Sandblasting intricate sheet metal?

admin

I'm approaching the home stretch of a candleholder project I've been working on for awhile now. It has 5 sheet metal flowers that hold tea lights. Each one is made out of 18 gauge sheet. Wondering what my options are to clean everything up for powder coat or paint?  My biggest concern is some bubbling or scale on the petals. Nothing huge, but I'd like to have everything nice and smooth. I could use a dremel with a flap wheel, but there are a bunch of nooks and crannies and curves that make it tough to really clean up. Is sand blasting a viable option on thin and formed sheet metal like that? Or am I better to just put the time in with a flap wheel and live with what I can't reach?
Reply:harbor freight has a few small hand ( economically priced) held sand blasting tools and you have a wide choice of blasting media that would work for what you want....Of all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:http://www.harborfreight.com/21-oz-h...gun-95793.htmlOf all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:Sand blasting will remove scale, but won't give you the same finish a brush will. What media you use will also affect what the surface finish looks like. Coarse sand will give you a rougher finish than fine sand will. Walnut shells or glass beads will give different results, same with alum oxide in differing grits.Thin metal can be distorted by using heavy abrasives and high pressure air. You'll want to fine tune the blaster based on how thin the metal is, how rigid the pedals are based on the shape, and how coarse the grit is. A fine grit with medium pressure might be the way to start. It might not be the fastest way to go, but it should be safe. Based on what you find, you can try to go up a bit in pressure, or change to a slightly coarser grit.Note sand blast sand isn't the same as regular play or concrete sand you buy at Depot/Lowes. It's well worth the money to buy good sand as it feeds well thru siphon blasters and won't clog up the gun with small pebbles and such like many sand types do..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I bought a Dynabrade sander, uses 1/2'' and 1/4'' x 18'' long belts. Works great on art work for tight spots. Get this attachment and it will go almost anywhere.http://www.amazon.com/Dynabrade-1128...J57RG5HCF6B1T5Here  is the sander,  http://www.zoro.com/g/Electric%20Abr.../00206369/None
Reply:I use glass beads on my steel roses, it cuts through the mill-scale  but doesn't deform the 18ga petalsMiller Spoolmate 200 w/t S-52 WirefeederMM 211'09 Miller Trailblazer 302
Reply:Originally Posted by Ian DuffinI use glass beads on my steel roses, it cuts through the mill-scale  but doesn't deform the 18ga petals
Reply:More tools to buy Will that HF blaster handle glass beads? Sounds like they're the perfect media for this project. I've never done this myself. Do I need a certain size bead or anything? Not sure what sorts of options I have when buying that. Do you guys use cabinets? cant imagine the mess you'd get without one. Thanks for the info! This forum is such an awesome resource.
Reply:Ian, does the glass reach into the folds of the flowers? My main concern is the outer ring of petals, but if I can clean up the little pieces of the inner rings that are visible, that would be excellent.
Reply:Originally Posted by jstrainMore tools to buy Will that HF blaster handle glass beads? Sounds like they're the perfect media for this project. I've never done this myself. Do I need a certain size bead or anything? Not sure what sorts of options I have when buying that. Do you guys use cabinets? cant imagine the mess you'd get without one. Thanks for the info! This forum is such an awesome resource.
Reply:Might also want to look into a needle scaler. Glass beads will give a smoother finish. Be sure they are glass beads, not crushed glass. Wet blasting gives a nice smooth finish and reduces warpage of thin metal. But that's not readily accessible to the average home user.Lincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Originally Posted by jstrainMore tools to buy Will that HF blaster handle glass beads? Sounds like they're the perfect media for this project. I've never done this myself. Do I need a certain size bead or anything? Not sure what sorts of options I have when buying that. Do you guys use cabinets? cant imagine the mess you'd get without one. Thanks for the info! This forum is such an awesome resource.
Reply:The candleholder isn't anything big.  10'' diameter base, flowers on 1/4'' rod, with the tallest one probably 12 or 14''.  I'd imagine I can just take it out to the back yard and blast away.Not quite in Philly.  Just a bit south, in Media.  About 10 or 15 minutes from 95 and the Blue Rt.
Reply:Originally Posted by jstrainThe candleholder isn't anything big.  10'' diameter base, flowers on 1/4'' rod, with the tallest one probably 12 or 14''.  I'd imagine I can just take it out to the back yard and blast away.Not quite in Philly.  Just a bit south, in Media.  About 10 or 15 minutes from 95 and the Blue Rt.
Reply:Yeah, trying to think this through.  It's tough for me to resist the temptation to run out and buy a bunch of stuff My question was initially more of a "will this work" than a "how do I do this myself" kind of question.  There are some powdercoating shops around me that I'm sure I could do it.  Just didn't know if it was even feasible to do it for such thin metal that is already shaped.My welding skill level limits me to artsy projects for now, but I'm really enjoying it, and see myself sticking with it.  Given that, I'll probably look into a blasting setup for home.  Come to think of it, I have an old Honda motorcycle project and there are some parts that definitely could do with a good bead blasting.
Reply:I have a saying I try to go with " If I have to rent or borrow it more than once, I should just buy it" of course that goes with reasonable expense...Of all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:This is similar to the one I have.http://www.harborfreight.com/abrasiv...net-42202.htmlI would have preferred a bigger unit, but I have no real space for a bigger unit. It's not bad for smaller items that occasionally need to be blasted. I just wish I had a better location to keep it as it's a bit of a pain to dig it out when I want to use it.Shop I used to work at years ago had a blast cabinet the size of the bigger HF cabinet. That was a lot more useful as far as getting bigger things inside, but it still used the basic siphon style blaster vs the pressure type some of the bigger commercial blasters use.I know a couple of rental centers that will rent blasters. I'm not sure if they rent blast cabinets or not as usually I'm renting the big pot blasters to blast a trailer or truck body rather than something tiny. None are really in your area. Georges Tool Rental is who I usually use and get my sand from, but they are out in Montgomery county or middle Bucks. Norris sales in Norristown was another place we used to use, but it's been a bit since I dealt with them as they really aren't in the direction I'm usually going. There used to be a place out near me in Doylestown that specialized in blasting, but again it's been years since I had to deal with them. I'm not even sure they are still around and they are way out of your way even if they are still around..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Norristown isn't too far away, assuming I'm not dealing with traffic.I had Bonehead Performance in Warminster strip / coat a motorcycle frame and some other parts a couple years ago with great results, but it is a hike.  Probably an hour to get there, which may be more trouble than it's worth.I think for now, I'll either look for a more local shop that can blast it, or just start with the basic HF gun linked above.  Honestly, the rest of the project can be cleaned up pretty well with a flap wheel.  It's just the flower petals that posed the big headache.  If I'm just doing them, I think I could get away with a cheap gun and doing the blasting outside.  Assuming it turns out well, I may buy or build a cabinet for future projects.Thanks again for all the ideas and information!
Reply:^^^DSW ^^^ has good information for you.Abrasive blasting doesn't mean it has to be as aggressive as what you would use to remove rust and paint from thick heavy structural steel. Various media will work and low pressure will be key.For stuff like you (OP) describe I use 120 grit aluminum oxide in a cabinet with a siphon pick up. It cleans and descales effectively and leaves a very fine, smooth but sharp profile that paints great.18 gauge should present no problems. I use a small carbide nozzle so it doesn't pull too many CFM from the compressor too fast.Glass beads are nice to clean metal but doesn't leave a sharp enough profile for paint adhesion for what I do but for what you are describing it would likely not be a problem. Crushed glass is sharper and leaves a sharper profile, never tried it but it is used on auto restoration with good results from what I understand.
Reply:Originally Posted by jstrainIan, does the glass reach into the folds of the flowers? My main concern is the outer ring of petals, but if I can clean up the little pieces of the inner rings that are visible, that would be excellent.
Reply:What about soda blasting for his application?Just curious as I've never used a soda blaster before.Lincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Originally Posted by Ian DuffinYeah it does, but that you can see down to far inside my flowers but it's clean none the less! Gives an awesome surface to paint, or just to leave at that
Reply:Originally Posted by jstrainAwesome!  Mine are pretty open in the center to allow a tea light to sit in them, but the rest of the petals are folded up relatively tightly.  But each course of petals sits a bit lower, so there is 1/4'' or so of the previous course sticking out that could stand some scouring.  Those are the really tough spots to get.I looked into the soda quickly this morning, but I thought it was just for surface cleaning, not actual material removal.  But I'm frequently wrong
Reply:For getting into the tight areas this might be an optionhttp://www.amazon.com/Paasche-AEC-K-.../dp/B0001I2ASGI have one and use it to etch glass and  clean tight areas on my art pieces.Can you clean the pieces before you assemble? Post pictures of what you are trying to clean. Might make it easier to suggest a method.Timmetalcraft by mooseSoutheast Michiganhttps://www.facebook.com/Metalcraftbymoose  Stupid Hurts!!
Reply:Originally Posted by jstrainI had Bonehead Performance in Warminster strip / coat a motorcycle frame and some other parts a couple years ago with great results, but it is a hike.  Probably an hour to get there, which may be more trouble than it's worth.Originally Posted by DSWI'm not all that far from Warminster. Your guess on time from your place to up here sounds about what I'd expect. I'd offer to dig out my blaster, but I'm going to be out of town until some time next week and I don't know what my schedule will be when I get back.Years a go I built a home made blast cabinet using plywood and some plexi using a siphon blaster and it worked ok.  ( yes I know wood is blasphemy, but at the time I wasn't welding and HF didn't exist back then) Getting the doors to seal well is usually the toughest part. HF and Snap on sell the gloves, but you can do a work around on those as well. A buddy of mine made up some dry gloves for diving basically using rubber dish gloves and some PVC fittings. The gloves got stretched tight around teh PVC pipe and then got rubber banded to keep them in place. I think several members here have made blast cabinets.
Reply:Thanks, dsw. I'm still a ways off from finishing. Just thinking ahead. I need to make a jig to bend some rod scrolls first, then weld everything to the base. The finishing probably won't be until February at the rate I'm going.Making a cabinet seems like a fun project, but I'm already waist deep in half finished projects   I think I'll give a shot with the HF gun out in yard. If it works well, I'll add the cabinet and a better blasting setup to the list of stuff to build and buy.
Reply:This is the kind of gunk I'm looking to clean off with blasting...
Reply:Originally Posted by jstrainThis is the kind of gunk I'm looking to clean off with blasting...
Reply:Originally Posted by JustmeThat looks like mill scale flaking off from the bending.   Have you looked into either cold rolled or pickled sheet? Then you would not have any scale to start with.   Or, you could use vinegar on your parts before you bend and assemble them.   Soak them over night and then just rinse the mill scale right off.
Reply:Ah!  I missed that.   I can see that now.
Reply:Yeah, each petal disc is flap wheeled clean while it's still flat. heating them up and bending them up and curving them is what's causing this mess.  This has been a really helpful thread. Given me lots of info and ideas for tools and equipment that will help down the road.
Reply:It is if you have a power washer that does at least 4gpm.  I use this one, available from Princess Auto here in Canada.  I'm sure HF would have something similar:http://www.princessauto.com/en/detai...it/A-p8067399e Originally Posted by papaharley03Might also want to look into a needle scaler. Glass beads will give a smoother finish. Be sure they are glass beads, not crushed glass. Wet blasting gives a nice smooth finish and reduces warpage of thin metal. But that's not readily accessible to the average home user.
Reply:Glass bead is a little pricey, but for small jobs it may not matter.I have been happy using 220 grit garnet.  I do not have a cabinet, so I don't recycle, so garnet is the cheapest way to go.   The guy at the abrasives store, which carries everything, including walnut, suggested garnet, as he said it lasts 2/3 as long as aluminum oxide, but is less than half the price.I have a bag of glass bead which I have not used.One issue that I have had with the HF sandblaster is getting the abrasive to feed evenly.   Sometimes I have to shake the tank to get it to feed right, but it still tends to be heavy one moment and light the next.   Maybe somebody has some ideas.   Perhaps I just need to put in more abrasive, I tend to put in a modest amount and then stop.A respirator is key.   Sand is no longer legal for blasting due to silicosis.Sculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:Well I bit the bullet and ordered the cheap HF gravity fed gun mentioned towards the beginning of the thread, along with some Black Beauty media.  Short of a few more bends and welding the stems together, it should be ready to blast in the next couple weeks.  Might even try to clean the flowers before welding it all together.Thanks for all the info.  Assuming I don't destroy my project, I'll post up some pics of how the gun and media worked.