The Firing Line Forums help bp guys
 Forum Rules Firearms Safety Firearms Photos Links Library Lost Password Email Changes
 Register FAQ Calendar Search Today's Posts Mark Forums Read

 April 1, 2008, 03:29 PM #1 hillbille Senior Member   Join Date: March 4, 2008 Location: west virginia Posts: 220 help bp guys heres one to scratch your head on. my son is in the pinewood derby thing, those wooden little cars, anyway the car can only weigh 200 grams, I was going to use 490 round balls I made for my 50 cal.. thing is how many grains(490gr) is there in a gram. I'm going to drill hole in the wood to put balls in what I need to know is how many balls to add. bottom line is how many grams does a 490 round ball weigh?
 April 1, 2008, 03:53 PM #2 grymster2007 Senior Member   Join Date: May 22, 2007 Location: In the oak studded hills near Napa Posts: 2,203 15.43 grains per gram 490 grains = 31.75 grams __________________ grym
 April 1, 2008, 04:01 PM #3 hillbille Senior Member   Join Date: March 4, 2008 Location: west virginia Posts: 220 grymster one more please, is a 490 ball 490grains or 490 cal.?
 April 1, 2008, 04:18 PM #4 mykeal Senior Member   Join Date: October 8, 2006 Location: Northern Michigan Posts: 2,772 A .490 ball is 0.490 inches in diameter, or 49 caliber. Pure lead weighs 11.34 grams/cubic centimeter. The volume of a round ball 0.490 inches in diameter is 8.0756 cubic centimeters. Thus a .490 round ball weighs 91.58 grams. I think.
 April 1, 2008, 04:22 PM #5 Jim Dandy Member   Join Date: November 23, 2002 Posts: 39 Bookmark this: http://www.onlineconversion.com
April 1, 2008, 04:25 PM   #6
Jim Dandy
Member

Join Date: November 23, 2002
Posts: 39
Quote:
 Originally Posted by mykeal Pure lead weighs 11.34 grams/cubic centimeter.
No, the DENSITY of lead is approximately 11.34 g/cm^3.

Quote:
 Originally Posted by mykeal The volume of a round ball 0.490 inches in diameter is 8.0756 cubic centimeters. Thus a .490 round ball weighs 91.58 grams.
No, the volume of a 0.490" round ball -- (4*PI*r^3)/3 -- is 0.061600872 cubic inches. This is equal to 1.009457431919808 cubic centimeters. We'll call it approximately 1 cubic centimeter for this application.

A sphere with a volume of 1.0 cubic centimeter and a density of 11.34 grams per cubic centimeter has a mass of 11.34 grams. (Weight is about 0.11 Newtons.) This works out to about 0.025 pounds or 0.40 ounces or 175 grains. Check your scale and see.

 April 1, 2008, 04:32 PM #7 hillbille Senior Member   Join Date: March 4, 2008 Location: west virginia Posts: 220 mykeal don't know where you got that but thanks for the info I was going to go with about 7-9 but with what you say it is closer to 2. but thanks for the quick response and answers.
 April 1, 2008, 04:42 PM #8 grymster2007 Senior Member   Join Date: May 22, 2007 Location: In the oak studded hills near Napa Posts: 2,203 volume of 1.2246 cm sphere = 1.0095 cm3 specific gravity cast lead = 11.35 11.35 * 1.0095 = 11.457 grams 11.457 grams * 15.43 = 177 grains I think! Jim Dandy gave the answer while my pea brain was still smoking through the question! __________________ grym Last edited by grymster2007; April 1, 2008 at 04:43 PM. Reason: slow
April 1, 2008, 04:45 PM   #9
Jim Dandy
Member

Join Date: November 23, 2002
Posts: 39
Quote:
 Originally Posted by hillbille mykeal don't know where you got that but thanks for the info I was going to go with about 7-9 but with what you say it is closer to 2.
Uh, you better check those numbers again. The figures grymster2007 and I have provided are consistent with what Speer says their 0.490" round balls weigh: http://www.speer-bullets.com/default...1=3&s2=7&s3=23

 April 1, 2008, 05:30 PM #10 mykeal Senior Member   Join Date: October 8, 2006 Location: Northern Michigan Posts: 2,772 Jim Dandy and grymster2007 are right. It is density (I knew that; my fingers didn't), and I still can't figure out how I got that first number. Pushed the wrong button somewhere.
 April 1, 2008, 05:34 PM #11 Hawg Senior Member   Join Date: September 8, 2007 Location: Mississippi Posts: 14,049 At least I'm not the only one that makes mistakes.
 April 1, 2008, 05:37 PM #12 Ricklin Senior Member   Join Date: February 22, 2008 Location: North Orygun Coast Posts: 934 If you are not making mistakes, you are not doing anything. __________________ ricklin Freedom is not free
 April 1, 2008, 06:17 PM #13 hillbille Senior Member   Join Date: March 4, 2008 Location: west virginia Posts: 220 ok so you are saying it is roughly11 1/2 grams, per 490 ball. which is back to the 7-10 range with the wood.
April 1, 2008, 07:49 PM   #14
Jim Dandy
Member

Join Date: November 23, 2002
Posts: 39
Quote:
 Originally Posted by mykeal Jim Dandy and grymster2007 are right. It is density (I knew that; my fingers didn't), and I still can't figure out how I got that first number. Pushed the wrong button somewhere.
We all have our moments. Hell, I had to figure and refigure to make up my mind I was right.

April 1, 2008, 07:51 PM   #15
Jim Dandy
Member

Join Date: November 23, 2002
Posts: 39
Quote:
 Originally Posted by hillbille ok so you are saying it is roughly11 1/2 grams, per 490 ball. which is back to the 7-10 range with the wood.
Yes, the 0.490" balls are roughly 11.5 grams. However, you didn't state what the wood weighs.

 April 1, 2008, 08:10 PM #16 Jim Dandy Member   Join Date: November 23, 2002 Posts: 39 FYI: I just went and weighed five (5) Hornady 0.490" balls on my Pact electronic scale; 178 grains, 177.2 grains, 177.6 grains, 177.5 grains, and 177.2 grains. This works out to an average weight of 177.5 grains or 0.025357142 pounds. My calculator says this is equivalent to 0.011501806 kg -- 11.5 grams.
 April 2, 2008, 04:13 PM #17 grymster2007 Senior Member   Join Date: May 22, 2007 Location: In the oak studded hills near Napa Posts: 2,203 Before I could remember the formula for volume of a sphere (4/3piRcubed), I used a rough approximation of 52.5% of the volume of a cube with a side length the same as the sphere diameter. Don't really know how I could remember that and not the simple formula!!! So how's the car coming hillbille? __________________ grym
 April 2, 2008, 05:46 PM #18 hillbille Senior Member   Join Date: March 4, 2008 Location: west virginia Posts: 220 six and one half balls put us just over weight. The balls took up to much space I drilled a 1/2 inch hole which the 490 ball just fit in but we could only get3-3 1/2 balls in, so I melted them poured them down the hole got not quite 6 1/2 in melted. all we need is paint then weigh it again with wheels and all on, if we are over i figured i could drill a small bit of lead out of hole. He has lost 2 years running but I let him do almost all the building and sanding, painting ect. some of these cars you can tell the parents did it all I know the kids probubly were'nt even in the same room. I think he has more fun building than winning, and thats what its all about, he is a good loser, something hard to come by in kids anymore. thanks for all the help from everyone.
 April 3, 2008, 12:28 AM #19 arcticap Senior Member   Join Date: March 15, 2005 Location: Central Connecticut Posts: 2,973 I remember when we built our pinewood derby car, there was a package of 2 pre-cast weights that were sold separately as an option for the car kit. I think that we had to drill the holes so we could choose where to place them. These weights were a little larger in diameter than a pencil and maybe 2 inches or so long, and they were designed to just epoxy in while keeping the car under the weight limit. We ended up putting powdered graphite on the axles which really helped!
 April 4, 2008, 08:17 PM #20 scrat Senior Member   Join Date: February 21, 2008 Posts: 214 i remeber that when i was a kid. use to use graphite on the wheels worked really good.
 April 5, 2008, 12:18 AM #21 shortwave Senior Member   Join Date: December 17, 2007 Location: SOUTHEAST, OHIO Posts: 5,950 polished the nails used for axles, kept working graphite into wheel by spinning each wheel on axle while pouring on graphite, smoothing out all the rough edges. just think hillbille , in a few years that boy will be tuning up your guns

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Hogan's Alley     Tactics and Training     Handguns: The Semi-automatic Forum     Handguns: The Revolver Forum     Handguns: General Handgun Forum The Hide     The Art of the Rifle: Bolt, Lever, and Pump Action     The Art of the Rifle: Semi-automatics     The Art of the Rifle: General     The Dave McCracken Memorial Shotgun Forum     NFA Guns and Gear     The Hunt The North Corral     Lock and Load: Live Fire Exercises     Competition Shooting     Curios and Relics     Black Powder and Cowboy Action Shooting The Skunkworks     Gear and Accessories     The Smithy     Handloading, Reloading, and Bullet Casting         Bullet Casting     The Harley Nolden Memorial Institute for Firearms Research The Conference Center     General Discussion Forum         TFL Photo Contest     Law and Civil Rights         Legal and Political     S.W.A.T. Magazine The Firing Line Gun Show     S.W.A.T. Exchange     Retail Deals and Feedback Forum Support     Site Questions and Tech Support (NO FIREARMS QUESTIONS)     Software and Function Testing

All times are GMT -5. The time now is 06:56 AM.

 -- vBulletin 3 ---- vBulletin 3 - variable fonts ---- Low profile (unsupported) Forum Home Page - Archive - Top