Pencil Box with Sliding Lid

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StrataBoy
Posts: 8
Joined: Sat Dec 04, 2021 3:18 am
Model of CNC Machine: OneFinity Woodworker X-50

Pencil Box with Sliding Lid

Post by StrataBoy »

Finished Box
Finished Box
Inside of box and underside of lid
Inside of box and underside of lid
Sketch outlining how to calculate the offset tool path
Sketch outlining how to calculate the offset tool path
I was looking for a way to use up some random pieces of scrap wood and decided a pencil box would do nicely. It will make a nice gift for my grandson.

The sketch above shows how to calculate the offset between the dovetail path on the lid and the dovetail path on the box. It will vary with the thickness of the lid as well as the angle of the dovetail bit.

It is also a bit tricky to machine the lid since you can't use tabs with a dovetail bit. Consequently I had to divide the toolpath into three sections. The order you cut these is important so that you maintain your reference datums until the last cut. It is also important how you hold the lid down to avoid having your bit collide with the hold downs.

Here are the basic steps assuming you are starting with pieces having dimensions specified in the sheets tab:
Start by cutting out the lid:
  • Create fixed datum references on the bottom and left edges that you can bump to.
  • Machine the top surface by engraving the name and cutting out the finger pull slot
  • Flip the top over and bump to the same datum references
  • Clamp down on the top and bottom edges very firmly
  • Trim off the curved end of the lid
  • Then cut the dovetail on the curved end of the lid
  • Now securly hold the lid down with clamps at both ends, then remove the hold downs from the top edge
  • Now cut the dovetail along the top edge
  • Bump to the new top edge and securely clamp down
  • Remove the bottom clamp that also provides the datum
  • Cut the dovetail along the bottom edge
Machining the box is a little simpler. But before you do anything you need to create a new tool path.
  • Delete the toolpath in the layer "Box Dovetail"
  • Turn on visibility to the layer "Dovetail Master", and then ensure the layer "Box Dovetail" is active
  • Create an offset toolpath from the "Dovetail Master". The amount of offset will depend on your lid thickness and dovetail bit angle. Reference the formula listed in the sketch above.
  • Extend the top and bottom vectors about 1 inch to the left of the box to provide a place for the dovetail bit to plunge before making the cut. You should also add a vertical line at the left end to close the loop on this toolpath.
  • Run the "Pocket Box Lid Profile" toolpath using this new toolpath
  • Run the "Pocket Pencil Cavity" toolpath
  • Run the "Profile Box Dovetail" toolpath using the new toolpath
  • Now test the lid to see if it slides easily in the box dovetail. If it doesn't, you need to create an additional pocket toolpath using the same path used to cut the first dovetail in the box. Now that you have a pocket toolpath instead of a profile toolpath, you can add a very small pocket allowance to widen the dovetail slot. If the lid still doesn't fit you can increase the pocket allowance and try again until it fits properly.
  • Once the lid fits nicely you can finish up by cutting the pocket for the magnet.
I finished my pencil box with Boiled Linseed Oil. If you use a different finish that builds up the material surface then your lid might become tight. You will need to compensate for this.

Hopefully the above description will make sense after you have the VCarve file open and have a chance to review it. As always, you may need to edit the toolpaths to use your bits and the appropriate feeds and speeds for your machine.

One final note, I ended up using a 1/16" endmill bit to pocket out the magnet holes in order to get a flat bottom hole. If you use a larger bit then there isn't enough motion in the XY plane to sweep over the center of the hole and you end up with a hump in the middle that will cause the magnet to wobble, which will make it difficult to glue it into place.
Attachments
Pencil Box.crv
VCarve file
(1.35 MiB) Downloaded 27 times

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SteveNelson46
Vectric Wizard
Posts: 1722
Joined: Wed Jan 04, 2012 2:43 pm
Model of CNC Machine: Camaster Stinger 1
Location: Tucson, Az.

Re: Pencil Box with Sliding Lid

Post by SteveNelson46 »

Pretty cool!
Steve

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TomWS
Vectric Craftsman
Posts: 283
Joined: Sat Mar 06, 2021 11:06 pm
Model of CNC Machine: OB Lead 1010, Mach3; OB C-Beam 1060 grbl

Re: Pencil Box with Sliding Lid

Post by TomWS »

@strataboy, did you slice the lid from the same block of wood? The grain of the lid is pretty well matched with the bit of grain showing at the top of the box. Good job in any case.

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SteveNelson46
Vectric Wizard
Posts: 1722
Joined: Wed Jan 04, 2012 2:43 pm
Model of CNC Machine: Camaster Stinger 1
Location: Tucson, Az.

Re: Pencil Box with Sliding Lid

Post by SteveNelson46 »

A while back someone made a project with a sliding lid using a slot cutter or keyhole type bit instead of a dovetail. If I remember correctly, it was on the bottom of a cribbage board.
Steve

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