Thursday, May 31, 2012

Painting Bicycle Frames

We have some bright, new colors appearing on the bicycles at Granja Peniel these days...

After only months of preparation....

Newly painted bicycle frames
Things are finally coming together....

It all started with a donation last November from a short-term Baptist work team working near Bogota.  They wanted to bless the boys in our program, so through Felix Pinzon they made a donation for the parts and materials to fix up their bicycles.  Of course, the boys would provide the labor and learn more about their bikes in the process.

We picked out the six frames in the worst shape - or in one case, a PINK bicycle that was somewhat an embarrassment for the assigned boy to ride.

Step one was to completely disassemble each bicycle, stripping it down to the bare frame.

Juan Felipe Garcia with the components removed from his bicycle.

Joel Garcia, looking forward to having a bicycle some other color than PINK!


Johan Egson Fonseca dismantling his bicycle in preparation for re-painting

The next step was to strip off the existing paint with paint remover and by sand blasting.

Johan applying paint remover to his bike frame 

Yordan Garcia sandblasting the frame of his bicycle
After some trial and error, we found that 40-60 grit silica sand works the best in our sandblasting pistol, with 125 psi air.  The ceramic nozzle in the sandblasting pistol was worn out, so fortunately Grant was able to buy some replacements cheaply while visiting the US in January...

Johan Egson Fonseca sandblasting

Bike frame stripped down to bare metal, ready for paint

We decided to build a special rack to hold the bicycle frames for painting using a spare piece of rectangular tubing and some wood we had on hand.  We still need to turn the frame end for end while painting, but the rack gives easy access for the spray gun.

The painting rack holds up to six frames, forks, or handlebars.

We wanted to use durable paint so that our efforts hopefully won't have to be repeated any time soon.  We ended up buying polyurathane automobile paint, which comes which is a two-part paint (dries fast!) with its special solvent.

The grey primer was fast and easy to apply, we used two coats.

Frames drying after primer was applied.

Since I bought only dark green and basic yellow, we had to mix the final colors.  We made some trial mixes to see how they looked, as shown in the photo below.  On the top row, the full green is on the left, the yellow on the right, and various combinations in between.  The rows going down the pane show increasing content of white paint.  We ultimately a bright green (top center) and a taxi yellow (bottom right).

Glass pane with various color mixtures. 

Alberto sanding the primer before applying the finish coat.


I applied all the finish paint, because the small, tubular shape of the frames makes them difficult targets to apply enough paint to shine, without causing the paint to run.


So as to avoid problems with overs pray, we painted different colors separately.

Here are all six frames with the finish paint.

Now it's time to put the bicycles back together, but that has to wait a bit more, until Grant returns from the US...stay tuned.





Thursday, March 1, 2012

Fabricating a belt guard for the compressor

The Lord, (or my concience), or both spoke to me during my trip to the US in January about the priority that I should put on making a belt guard for the compressor.  We have been operating the compressor since 2005 with open V belts, which presents a significant hazard.  Thankfully, we haven't had any injuries or incidents, but the time was way overdue to fix this unsafe situation.

So, my first priority upon my return was to build a belt guard, something that I started back in 2005, but allowed to fall by the wayside in favor of other more interesting and pressing tasks.

The compressor belts with the piece of the guard that was completed back in 2005.
Building the top half of the inside frame

The top inside frame now in place

Now the wire mesh added to the new frame

Cutting and welding the angle iron to curve the outside frame

The completed outside frame

Outside frame covered with wire mesh

The complete belt guard in place

Now all we need to do is paint it...
I'll add a finished photo once we do get it painted, along with several other recently welded up items....

Wednesday, February 15, 2012

Fixing Bicycles - Esteban's Bike



Esteban Zambrano working on his bike in July 2011.  Six months later, we still hadn't discovered the real problem with this bicycle....

One bike had been in the shop for months because the coaster brake wasn't braking or accelerating properly.  This yellow BMX style bike, which belonged  to my son, Keegan, when he was young, is now assigned to Esteban Zambrano.  So, in early February, Esteban and I replaced the old coaster hub with a new one.  He happily rode off to try it out, but we both were puzzled when he started having problems before he even passed through the big doors of the shop.  This time, though, I could see that the problem wasn't with the coaster brake hub.  The pedals were moving - but the chain wasn't moving nearly as much.  Hmmm.

So, we pulled apart the one-piece (Ashtabula type) crank and bottom bracket, looking to tighten up the chain ring.  We tightened it as much as possible, and then Esteban gave the bike another test drive.  He made it out the door, but going up the hill behind the shop, the disconnect between the chain ring and the crank returned.  I was tired, it was late at that point, and we just parked the bike and went to dinner, feeling frustrated.

We took the bottom bracket apart several times


Next day, I compared Esteban's bike with another of similar (Ashtabula type) one piece crank - and finally discovered that one important component was missing on Esteban's bike.  The missing part was a stub bolt from the drive side pedal crank that passes through a hole in the chain ring.  This bolt had apparently broken off, because there was an uneven surface left on the pedal crank.  In the days before, I didn't even notice this problem....

So, I got busy with the arc welder and in a short time fashioned a new stub bolt to secure the chain ring in its position.
New stub bolt welded onto the pedal crank to secure the chain ring on Esteban Zambrano's bike, shown in the background.
On the next test drive, Esteban found that he may as well have had a new bike - the difference was astounding!

Subsequently, I did take apart the coaster brake hub that we had replaced on Esteban's bike - and found that it had a cracked brake shoe assembly.  I suspect that the resulting impaired braking action may have caused the operator (Esteban or his predecessor) to exert undo force to get the bike to stop, therefore overstressing the stub bolt and causing its failure.




Friday, February 10, 2012

Fixing bicycles - Donation


Jordan Garcia adjusting the seat on his bike - using our new Park Tools bicycle vice, which is so convenient.

Of all the work the children do in the shop, maintaining the bicycles is what most affects them directly.  You can imagine that each boy is very interested in the condition of the bicycle assigned to him.

Last December, we received a generous gift of about $500 US from a Baptist short-term team from California for bike parts to fix up the bicycles.  Last fall, with all the focus on building things for the fair and other projects, we hadn't kept up with the maintenance on the bikes, so this wonderful gift was very timely.

Felix and Juan Felipe working on Juan's bike.

Felix and I decided one strategic move we could make with the help of the donation would be to equip all the bikes for the smaller kids with coaster brake hubs on the rear wheel.  The smaller kids tend not to have sufficient grip strength nor sufficient coordination to make other braking systems work well.  Also, coaster brakes are very low maintenance, which is attractive when we have so many bikes to take care of.

Ironically, when I went shopping for coaster brake hubs in Bogotá in December, I didn't find any for sale.  The retailers said they expected a new supply to arrive in late January.  So, after I returned from my trip to the US, I tried again and was then able to purchase 6 new hubs at $31,000 pesos ($17.22 dollars) each, made by Velosteel in the Czech Republic.  These hubs are well made - using a Sachs design patented in 1904, but are different than coaster brakes commonly available in the US.

So, we began the process of replacing hubs and in some cases the rims, too, on some of the smaller bikes.  I found that the spoke pattern for a 16" diameter wheel has to be different than that on a 20" wheel, because the rim has only 24 spoke holes, instead of 36.

So, we began the process of replacing hubs and in some cases the rims, too, on some of the smaller bikes.  I found that the spoke pattern for a 16" diameter wheel has to be different than that on a 20" wheel, because the rim has only 24 spoke holes, instead of 36.

Kevin Garcia (left) and William Gomez lacing spokes on this new, aluminum, wheel for William's bike

Julian Garcia (left) and Alberto (right) working on their bikes

Julian Garcia installing the tire on the new wheel for his bicycle