Less is More? Polishing Too Much

[picard1963]

Hey everyone.......first time posting so please forgive any posting faux pas.

I am having a debate with a buddy. Can an axle be TOO polished? There is the notion that a rougher axle prep (say at 400g or 600g) would hold graphite better and perhaps allow for a "smoothing" over those "Rocky Mountian" sized scratches (relatively).

By the way, just got Doc Jobe's BGB.......am looking forward to reading that and this forum. Got two more years to figure this out!

[sporty]

Well, Like anywhere you go, there is always a range of thoughts and views and opinions on jsut about anything and everything.

I personally feel 1 micron is the place to be. better, does not hurt in my 2 cents of of the world.

However, this also, has to replace to how you prep your wheel bores also.

There is a few ways to prep your wheel bores and still have some good speed and good results.

And so, with that in view of everything. The axle polish process may differ, depending on your bore prep process is.

There is a link between those two.

But I dont think I would ever go less than 2 micron.

Now you might ask what is micron ? well many MFG of sand paper, all range differently in grits. meaning you might buy a piece, that says 600 grit or 5,000 grit.

But the key is to focus on what the micron rating is, thats the standard rating to look for and know !



Hope this helps.

Sporty

[picard1963]

Thanks Sporty! Lets just say for discussion that the bores are polished and burnished accordig to Jobe.

My buddy and I have had experiences with just roughing in some axles for some practice, say to 600 grit. Pour the graphite to 'em, burnish a bit (spin, spin, spin or hurry up with a Dremel). These practices were more for alignment than final prep.

BUT! The run times were pretty danged good! In our debate, I contend that "it wont last for an actual full-blpwn race" because the coating will give way and the scratches will come through.......then quick deterioration, maybe even bore damage.

[picard1963]

Also, being a newb to the site, if I'm in the wrong area or haven't done due diligence in searching posts, please feel free to let me know!

Thannks!

[sporty]

ya you in the wrong area, but its okay. but in the future,

General Car/Truck Racer Topics or


Car & Semi-Truck Construction


And, well I have not tried doc jobes stuff in years. So not of much help.

But I would not go less than 1 micron.

Im taking a guess here, and just a guess. but sounds like that might be around 3 micron that you are refering too.

Sporty

[picard1963]

sporty......didn't know how to point to previous post. But thanks for getting me down to 1 micron.

I still wonder about the "grabby" nature of anything more "rough". I was looking at: http://www.fastpinewoodderbytips.com/pi ... rby-axles/" target="_blank (not meaning to tout any product).

Thanks!

Picard1963

[FatSebastian]

Can an axle be TOO polished?

If it helps, that was also discussed briefly in this old topic.

BUT! The run times were pretty danged good!

Better than a finer polish? Have you tried a controlled experiment in "unpolishing"?

[gpraceman]

Also, being a newb to the site, if I'm in the wrong area or haven't done due diligence in searching posts, please feel free to let me know!

Please only post your question in one forum, not multiple.

[picard1963]

Can an axle be TOO polished?

If it helps, that was also discussed briefly in this old topic.

BUT! The run times were pretty danged good!

Better than a finer polish? Have you tried a controlled experiment in "unpolishing"?

FS, if you mean have we tried prepping various "polish grades" similarly with graphite and then comparing speeds, no. My friend and I were just having a friendly debate. We were both surprised at a week-before-actual, "prep-race" where his car was performing better than expected with just a cursory axle treatment at 400 grit.

(Here's hoping I did this quote thing right......I'm way better at pinewood derby skills than I am at posting skills)

[picard1963]

Sorry Randy! First time post ever........just wanted to get in the right spot.

[Stan Pope]

FWIW, 600 Grit (US) is about 15 micron, same as Micromesh MX 240.
One fellow recommends 1000 grit as "the happy spot for graphite". 1000 grit is about 11 microns. (11 microns is about half a thousandth of an inch, which is about the same setting capability as you would get on an inexpensive hobby lathe such as the Harbor Freight 7"X10" Lathe.)

I don't have an opinion (yet) on where the grahite "happy spot" really is, taking into consideration how many runs will still get near best performance and how rapidly the bore will deteriorate.

I think that 15 micron is a good stepping stone toward 2 microns:
30 micron: Micromesh MX 180
15 micron: Micromesh MX 240
8 micron: Micromesh MX 400
4 micron: Micromesh MX 800
2 micron: Micromesh 12000

I think that I recall reading that dividing the measure by 2 to get the next step is "good practice."

[picard1963]

FWIW, 600 Grit (US) is about 15 micron, same as Micromesh MX 240.

I think that 15 micron is a good stepping stone toward 2 microns, all using Micromesh:
30 micron: MX 180
15 micron: MX 240
8 micron: MX 400
4 micron: MX 800
2 micron: 12000

Thanks Stan! I recognize most of those grits/back# from an old kit another "crossed-over" friend of mine left me. It stopped at MX1200 (3 micron).

So, I assume that, after seeing FS's, Sporty's and now your replies (and doing some more self-help reading here on DT), there is a general "concensus" that axles most likely need to be VERY polished (as opposed to "rougher-to-hold-more-graphite").

And I've also now read enough to know that I need to understand the "whole car" so I don't take any of this of context (Sporty's perspective: whatever works for you, but here's what's worked for me; and Sebastian's "call for data" with some very helpful linkage.....love the Thorne 2013 version btw).

Love the site and the fact you guys are willing to help folks out!

Thanks!

[Stan Pope]

Note that while you were replying, I was editing, so my prior post changed since you replied!

IIRC, the MX series from Micro Mesh is intended for metals whereas "Regular Micro Mesh", e.g. 12000 (2 micron) is intended for plastics. Regular Micro Mesh does seem to work with metal, but may wear more quickly! We will see some pics from Brady in a few days that should show some comparisons between MX and Regular.

[sporty]

I use the regular micro mesh and I have some of the MX.

The MX does work better for metal, but poorer for plastic.

Now, there is something stand left out. That I have mentioned before.

the 12,000 regular micro mesh, wears to 1 micron. even tho rated at 2 micron, it will wear and to 1 micron. And typically it does not take long to get to the 1 micron rating.

Thats why i most often will call 12,000 grit 1 micron. I did testing to also prove that it went to 1 micron.

I have used sub micron, strips and powders and polishes. and at one time your standard automotive wet sand paper and grits.

The reason I say these days, what works for you. because as I mentioned, your prepping process is going to be connected to your bore prep proccess.

So some can get away with less prep on the axles.

The ultimate feeling tho here from me. Is 1 micron is the way to go on the axles.

Keep in mind plastic is softer then metal, so wear is going to happen in the wheel bore first.

It could also be a factor of why this friend or so forth, or you find it fast for a few runs, then it slows.

And I'm not sure what fast is to you ? every track and timer seem to be different enough its hard to compare times.

But the gold standard sue to be for graphite, sub 3.0 on a 42 foot best track was fast !

Sporty

[firstplaceloser]

Hey guys, I am the friend picard1963 was referring to in this post. I didn't get a chance to post yesterday and it seems you guys have covered the topic pretty thoroughly. I just wanted to give some insight on what we did and the results I saw. At the test day we didn't have the race day axles ready, so we quickly cut a set of Revell axles with 400, 600 polished them and used the raw wheels. Then we dusted them regular powder graphite. Put them in the car and ran it. We turned the fastest times that day, not to mention faster than the 1st and 2nd place winners at the district race the next week. We thought the times were fast so we figured, hey the race day axles and wheels (which is, too be short, axles to 3000 grit then polished and wheels bores polished then graphite coated) will be even faster. WRONG! We got smoked! Now I know there are many multiple factors in play such as the other cars were faster than test day, we didn't do something properly during the prep process, yada, yada, yada. But what brought the question to mind is I know the other cars axles weren't prepped to the degree, meaning to the fine grit sandpaper, like mine or picards were and they beat us. Also that the test day axles were faster, which lead to this debate.

Although you guys have seemed to convinced me otherwise now. I think I will go with sporty's prep method and put my mind to rest...

First post, I hope I did it right. I have some more questions but they are off topic so I will start new thread on those. Thank you guys for the help.