Proper way to do chassis cutout?

[T Wilcox]

Cabinet question for both combos and head cabs:
Just wanted to check and see how others are cutting chassis cutouts? In the last couple I've done I used a jig saw and they didn't turn out horrible but the rounded edges were far from perfect. I'm thinking maybe the best way would to create a jig for my router to follow but wanted to check here and see if anyone had a better suggestion!?
Please let me know the proper way to do this
Thanks in advance!

Todd

[ChopSauce]

I use a hole (?) saw to cut the rounds and a copying bit (on a router) to cut the straight lines using a ruler held tangent to the rounds. I use a jig saw too, to do approximate rough cuts, so the copying bit does just the finishing.

If you make several cabs, a jig bolted using the holes for the chassis, would be handy for sure.

[T Wilcox]

I use a hole (?) saw to cut the rounds and a copying bit (on a router) to cut the straight lines using a ruler held tangent to the rounds. I use a jig saw too, to do approximate rough cuts, so the copying bit does just the finishing.

If you make several cabs, a jig would be cool, too.

So like a 1/2" - 3/4" hole saw or so? I think I used a paddle bit on one but when I went to catch the corners with the jig saw I didn't use a ruler and it did not line up perfectly. Ended up sanding/filing it but was too late to get the line perfect
I do plan on making a few more cabs but every chassis may be a different size, main thing is getting that radius cut in the top corners
Your ruler idea may work. Maybe clamp a square to the board and use it as a guide with a 1/2" router bit. I got some leftover wood I will practice on first

[Geeze]

I use forstner bits - flat drill bits with a center point for alignment. Most of the home centers carry them up to 2-1/8". They drill very clean holes [clamp board to base for clean bottoms] and don't wander off on wood grain.



I use a table saw for the straight cuts





Gives a good surface without much sanding





Russ

[T Wilcox]

Geeze
That cab looks really nice! Using the table saw is not a method I considered but it looks like it worked great and I have pretty much everything I need to do it.
Thanks for posting!

Todd

[ChopSauce]

Geeze, your woodworking makes me jealous ...

Your ruler idea may work. Maybe clamp a square to the board and use it as a guide with a 1/2" router bit. I got some leftover wood I will practice on first

You got the idea. I manage to do the cutout prior to cutting the board for the top to the final size, so I can even bolt the (drilled) ruler on its edges.

I use that kind of drilling "hole saw" thing



with apologies for the Google translation ...

But of course there might be more suited tools to do that - especially for the drilling "hole saw" thing doesn't necessarily make for a sharp cut on soft wood.

At least I could do that



even though the right edge on the picture was a "oops" one that was somewhat "rectified" with the ruler and the copying bit, afterwards : if you look carefully it doesn't look that straight.

[Stephen1966]

I would stick with a router, a bearing bit with drop in guide bush and a template. You can muck up on the template but just make another one. If you're making the cutout towards the end of the cabinet build, and muck it up, it sucks. If you use a table saw, the bottom edge of the cut is always further out than the top edge

Good health,

Stephen

[Phil_S]

ChopSauce: hole saw is the correct name of that thing in English!

As for cutting the round corner, remember, if using the Forstner bit and table saw, you must account for the cut being longer on the blind side than on the top. This can be minimized by raising the blade as high as it goes. (See the picture from Geeze.) You might consider using a 7.25" blade instead of a 10" blade. Be careful not to go too far.

I think my preference would be to make a plywood template, basically a rectangle open on one side and use the router. First remove most of the waste with a jig saw, coping saw, or whatever you have. Save the scrap cut out to balance the router as you make the finish cut.

There is more than one good solution. Do what works best for you based on your skills and the tools you have.

[Stephen1966]

ChopSauce: hole saw is the correct name of that thing in English!

As for cutting the round corner, remember, if using the Forstner bit and table saw, you must account for the cut being longer on the blind side than on the top. This can be minimized by raising the blade as high as it goes. (See the picture from Geeze.) You might consider using a 7.25" blade instead of a 10" blade. Be careful not to go too far.

I think my preference would be to make a plywood template, basically a rectangle open on one side and use the router. First remove most of the waste with a jig saw, coping saw, or whatever you have. Save the scrap cut out to balance the router as you make the finish cut.

There is more than one good solution. Do what works best for you based on your skills and the tools you have.

It's true, you don't need a workshop full of machine tools to do this. If you're serious about it though why not invest in a router and a straight bit and another radius bit for all your cabinet edges? All the routers I've bought came with a guide bush then all you need for a template is piece of MDF cut larger to accommodate the diameter of the guide bush. It can be a lot easier to set up than a table saw and the larger diameter blade incidentally, will shorten the cut on the blind side compared to a smaller diameter blade (think about it) but you can only lift the blade so high in the table and you will always have to account for the long (bottom) side of the cut. Table saws work well when cutting finger joints (where the edge of the cut is made by the top of the blade) when the piece is clamped to the vertical at the back of the sled like in the first photo, where the first cut is being made. We have to make our own sleds though and that's another chapter! That second cut where the board is laid flat is always going to end up unevenly cut though. If you're covering with tolex, it's no big deal because you can fill any dings with epoxy and with pine, you will probably end up needing to do that anyway. Those hole saws are not really meant for fine woodworking though, they are basically a circular saw blade and like a saw they have a kerf which can be wildly uneven from bit to bit - it might have 1" stamped on it, but you are unlikely to get a 1" diameter hole using one. They are ok for getting a hole started, but for more precise diameter holes you need the forstner bits which are more like circular chisels! Pay more for these, the cheap ones don't last five minutes.

You are basically talking about cabinet making skills. And if you put in the time you can go from everything using just hand tools to using power tools, like jigsaws and routers, to machine tools like pillar drills and table saws. All with exquisite results possible. There's no single way it can be done, and personally, I utilize all of them. Practice on offcuts first though. The hand tools especially, need to practiced in order to get the feel for them and their techniques. Forgive me if this seems so obvious, I don't know what you don't know. But if you think you need to learn any of these techniques with power tools or whatever, there are dozens of cabinet making tutorials on YouTube. Something for everyone.

Edit: you might also check out template making for the router. Luthiers often use templates with routers for the body shapes and there are plenty of videos showing how to prepare the templates. MDF is really easy to work with for one offs, but plywood, even plexiglass are viable alternatives.

Good health!

Stephen

[alkuz1961]

[ChopSauce]

Thanks for the details. The copying bit should make for a cleaner round than the hole saw, for sure, but I wanted to do a larger diameter on my tweedish cab. Possibly I've been using a Forstner bit on the shown Voxish, but I don't remember for sure.

So, double sided tape is strong enough to maintain the template... I wouldn't have trusted it...

[Dr Tony Balls]

13.jpg
P1040664.JPG
P1040665.JPG
P1040666.JPG
P1040668.JPG

Yup, this is how I do it. I've done it with a router table before but lately i've been doing it with a Bosch Palm Router....easy peasy.

[Stephen1966]

Thanks for the details. The copying bit should make for a cleaner round than the hole saw, for sure, but I wanted to do a larger diameter on my tweedish cab. Possibly I've been using a Forstner bit on the shown Voxish, but I don't remember for sure.

So, double sided tape is strong enough to maintain the template... I wouldn't have trusted it...

In some cases, too strong - it can pull out the grain of softer woods; and or leave a glue residue on the wood which is harder to remove. You might also try masking tape and superglue. Masking tape on one piece, masking tape on the other, superglue between. A low tack tape over a larger area is perfectly adequate for running a router around.