2025-09-01

How I installed the padded seat from the Schwinn 290 recumbent exercise bike on the less expensive Schwinn 230 model

Caveats:

  • YMMV. This advice comes with no warranty. It’s based on the 230 I just bought from Schwinn and the replacement parts diagram I just found on their website for the 290. Maybe your bike is different and won’t match. Maybe you’ll cross thread a bolt and ruin it. 
  • I’ve only just installed this, so it’s possible it could loosen up or fail in some unpredictable way with further use.
  • I discovered this by guessing and taking a chance. I was hoping that the engineering team adhered to a practical standard. I got lucky.
  • This happened because I didn’t want to spend money on the extra features of the 290, but when I received the 230, the plastic seat bottom made me sad. It’s not a bad seat! I just hoped I could do better. It remains to be seen if the padded seat is actually better
The padded seat bottom for the Schwinn 290 recumbent bike (about $50 at the time of this writing through the Schwinn Fitness replacement parts site) will fit the bolt hole pattern on the Schwinn 230 (the less expensive model that comes with a hard plastic seat) without drilling, but:

  1. You’ll need to buy a set of four coarse thread M8 x 40mm bolts along with matching lock washers and regular washers. Hint: take the new padded seat to your local hardware store to check the fit for all four bolts, because bolts come in different thread pitches and different bolts might even be mixed up in the same parts drawer bin.
  2. Leave everything as loose as possible until you get the threads started for all four bolts, because the new seat might be off by perhaps a millimeter and require some finagling.  
Cheers, and happy half-assing,
Chickpea Salad Sandwich Disliker


2022-06-27

That Fkn Donut

I made The Donut, apologies in advance. Thanks to Blender Guru for his tutorials. Want a mind-bending rubix-cube type project to stave off dementia? This one is highly recommended.

https://www.youtube.com/watch?v=nIoXOplUvAw&list=PLjEaoINr3zgFX8ZsChQVQsuDSjEqdWMAD


My two innovations are:

  1. Hard candy spheres FTW
  2. The green sphere got lost in the donut hole shadow so i put a 1 milliwatt light inside it to make it sparkle a bit

 



2021-07-02

Building a POT Clone Guitar Pedal Based on the PedalPBC Pauper Schematic - Part the Bth

I spent about 3 hours debugging, which is actually better than I had any right to expect. There were 3 missing solder joints in the wire superhell on the back of the perfboard. 

Assembly Gutshot

 Here's the guts installed in the enclosure. Mocking it up on the cardboard probably made the difference between success and me throwing this whole thing across the room in disgust.

 

 

 

 

 

 

All Soldered Up 

Here's everything all together. I mean, I gotta admit it worked out:
  • The in/out jacks clear the tops of the side switches
  • The in/out jacks don't stop the cover from seating
  • The DC jack, although it's a 3-connector type, does clear the center mode switch

 

 

 

 

 

 

 

Assembled

Here's the best possible viewing angle for this thing. From here you can't see the controls are all misaligned, though you can see the (LOL) washers I had to put on the DC jack (LOL) because I drilled the hole too big with my brand new step bit. Love that thing though.






 
 
 
 
 
 
And now here it is next to my first pedal, a clone of a Colorsound one knob fuzz (it has a bonus input sensitivity knob).

Sound

It's anybody's guess whether I really got this correct. Are all the component values actually right? Did I mess up something in one of the feedback loops? Who can say? But it sounds nice. I'm not sure I can really tell if the mids and turbo switches are working, or even if I have them labeled backwards. 

But it sounds like...an overdrive. I don't even like overdrives except in front of distortion. I think if I had to choose between this blues breaker-style pedal, and a screamer-style pedal, for use in front of an regular (not high gain) amp, I'd pick this one. It seems to have less of that screamer crackle haze in the top end.

2021-06-15

Building a POT Clone Guitar Pedal Based on the PedalPBC Pauper Schematic - Part 1

References: 

  • PedalPCB Pauper build docs here: https://www.pedalpcb.com/product/pauper
  • I get most of my parts from Small Bear:http://smallbear-electronics.mybigcommerce.com
  • I don't need another overdrive. I already have a Strymon Sunset I'm pretty comfortable with, so I don't know why I'm doing this.

Perfboard Layout

I've already perfboarded a clone of the Colorsound one knob fuzz, so I felt ready. Was I wrong. The layout for this took me literally 20 hours, I’m not kidding. Drawing, erasing and redrawing to the point of nausea. Felt 10x harder than the little fuzz. It was a learning experience, and I will do better next time, but holy crap. The feedback loops around gain stage one were hard to map, and the output tone section was eye opening - look at those weird little loopy bits on the right side. This is a particular flavor of mental effort that I've never tried before - nothing in my life had prepared me for it. 

Managing to put VREF (1/2 rail) in the places it was most needed was interesting. I couldn't get it from the pots to pin 5 of the op amp, so down below in the rear perfboard image you'll see little wires everywhere. In this layout, little wires are be required for:

  • Tag A, going from stage one to stage 2
  • Tag B, going from stage 2, to one side of the clipping section, and on to the tone section
  • The VREF to the IC, as mentioned above
  • Ground to the IC, and to the input common

Perfboard Solderjob (Front)

Note that my layout failed to account for the large size of the 100uf electrolytics, as well as the 1uf poly caps. The layout assumes that all resistors are loaded vertically and take just two adjacent holes, and that all caps take 3 adjacent holes - neither having much width. So you'll see my optimistic layout sprawls quite a bit when I got to the supply filtering (C10, C11).

Perfboard Solderjob (Rear)

The solder side of the perfboard is a two layer wire superhell. I've seen other boards where people sort of draw traces on the pads, bridging them together in relatively neat lines. Haha lame! I solder the components in, then I bend all the wires over to touch each other. I used thicker leads from some weird old power resisters for the posts, and bridge the components to those. I'm not proud of it.

Control Layout (Front)

This is the what the front might look like. I'll do all the wiring on this jig so I don't have to work in a 125B enclosure. I'm bringing the dual gang DIP and internal treble trimmer out to the front, like a daft nutter. The only thing I'll have to solder when it goes into the real enclosure is the DC jack, which unfortunately has an internal nut.

Control Layout (Rear)

Here I've trimmed the board on a band saw with a metal cutting blade, so it fits easily in the 125B. All the jacks will go at the top (in/out/power). I've calculated that, in a perfect world, the plastic 1/4" box jacks will ride a couple of millimeters over the terminals of the left and right switches, while the 2-terminal power jack will clear the top of the center switch housing by a similar amount. My pedal calculations are often wrong. Yes, the left and right (canonically DIP) switches are SPDT here, which is an extra throw, but if this pedal doesn't work out, then...SPDTs are more versatile and cost very little more.


The plan is to wire up just the potentiometers and test. All of the switches have a default off position, so leaving them unconnected should put the Pauper/POT in "boost" mode for the first test.

I give this a 50% chance of being an undebuggable nightmare that I have to scrap in defeat. Witness me.


2020-05-16

A Problem with The Mixer Control on My USB Audio Interface Made Me Think All Guitar Impulse Responses Sound Bad

For over a year I thought something was wrong with my guitar cab IRs when I played direct into my DAW. My setup is a bunch of pedals going into my audio interface like this:

IR Loader in DAW <-- USB Interface <-- High Gain Pedal <-- Boost Pedal <-- Tuner <-- Guitar

Yes, I play with no power amp, real or simulated, although I'm told a tube power amp is used to generate most guitar cab IRs, so maybe I get some tube sauce for free there.

Symptoms

  • IRs sounded like they had too much room sound. As if they had a small ambient room reverb on them. Like how I'd imagine it would sound if you mic'd an amp from too far back. You do you, but for high gain I want my mic'd sound pretty dry.
  • Sometimes my high gain tones sounded spitty and gross. I couldn't dial out the fizz and crackle without losing the whole top end. Sometimes it verged on unplayable.
  • One week or one session things sounded great, the next week I thought I was crazy to like that sound. That's normal for me, where one day I think a tone is perfect and then next I dislike it, but this was nuts.
  • I thought I was going crazy.
  • I thought...maybe IRs are overhyped bullshit?
  • I thought...maybe there is something wrong with my pedals?
  • Then the other day I suddenly realized that I could not get the sound in my phones to sound like the sound that was recorded in the DAW. This should not be the case ever. I was supposed to be hearing 100% DAW playback sound from my interface, in both my phones and speakers - the same sound that is recorded in bits and bytes.

Cause

  • The mixer knob on my audio interface had always let a tiny bit of direct sound into my phones/speakers, even when I had it turned all the way to "Playback". I knew this all along, but I didn't think about it, because I am a dumbass.
  • The way I knew this was: with the guitar track record button turned off in the DAW, if I turned my phones up loud I'd hear a bit of high gain junk when I played. It sounded like an industrial guitar track. I figured, that's weird...but how much can it hurt?
  • A lot. It can hurt a lot. It can make you think that IRs are stupid, when the entire rest of the world seems to like them a lot.
  • This was especially apparent when I had my DAW session really quiet, which happens sometimes because I'm shit at gain staging, and I forget things. When that happens, I have to turn up my phones or speakers to compensate, and the proportion of direct sound to DAW playback sound would go up. It turns out that those were the really bad days.

Approaches

  1. Live with it. Gain stage my projects so that the proportion of fizzy direct sound is as small as it can be compared to the project level. Probably a good idea anyway? You tell me, but probably.
  2. Get a new audio interface and hope it didn't happen there. My current audio interface is very low end, and out of production, so I figured what are the chances this happens again? This probably would have been a good approach.
  3. Hack up my current audio interface with a soldering iron.

Solution

I chose approach I nearly always take: hack shit up with a soldering iron. I don't recommend this unless you know what you're doing, and are ready to replace your hardware if you break it. I came so close to breaking mine.
  1. I took the interface apart. Lots of screws holding in the mic/instrument combo jacks and MIDI connectors, nuts holding in the pots and 1/4" jacks, and a single riser board for the top set of pots. This part was easy and fun.
  2. I located the stereo B10K pot, and discovered it is a standard voltage divider. If you don't know what one of those is, you can stop now. I sorta know what a voltage divider is. That gave me incorrect levels of confidence.
  3. Turned it all the way up to "Playback" and found it was 1.6 ohms on one set of legs, and 10K on the other. Voltage divider? I decided it is. What else could it be, it's a mixer pot? Right? I'm probably wrong.
  4. Got the pot off the board. What a nightmare. I am terrible at desoldering parts that have more than a couple of legs. My solder sucker is half broken, the tip is all melted and fuzzy, I can never get solder wick to work, my hands are shaky, and I'm just terrible at this. I ended up literally destroying the pot with a pair of nippers and pulling the chunks of plastic off the board, leaving only the legs. I was able to get the legs out by applying heat and pulling with the needle nose pliers. I mostly didn't scrape any board traces by accident. Mostly.
  5. I soldered the 1.6ohm set of through holes to short them out using clipped off leads from an old resistor, and left the 10K stereo set open.
  6. Apparently I didn't cut any traces or chip any important surface mount resistors.

Results

  • Now, when I have my DAW record button off, and my monitor level all the way up, and playback is stopped, and I hit the guitar strings, I hear literally nothing in the phones or speaker. You obviously want to watch your ears doing this, and make sure you turn in back down fast.
  • My IR setup sounds the way I imagined it should - very dry, no fake "room sound" effect.
  • My guitar tone sounds the way I imagine it should - no industrial guitar fizz, unless I put it there on purpose.
  • I feel stupid, but I'm recovering slowly.
  • I didn't get an excuse to buy a new audio interface, which is a bummer because I am am a monkey that likes shiny new things, but good because the fun wears off on those even quicker than most gear.



2014-11-23

Built my own vocoder in Reaper DAW - For No Reason

This is a seriously backwards project. It's built in Reaper using only stock plugins. Keep in mind the important fact that I am not a genius. There are probably a hundred better ways to do this just in Reaper, and there are probably 10,000 better ways to do it in an audio programming language. People build these with analog electronics, too, but those are pretty high on the parts count. I wanted to spend a nice day off on this, not a terrifying rest of my life.

An interesting but incorrect fact: the Wikipedia article on the Vocoder says it was invented to compress and more easily encrypt voice transmissions, which is obviously wrong! It's clearly used for making robot sounds.

To download a zip of the full Reaper project, click here. Here is what the project looks like:

Here's the output from my Reaper vocoder: https://soundcloud.com/superbonuspak/reaper-daw-diy-vocoder-experiment-1

And here's how I think it works:
  1. Mod Generator is the voice that will modulate the noise. I called it that because originally I used the JS: synthesis/tonegenerator to sweep my frequency bands, before I replaced it with my voice. The sends go prefader from here to each of the Bandpass X tracks - prefader so that you can turn it down (don't want to hear myself dry) but it still goes to the sends. This has a copy of me on it saying something.
  2. Noise Generator is the sound to be modulated. I called it that because originally I used pink noise. That still works fine. You can replace the ReaSynth on that track with the JS: Liteon/pinknoisegen and you'll get something that sounds less musical, and slightly more voice-like. Ha ha not really. But less musical.
  3. Bandpass X (where X is a number from -1 to 5). This simply receives the Mod Generator voice and bandpasses it way narrow using ReaFir. Each band (each X) is a different notch in the spectrum, from about 300hz to 1500hz.  Why that range? Because I got tired of making bands. Why is there a band -1 and 0? Because after I did band 1-5 I realized I wanted to go lower, and I didn't want to redo all the filters. I just couldn't face it. Like Mod Generator, these are also pre-fader so it can be turned down all the way but still do the sends.
  4. Noisemod X uses the Bandpass X send as sidechain input to a JS: SStillwell/expander. The noise comes in from the Noise Generator track via prefader sends, it is filtered with an exact copy of the ReaFir bandpass from its associated Bandpass X, and then goes into the expander, where the output from Bandpass X is sidechained in on 3/4. The expander has a high ratio and carefully tweaked threshold. These are the only tracks that are allowed to make any noise.
This is obviously not a practical way to build a vocoder, but I did learn some of the basics. I think it says something good about Reaper, that it's got the routing mojo to handle this. And I may use Reaper to explore more basic synthesis ideas in the future - it's almost like a bunch of little modules that can be connected by wires, very inexpensively.





2013-05-26

Raised Bed Garden with Integral Fence and Access Doors

This is my raised bed vegetable garden, designed to keep out nature's little Dr. Lecters. We have a herd of deer, a gang of woodchucks, a squirrel riot and a insurgent army of chipmunks that will fight a dog over a bone. I don't know if this will work or not, but it's a try. Check it out, the sides open on hinges:
Eye hooks with bungee cords hold the doors closed, necessary because this thing is built to such loose tolerances that I am ashamed. I guess the idea was (there was an idea) that it would be easily disassembled and loosely coupled so it would go pretty much anywhere and hang together. In that respect I guess I succeeded. I guess.
It started as a box of 1x12 #3 cedar, 8 feet by 4 feet (or so). It was important to keep the long side exactly 8 feet because so much of the wood is on those sides, so the short sides are butted in between the long sides and cut a couple of inches shorter so that half-lengths would span it. The mesh is 1/2" galvanized 19 gauge "hardware cloth". It doesn't remind me of hardware and it's nothing like cloth but what can you do - that's what they call it. This is the floor that stops the woodchuck from digging up through the bottom.
I leveled it in the yard somewhat, but not completely. That's important, because I should have leveled it perfectly. Why did I not? Well, why do I do anything? For some reason on the day I was doing this I decided it was good enough, not really thinking through the concept of swinging doors that would want to be level, and how that would match an off-kilter base. I think it's because I was facing the task of dumping 1.2 yards of topsoil into this with a wheelbarrow and a car ramp, and I got everything all mixed together in my head.
There you go, almost ready for dirt.No, wait, don't do it! What if I filled it up now and then I want to drive my U-posts into the corners and they hit a big rock and I had to dig the whole corner out? Or, worse, move the whole frame because the rock was too big? First I need to put in the posts.
Posts and dirt. I bent the flanges on the posts because I want them to go right into the corners.
That's a good one. It looks great. The face of the post is right up against the box corner so that when I face the U-post with a 1x3 cedar plank the bottom of the plank will be flush with the wood of the box, and therefore the door will close with no gaps. Sounds great but the fact is that this post is not completely vertical, so when I goof around with it to get it more vertical it will open up a gap down there. But probably no bigger than the 1/2" of the fence I'll be using.
A door. 4 by 8, the reason I fought to make sure the box was exactly 8 feet long all the time. So I wouldn't have to cut those long boards at all. The verticals are just a 1x3 cut in half.
Fastened with stainless wood screws. The long end is going up to the left.
Then a strip of 1x2 cedar is used to make the short sides flush, plus secure the mesh as well and hide the bitter nasty cut ends from the door user.
In my imagination this board would be flush with the face of the box. Imagination is a wonderful thing, but actual thinking would be better.This is a 1x3 board bolted to a U-post in the corner. That's the reason for the U-posts instead of T-posts - they have 1/4" holes in them every 6 inches or so, making it easy to attach things to them.
That's the four 8 foot 1x3 cedar boards stuck to the corner U-posts. That's a 1x6 cedar board perfectly level at a distance above the box that will allow the 4' x 8' door fully cover the opening. I attached it with a longer bolt through the U-post and the vertical face board. However in two of the cases, the horizontal board actually fell between two pre-existing holes in the U-post, and I had to make new ones. It's only mild steel, but it gave me a hard time. Plus I had to drill in place, which is always fun.
Hinge detail. These went on easily, but that's mostly because this a high-tolerance situation. See how the 1x6 bolted across the face boards becomes a header for the T-hinge? So the door in theory is flat, thanks to those 1x2 strips, and has a flat place to get flush against. Except for reality of course.

Reality intrudes in the form of the gap at the foot of the face boards where they touch the box, as I said. It intrudes in the form of a bulge in the side of the box, presumably from the weight of the soil. Basically the door corners don't want to go flush, so we encourage them with some biggish eye hooks and some rubber bungee cords.
There's two tomato plants, some climbing cucumber (they climb?), broccoli, cauliflower, celery and hopefully some romaine. Who knows, it's going to be a veggie brawl in there and I've never done this before. I guess we can throw some deer netting over the top. We could put another course of mesh around the sides if we need more height for the tomatoes...

Who knows what's going to happen.

2012-02-04

Buckyball Squid - Oh, Yeah!

This is my favorite original.  It's got physics mojo, relying on some kind of magnetic pole thing to keep the squid arms floating away from each other.  I hung the squid head on a length of monofilament threaded and knotted through a plastic washer I made from a drink cap.  I chose to hang the head and then attach the legs.  When attaching the legs, you move them in slowly to give them a chance to tell you if they're going to freak out and stick to the next leg over. Don't let them.  You know how it is - magnets.

 Squid hole view.  The head is a stack of 3-ball-side pentagons with a hole in the center.

Buckball Penta-Cannoli Torus

Guy at work got a set of these as a present.  They are ephemeral, occasionally frustrating, odd, and sometimes rewarding.  Here's a 5 sided torus made from little cannoli shapes.

 First make 5 of the pentagons.  We left the hole in the middle.  The shapes have 4-ball sides.  The hole may help with allowing the cannoli tubes to flex when you place the last tube.
 Here are the five.  If they don't want to line up square, you may have to unzip your cannoli and flip it the other way.  You know how it is.  Magnets.  The last one goes in tight; you have to simultaneously pry open the nearly-complete torus and make sure you get the match-up correct, too.  Took me two tries.



2012-01-31

Building An Awesome Fishing Joke

I came up with this one at work today.  It arrived suddenly, like a cleansing bolt of inspiration from the realm of the divine.  You know what I'm talking about.

Q:  What did the alien trout say to the fly fisherman?
A:  Take me from your leader.

Genius?  I leave it to you, dear reader...but I think you do well to consider the alleged source.

2012-01-09

Inexpensive Meade 4.5" 114mm F=1000mm F/8.8 DS-2000 Reflector - Disassembly and Focuser

This is a telescope someone gave me as a gift many years ago, purchased from a chain photography store.  It's part of the DS-2000 starter kit, which comes in both refractor and reflector form, and has a computerized drive system.  But I never got it collimated - or rather, I screwed up the collimation so badly that it saw poorly.

I have decided to clean it up and get it working, if possible.  To do that, I'm going to have to take it apart.


There it all is, taken apart.  Just do it.  Three sheet metal screws hold the plastic end rings to the ends of the tube.  Three machine screws hold the focuser to its port in the side of the tube.  Three thumbscrews hold the three tines of the diagonal to their slots in the tube.

I read that the focuser is "lubricated" with something that is practically tar, and that this gunk will eventually cause the stripping of the cheap plastic gears.  And I don't doubt it - that stuff was like...like...I can't explain it.  Tar is a good word.  First take the screws out of the square lid covering the gears.


Then you'll see a thin spring metal device that I believe is intended to push the shaft gear into the linear gear of the focuser tube.


Then under that, the gears.


This is about as complicated as the interface between two dirt particles, but there's one thing to watch out for, which is this side-play tensioner or what-have-you.  It's a screw pushing a rubber nub into the smooth side of the focuser tube directly opposite the gear drive.  You can see the nub just sticking out in the inside.  If I lost mine, I'd make one out of a couple layers of bicycle inner tube glued together or something.


Here's the mirror!  It's kinda ratty looking, but it makes your face look really big and is therefore fun to play with for a few moments.


I wanted to put a center mark on it.  I'd free-styled a red sharpie dot on it when I first wrestled with it, years ago, but I did it when it was still in the tube and - whatever.  It was ridiculous.  Took me ten minutes to get rid of it with isopropyl alcohol and a series of cotton swabs.   So I tried various techniques of marking the center, including this one.  Thales theorem rocks, but actually I wanted a ring around the center so a laser collimator would still work later.  Some people use those binder reinforcement rings, but WTF - I can do the same thing forty times harder, without spending $1.29.  Right?  Am I right?  So I wanted to mark a circlish thing around the center and hit upon a genius method.


It's metal ruler with a stop, in the form of some vice grip pliers, attached so as to place the end of the ruler, when the stop is at the edge of the mirror, a fixed distance from the center.


In the center of the mirror you can see the faint lines of Pigma Micron 005 I used to delineate a square with chopped corners - an octagon.  Then I stuck tape up to the lines and cleaned up the mirror.


Not very clean yet.  It's amazing, after getting a nice camera and cleaning some old lenses, how difficult it is to clean optical glass.  Some of the flecks are little grease spots that smear around but never want to leave - you almost have to nudge them off the edge of the mirror.  Some of them are pits from either bad manufacturing or awful storage conditions (my bad).  Some of them are scratches I put there.  Some of them either change every time I look at them or are permanent.  After about ten minutes of struggling, I got it as clean as I could and reassembled the scope.

I'll try collimating it next.

2012-01-07

Installing an Acoustic Strap Button

I'm doing this partly to take pictures with my new camera, and partly because I haven't blogged much lately.  The one people who read my blog will be pleased, I know - you're intensely welcome and you know I like you alright.  But also my project acoustic refret straight-pull conversion needed a strap button, and I don't like the idea of the thing that loops around the headstock.  Why?  Because I have strong opinions about things I know nothing about.

For guidance, I consulted this article on frets.com - frets.com seems to have stringed instrument mojo about stuff.  Pointless aside: I also like the articles at Fret Not Guitar Repair, which has a wonderful name and great information, but the stuff she works on is way out of my class (search for "acoustic" on this blog to see an example of my class of work on my class of instrument).  I pretty much drill holes in things and hack them up with cheese graters.

This is where I plan to drill a hole.  Somewhere...on there. Too much toward the back and the guitar will want to flip forward, maybe, and too much toward the front and there could be a flying monkey attack.  I'm feeling whimsical.



The button will go in the middle.  But I've got to check that I won't hit any metal.  Does this thing have a bolt on neck?  I have to check, I cannot recall.


I'm no expert but I don't see any bolts here.  Let's drill with abandon.  I selected a bit that was about the size of the screw core and taped a stop to it so I didn't go shallow or through:


Then I screwed in the button, taking care lest I drilled the pilot too small and began to strain the wood.


That's ten minutes of work and I feel like a genius, plus my guitar doesn't fall on the floor when I get up, anymore.

2011-11-19

Building a Watercolor Painting

I've taken up art.  I've decided I'm gonna back off on building/cutting/modifying objects for a while, except for the LCD monitor I'm going to attempt fixing in my next post. So armed with some supplies from the local art stores and a 1978 edition of The Watercolor Painting Book from the local library, I decided to do my own rendition of "Demonstration 10.  Winter Landscape".



That's it.  I call it "Early Snow" since I used way too much green in there.

Here's my Reeves paints, which I got in a set obviously.  The individual tubes are marked for color fastness and one or two are not excellent, just good.  A fact I will have to remember if I ever embark on a paint I anticipate keeping.  And still, even with 18 tubes of paint, all the instructions call for colors I don't actually have.  So I make it up.


Here's the paper.  Commonly available Strathmore, cut into quarter sheets to conserve badness.  There's enough bad art in the world and I don't want to create too much at a time.


Here's a nice shot of my brushes.  Nice because in focus.  I use them indiscriminately.  I think I need one called a "rigger", though, for fine lines (originally rigging on ships, so I hear).


And finally during cleanup, my palette.  The colors were pretty in the water, but don't show as well in the photo - nothing does, because my camera sucks.  I cleaned the palette out completely because I'd crapped up all the little color blobs so thoroughly that not one of them was uncontaminated with barf gray.


Building art is fun.  I'm going to do it again.

2011-10-21

Third Attempt at a Homemade DIY Table Tennis Racket

Why I Need to Build Another Racket
My first racket, when combined with LKT Rapid Speed 2.0 rubber on both sides, weighs 220 grams.  That's 130 for the 7 ply fiberglass reinforced blade, plus 90 for the rubber and rubber cement used to glue it on.  I played with it for an hour and it's too heavy.  Okay for predictably looping the forehand, pleasant to smash with, but horrible for backhands, where the wrist is more involved.  And because I didn't build up the handle enough, I always had the impression it might slip out of my hand and kill someone.

Who knew building a ping pong paddle could be so hard?  I felt I had to do a few things differently:
  1. Lay off the fiberglass.  The fabric I have is too thick, I think, and it brings in way too much plastic resin.  It's a theory.
  2. Use clamps instead of weight to form the laminate.  I need to drive more of the glue out, thin out the glue lines.  Glue provides little strength on its own.
  3. Less layers and a bigger, monolithic core.
I also rough-cut a piece of birch plywood to shape, to see how the weight came in.  
Left to right:  original 3 ply butt joined blade proof of concept, 80g; finished 7 ply blade, 130g; 2x LKT Rapid Speed with leftover rubber cement, 90g; rough-cut birch blade, 104g
Not good enough.  So I began to calculate.  The idea was to calculate the weight of a cut out blade based on a ratio from the 6"x10" whole board. That way, I could measure the boards going into the paddle and determine how it would turn out in advance.  I used the birch plywood and the remainder pieces as my sample, and calculated a bunch of stuff from it.
These calculations are all crap
The problem is that the birch plywood I started with was not cut to the final 10" length, but 12".  So my golden ratio of 0.57 was relatively useless.  And I didn't feel like doing it again.  I wanted action, not words!  I still think this is a good idea, though.  I really should do it.

So my next attempt was a 5 ply:  3/16" balsa core, two transverse 1/32" basswood plies, and finally two longitudinal 1/32" basswood plies.  All this wood came from National Balsa, which has been my choice of suppliers so far.  I didn't even pay for the balsa.  It came as part of the packing, to prevent my 6" wide 1/32" thick basswood sheets from breaking.  Sweet.

Here We Go
Per my new plan, this time I clamped rather than weighted.


Those are 1/2" granite tiles on an old desk, with a length of oak on top to keep the metal off the stone.  The glue is two part epoxy left over from my guitar project.  Next I needed a method to measure mass, or Earth weight.
This scale is a 500g model from Harbor Freight for ~$13.  It works consistently.
Once the piece cured and I cut it to shape, minus a couple millimeters per side to cut the weight further and make it easy to fit my old rubber sheets, it was about 87 grams.  Too much, so I hollowed the handle.
Blade with hollowed handle section.
I do all this work with a bandsaw, files, a Stanley SurForm cheese crater, and 100 grit sandpaper.  While I have a router, I do not have a router table.  That's why it looks totally unprofessional - I don't make templates and route around them.
Handles ready to be applied.
I decided I didn't need the end to be closed.  I broke it out completely.  The handles are more 3/16" balsa plus a layer of 1/16" basswood on top.  The completed blade is a good weight, IMO.
Completed blade, 91.2 grams
LKT Rapid Speed rubber reapplied and trimmed.
Assembled racket, 175.4 grams
Not bad!  Nearly 45 grams lighter than that beast I built the first time.

Playing Impressions
The completed paddle is in line with "real" paddles I've played with in the past.  Again, the handle isn't thick enough, thus the hockey tape.  I can flip the backhand much better than the 220gr monster, and it's only 5gr heavier than my friends preassembled Stiga Cannon.  It is of course much spinnier and hard to handle.

I am not a rater player, I haven't even come out of the basement yet, so I don't know how this blade and combination rates.  ALL?  OFF?  Who knows.

Now I have to get used to playing "real" rubber again.  The old monster blade, at 130gr naked, will be converted into a sandpaper paddle.

Relative Paddle Weights
  • "Ping Pong, the Original" 4 pack of preassembled paddles: 135g - 141g
  • Stiga Cannon preassembled paddle: 171g
  • My second blade, the "beast": 130g
  • My third attempt, hollow handle:  91g