4 oz tungsten round?

[whodathunkit]

Hmmm... My understanding was that best time was found with a compromise between those two conflicting requirements.

Nothing can be sliced so thin that it doesn't have two sides.
Thanks Sporty & Stan.

[Stan Pope]

You should be able to get tungsten welding rod in the right size. Hard to cut but possible with proper tools.

The small stuff, like 1/8" dia, is very brittle. It breaks easily when held in a vice and hit with a hammer. The break is not well controlled and, if not restrained, the pieces broken off will fly across the room. I slipped a length of latex tubing over the free end to keep mine from flying off!

1/2" dia rod would need a much bigger vice and hammer and tube, I think!

And small rounds are not a satisfactory solution, since their packing density isn't very good!

[sporty]

... And thanks Stan for the breakdown.
...

You're welcome.

Sporty, I'll blank out that post if you wish. Let 'em figure it out for themselves???

No, Stan, thanks for doing it.


I'm retired, I doubt I'll ever build another car. If I do, it will only be a grand kid, or a little guy or girl who would ask for help.

The cubes do weight 4oz though, 24 of them.

I usually have a tad bit of weight on the top for fine tuning and adjustment. Those were old pictures though.

Sporty

[Stan Pope]

... And thanks Stan for the breakdown.
...

No, Stan, thanks for doing it.

Just a few minutes spent using http://www.stanpope.net/cmcomput.htm, building up piece by piece. The 0.24 and 1.96 oz numbers based on weighings of "similar parts" here. My grandson and his daddy weighed them carefully for me! But recognizing that "similar" is not "exact", I identified the numbers as "approximate!"

I usually have a tad bit of weight on the top for fine tuning and adjustment. Those were old pictures though.

Thought I saw a trim weight under the rear axle area???

[Nate]

Thanks for the advice guys!

So Sporty, what you're saying is that you've the COM being lower is way more important than it being concentrated? That makes sense.

I think I'll attempt that weighting style this time around, with a couple modifications to the body. I ordered about ten yards of 3/8" carbon fiber tube for another project last year, and still have some left. I should be able to get a tad less mass in the front end by using that as a mid section without sacrificing stiffness.

Out of curiosity, what size cubes are you guys using, Sporty & pwrdbytungsten?

Stan, that's a sweet little web tool!

[Stan Pope]

Thanks for the advice guys!

So Sporty, what you're saying is that you've the COM being lower is way more important than it being concentrated? That makes sense.

I think I'll attempt that weighting style this time around, with a couple modifications to the body. I ordered about ten yards of 3/8" carbon fiber tube for another project last year, and still have some left. I should be able to get a tad less mass in the front end by using that as a mid section without sacrificing stiffness.

Out of curiosity, what size cubes are you guys using, Sporty & pwrdbytungsten?

Stan, that's a sweet little web tool!

Thank you.

The carbon fiber is probably more work and risk than worth.

The cubes are 1/4". Smaller cubes are available, but are probably less useful in an extended wheelbase design.

[Nate]

1/4" cubes. Excellent.

I've used carbon fiber before and have a method developed with little to no construction failure risk. Basically, you dril a hole through the body from the front, then remove material around the rod while the block is still whole. Epoxy the carbon fiber tube in place. Drill for axles (the axles may protrude into the tube, no big deal), weights, and whatever else you need square while you still have the large square surfaces to reference. Then remove the remaining wood in the body area, and shape where needed. Boom, you have a square, solid, body with all sections made from ideal materials.

[Stan Pope]

I've used carbon fiber before and have a method developed with little to no construction failure risk.

Cool!

[sporty]

The lead sheeting, is what I use on top of the car and just clear tape over it. I sometimes use tungsten putty also. and clear tape over that also. It depends. But nothing under the car. smooth and covered with the monokote.

I have noticed for awhile the cubes verying in weight, or bigger than 1/4, as to what they claim they are selling.

The best 1/4 tungsten cubes I ever got were from max-v a few years ago. but seems the next year and after they were not the same, a tad bigger or something. and no they were not the 1/8th cubes. I them also.

But it could have been 3.96 oz. with .04 of glue. lol

[Stan Pope]

You're right, Sporty! The trim weight was on top... in pic IMG_0752.jpg! And the reflections I think I see would probably be the clear tape! (I was writing from what I was remembering and didn't go back to check that detail. Sorry!)

Current batch of MaxV cubes seem well behaved. Consistent weight to 2 decimal places, and less than 1% variance in size dimensions. Individually they weighed in at 0.16 oz. and groups of 6 came in at 0.96 oz. All in all, better than I expected. I'll reweigh the 12 cube assemblies after they have been glued together. Then all that will be left unaccounted for is the epoxy that holds the cubes in the car and the decorations.

I think Grandson likes not having to beat on more lead for this car ... although his opinion might change if I brought in my grandfather's anvil for him to use. The rascal weighs about as much as I do, so would not be an easy job. Maybe I should take Grandson over to where the anvil is stored!

[rpcarpe]

Although not ideal, I did make 4oz LEAD rounds this year. Used a 1 1/4" forstner bit to drill out some close grained wood. Poured in molten lead and waited. The cooled round ended up about 3/4" in height. Drilled a 1 1/4" pocket in the rear of the car, just over the axle and glued in the weight. Got one Pack champ with that design.

[Nate]

That works if you've got a thicker car.
What also works great (and I had to do with the OP design) was melt it into a brass tube. If I'd melted it into the pine it would have incinerated the < 1/32" thickness of pine remaining.

If you want a round, it needs to be about 1.75" long and 5/8" diameter for just over 3.5 oz.
A really nice weight/dimensions calculator that does lead, brass, steel, tungsten, etc:
http://www.matweb.com/tools/weightcalculator.aspx" target="_blank