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Friday, April 29, 2016

Folded Cube Table / Stool / Bench


Around 1pm Thursday my oldest daughter tells me she has a project due 9am Friday for her design class. Okay, sure I'm happy to help. Turns out it is THE project, which they had the entire semester to do and is 1/3 their grade. I leave the room and stew for a few minutes because I'm very angry, get over it, fetch my daughter and we go to work. We take care of the paperwork portion, then the prototype requirement, and by 4pm-ish we are in the shop starting work on the actual build. We discuss lots of options but realistically we only have time for plywood. The idea is a cube table/bench/stool made of 8 triangles (legs) and 1 square (the top). Everything is mitered. It was tempting to say, 'It will be butt joints, glued and brad nailed,' and we would have been done in half the time but this is a design project, not a: make Dad's life easy project.

We cut squares, then bisected the squares to make 45/45/90 triangles for the legs. I hot glued plywood scraps to the sled for registering the squares. The hypotenuse doesn't need to be precise, just cleanly cut. To prevent splintering, we set the blade about 1/8" above the sled and ran the squares backward over it. After scoring all the pieces, we raised the blade and cut through.


Miters were cut by burying the blade into a sacrificial fence and sliding the edge to be mitered along the fence. The benefit is you can cut your pieces to finished size before mitering. I recommend running each piece through twice, first with the miter gauge to remove some waste then a second time against the fence to cut your final miter. That reduces the cut off and prevents it being trapped under the blade.


What luck. Two nasty storms, with hail, came through a few hours apart and both knocked out the power. At one point we busted out my Goodell miter saw from the early 1900's and using a battery powered light, kept working. Here she is making a test cut to make sure we are at exactly 45°, the old miter box was dead nuts.



Here are pictures of the glue up, which was tricky because everything is mitered and wanted to slip around. We considered biscuits or splines but with all the glue surfaces they weren't necessary for strength and we were against a deadline.


There wasn't time for a finish but that's how it goes when you procrastinate. We worked until around 2:00 am -ish; 4am now and I'm still wired from too many cups of coffee. I'll get more pictures when she brings it home again. [update; finished picture at top] Considering it was last minute, I'm proud of the result and proud of her work ethic today. (Not proud of her putting it off until today, we are going to have a talk about that.) I don't think it would have been much better if we had more time. The miters came together extremely well considering how many there are. Four of the triangles are mitered on three sides. The top is mitered on four sides. The remaining four triangles are mitered on two sides. And lord help me, she wants to build another one from solid wood.

Friday, April 8, 2016

Upgraded Dust Collector Filter

Upgraded my Delta AP400 dust collector to a Delta 1 micron bag. The original was 30 micron. The new bag is much thicker, so much that it stands up on it's own. The 30 micron bag snapped up when inflated and was as taught as a balloon. Despite being thicker, the new one is pretty much the same with the collector running or off so I guess that means the new bag has less resistance; a lot less resistance.

 

Thursday, March 17, 2016

Will Home Made Spindle Washers Cause Run Out?

If you've been woodturning for awhile and use scroll chucks then you've probably had a chuck that seized on the threads and is difficult to remove. Grease or oil will not prevent stuck chuck but there are anti-seize compounds based on copper or graphite that can help. Another way is a plastic washer, called a spindle washer, that prevents the chuck from getting super tight. These washers can be purchased commercially or made in the shop.

I tend to pack rat jars and containers for various uses. One day a plastic jar lid caught my eye and I decided to make a spindle washer. After some experimentation I found that larger, thicker, lids like those from peanut butter, peanuts, mayonnaise, etc. made better washers. Pass on any lids with writing or other decoration. My method is simple, drill a 1" hole in the center of the lid (use whatever size matches your spindle), mount it on the lathe held in place with a faceplate or chuck and use a parting tool to remove the outside rim. It doesn't have to be perfect. You can make them any size you want. Most of the time I can remove a chuck using only my hand, occasionally after a long turning session I need a little leverage but the washer still prevents the chuck from seizing up tight.




A common concern is that plastic lids are not made with any precision and will cause excessive run-out which expresses itself as vibration. I decided to test a homemade spindle washer and find out how much runout it introduced.

First I measured a washer using an iGaging digital caliper accurate to 0.001" and with a resolution of 0.0005". Now I don't remember from what kind of lid this washer was made, I've had it for more than a year. But measuring various points around the washer, the deviation was never more than 0.0005" so the total variation is withing 0.001" which I found quite impressive.


Next I chucked the largest Forstner bit I own into my Nova G3 and tested runout using a dial indicator against the shank. The results were surprising. The very first test was after turning a handle for a beater chisel and I did not clean the threads beforehand, consequently it had the greatest runout of any test. Really, that test should be thrown out but I included it. The three remaining tests were done with clean threads.



The runout will be magnified as you move away from the center so if my test piece were 2" in diameter, the measured runout would be approximately doubled. Testing shows the washers introduce some runout but less than what the chuck itself introduces. So claims they introduce wobble are valid, however; the chuck introduces even more wobble so how much is acceptable to you. At the end of the day these are wood lathes and I'm not attempting to make precision parts so for me the washer is an acceptable trade off.

Monday, February 22, 2016

Restoring an old Superior buffer/grinder head part1

No idea of the age but it's in good condition. Marked Superior, Made in USA. If anyone has information about these I'd love to know.

 



I ground down the casting seams and defects, filed, wire brushed, then sanded before shooting a primer coat of machine gray. My plan is a two tone paint job in turquoise and off white.


Friday, December 4, 2015

Experiments with acoustic horns as mobile device amplifiers

Before jumping in I have to make it clear that horns are not amplifiers. If I don't, I'll get a bunch of messages enlightening me. But horns do make sound louder and when paired with cell phones are commonly called "passive amps", and even though that is a misnomer what else should we call them? "Phone horn" doesn't have a nice ring. "Impedance matching device for mobile audio electronics" sounds like the title of a patent application. What's the big deal and what's the difference between an amplifier and a horn? An amplifier adds energy to the system, it makes the speaker vibrate harder, moving more air, and increases sound output. Horns are different, they make speakers louder by making transfer from the relatively dense speaker to the relatively rare atmosphere more efficient. Sound travels easier through dense substances like water and less easy through gasses like air. The horn helps the sound energy transfer from one to the other and the result is louder music. If you'd like to hear a smart person explain it, click HERE.



My first ever "horn" was a piece of PVC pipe with a slot in the middle for my phone and the ends cut at an angle toward the listener. It sat on two feet to prevent it from rolling around. It worked "okay". I don't own it anymore and can't find a picture but you may have seen similar speaker stands, maybe with bamboo.

My second (and real) horn which I'm calling 1.0 is based on a design by Dustin Penner. What Dustin brought to the table is a easy to make flat horn from 3 pieces of wood. I made it smaller and changed the curves slightly but overall the result is impressive.


Horn 1.0

Horn 2.0 is based on a folded horn design by MXX on Instructables. This style of horn is usually seen on bass heavy concert speakers and definitely has a warmer but slightly muddier, sound. The downside is this speaker is much more difficult to build than Penner's. 


Horn 2.0

Horn 3.0 is a folded version of v. 1.0. (Probably should be called 1.5) If you are unfamiliar with folded horns, just imagine a trumpet with all it's turns. A horn doesn't need to be straight. 3.0 is much louder than the two previous versions. In my test, it was 12-14 decibels louder than the previous horn designs but the sound is also a bit harsh. To me it sounds like the small transistor radios that were popular in the 60's and 70's. 






Horn 3.0




Saturday, November 21, 2015

Walnut Trestle Sewing Table

Inspired by an 1840-ish Shaker table originally made in Harvard. I redrew this full scale from a sketch in Shea's "Making Authentic Shaker Furniture" and created full size patterns for the feet and legs. The leg tenons extend all the way through the feet. The feet each have half a mortise which makes construction much simpler. The feet join together and are pinned to the leg. The leg, stretcher, and battens all interlock. The top is attached with screws in elongated slots.









Sunday, November 1, 2015

Refurbishing a Delta Homecraft Lathe Headstock

I recently purchased just the headstock for a Delta Homecraft Lathe. Delta sold different models of lathes with this same or very similar headstock from the early 30's until the mid-50's so I don't know when specifically this headstock was sold.

Before and After


I stripped the headstock down completely, cleaned and looked at every part. The Timken tapered roller bearings are in excellent condition and did not need replacement. The spindle threads had some minor damage which I repaired with a needle file. 


Unfortunately the indexing pin point was damaged sometime in the past but is still usable. 


Since I was down to bare metal I filed the casting seams fairly smooth


And repainted with Rustoleum Dark Machine Grey.


One little mishap during the process, the badge was damaged. 




Now what to do with it? My original plan was to make a bowl lathe / disc sander. I might still do that or might end up reselling it.