Best approach for cutting mortices inside rebates?

This forum is for general discussion regarding VCarve Pro
Post Reply
garionh
Posts: 9
Joined: Sun Aug 05, 2018 1:32 am
Model of CNC Machine: CNC Router Parts 4'x8'
Location: Melbourne, Australia

Best approach for cutting mortices inside rebates?

Post by garionh »

Hey guys,

Building a bookcase-like part from 18mm material. I have designed the shelves to sit in 9mm rebates, and added a 150mm-wide mortise-and-tenon to the centre of the shelf (images below illustrate this better than I can describe it in words!).
Sketchup drawing of the entire unit, exploded.
Sketchup drawing of the entire unit, exploded.
Desired top-and-side join detail.
Desired top-and-side join detail.
Desired shelf and side detail.
Desired shelf and side detail.
Designed in Sketchup, imported into V Carve Pro V9, added fillets in V Carve Pro, all good.

Now it's time to set the toolpaths on the larger side panels (the shelves are easy of course). Because there are two tool paths on top of each other - the through-mortise, and the rebate, I am not sure how to make the geometry for toolpaths. I feel like there should be two sets of geometry, one for the mortise, and one for the rebate. So should I just draw more geometry on top of existing geometry?

Some of the edges form part of the whole side panel, so it seems like I need to split or "break" those edges around the mortise so I can select only the mortise-related geometry to make a toolpath. Is that even possible in V Carve Pro? Is it the right approach?

Help! :)
Attachments
centre open shelves v2.crv
V Carve Pro job file.
(37.5 KiB) Downloaded 100 times

User avatar
martin54
Vectric Archimage
Posts: 7339
Joined: Fri Nov 09, 2012 2:12 pm
Model of CNC Machine: Gerber 48, Triac PC, Isel fixed gantry
Location: Kirkcaldy, Scotland

Re: Best approach for cutting mortices inside rebates?

Post by martin54 »

I can't open the file because I only have v9 on this machine, I don't use sketchup but have read (I think) that there are 2 import types, one as a 3D model & one as 2D vectors, if that is the case then importing the 2D vectors will probably give you the 2 sets of geometry you need to toolpath them separately :lol:

garionh
Posts: 9
Joined: Sun Aug 05, 2018 1:32 am
Model of CNC Machine: CNC Router Parts 4'x8'
Location: Melbourne, Australia

Re: Best approach for cutting mortices inside rebates?

Post by garionh »

Thanks Martin54,

Here's the import vectors options I have - no 2D / 3D option there...?
Options I see when importing vectors.
Options I see when importing vectors.
After importing vectors and un-grouping them, I can select things like this panel (not useful for this job, as that's not being cut):
Selecting a panel.
Selecting a panel.
And this, the rebates (perfect for this job):
Selecting rebates. All good.
Selecting rebates. All good.
But not this, the mortise (which is the problem I am trying to solve):
Cannot select mortise.
Cannot select mortise.
Of course, I could just over-draw a rectangle for the mortise, but I understood that was not the best way to resolve this... Or maybe it is in this case?

thaks.

User avatar
FixitMike
Vectric Wizard
Posts: 2173
Joined: Sun Apr 17, 2011 5:21 am
Model of CNC Machine: Shark Pro Plus (retired)
Location: Burien, WA USA

Re: Best approach for cutting mortices inside rebates?

Post by FixitMike »

Put the mortise on a separate layer and group the vectors to make it easy to select. The mortise will have to have all 4 sides to make a complete vector to be pocketed.

Don't forget to include clearances (dogbone fillets) where necessary for inside corners.
Good judgement comes from experience.
Experience comes from bad judgement.

garionh
Posts: 9
Joined: Sun Aug 05, 2018 1:32 am
Model of CNC Machine: CNC Router Parts 4'x8'
Location: Melbourne, Australia

Re: Best approach for cutting mortices inside rebates?

Post by garionh »

Got it, thanks Mike.

User avatar
Adrian
Vectric Archimage
Posts: 14544
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: Best approach for cutting mortices inside rebates?

Post by Adrian »

As an aside the 2d/3d import part of Sketchup is controlled by how you import the file. If you use the import 2d vectors command then you get the 2d vectors as you have and is what you want in this case. If you use the import component command on the modelling tab then you get the 3D version of the same thing.

User avatar
adze_cnc
Vectric Wizard
Posts: 4324
Joined: Sat Jul 27, 2013 10:08 pm
Model of CNC Machine: AXYZ 4008
Location: Vancouver, BC, Canada

Re: Best approach for cutting mortices inside rebates?

Post by adze_cnc »

Here's my take on the mortise and dado problem. Shapes placed in appropriately named layers. "Dog-bone" fillets presume a 6mm cutter.

Why I extended the length of the mortises by 12mm is the question of the day...

I can see the following toolpaths (all presume 6mm cutter):
  1. pocket for dado
  2. pocket for mortise (start depth=mortise depth; cutting depth=thickness-mortise depth)
  3. outside profile to cut out the gable and shelves
Steven

EDIT: I knew something was wrong: I only had to extend the mortises by 6mm. Sigh.
centre open shelves v2 - rev srh.crv
Shelving unit revised 2018-10-16 by srh
(32.5 KiB) Downloaded 101 times

garionh
Posts: 9
Joined: Sun Aug 05, 2018 1:32 am
Model of CNC Machine: CNC Router Parts 4'x8'
Location: Melbourne, Australia

Re: Best approach for cutting mortices inside rebates?

Post by garionh »

Hey Steven,

This looks great, thanks.

To make the mortises, did you just draw rectangles over the existing geometry (on a new layer), then add fillets?

Also, when you say 6mm, do you mean 1/4-inch (6.3mm)?

User avatar
adze_cnc
Vectric Wizard
Posts: 4324
Joined: Sat Jul 27, 2013 10:08 pm
Model of CNC Machine: AXYZ 4008
Location: Vancouver, BC, Canada

Re: Best approach for cutting mortices inside rebates?

Post by adze_cnc »

Mortises: I just moved your vectors to the new layer and added the dog-bone fillets.

I saw your file was in mm so I figured you'd be using metric cutters. By the way: I'd never refer to a 1/4" cutter as 6.35mm (except now)...

It would be easy enough to recast the fillets into 7mm ones to match the shelves.

The dadoes were drawn over the existing vectors (to get the dado height and gable width). They were then lengthened by the "set size" transform tool changing the x length (unlinking the X & Y axes and anchoring to the centre).

Post Reply