Will a CNC help get projects finished??

[Carl Beckett]

Today I just fired it up and knocked out a bunch of dovetails on a project that I started over 5 years (and a shop move) ago...

In those days I hand cut dovetails - the bottom two rows. Then the pieces for the top rows sat all this time, and are not so flat anymore.

But I decided to just 'get er done' today - cleaned up some of the work in progress and ran the remaining dovetails on the CNC. An afternoons work while mutitasking on another project.

Things went fairly smoothly, although the first set were too tight - I remembered I bought that routerbit from a resharpening clearance and it was not the full dia - so went back in Vectric and added a slight offset cut which helped (still a little tight imo, but after test assembling likely to loosen up). This wood is a spalted Beech I got from a guy who was learning to mill - quite cheap and at this stage of project drag-out air dry time is way past the minimum.

Progress - and in a way that I am inspired to finish this project - its downhill from here.

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[John TenEyck]

The CNC is a great time saver when you have to make a lot of the same parts, but only after you have developed the toolpathing. But getting to that point can be a real time sucker. For only a few parts, that can be done by traditional techniques, it's often not worth the effort.

John

[Carl Beckett]

The CNC is a great time saver when you have to make a lot of the same parts, but only after you have developed the toolpathing. But getting to that point can be a real time sucker. For only a few parts, that can be done by traditional techniques, it's often not worth the effort.

John

No doubt. That is why I posed it as a question...

Indeed I made considerable progress getting this phase of the project done. But - the project is not done - to be seen if that takes another 5 years or not.

And there was a pause where I had to have a coffee and re-read how to switch back from the indexer to the X-Y setup. That set me back 15-20 mins. I will suggest those 'memory' hurdles due to not utilizing them daily... like many other memory hurdles...

[Jim Becker]

I use my CNC machine for a lot of things that I presumably might be able to do faster in some manual way. Why? Because I enjoy it. All of my tools are supposed to "bring me joy" in some way...presumably. Doing things in different ways sometimes opens up opportunities and sometimes forces learning and "re-learning".

[Michael Burnside]

I’m with you Jim. I try to incorporate my CNC on almost every furniture project I do. Doing so have made me pretty proficient at creating a set of tool paths and it’s fun!

[Carl Beckett]

I do indeed suffer from the 'kid with a hammer' behavior...

On these dovetails I had some past files I could have worked from, but ended up just redoing from scratch. This was the desire to change my approach with multiples that were not 'repeats' - that is, I flipped my reference surface but also zero'd the file on the center of the board not the edge. Each board was a different height (progressive drawer heights).

So a learning after doing previous projects. And made repeats easier in this case (if I had a large batch all the same dimension I would side reference). This batch I did not reset zero of the machine each time, instead referenced to a line and loaded each new piece to the line as 'good enough', since all the relative cuts that determined fit were done by the machine. And the cam loaded clamp makes it quick to load the next piece.

Is there some trick by which a board could be center referenced each time, independent of absolute width? That would be useful. Right now it is eyeballing to a line (adequate but still requires attention)

[Jim Becker]

You could center reference by having an indicator on the surface that you clamp the workpiece to...mark the board center on the end of the board, clamp it in place temporarily so you can line up the center lines (board presumed flush with the table at this point) and install a temporary stop fence on one side so you can then loosen the clamps and move the board vertically to the proper exposure for cutting. You don't have to change the temporary fence until you change to a different board width so you'll want to batch things accordingly. Doing this will allow you to repeatedly cut the same general joinery pattern on any width board. That said, you'll want to write out multiple files because you don't want to be "cutting a lot of air" when you go to a narrow board as compared to a wider board.

[Carl Beckett]

You could center reference by having an indicator on the surface that you clamp the workpiece to...mark the board center on the end of the board, clamp it in place temporarily so you can line up the center lines (board presumed flush with the table at this point) and install a temporary stop fence on one side so you can then loosen the clamps and move the board vertically to the proper exposure for cutting. You don't have to change the temporary fence until you change to a different board width so you'll want to batch things accordingly. Doing this will allow you to repeatedly cut the same general joinery pattern on any width board. That said, you'll want to write out multiple files because you don't want to be "cutting a lot of air" when you go to a narrow board as compared to a wider board.

Yes, I partially did this by aligning to the center mark by eye, then resetting the guide/stop for that set. I then just abandoned that and set by eye each time since the height (vertically clamped workpiece) needed to be loaded/set each piece, and no reason to fight two separate references.

As the workpieces got smaller indeed there was some cutting of air. 'Not efficient' - but, as with most programming I do (sw language or otherwise), I do not need efficient run time, since the overall task efficiency is paced by my limited programming and setup skill. So inefficient run time is made up if programming and setup are minimized for the overall. Although not 'eloquent'.

I cant think of an obvious way to align a board on center - maybe some type of scissor contraption clamp... (am imagining a 4 bar type mechanism that compresses from both sides simultaneously - this could be doable)

[Jim Becker]

I have a small tool used for measuring center and it's based on the scissor like arrangement that you mention. It's conceivable that something like that could be scaled up for the purpose. You'd have to consider the level of effort for both use and personal interest. Here's a link to the tool I mentioned..I use it more often than I ever imagined and not just for guitar projects.

https://sqwayretools.com/shop/ols/pr...-centersqwayre

[Carl Beckett]

Thats interesting, had never seen before.

Another option I was thinking about was a basic self centering vice. I only need it for location - so it could sit adjacent (or in this last project on the surface 90 degrees out) - and have a couple fingers that stick out and 'clamp' to the center point. Would not need high force, since the workpiece would be clamped in place via the cam.

But your scissor concept could just have the center finger clamped to the base. Zero on that. Then modified outside fingers just cradle the workpiece and slide it until snug - at which point its on center and could be clamped.

One step to position the piece on centerline, that stays out of the way of machining. And could enable repeats to center line.

I find I use this center reference more and more to obtain symmetry. Also makes the programming easier since it is not absolute.

May mock something up...

[Michael Burnside]

That's a cool tool Jim. I use something similar. For CNC work it's great. I can cut out the drawer faces and if I want to setup an interesting pattern, fluting, etc., I just find center and use this tool to determine the subsequent spacing for other tool paths. So basically I measure the real project and create a quick tool path.

Here is the one I have: https://www.rockler.com/m-power-poin...k2-layout-tool

[Jim Becker]

Yea, Tim Sway comes up with some very handy tools that absolutely can have more applications than just guitar building. I used that center finding tool on the recent outside bench restoration to help locate the holes for the hardware. I just bought another thing from him...it's a small metal rule, dual scale. But unlike most where there's inches on one edge and millimeters on the other edge, this one has inches on one side and millimeters on the other side...both edges on a side can be used for measuring which gets away from some awkwardness that comes with only one edge being available.

That Rockler tool is nice...and can handle larger things. 'May have to get one at some point. Thanks for pre-spending my retirement money,

[John TenEyck]

I do indeed suffer from the 'kid with a hammer' behavior...

On these dovetails I had some past files I could have worked from, but ended up just redoing from scratch. This was the desire to change my approach with multiples that were not 'repeats' - that is, I flipped my reference surface but also zero'd the file on the center of the board not the edge. Each board was a different height (progressive drawer heights).

So a learning after doing previous projects. And made repeats easier in this case (if I had a large batch all the same dimension I would side reference). This batch I did not reset zero of the machine each time, instead referenced to a line and loaded each new piece to the line as 'good enough', since all the relative cuts that determined fit were done by the machine. And the cam loaded clamp makes it quick to load the next piece.

Is there some trick by which a board could be center referenced each time, independent of absolute width? That would be useful. Right now it is eyeballing to a line (adequate but still requires attention)

I do this in a couple of ways. For projects that use blanks that are not of constant size, I draw center lines on the blanks and align them by eye with center lines on my spoil board. This gives a close, but not perfect registration. For projects where I have blanks of constant size, I either use a right angle fixture to index a corner into, or I make a template with a cutout into which the blank will fit. The later can be used for parts of any shape. The later two methods give excellent registration.

John

[Carl Beckett]

For projects that use blanks that are not of constant size, I draw center lines on the blanks and align them by eye with center lines on my spoil board. This gives a close, but not perfect registration.

John

This one.

Have found a couple ways to 'auto-align', but they need mockup and is a design project in itself.

For now am using the align to a line approach as you do. 'Adequate' for the precision that I work with.