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General discussions for car and semi-truck racers.
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ragin_cajuns
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newbie

Post by ragin_cajuns »

two questions

this year is my sons first itme particpating in a pinewood derby race. when poliching the axles with fine sand paper (400 and 600 grit) should it be wet or dry?

also, if suing graphite powder on the axles to reduce friction is good would it also be good to use it on the tire surface? the part that touches the track?

thanks,
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whodathunkit
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Re: newbie

Post by whodathunkit »

:welcome: ragin_cajuns,

When I polish axles I like to have the sandpaper wet.. useing the wet dry type sanding papers.
400-600-1000-1500-2000-2500 & 3000 grit sand papers.

When useing 2 & 1 micron aluminum oxide polishing papers you can use your fav auto polish
with the polishing paper. And you'll want to skip useing the water on the mircron papers.

When using graphite powders to reduce friction on the wheels.
You'll want to polish the iner & outer hubs.. as well iner rims of the wheels.
And yes you'll even want to polish the wheel bores as best you can.

There are topics about polishing the tread surface of the wheel with graphite on DT.
Polishing this part of the wheel and running the car on an aluminum track could cause your
back wheels to brake lose at some point on the track.
Not only that this could cause your car to foul the track with a graphite trail
from the graphite coated wheels getting the car DQ.
Last edited by whodathunkit on Mon Feb 18, 2013 5:42 pm, edited 2 times in total.
What type of automobile can be spelled the same forwards & backwards?
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sporty
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Re: newbie

Post by sporty »

What is the sand paper you are using ? is it rated to be wet ? meaning can it be used wet ? not all sandpaper can.


If it is rated that you can use it as wet sand paper, then it can be used either way.

Some people do add or rubbing graphite onto the wheel treat surface, some only prefer to do the right front rail rider wheel, Do you know how to rail ride ? or what rail riding is ?

Some people do not use graphite on the surface of the wheels and some do. people also decide if its a wooden or a aluminuim track too. There our factors and reasons, why people do it.

I prefer not to have anything on the rear wheels.


Sporty
ragin_cajuns
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Re: newbie

Post by ragin_cajuns »

thanks - it is a wooden track i believe and i'm not sure what rail riding is.

speaking of sandpaper where can you find the finer grits and the aluminum oxide poliching paper? Lowes, HD and local hardwarde stores don't have them. is this somehting you cna just generally find online?

thanks,
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Re: newbie

Post by Speedster »

Welcome to DT.
The vendors servicing Pinewood Derby will have those fine grits. Auto Zone has an Assorted Pack consisting of 1000, 1500, 2000, 2500, Part # 03006. They then have a single sheet of 3000, Part # 03064. They are wet or dry except for 3000 which is wet only.
I would recommend you buy Troy Thorne's new book, "Building The Fastest PINEWOOD DERBY CAR". It will answer a lot of your questions very quickly. You can get it on Amazon. I've been told Hobby Lobby sells the book.
Best of Luck to your Racing Team.
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Ickabod
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Re: newbie

Post by Ickabod »

ragin_cajuns wrote:where can you find the finer grits and the aluminum oxide poliching paper?
I found a variety pack at Hobby Lobby that ranged from 600 to 12,000.

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Stan Pope
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Re: newbie

Post by Stan Pope »

Ickabod wrote:
ragin_cajuns wrote:where can you find the finer grits and the aluminum oxide poliching paper?
I found a variety pack at Hobby Lobby that ranged from 600 to 12,000.

Ick
Does that "pack" consist of MicroMesh? The numbers don't sound like grit. There is a nice table which translates the various nomenclatures, including the micron size, at http://www.sisweb.com/micromesh/conversion.htm and another at that was mentioned recently by someone here on DT (but I can't find it at the moment).

A couple of vender web sites, including Amazon, mention speciically Micromesh and grits from 1500 to 12000. Other's refer to Micromesh's "rating". These don't appear to be "grit" sizes.

Sisweb also has a good description of the various ilks of Micromesh and their applicaiton.
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Re: newbie

Post by rpcarpe »

I also ended up with a pack from Hobby Lobby... I just went from 'rough' to 'smooth' to polish axles. Didn't worry so much about the micron size.
My wife started a new support group... Widows of the Pinewood Derby.
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Stan Pope
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Re: newbie

Post by Stan Pope »

rpcarpe wrote:I also ended up with a pack from Hobby Lobby... I just went from 'rough' to 'smooth' to polish axles. Didn't worry so much about the micron size.
Good plan! So long as you stay with one product series, that should work fine!

If you mix MicroMesh and MicroMesh MX or mix MicroMesh and Wet/Dry, then you can't go by their rating numbers ... you need to convert to a common measure!

I printed a few copies of the Sisweb chart to leave lying about my shop, 'cause I can't remember those details!
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Shawn Stebleton
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Re: newbie

Post by Shawn Stebleton »

We go from 600 through 1000, 1500, and 2000 wet/dry sandpaper, then follow up with an assortment from K&S. Their micro assorted sanding film (plastic-backed) includes:
44 micron silicon carbide
23 micron aluminum oxide
8 micron silicon carbide
1.5 micron cerium oxide
0.5 micron chromium oxide

It makes a nice progression from rough to smooth. We didn't worry about micron size, either. Just went by feel. When showing my younger son the sandpaper and sanding film his first year, when he got to feeling the 0.5 micron chromium oxide he remarked "that's almost like paper!"

Since we don't have a drill press, I hold the portable drill steady while he does the work moving the paper back and forth along the shaft. I taught him how to wet the paper before applying it to the axle. I also taught him WHY. He doesn't like doing the sanding (it's "dirty"), but knows that the better it is polished, the better his car will perform.

I have an 8x lupe that helps in seeing scratches. He likes looking through it, comparing an untouched axle to what he has done so far on the one he is working on at the time. He likes the shine at the end, because he knows it can go fast!

[Edit: fixed names of grit material]
Last edited by Shawn Stebleton on Wed Feb 20, 2013 10:42 am, edited 1 time in total.
Shawn
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Stan Pope
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Re: newbie

Post by Stan Pope »

Shawn,

Check the sandpapers. It appears that you may have a significant overlap, since the 44 micron stuff would have a CAMI grit number between 240 and 320! Reference http://en.wikipedia.org/wiki/Sandpaper#Grit_size_table
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Shawn Stebleton
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Re: newbie

Post by Shawn Stebleton »

Stan Pope wrote:Check the sandpapers.
Hmmm... I will.

Going by "feel" only, there is a natural progression of roughness to smoothness. The roughest of the 5 in the K&S set "seems" a good bit smoother than the 2000 grit wet/dry.

The numbers I quoted above were from an online supplier that has the same kit. Mine is mis-marked with the 44 micron item listed as 23 micron (i.e. it lists two different formulations of the same grade of sanding sheet). I purchased mine at a store local to a relative's house in Michigan that specializes in miniature figurines, and it may be their label on the bag. I purchased it about 6 years ago.

If we can skip several of the overlap steps, my son would be happy. I'll have to try polishing a raw axle with 600 grit wet/dry and another one with what is listed as 44 micron and see which has worse scratches left over. Now I have a good use for the reject nails!

Thanks for the heads up on it.
Shawn
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