Block sanding round stuff

[idrivejunk]

Hey all, I'm blocking out a show car, a Model A with everything welded together. I did OK in the bondo stage, but now I'm blocking the first primer application and having difficulty with some of the curves, like the top of the front fender I did this morning. Got 3 more fenders to go and I know some of you have been there done that so I thought I would ask you guys if you have any brilliant solutions to offer up. Please?

I'm using 180 grit continuous roll blocking sandpaper and have Durablocks, 3M and Hutchins, several improvised ones too. I was able to shape that left front successfully after I stuck some paper to a 1" x 6" piece of 18 gauge steel scrap.

What do you use on top of the fenders?

[zzford]

I'd go with a long flexable, yet kinda stiff block.

[WZ JUNK]

I second ZZ.  Change your sand pattern a lot.  Back and forth, up and down, diagonal both ways.  Just plan old hard work.  A guide coat will tell you how you are doing.

John

[phat46]

I use a foam rubber that was used in the steel rule dies where I used to work for ejecting cut cloth parts from the die. It was flexible but very firm and resiliant. But I have never seen it anyplace else so that probably won't help you.

[Digger]

Your local auto paint supplier should have some 3M foam sanding pads and like WZ Junk says "back and forth and diagonal both ways." Probably have to get sheet paper for the foam pads.

[enjenjo]

I use a foam rubber that was used in the steel rule dies where I used to work for ejecting cut cloth parts from the die. It was flexible but very firm and resiliant. But I have never seen it anyplace else so that probably won't help you.

I use the same thing. It is available from McMaster Carr

[idrivejunk]

Hey thanks for the replies! I did the rear fender today and used my little metal strip, its actually longer than I said. Took a pic of it too so I can show ya.

Interesting sounding foam you guys are talking about. I need to see some. The problem with using a flexible block is that if you bend the block, you bunch up the sandpaper creating wrinkles. Not good. The best thing I found in a production block for the job was the little short 3M soft foam one you see laying on top of the rear fender. It worked OK with like y'all said, a lot of direction changes and staying moving. But it leaves the longer irregularities there. When I carved the filler, I mostly used a flat 9" Hutchins seen sitting on the rumble seat lid.

I think next week I'll make a larger version of this metal strip idea because its working pretty good. I just bend the strip to match the contour then stick sandpaper to that , then hold onto the sandpaper as I block. Thanks for the input everyone. Sounds to me like someone needs to make a good tool for this.

[idrivejunk]

I use a foam rubber that was used in the steel rule dies where I used to work for ejecting cut cloth parts from the die. It was flexible but very firm and resiliant. But I have never seen it anyplace else so that probably won't help you.

I use the same thing. It is available from McMaster Carr

Looked at their website, wow lots of options in bulk foam. Any idea what they call it?

[phat46]

I use a foam rubber that was used in the steel rule dies where I used to work for ejecting cut cloth parts from the die. It was flexible but very firm and resiliant. But I have never seen it anyplace else so that probably won't help you.

I use the same thing. It is available from McMaster Carr

Frank you should have had Fat Cat hook you up when he worked making steel rule dies. We had two types of foam for the dies, a soft foam and a much more firm foam that was used in the vacuum systems dies where a huge hood was lowered over the die and the air vacuumed out till the material being cut was a solid block, sometimes up to 20 layers. That foam had to be much firmer and more resiliant to work. We used to get it my the semi trailer about every two months. The foam was stacked on pallets and double stacked in the trailer. Each pallet had a top and bottom sheet of foam that was dunnage. the sheets were about 5'X6'.  I was able to have as much as I wanted, I guess I should have made a few thousand  "Curved Surface Sanding Pads" (tm) and gotten rich...heck i could have made a die to cut them out 50 at a time!!!  

[enjenjo]

I use a foam rubber that was used in the steel rule dies where I used to work for ejecting cut cloth parts from the die. It was flexible but very firm and resiliant. But I have never seen it anyplace else so that probably won't help you.

I use the same thing. It is available from McMaster Carr

Frank you should have had Fat Cat hook you up when he worked making steel rule dies. We had two types of foam for the dies, a soft foam and a much more firm foam that was used in the vacuum systems dies where a huge hood was lowered over the die and the air vacuumed out till the material being cut was a solid block, sometimes up to 20 layers. That foam had to be much firmer and more resiliant to work. We used to get it my the semi trailer about every two months. The foam was stacked on pallets and double stacked in the trailer. Each pallet had a top and bottom sheet of foam that was dunnage. the sheets were about 5'X6'.  I was able to have as much as I wanted, I guess I should have made a few thousand  "Curved Surface Sanding Pads" (tm) and gotten rich...heck i could have made a die to cut them out 50 at a time!!!  

He did hook me up, but he has not worked in that industry for 15 years now. I had to find another source, because I used up what he got me.

I am going to have to dig through me records to see what I got. Found it  8630K179

[idrivejunk]

Neoprene spring rubber, I'll be danged. Sounds a lot like Durablock material which is so expensive. I should order a thick piece and cut out a set of blocks.

Hutchins and Eastwood both have flexible blocks. Eastwood even has these really expensive ones with removable metal rods running through them so you can adjust the flexibility. But nothing in an adjustable block to hold a fixed curve, so unless you can bend the block and hold it that way while you stick paper to it and sand, theres gonna be wrinkles in the paper that make deep scratches and prevent full surface contact. I reckon theres no miracle product, and thats what I needed to know. Thanks again guys.

[wayne petty]

what about the long board sanding block that has a turn buckle between the tops of the handles..

does 3m still make feathering disc adhesive...   08041?


what i am talking about is an ATD 9559  adjustable file handle more than likely for vixon files..

or the simmons model 81-93370

its adjustable like the famous machine from racine.. concave or convex.. it serves either......  


i found something currently available.. sorry i was in an early 90s california  tool company  catalog.. #94

http://www.shoptoolsforpros.com/fabrication-tools/files-rasps/aes-429-14-inch-adjustable-file-holder.html



i would imagine that installing one of the straps you have created.. with sand paper glued to the top...  or a layer of dynatron 660 urethane bumper repair kit spread onto the surface of a long dull vixon file...  smoothed.. so you can glue sand paper to the surface..   i don't know how much  ripples you might get..   you might want to since you are sanding on convex curves...   want to spread the dynotron 660 on the file surface when its concave..  so when you straighten the blade slightly.. it will stretch tight...  and also allow you to bend it a little tighter without bulging the stuff out between the

this is just an idea.. of how i would goldberg it..

one might be slightly better off with something like teflon spring strips instead of an old vixon file to adhere the sand paper strip to the adjustable file holder...

i cannot think of anything except perhaps a double rocker device... to spread the load and allow the tool to be flexed to close to what you are sanding.. as what you are sanding does not really seem to be a fixed curve on the front fender..


Now.. if you can glue some of that special foam to it... now we are sanding in a curve...   you might again.. try some of that dynotron 660 as the adhesive.. i have used it to fill hollow motor mounts to remove the AIR spaces. firm them up.. prevent them from breaking again..


again.. flex the file body into a concave shape just a fraction smaller than what you are going to be sanding on..

then install the sand paper into the feathering disc adhesive..  this will allow you to open it slightly to reach your exact curve without wrinkles...  and without ripping the paper loose from the sanding block... be sure to remove the sand paper from the file body before going to lunch or home...  that is if they let you eat lunch...

you could also have somebody cut and drill holes in a 18 or 20 gauge piece of stainless steel strip... so it will be as wide as your bulk roll paper...

do you have a grey primer TEE shirt.. with the karate kid sort of image on the back.. spray gun in the left hand.. sanding block in the right...    spray on..  sand off..  instead of wax on .. wax off..

[idrivejunk]

Awright Wayne, now we're talkin. Twenty bucks, I must get one. I've used AES stuff before and gotten it locally. Never been impressed with quality though. I was just brainstorming about tacking a couple nuts to the backside of a 2-3/4" wide strip of mild steel and using a piece of all thread somehow. The tool you posted is what I envisioned, just wasn't finding it. Not sure if I can get one of those in my hands by the time I need it but I'll check around.

Leave it to Waynecyclopedia, thanks again man. Next week I'll be griping about the convex curves, theres some big ones. The sandpaper I'm using is Pressure Sensitive Adhesive backed, so no glue issues. The bumper repair plastic idea crossed my mind too. Oh and if I were depicted on a T shirt it would be more Rat Fink-esque than Karate Kid-ish. Ha!

[enjenjo]

If you use the spring rubber, and psa paper, the rubber will stretch, rather than wrinkle the paper. You can also make stiffening rods out of  piano wire, grind one end to a chisel shape, and "drill" them into the rubber with a hand drill.

[wayne petty]

you are probably still going to want an 24 inch strip of teflon spring liner strip.. with some stainless steel strip to back it up if you want the backing surface wider than the body of the tool..  as these are made to attach a vixon file to the face...  remember those...     darn things so sharp they are dangerous to handle..   i still have one left.. screwed to the side of a 2x4 as a handle.

i don't know what the actual surface is like..  as its been many years since i handled one..