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random #4: homemade walnut pegs

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Blog entry by Gary Fixler posted 03-04-2009 02:47 PM 6276 reads 1 time favorited 14 comments Add to Favorites Watch
« Part 3: Anthropomorphic tools - My DeWALT sander is watching me Part 4 of random series Part 5: Ouija Router »

(don’t miss the video at the bottom!)

I’m currently building a rack for lumber shorts and cutoffs under 3’ in length. I wanted to do a bit more than slap together Home Depot plywood and solids this time, though. One small ‘extra’ will be exposed pegs through the sidewalls to help support the thin ply shelves (they’re also getting #0 biscuits – I like overkill). These pegs will be flush-sawn, sanded, and finished with the rest of the rack, and most importantly, they’ll be walnut, for beauty and contrast. So I needed walnut pegs. I had a 3/4” square rod I’d ripped from a 5’ plank from a separate project, and from about a foot of the end of that, I used my bandsaw to free 32 little ~5/16” “blanks.”

32 square walnut pegs cut from a 3/4

32 square walnut pegs cut out of a larger square rod on the band saw

Back in my little machine shop inside, I set up my Sherline 4400 CNC mini lathe to turn the little things on centers, and wrote a blurb of Python to output the g-code to do the work for me of turning each to precisely 0.25” diameter. My lathe isn’t trammed properly, so it added its own taper, which worked out for me, as it’s 0.002” under the mark on one end of each, and the same over on the other. I can drive in the narrow sides, and they’ll tighten up as they go in.

I made a nice little pile of walnut dust as I went:

walnut wood dust on my Sherline 4400 CNC mini lathe after cutting 32 short, 1/4

The 32 little 1/4” pegs came out so perfectly, and now I have the code ready for whenever I need to turn some more in whatever crazy wood I need pegs made out of. I noticed a chunk of the silver birch out front was coming free (someone before I moved in cut it in half, and was a bit sloppy about it), so I pulled it off, sawed it up in the band saw, found it was riddled with tunnels and live, squishy bugs, but managed to get a piece large enough to turn in the lathe, and it made a really nice, usable little birch peg for me. If only I had a robot arm that could feed in blanks, and remove finished pegs, I’d have my own little peg-maker working behind me on the workbench here in my office.

32 homemade 1/4

32 homemade 1/4

My code exposes some variables to me, so I can change the step amount (how much to shave off) each pass, how long the peg is, so I don’t run past it into the tail stock, and how fast to make the movements. Each peg took about 2:30, though I could probably push it to under 2 minutes. However, between centers, such a tiny piece of wood slips a lot, because I can’t tighten it up too much, or I’ll just split the little blank apart. This means if I cut too aggressively, the peg just free-spins on the centers, jamming in place. This happened a lot until I started tightening up a lot more, then I was able to increase cut passes from 0.002” each pass (which still occasionally jammed) to about 0.02”, dropping the time from 28 minutes to under 2.5 minutes.

Here’s a “blank,” with a finished peg next to it:

walnut blank and 1/4

I had fun editing together a little video of the process (which you can see much more sharply at YouTube here):

More pics and descriptions in the Flickr set.

-- Gary, Los Angeles, video game animator



14 comments so far

View gizmodyne's profile

gizmodyne

1765 posts in 2840 days


#1 posted 03-04-2009 03:53 PM

Fancy method. Nice video.

I have used a different method by pounding through a dowel plate. http://www.lie-nielsen.com/catalog.php?sku=DP
Takes a bit of time.
Have you used one?

-- -John "Do I have to keep typing a smiley? Just assume it's a joke." www.flickr.com/photos/gizmodyne

View Scott Bryan's profile

Scott Bryan

27251 posts in 2572 days


#2 posted 03-04-2009 04:03 PM

This is an interesting technique, Gary. I agree that you could have just bought the dowel rod but then you would have missed out on the fun of making your own. If I have the tools and the time I would rather make something than buy it. Nice job.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View kiwi1969's profile

kiwi1969

609 posts in 2192 days


#3 posted 03-04-2009 04:11 PM

That is a sweet little setup Gary, of course you could have done it with a dowel plate and a mallet in about 2 seconds each but where,s the fun in that, right?. I guess thats the luddite in me trying to get out after too many years on the CNC,s and more than a few mind numbing months on the copy lathes. Not sure if I can put a copy attachment on a treadle lathe but I,ll keep you posted.

-- if the hand is not working it is not a pure hand

View HokieMojo's profile

HokieMojo

2103 posts in 2479 days


#4 posted 03-04-2009 04:20 PM

I read somewhere that square pegs in round holes, while counterintuitive, can have a beneficial effect. Wish I could remember where I heard it. I think it was somethign Chris Shwarz wrote.

either way, that came out wonderfully. way nicer than the walnut dowels that I bought at woodcraft.

View hObOmOnk's profile

hObOmOnk

1381 posts in 2878 days


#5 posted 03-04-2009 04:30 PM

I use the same method taught to me my by my Appalachian elders – a dowel plate.
I had a dowel plate made for me at a local metal shop about five years ago and it still works.
I’ve used many local woods for dowels, including: walnut, cherry, oak, ash, maple, hickory and hackberry.

Armed with a homemade wooden mallet, then whack, whack, whack and out comes a peg.

For large diameter pegs, I use a doweling cutter, then cut pegs to length.

-- 温故知新

View Matt's profile

Matt

181 posts in 2123 days


#6 posted 03-04-2009 04:41 PM

G-code and Python. Now you’re talking my language. I think I could do this on my tabletop CNC and just cut them from a thick board vertically. Of course I would need several profiling cuts for each one. Not nearly as fast as your setup. Can I get a peek at how you use Python to generate G-code? I wan’t to write some Perl or Java to generate G-code for making holes then add it as a screen in Mach.

Good stuff.

-- Matt - My Websites - http://www.bestinwood.com - Hand Tools :: http://www.workshopgarage.com - Small Shops

View PurpLev's profile

PurpLev

8476 posts in 2399 days


#7 posted 03-04-2009 05:02 PM

looks great, nice to see it all coming together .

seems very repetitive those, how far can you open the lathe? it would make it more efficient to make one long dowel and cut it into pieces, then cut the pieces and make smaller dowels – unless your machines are limited in that respect.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View David's profile

David

1970 posts in 2889 days


#8 posted 03-04-2009 11:39 PM

Gary -

Very interesting post! Thanks.

-- http://foldingrule.blogspot.com

View hObOmOnk's profile

hObOmOnk

1381 posts in 2878 days


#9 posted 03-05-2009 12:45 AM

Here’s a link to an article on how to make and use a dowel plate for peg making:

Pegs

-- 温故知新

View kiwi1969's profile

kiwi1969

609 posts in 2192 days


#10 posted 03-05-2009 01:24 AM

Sorry I thought “python” meant monty python, geez i,m a caveman.

-- if the hand is not working it is not a pure hand

View sidestepmcgee's profile

sidestepmcgee

158 posts in 2475 days


#11 posted 03-05-2009 01:24 AM

I like your creativeness but here in tallahassee FL any power saved is good seeing how our local power suppliers are out to make a dollar off a penny.Plus I cant get you to write me a code whenever I want.very cool though,thanks for posting

-- eric post, tallahassee FL

View Gary Fixler's profile

Gary Fixler

1000 posts in 2132 days


#12 posted 03-05-2009 05:54 AM

gizmodyne: I’d seen something like that once before on GaryK’s awesome birdcage project. I didn’t know they were a for-sale item, though. Thanks for the link.

HokieMojo – I’ve heard that somewhere, too. If the wood can handle compressing like that in a clean way, it makes sense to me.

Scott, kiwi, and Randy – believe or not, my lathe is substantially quieter than anything with a mallet. I made these late one night over the weekend – well after midnight, when I wouldn’t have been able to bang on something with neighbors on 3 sides of me, but my tiny lathe can’t be heard outside :) I agree that it would be faster during normal hours, however, with a doweling plate. This just gives me a nice, very quiet option to keep working after-hours when I’m not allowed to be banging away in my shop.

Randy – I haven’t heard of a doweling cutter. I’ll have to look them up.

Matt – I’m not sure if you know any Python, but it’s as easy as print statements to spit out whatever info you want when you run your code. I’ll follow up this comment with another that has the code I used.

PurpLev – I can get something almost 16” long between centers on this lathe. The problem, however, is deflection. This happens regardless of whether it’s wood, metal, aluminum, or plastic. Basically, the farther you get from the supported ends, the more the cutting tool tends to push the material away from itself. You’ll end up with properly sized ends, and a fat middle that’s quiet out of spec with what you wanted. One thing made to counter this is a follower rest, or if you’re working on the end of a part – say, drilling through the center of it, a steady rest. Those are the ones made by Sherline, who make my mini mill and mini lathe, and those links are pretty good reads on the subject. It’s expensive stuff, though, because all of their stuff is really meant for machining small machine parts, accurate to 0.001”. I haven’t had enough need to splurge on these kinds of rests yet.

David – thank you!

Randy – that’s a cool read. I may end up making one of those, or breaking down and buying one :) I’ll have to see how much use I have for dowels for awhile first.

kiwi – believe it or not, Python, the programming language, is named by its creator, Guido van Rossum for Monty Python, which he enjoys. People working in the language are encouraged to use tongue-in-cheek references to it whenever they like. Thus, two of its most popular editing/testing environments are Eric, and IDLE.

eric – I agree with saving power, but I save quite a bundle all the time with my usual conservative energy use. My energy bills are incredibly low, so much so that I determined that I can’t save more money with most of the ways people do. An example is a pelletizer and pellet stove. I determined that if I spent about $3500 on the very cheapest set of those, it would take me on the order of a few decades to make the money back from what I’d save in my very tiny heating bills. I even added in what I spend per year on A/C in the warmer months, and even if pellets could also cool the room, I’d still need the stove and pelletizer to work for about a decade, heating and cooling to make it worthwhile. I’m not sure why this is, other than that I’m single, and don’t use much in the way of appliances. Maybe California’s energy costs are really low.

-- Gary, Los Angeles, video game animator

View Gary Fixler's profile

Gary Fixler

1000 posts in 2132 days


#13 posted 03-05-2009 06:56 AM

Matt – I went and posted my Python code to pastebin, checking the ‘forever’ radio button so it should remain up there. I syntax highlighted it, too, so it may be marginally easier to read. The output would be something like this, and that can be loaded directly into EMC2 on my Ubuntu Linux box, which controls the mini mill and mini lathe.

G-code has loops, and it would be a tremendously smaller output program to use them, but it’s so much easier to code a loop in Python and just spit out straight, imperative commands. Anything with large loops in g-code makes EMC2 take ages to finish parsing it all before displaying the cut paths in its viewer, and allowing you to proceed to the actual cutting. I’m not sure there’s really any savings to shrinking even enormous things down, except for the original filesize, because EMC2 is only going to blow it all back up in memory before letting you get around to cutting.

Eventually I want to get around to wrapping this stuff up entirely into something more visual, like a proper CAD package with automated g-code outputs, but it’s so much work, and I’m so busy and also lazy :)

-- Gary, Los Angeles, video game animator

View Francisco Luna's profile

Francisco Luna

936 posts in 2144 days


#14 posted 03-07-2009 01:19 AM

amazing!.....is it possible to make a 3” diameter, Hard Maple Bench Screw with tht CNC???....for sure it’s possible, I just want to throw the idea and see what others think….

-- Nature is my manifestation of God. I go to nature every day for inspiration in the day's work. I follow in building the principles which nature has used in its domain" Frank Lloyd Wright

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