Sanding a disc

[Radkow]

As you know light sanding is allowed. I was wondering what are the limits and what can be done. Can I use some coarse sandpaper on a nice smooth lat64 disc to add some texture and lower drag? I'm not trying to play with illegal discs but I'd love a premium plastic break in with baseline glide

 

[krupicka]

The point of allowing sanding is to repair dings from wear, not intentionally change the flight pattern.

 

[ThrowBot]

Back in my younger days, I would have looked up PDGA rule 801.02B:

"A disc which has been modified after production such that its original flight characteristics have been altered is illegal, excepting wear from usage during play and the moderate sanding of discs to smooth molding imperfections or scrapes. Discs excessively sanded or painted with a material of detectable thickness are illegal."

http://www.pdga.com/rules/official-rules-disc-golf/801-general/80102-discs-used-in-play

There's a little wiggle room in there, but not much. It sounds like the OP is trying to alter the original flight characteristics, which is expressly not allowed.

 

[Dr.Smooth]

Don't worry about rules unless your competing.

Sanding will help with the grip as well on some of the more modern day champion esque plastics.

Sanding will not lower drag! It will only increase it. Is it noticeable? Not at first but as you sand and sand you will ultimately alter the flight of the disc which is fine.

Keep sanding young man!

 

[BirdieMachine]

If there is flashing on the bottom edge sand that off, otherwise buy an understable disc.

 

[kerplunk]

Don't worry about rules unless your competing.

Sanding will help with the grip as well on some of the more modern day champion esque plastics.

Sanding will not lower drag! It will only increase it. Is it noticeable? Not at first but as you sand and sand you will ultimately alter the flight of the disc which is fine.

Keep sanding young man!

More drag but also more glide, I believe. So, the net effect may actually be a longer flight, depending on the disc and throw.

 

[Mulligan]

I keep some ultra fine sandpaper around for fixing issues from dings, cuts, and flashing.
You don't want or need anything coarse. Just get super fine stuff and work it a tiny bit more.
Great for flashing and for an after cleaning from any ding/cut that requires melting plastic w a lighter.

 

[ToddL]

Don't worry about rules unless your competing.

Sanding will help with the grip as well on some of the more modern day champion esque plastics.

Sanding will not lower drag! It will only increase it. Is it noticeable? Not at first but as you sand and sand you will ultimately alter the flight of the disc which is fine.

Keep sanding young man!

It'll increase friction drag but can possibly decrease pressure drag. Same thing as dimples on a golf ball. I have my doubts whether it'll be very significant on a low profile, low drag object like a disc, though.

 

[Mr. Butlertron]

Don't worry about rules unless your competing.

Sanding will help with the grip as well on some of the more modern day champion esque plastics.

Sanding will not lower drag! It will only increase it. Is it noticeable? Not at first but as you sand and sand you will ultimately alter the flight of the disc which is fine.

Keep sanding young man!

Why sand when you can file . Filing works a hell of a lot quicker than sanding. Go to a dollar store (OP) and buy a cheap file and start experimenting. You'll have the results you're looking for in no time flat

 

[PhattD]

Friction and drag are not the same thing. A rough surface will increase friction (ie it's interaction with another solid surface), but will decrease drag (resistance moving through a fluid). It's counter intuitive, but true. One of the first time the phenomena was noticed was when it was discovered that new golf balls didn't go as far used ones. It was also discovered that boats with a small amount of marine growth on the bottom would go faster. Just google it. You'll get 100's of articles explaining why a rough surface has less drag than a smooth one.

In terms of legality. The rules give specific reasons where light sanding is allowed. Reducing drag isn't one of them.

 

[tomkat]

I just completely 'de-glossed' the top and outside rim of a completely seasoned Champ Valk with light sandpaper ... seems even a bit more consistent than previous, but also seems like I am getting slightly less distance ... I only threw it once since sanding, so after I have been out a few times with it I will have a better opinion on the results ...

 

[ToddL]

Friction and drag are not the same thing. A rough surface will increase friction (ie it's interaction with another solid surface), but will decrease drag (resistance moving through a fluid). It's counter intuitive, but true. One of the first time the phenomena was noticed was when it was discovered that new golf balls didn't go as far used ones. It was also discovered that boats with a small amount of marine growth on the bottom would go faster. Just google it. You'll get 100's of articles explaining why a rough surface has less drag than a smooth one.

In terms of legality. The rules give specific reasons where light sanding is allowed. Reducing drag isn't one of them.

There are several types of drag that all add up to form total drag. Friction drag, pressure drag, wave drag, interference drag, etc.
Friction drag is pretty easy to visualize. A rough surface moving through a fluid will have more friction and more friction drag. A surface moving through a highly viscous fluid will have more friction and more friction drag. A golf ball with dimples in it will have more friction and more friction drag.
Pressure drag is a little different, and it's what PhattD is referring to. On a golf ball, adding the dimples reduces the pressure drag by more than it increases the friction drag, so there's a reduction in total drag. A disc is a more aerodynamic shape than a ball, and it doesn't have the large pressure drag initially that a sphere does. Adding dimples to a disc won't result in as significant a savings in pressure drag as adding dimples to a ball.

 

[FredV]

sanding a disc

Why sand when you can file . Filing works a hell of a lot quicker than sanding. Go to a dollar store (OP) and buy a cheap file and start experimenting. You'll have the results you're looking for in no time flat

The current rules do cause some concern: The provision about sanding is in the section that covers exceptions to the rule prohibiting modifications that alter original flight characteristics. However, light and moderate sanding of scrapes and mold imperfections are better defined as corrective measures- not per se flight altering modifications permitted under the exceptions clause. Considering sanding separately, it is clear that only the precise area of a scrape/gouge resulting from play may be treated with light or moderate sanding. Excessive sanding of any part of a disc would, by contrast, be an impermissible flight altering modification which is not otherwise covered in the theoretical provision describing acceptable corrective treatments.

As to the use of a file to treat scrapes etc.- Light and moderate use may be seen as an equivalent to light to moderate sanding. Both could well be regarded as corrective measures, not modifications that aggravate alterations of original flight characteristics. Great care would need to be used when taking a file to an injury. The current rule does not take a 360 degree look at what may be reasonable responses to a disc with undesirable changes in its condition as a result of play. Lots of things can happen to a disc during play; the current rule relates to one casualty and one treatment.

I would be prepared to defend the use of a fine file to correct a scrape or burr as not prohibited. That is, the treatment is not such that the original flight characteristics have been altered. Instead, the divergence from the original flight characteristics cause by the scrape has been reduced.