa Valley Funeral Services - Parker

View Michael W. Harwood's obituary, send flowers and sign the guestbook.

www.legacy.com

Im speechless.
. No, I did not know.
We were actually pretty close friends for a while. He built the pickups for Arachnophilia. We were collaborating on some other stuff... but unfortunately kinda lost touch.
Super good dude. And...Eclectic genius.

I was busy at the time of his passing with my new gig.
Ohhhh this sucks so bad.
@Beej where did you see this posting?

 

[Beej]

Im speechless.
. No, I did not know.
We were actually pretty close friends for a while. He built the pickups for Arachnophilia. We were collaborating on some other stuff... but unfortunately kinda lost touch.
Super good dude. And...Eclectic genius.

I was busy at the time of his passing with my new gig.
Ohhhh this sucks so bad.
@Beej where did you see this posting?

Sorry you had to learn here. I googled his name to look up one of his threads and an obituary came up so I clicked and... sadness. I'm the same age and have been brought back myself, so my feeling of borrowed time comes up with these things.

 

[Rôckhewer]

Sorry you had to learn here. I googled his name to look up one of his threads and an obituary came up so I clicked and... sadness. I'm the same age and have been brought back myself, so my feeling of borrowed time comes up with these things.

I appreciate you finding out.
Breaks my heart that I lost touch with him.
Was going through our old emails.... there's probably a couple hundred between 2015 & 2017.
Not only were his projects cool and innovative.
The guy was an outstanding author.
I have half a dozen emails with amazing synopsis of short stories he had in his head.
And a couple audio tracks from same!
Very cool stuff.
Seriously quality fantasy fiction. But he wasn't confident enough to seek out a publisher, despite my enthusiastic encouraging.
I need to round up a few of the build threads he posted here also. A couple of them contain brilliant fictional "backstories".
I need to compile all these. Maybe his kids will appreciate it... I'll see if I can get in touch.
I know I will treasure them.
Maybe I'll post them here.

...fairly gutted right now

 

[Beej]

I appreciate you finding out.
Breaks my heart that I lost touch with him.
Was going through our old emails.... there's probably a couple hundred between 2015 & 2017.
Not only were his projects cool and innovative.
The guy was an outstanding author.
I have half a dozen emails with amazing synopsis of short stories he had in his head.
And a couple audio tracks from same!
Very cool stuff.
Seriously quality fantasy fiction. But he wasn't confident enough to seek out a publisher, despite my enthusiastic encouraging.
I need to round up a few of the build threads he posted here also. A couple of them contain brilliant fictional "backstories".
I need to compile all these. Maybe his kids will appreciate it... I'll see if I can get in touch.
I know I will treasure them.
Maybe I'll post them here.

...fairly gutted right now

Yeah, he had some interesting stuff going on! The thread I was looking for was for "Nucifera" which turned out to be the 'nut bringer' with ensuing fun.

I've learned that you can bring up all threads by a person by clicking their name/avatar and on their profile page there is a drop down for 'more options' and under that menu is 'find all threads by xyzuser'. Here's the cut/paste, not sure if this works:

https://www.talkbass.com/search/78262/?q=%2A&t=post&c[content]=thread&c[users]=michaelwayneharwood&o=date