View Full Version : Wooden Precursor to a CNC machine

12-21-2011, 07:33 PM
Erco should love this:


It's kind of an old school precursor to a CNC machine and quite interesting.

12-21-2011, 08:22 PM
Sa-Wheat action!

12-21-2011, 08:34 PM
That is too cool. I think I'd like something a little more stout than the hose clamps to mount the router, but otherwise pretty darn sweet.


Erik Friesen
12-21-2011, 09:20 PM
Nothing wrong with wood. I built this using oak for the frame, have had very good results.

Loopy Byteloose
12-22-2011, 05:12 PM
Just use more hose clamps if you are nervous - after all, they are stainless steel. I have a very similar router here. IF you look closely, he did cut out a curved bed for the router and that adds a great deal of lateral rigidity to the setup. Without it, those hose clamps would never retain the router on its axis.

This is truly a thing of beauty and shows how extremely useful a router can be when built into a table configuration. Since the router spins at a rather fast 20,000 rpm and since there are a lot of good sharp bits made for it - one can do many precise cuts.

In general, good wood-working joinery only requires one to be as close as 1/32nd of an inch. And the reality is that for nearly anything most of us do, that is quite adequate.

12-22-2011, 10:14 PM
Yep! That was nice. Quite an inventive guy.

12-23-2011, 12:15 AM
In general, good wood-working joinery only requires one to be as close as 1/32nd of an inch. And the reality is that for nearly anything most of us do, that is quite adequate.
Rest his kind soul, but I think James Krenov just rolled over in his grave... :smile:


12-23-2011, 06:14 AM
Eh... 1/32?

If my teacher had heard that from one of his studnts, he'd have failed not only in practical, but at least one of the theoretical classes, too.
(I had a year at a school were they taught furniture carpentry.)
My father, who built wooden boats(from 12' skiffs up to 32' ocean-going fishing boats - and by ocean I mean the North Atlantic) would be horrified if anyone suggested that kind of sloppy work!
(I learned how to clink copper seams before I learned how to ride a bicycle.)

The only place 1/32 is 'acceptable' is in buildings.

12-23-2011, 08:28 AM
It's pretty cool for something built out of wood to hold 1/32".

Loopy Byteloose
12-23-2011, 12:13 PM
The builder actually demonstrates that his joints are within .002" of perfect. But the reality of wood is that it changes dimension with ambient moisture in the air and while one might machine a piece of wood to such tight tolerances, the weather with eventually do its thing.

Just consider that most traditional wooden boat builders would soak their hulls to get them tight. Table saws, radial arm saws, and much more are generally gauge no further than 1/64th of an inch. You all seem to want 1/256th or better.

There are exceptions, such as decorative inlay. One can do much better with tricks of craftsmanship.

I once was working on a 20 story office building as a carpenter and the foreman ran off to get a builder's transit to level the floor. While waiting for him, the laid out the entire floor with spec with a chalk line, plumb bob and carpenter's level. After being scolded for supposedly wasting time, he check it all and found nothing in error. (How do you think they built those pyramids?)

12-23-2011, 12:26 PM
@Loopy Byteloose

But the reality of wood is that it changes dimension with ambient moisture in the air and while one might machine a piece of wood to such tight tolerances, the weather with eventually do its thing.

That is a fair statement, but consider indoor furniture. The furniture that is available nowadays has tolerances of 0.031" or much greater, and this furniture never lasts very long. Whereas furniture that was built when craftmanship actually meant something will hang around for centuries.


EDIT: I would much rather trust my spine to a chair that has 0.002" for joinery tolerances than one that utilizes 0.031" for tolerances.

Loopy Byteloose
12-24-2011, 09:52 AM
Wood is a rather huge topic and yes there are certain varieties and levels of craftsmanship that have been around for centuries.

Sadly, over half the wood used these days is for paper and we are cutting down trees and putting them into use faster every year.

Fine woodwork starts with selection of excellent quality wood that is properly seasoned, but very few business want to store wood for several years while it seasons before it goes to market. And the slower the wood grows, the denser and stronger it is. Many second and third growth forest are faster growing due to forest management techniques. So what once was an excellent timber is now merely passable. And the lumber grading institutions are now grading as 'select' what was once merely 'standard' lumber.

If one goes into all the details, I suppose .001" would matter. But the final product needs to be properly sealed with a suitable finish to keep it stable and kept away from standing water. After all, when exposed to harsher environments - wood rots. And no amount of chemical preservation will completely prevent expansion and contraction from humidity changes as the internal leverage of this is huge. So wood cracks (or checks as a lumberman might say).

Some varieties of wood are renown for strength and stability - try iron wood, teak, and yew wood. All have particular handling requirements and all are subject to over-cutting of existing supplies.

So if you are building something out of plywood, chipboard, and small hardware store dimension lumber - 1/32nd is adequate. If you are building fine furniture that you want to last 1000 years as a museum piece, quality control is up to you and often modern epoxy and other glues can provide more durable strength without machine shop type of fitting.

One of the things that is most lovable about woodworking is that hand tools and not heavy machinery can create something that is beautiful and lasting. One can even make one's own block planes and chisels. And you don't need a fork lift and a flat bed truck to move your wood shop. (Makerfaire is attracted to this self-replication, but it originates in traditions of woodwork, ironwork, and leather craft.)

CNC is wonderful, but I am a bit daunted by how electronic printed circuit boards have gotten so compact that larger and larger amounts of cash are required to assemble components on a one off basis. Is the independent craftsman a thing of the past? I fear soon that will be so. But it was nice to have industry self-replicating by sweat equity rather than requiring huge IPOs.)

Watching the Discovery Channel here, I noted a comment by one of the men landing on the moon say, "Man must explore." That makes a great deal of sense to me. Craftmanship is really a wonderful way to explore. But for the average individual, is that becoming less possible? I fear so

(How did I get atop this soap box?)

I do suspect the reason today's furniture never last long is the same reason that software gets updates so often. People need to feed the financial system rather than live frugally within their means. Taxes, rent, college tuition for the kids, and mortgage payments.

12-24-2011, 10:07 AM

How did I get atop this soap box?

I am not sure how you got up there, but if the joinery has tolerances of more than a couple thousandths, I sure hope they used very strong adhesive for gluing it together. :)

Just kidding Loopy


12-25-2011, 03:28 AM
Actually easier for me to get wood. Have a few hobby places that sell different types and there is a huge place that sell exotic woods from around the world about 35 miles south of me.

Did this "wood project" a few years back. The wood is walnut and just used hand tools.Dremill, Small modelers saws, Trim saw, Except for the brass shielding. Its all walnut and balsa wood.


and here


Shipping container

Better still shots

But love etching brass!

Loopy Byteloose
12-25-2011, 03:03 PM
Many have built CNC milling machines for wood that cut with routers. I imagine that it wouldn't be that hard to have a CNC lathe for wood with router cutting tools as well.

Oak is wonderful, if it is well seasoned. Green oak wood warps with every cut. Walnut is nice, so are birch and holly.

12-26-2011, 03:12 PM
These pictures are NOT of a CNC machine, but examples of wood joinery that can exceed 1/32 tolerance...

It is part of the smile making machine of Xmas season 2011, all built in a matter of hours by the "Hammer Brothers"...
Note the gaps of 1/4 inch or more..
it is a structural part of this assembly...
(Using a lever and string system,
the weight of the "plane" moves the "brick wall" up about 2 feet when the "plane" reaches this section of track.)
Here is an action shot of what this structure does,
With this apparatus, every flight comes with a huge grin...
And here is a view of the end of the runway from the cockpit...

Anyways, Loopy is correct about not allways needing close joinery tolerances in every wood working project.. :smile:

I hope everyone is enjoying the holiday season.