Block Sanding...

[DocJr]

Hello All,

Some of you may have seen some of my sketches in other parts of the forum, thanks to any compliments I have received.

Even though I don't "Build" cars, I do however build models. Now, don't take that the wrong way, I'm not by all means a "Model Builder" haha

When I was in school (Graduated with a Bachelor's in Industrial Design) I had started a model of my grad project which is a 2014 Ford Starliner. She's done 1/5 scale, about 32 inches long. I started the build using a clay model, time constraints were tight, it wasn't at the quality I wanted it to be, but I had to get it moulded and 'glassed. Now what I have (and what I graduated with) is a 32 inch model that needs a lot of bondo work.

Here's my question...What makes a good sanding block/board? Obviously I could go all out and buy Durablock's 95 dollar kit..but I don't think so..it just doesn't add up, that would be like buying a 6 figure block for a 6 figure build haha. I mean..don't get me wrong, I will if I have to (or at least buy a used one). But is there anything "Laying around" that I could use?

For smaller models, maybe 8-12 inches long, I was taught to use a pink pearl eraser...PERFECT for the size. But the eraser is too small for the larger surfaces on my model. I think I want something 4-7 inches long. I have also used pink foam (Like owens corning insulation) but that tends to "wear" and ends up ruining the panel I'm working on...

Any suggestions? And thanks a lot!

Nelson

[LSx_88_Ciera]

paint stir stick is one of the best blocks on the cheap especially when working small areas.

[wiedemab]

I would agree that a paint stick works pretty well on small areas. I've used dowel rods in certain instances too.

I'm trying to picture 1/5 scale....... You are probably going to need some small blocks.

Dad and I talked to Dave Lane and he cuts pieces of plexiglass/lexan to shape for odd areas so that he could get them smooth and flat for final wet sand and buff.

Good luck - - - a lot of it is just being creative and finding anything that will work.

[DocJr]

Thanks for the input guys, though I'm a little confused. The items you guys mentioned are hard objects... objects that will facet the body work, the sanding blocks need to "Give" a little to wrap the contours, am I correct?

But yea, I guess I should think more outside the box and try anything lol or just look for a few used ones, or go buy a cheapo somewhere.

Thanks
Nelson

[LSx_88_Ciera]

A block for removing highs and lows needs to be rigid if it is flexible it will just follow the uneven surface. You need a flexible block for finish sanding not shaping.

[LSx_88_Ciera]

Technique is also very important it is best to work with the block perpendicular to the large radius of the panel and work at angles 30-45°.
Here is an image to explain what I mean. The hood may be contradictory so I will explain in the front the large radius is left to right but in the rear it is fore and aft.

[ErikLS2]

My whole car was pretty much blocked with paint stir sticks and it is laser straight. Be sure to get the thick larger ones for 5 gallon buckets, Home Depot has them behind the paint counter and you have to ask for them. You can cut them down for smaller areas.

I had bought one of those big long ridgid foam sanders that you put the metal rods into, hardly used it at all.

[Tom Welch]

use your imagination, almost anything that has a smooth surface, flexible or rigid can be made into a sanding block, hoses, foam shapes, pieces of wood and metal, even cylindrical batteries can work, think aaa, and aaaa sizes, i have even used a crayon when i didnt have anything else that would fit the contours i was working with.

[DocJr]

Hey, thanks again guys, you put me on the right track. I'm understanding fairly well. I'm slippin' out to Home Depot tomorrow to get a can of bondo lol, I may as well get some sticks while I'm there. I need to find a place that sells styrene too (Didn't want to resort to online purchasing) Man I wish I was still in school, some of those materials were the f word...free LOL

Thanks for the diagram too LSx I knew about the 45 degree angle, but I wasn't aware of the perpendicular to the larger radius.

I'll start looking for odds and ends, and find stuff to get the job done. Any other tid bits, and helpful hints would be greatly appreciated, after all, I am treating this model like a ridler winner HA!

[JRouche]

Scaling. Thats a difficult world. Prolly an engineers worst mathematical dilemma . Things just dont scale linearly. And the artist has a better understanding of it I think.

A true artist can accommodate for scaling, its a gift that is not given to many. Where an engineer has to rely on numbers and factual information. Mostly trying to get into the artists realm through numbers.

Im not an artist or an engineer. But I think you cant take the meathods for full scale body work and apply it completely to the scaled model. Or even slightly.

Some of the ideas are great. But the tools used should be different.

Unless you use scaling for the work. Meaning.. If a guy uses paint mixing sticks for block sanding on his full sized car for the details then that doesnt mean you can take a similar stick, of a smaller size and expect the same results. Scaling is not linear.

You will flat sand the car, even with a much smaller stick. And the filler itself is not good enough. The grains of filler are too large. If you are really serious you use a filler that is suited for the job. Scaled down. And you use tools that are also scaled down.

So the filler might be more like spotting putty and the blocks will be more like 1/4" pieces of wood, soft wood (again, the scaling, it is more than size but other qualities, like the hardness of the wood for a sanding block). Or the hardness of a rubber sanding block. Scale it ALL down, including the materials, not just the tools. JR

[DocJr]

Hey JR,

You have valid points also...however, wouldn't working on a scale model be easier, using normal tools? I was thinking of it like this...Pro's use a "Long Board" for roofs, deck lids, and hoods...wouldn't it be their dream to have larger tools? You could true up a surface on a scale model quicker because you cover a greater area...the whole area at once! as far as flex, and rigidity...that's where I'm getting even more confused, I'm just wondering what would be best. Like I previously stated, a pink pearl eraser works wonders on a 1/18 scale model..

As far as spot putty...that's basically the same chemical formula of a high build primer, which is going to be my last step before paint.

I totally understand scaling...its like people painting models with "Flake" it doesn't make a lick of sense...a normal metallic paint job on a model is probably scaled to flake. Same with carbon fiber...if I use it...it will be airbrushed, not the real thing, wayyy to big....headlamps will be mini mags (LED's) etc.

It's an interesting topic, thanks for the discussion, I'm still open for suggestions/recommendations, whatever you wanna call it haha

[elitecustombody]

There's not much to add,but I can give you few tips, if you decide to use paint sticks or any hard object, first is slightly bevel the edges and corners on the block/stick,that way you won't gouge any surrounding curved or raised areas, second, wrap the stick in masking tape about 5 times ,by wrapping ,I mean run a few piece of tape across the stick,make sure that are no wrinkles or bubbles trapped, this will help keeping the sandpaper from clogging especially on finer grit paper, this trick works on anything from 120 grit and finer,heavier grit paper will work fine without it.

I also like using stainless and aluminum rulers,aluminum angle wrapped in tape, some are very rigid and work great as a block,other have some give and work well when finish sanding,aluminum angle will work only on flat surface,

And if you're looking for true razor straight lines, you will have to use long boards,they should be at least in half length of a panel, so if you have a 50" panel,use at minimum 25-30" board, remember, the longer the board, the more straighter the lines, yes, you can tinker with a paint stick and block the whole car (I'm talking full scale car)and when it's all done,look down the side and you will see ripples, unless that paint stick was about 3 feet long

Also while you're at Home Depot,pick up some PVC pipe and rubber hose,they will come in handy working on your project

Good luck

Stefan