tight grain or wide grain block

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
User avatar
davet
Master Pine Head
Master Pine Head
Posts: 539
Joined: Wed Jan 16, 2013 1:33 am
Location: MN

tight grain or wide grain block

Post by davet »

Which is better when choosing between 2 BSA blocks. Grain that is closer together or further apart? We'll be drilling our own axle holes. Thanks.
BallBoy
Master Pine Head
Master Pine Head
Posts: 196
Joined: Sat Jan 08, 2011 8:46 pm
Location: SoJo, UT
Contact:

Re: tight grain or wide grain block

Post by BallBoy »

A block with grain close together (tight grain) will weigh more than a block with the grain farther apart. The growth rings are harder than the wood between the rings. A block with grain farther apart (loose grain) will weigh less than a tight-grained block. It will also be much easier to drill, cut and shape. Whether you choose a tight- or loose-grained block go with vertical grain. Tight-grained wood with vertical grain is much more dimensionally stable (less prone to warp or twist) than other cuts of wood. If the grain isn't vertical then the grain is more likely to make your drill bit wander.
User avatar
davet
Master Pine Head
Master Pine Head
Posts: 539
Joined: Wed Jan 16, 2013 1:33 am
Location: MN

Re: tight grain or wide grain block

Post by davet »

Thanks. Not sure I've ever seen a block with the grain running vertical. I've only seen ones with grain running front to rear. Is that what you mean?
BallBoy
Master Pine Head
Master Pine Head
Posts: 196
Joined: Sat Jan 08, 2011 8:46 pm
Location: SoJo, UT
Contact:

Re: tight grain or wide grain block

Post by BallBoy »

davet wrote:Thanks. Not sure I've ever seen a block with the grain running vertical. I've only seen ones with grain running front to rear. Is that what you mean?
I'm talking about the end grain - what you see when you look at either the front or back of the block. This post has a picture of some blocks with vertical grain.
User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3344
Joined: Sun Feb 13, 2005 1:00 am
Location: rockfalls, Illinois

Re: tight grain or wide grain block

Post by sporty »

I did a topic post awhile ago on here about wood grain.

Tight grain is heavier, I like it for my thin cars, its stronger.

The wider grain is lighter and seeker. I don't like to use it for super thin cars.

But it's ideal for many people who make thicker cars.


The tighter grain wood aside from thin cars being ideal. It flexes less, when very thin.

Naturally the lines should run the length of 7 inches as straight as possible.
Viewing the lines, if you were looking at the top of the car.

There's a views posts here with pictures and examples.
User avatar
davet
Master Pine Head
Master Pine Head
Posts: 539
Joined: Wed Jan 16, 2013 1:33 am
Location: MN

Re: tight grain or wide grain block

Post by davet »

BallBoy wrote:
davet wrote:Thanks. Not sure I've ever seen a block with the grain running vertical. I've only seen ones with grain running front to rear. Is that what you mean?
I'm talking about the end grain - what you see when you look at either the front or back of the block. This post has a picture of some blocks with vertical grain.
a-ha. Now I see. Now I'm curious to see what I have when I get home.

As an aside, when my boy was building a Raingutter Regatta boat we had 2 wood floats in the kit. One weighed twice what the other weighed. We went to the Scout Shop and weighed every boat kit they had. Just put th entire box right on the scale. We took the 2nd lightest one. The lightest kit was actually missing the wood floats. Might work for derby cars also.
User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 12:37 pm
Location: Bellevue, WA

Re: tight grain or wide grain block

Post by Noskills »

Davet
I weight the whole box as you suggest. Boxes are about 4.5 to 5.9 oz. I take the lightest and pass out the rest when I can.
Noskills
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
User avatar
Vitamin K
Pine Head Legend
Pine Head Legend
Posts: 1249
Joined: Sat Apr 20, 2013 7:26 pm
Location: Spotsylvania, VA

Re: tight grain or wide grain block

Post by Vitamin K »

I just can't see myself weighing boxes. I just couldn't weather the kind of looks I'd get. :sweating:

I think if really needed to drop more weight from a 1/4" thick chassis, I'd cut out sections and put in balsa inserts.
Noskills wrote:Davet
I weight the whole box as you suggest. Boxes are about 4.5 to 5.9 oz. I take the lightest and pass out the rest when I can.
Noskills
User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 12:37 pm
Location: Bellevue, WA

Re: tight grain or wide grain block

Post by Noskills »

Vit K,
As the cubmaster I have 2 cases of kits to weigh in the privacy of my own garage. ;)
It's good to be the cubmaster.
Noskills
"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite
User avatar
Vitamin K
Pine Head Legend
Pine Head Legend
Posts: 1249
Joined: Sat Apr 20, 2013 7:26 pm
Location: Spotsylvania, VA

Re: tight grain or wide grain block

Post by Vitamin K »

Well, given the amount of work required to be Cubmaster, that sounds like a fair trade...
Noskills wrote:Vit K,
As the cubmaster I have 2 cases of kits to weigh in the privacy of my own garage. ;)
It's good to be the cubmaster.
Noskills
User avatar
davet
Master Pine Head
Master Pine Head
Posts: 539
Joined: Wed Jan 16, 2013 1:33 am
Location: MN

Re: tight grain or wide grain block

Post by davet »

Vitamin K wrote:I just can't see myself weighing boxes. I just couldn't weather the kind of looks I'd get. :sweating:

I think if really needed to drop more weight from a 1/4" thick chassis, I'd cut out sections and put in balsa inserts.
Noskills wrote:Davet
I weight the whole box as you suggest. Boxes are about 4.5 to 5.9 oz. I take the lightest and pass out the rest when I can.
Noskills

Just think about it. You may be racing a guy that DID weigh the boxes, took the lightest one then cut out the middle and installed Balsa inserts. :wall:
User avatar
FatSebastian
Pine Head Legend
Pine Head Legend
Posts: 2804
Joined: Wed Jun 17, 2009 2:49 pm
Location: Boogerton, PA

Re: tight grain or wide grain block

Post by FatSebastian »

BallBoy wrote:A block with grain close together (tight grain) will weigh more than a block with the grain farther apart.
Sounds plausible, yet I was unable to affirm a definite correlation between block weight and grain density. Perhaps others have better data?

Maybe just as important is the orientation of the grain, about which the scale reveals nothing. :(

A highly competitive car will usually have a small fraction of the original block contributing to the final weight of the car regardless.
User avatar
sporty
Pine Head Legend
Pine Head Legend
Posts: 3344
Joined: Sun Feb 13, 2005 1:00 am
Location: rockfalls, Illinois

Re: tight grain or wide grain block

Post by sporty »

Maybe this will help some,


ive build over 250 cars, I stopped keeping count after that.


The kits, sometimes, very in types of pine, and quality.


I think when building 1/4 thick cars or thinner, The heavier denser wood, flexes less and is more stronger, this is due to tighter grains.

The lighter wood, with less wood grain lines, is lighter but weaker, at that 1/4 or less thickness. Ive had cars break !

If you are doing a bigger size car, then the lighter wood is fine, if you are going for a thin 1/4 thick or less car, even with balsa filled in the gaps. I recommend the heaver wood.

But keep in mind, the grain lines, is really what to look for, that provides the strength for the wood to be thinner, and not flex and super thin sizes.

I recall the silly years, back when we first started learning, baking blocks, ect. oh brother. The silly things you think you should do or try.

I mention the grain lines, because, I have seen heavy bsa wood out of the box, that had bad grain lines or little grain lines. but it was a different pine or something and was very heavy. but when I tried it, and cut it to 1/4 thick and then thinner yet. after about th 3rd stop section hit, it broke !

Another option, was using a thin coat of epoxy over the wood, to help give it strength. I did this for a bit, then realized the weight I was adding to resolve this strength issue, was costing me on heavier wood.

I like to be around 10 grams. and I didn't paint those cars, light r/c thin monokote. so I was using 4 oz of weight, tungsten cubes and then some tungsten putty.

And a added bonus, all this buried in old posts here.

1, 1/4 cube of tungsten, placed differently will change the track times some. minor about. two cubes. to me is a factor. so when you start giving up 2 or even 3 cubes, that's a loss of speed, over having that weight in the sweet spot areas.

Image below, ideal grain lines.


Image

this looks to be 10 to 11 grain lines, I have used wood with 16 grain lines in it. 9 to 12 grain lines like the picture shows, how it runs down the wood. seems to be about what I more often find in many of the kits, after picking thru batches of them. Id buy 10 or 12 kits at a time, then I went to max xv, buying full blocks. I get two cars out of 1 full block. Well I have bought wood from many, but max-v, seems to have the best wood blocks in my mind.
Sporty
User avatar
davet
Master Pine Head
Master Pine Head
Posts: 539
Joined: Wed Jan 16, 2013 1:33 am
Location: MN

Re: tight grain or wide grain block

Post by davet »

Very good info. I hadn't even considered picking a grain that would better suit a thin car. Prior to our first race last year I was pretty nervous that it might break. I don't know what kind of grain it had but we took it down even further as we progressed onto Council. For the Council race we had taken enough off that it now had a little flex when I twisted by hand. I think we went as thin as we could go. The middle was cut out too. I bought 4 blocks from Max V. 2 are very wide grain and 2 are very tight. Thank you very much guys!
BallBoy
Master Pine Head
Master Pine Head
Posts: 196
Joined: Sat Jan 08, 2011 8:46 pm
Location: SoJo, UT
Contact:

Re: tight grain or wide grain block

Post by BallBoy »

FatSebastian wrote:
BallBoy wrote:A block with grain close together (tight grain) will weigh more than a block with the grain farther apart.
Sounds plausible, yet I was unable to affirm a definite correlation between block weight and grain density. Perhaps others have better data?
I think the phrase "will weigh more" was overstating reality. The growth rings (wood grain) are more dense than the wood between the rings. Greater density = greater mass = more weight than the same object with less density. There are a lot of variables that go into a pine tree growing (e.g. soil, wind, climate) which affect the lumber that comes from any given tree. Two trees that have radically different growing properties can produce similar looking lumber with condsiderably different weights. A rule of thumb is that tighter grain = heavier lumber.
Post Reply