Rotisserie and media blasting questions

[jcook]

I have started modifing a couple engine stands for use as a rotisserie. Making the base a little wider, 48", and need to raise the rotating part to about 36"Wondering if anybody out there has anything like that and maybe post some pics so that I can make sure I'm on the right track. Next, I want to have the whole body blasted. My research tells me that plastic media is the way to go, any other opinions? Does anybody have any experiance with a shop in Texas that does that kind of work. I really want to get some feedback before I spend the money. Located about two hours east of Houston and I don't mind trailoring it across the state so long as its worth it.

[So Cal Mark]

out here they are using soda for blasting. Make sure you build bars to support the body at the door openings

[maytag]

jcook:
I build my rotisseries very differently than what you are doing, so I don;t have any pics to help, but I would suggest finding a peice of square tube-steel that fits over the upright on your engine-stands. Cut it to the length you need, then cut the upright in half and slip both ends into your new 'sleeve', and either bolt'em down (so you can dismantle it later) or weld 'em up.

RE media-blasting:
There are as many opinions about this as there are body-shops and media-blasters.
Your main media are, of course,

sand - which can heat the metal, warping it. also messy. very messy.

plastic - usually more expensive and harder to find a shop to do it. The end result dissapoints some, because the plastic will not strip some things that other abrasives will.

soda - I'd stay away from this. It does a decent job of blasting, and the clean-up isn't bad (see below), but many, many high-end body shops are discovering (the expensive way) that many paints react poorly to the soda, which is impossible to completely remove from every nook and cranny, and is fine enough to leave "residue" in some surfaces that are not easily cleaned or removed.

Walnut-shells - many consider this the preferred media, because it is abrasive enough to do a good job, yet doesn't heat the metal the way sand does. Some have questioned wether oils are transferred to surfaces, but I haven't seen this occuring.

Dry Ice - new to the automotive paint-prep world, dry-ice blasting has been used for decades in other (mostly industrial) applications, where clean-up-access is difficult. The benefit of course is that the media simply evaporates, and it does not have any of the negatives associated with the other media-types. The down-side is that you may have trouble finding someone in your area who'll do it.

Let us know what route you go!

[pope]

I also would stay away from soda. It becomes a powder, is attracted to seams and sits in seams and attracts moisture, no matter how hard you try to remove it with blasts of air. A year later, after you painted it, bubbles start to form. It is the only media that attracts and retains moisture.
Your media will change depending on what surface you are working on. I would leave aircraft stripper to do the exterior paint panels and media blast everything else.

[mdrburchette]

I had my shell sandblasted with no ill effects. The only thing I would not have sandblasted would be the hood, especially if it is a flat hood. They do tend to warp. You will be vacuuming and blowing sand out of every little nook and cranny for days and when you finally have it all ready for primer, the vast majority of sand will decide to let loose. I bet I flipped my shell over 40 times, vaccuuming and cleaning the sand out and as soon as the primer hit the body, a ton more started pouring out of crevices. In this pic you can see all the sand that fell out of the shell:

[pope]

Beach party at Denises!

[jcook]

Thanks for the tip on the doors Mark, I hadn't thought about that but see that it is needed. I hope to eventually have you exhaust system on my car.

[jcook]

Is there anybody in the San Antonio area that knows this shop? http://www.drbplasticmediablasting.com/ I like what I see, he seems proud of his work, but would like to hear from someone that knows fo sure.

[mdrburchette]

Beach party at Denises!

I'll bring the Mai Tais and lawn chairs! Yahoo, I love a party.

[baltobernie]

One of our club members fashioned a rotisserie using engine stands as you described. He failed to connect the two stands together with a suitable beam, and the car fell over when rotated. Fortunately, nobody was hurt, but the car suffered damage. After strengthening the structure, and building "outriggers" for the stand legs, he's back in business.

Looking at the finished "product", I think he'd been cheaper and quicker to build a rotisserie from scratch, like Denise did. I don't even like walking near the damn thing. Y'know, cars don't have their mass evenly distributed. They definitely have different centers of gravity depending on the degree of rotation, and a wide, stable base is required if you want to do anything other than spray sand on it.

[racydave]

Some rotissary ideas, and cross bracing on my 61.http://www.flickr.com/photos/wwwfiatspi ... 060465268/

[maytag]

My last rotisserie was built from less than $100 worth of scrap metal, salvage-yard bearings / hubs and grade-8 bolts.

It had full adjustability any dimension you could imagine, including the most important one that most overlook: center of gravity. if you want your ROTISSERIE to ROTATE, you need to have this pretty-close to dead-on.

I also managed to incorporate a cheap salvage-yard brake caliper into a locking-mechanism for it, so it wouldn;t spin when I didn't want it to!


you can get the idea here: (that's my '66 Datsun Fairlady on it)


if you're interested, I can sketch it out for ya.

[Curly]

This may be similar to what jcook is proposing. The engine stand at the front is a home-made unit, the one at the rear a cheap Chinese import that I extended vertically by about 8". It worked a treat
Media blasting was carried out successfully using plastic beads on the panels and garnet on the undersides.





It was a bit of fiddling around, but I removed the car from the rotisserie to transport it to the panel shop where it was refitted and spray painted. The guys at the panel shop really appreciated being able to move it around easily.

[Curly]

Sorry - double post

[mdrburchette]

That downdraft booth sure beats the heck out of my curtain and exhaust fan.