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Tips and Tricks

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  • Tips and Tricks

    Hello again all,

    In my infinite wisdome (which is wedged soewhere between "slim" and "none" lol) I thought that maybe a tips and tricks thread should be started. I'll occasionally post helpful tidbits in this column from time to time to help you guys out with questions you may have. I fully encourage each of you to do the same! If you've found something that works for you and may help others please,by all means... feel free to share your success (no matter how unconventional it may seem. If it works, it works. plain and simple). Any question in THIS thread will be ignored, I'm sorry to say. That's what the rest of the board is for. I just thought it'd be nice to come onto at least one thread and get nothing but helpful items that apply to what you guys are looking for as opposed to a whole discussion about every nuance there is in each process. Again.... feel free to post your own success stories and back them up with pictures if at all possible. I'll do my best to do the same.

    Again........tips and tricks and helpful hints only please. If you have a question or there is something said that puts the post in dispute...you always have the ability of contacting it's author via many means and asking specifics about what he/she said. The author always has the right to erase the post if a mistake or error was made as well, mind you. Anything goes....powder comments, oven tips, hanging, coating booth solutions, you name it. If it applies to Powder Coatings, it has a home here assuming you've had luck with it or find it helpful to others. As always......have fun with it,folks. Thanks and regards to all.....Russ

  • #2
    Surface Preperation

    OK folks....just a brief note on surface preperation.

    A lot of schools of though are split on this one. There are basically two types of adhesion at play. Mechanical and Chemical bonds. Some are gung-ho on the chemical side whereas yours truly likes the Mechanical. (assume we're deciding wether to put a nut and bolt onto something or to superglue it if that helps).
    I've found that in preperation for most types of powder coating, a nice degrease,media blast and solvent wash works best. Of course....the solvent wash could be parlayed by a phosphate wash to get you that home run on your parts. This is what I've found best let's say on mild steel that's fresh from tha machine shop or taken off of one of my cars.

    1) Degrease with a nice solvent. Anything that basically takes the grime and process oils off. Mineral Spirits will do just fine. Wipe off excess solvent with a rag and let dry.
    2) Media blasting. While I do prefer a nice black oxide sandblast to either remove old finishes or paints, it's also a good "surface prep" due to the profile that is acheived. Glass bead to heavy rough oxide falls within this category.
    3) Washdown and smut removal. There are a lot of different directions one could go with here. One way is an ultrasonic clean and a dry off stage in a warm oven. Others may just blow off with compressed air and a quick wipe down with denatured alcohol. Still another process is phosphating the part and then coating. All are acceptable means of degreasing in preparation.
    4) masking and blocking parts to not be coated. Caswell here sells some fine tape that you guys should pick up. Great stuff for high-temperature range where you guys are working. Simply lay it on at this stage and peel off after your part has cooled down from cure. Works much the same as masking for wet-spray applications. You may need to "help" the tape off by scoring a line with an X-Acto knife or sharp blade, but the results are fantsatic. Powder where you only need it!

    There it is in a nutshell, folks. It all equals "what can you do before the oven" as far as how good your finished product will look. Take your time. If only degrease is available to you....do it to the best of your ability and be thorough. If only phospahte (which Caswell also now sells) then do a good job of it. It's all in the preperation. I can't say that enough. Show stopping paint jobs on cars don't just "happen" do they? NO way. They go through HOURS upon HOURS of preperation to have that drop dead sexy look about them. The same holds true for your powder coated parts. Take the time and use as many of these steps as necessary to compliment your work. After all....this is where the men and women get seperated from the girls and boys . Aside from that....have fun with it. Take care all......Russ

    Comment


    • #3
      Coating Technique

      I've had quite a few questions brought to me about "what is or isn't the best technique" in powder coating. There's some general rules to follow here but I've got to say, there's no right or wrong way. Just what works for you. Let's start off with the basics and we'll touch on the advanced stuff in future posts (overcoming Farraday-Cage effect, mottled coatings,and the such). If you have a problem applying....please read on.........

      Basic principals of the powder coating process are thus : You take a polymer (your powder) and disperse it mixed with air, force it through a tube that has a charged direct current field and it therefore becomes charged through osmosis( just being within the charged field). It is then exited the spray gun and attracted to a substrate (whatever metal you are coating) which has a ground attached. There is NO difference between this process and say....rubbing a balloon on your head and then sticking it to the wall. Positives and negatives attract, therefore you have adhesion.
      Onward and upward.....
      I generally start off with my gun a distance of 18-24 inches away from the part. I coat much in the same manner that anybody would with a spray gun or can, the only difference is that I make tiny circles with the tip of the gun while doing this. It helps diffuse the powder that much further and eliminates "spitting" onto the parts. Start in the upper left corner and move to the right. Work "past" the part. Get nice even coverage all over and turn the part around. Same process until the whole thing is evenly coated. At this point I stop and look at what I just did. If any spits or uneven waves in the powder...I can fix it easily using the same process...just blow it off first.
      Now...let's just say for example you have a flat piece of sandblasted cold steel. Maybe 12 inches square. What you are looking for is a "dusted" fluffy type of effect. Think of it this way. You've seen your car windshield with a fresh coating of morning dew on it, right? Well...multiply that by two and that's what you should have looks wise on your part. *Just* barely past noticing raw metal under your coating. Don't worry if you can still see metal in the light. The melt and cure of the flowed powder will cover that up just fine. Any excess and you will notice an orange peeled effect to the powder. lumpy bumpy wavy and pock marks mean excess. Too bright a shine from the substrate and it's not heavy enough. Take your time, work slowly and deliberately and the results will be just fine. If you don't like what you see....blow it off and do it again. That's the major advantage that powder has over all other coatings.
      Voltages for you guys should be in the 20Kv range for a good solid coating. As for second coats like a clear over a colour, we'll attck that on another post. There's no difference between metallics, clears and pigmented powders! They all spray and coat the same. If your metallic has a wave to it or the metallic flake looks a bit odd, you are too close. Back off and re-spray the part. Same goes with clears. Although a finer powder due to lack of pigment.....you should still have that "morning dew" appearance to it. Again, please note...this is for one-coat process only.
      Using this method will usually build a coating of 1 to 1.2 mils which is where you want to be. Until you get a feel for it (and yes, you will) experiment on a bunch of different parts. After all....powder is 100% reclaimable and can be sprayed over and over again, so you have no excuses. Practice makes perfect folks. I hope something in there helped somebody. Take care all......Russ

      Comment


      • #4
        Surface Preperation Re-Visited

        Yet another long winded post by yours truly on surface preperation,folks.

        I know I drone on and on about surface prep, but it really is key in the finishing process. I can't stress to you enough how important it is to do the work here as opposed to be sorry for it later on. After all...as many of you know, removing powder coating is a royal pain in the you know what if your results didn't come out good. In order to avoid that messy process, maybe some of these tidbits will help.

        Ok...so let's just say you have a sharp 90 degree angle on your part and you're ready to powder coat. Hold up right there. Powder coating HATES those edges. As a matter of fact (as some of you have no doubt experienced) it pulls back from a sharp angle only to leave a bare unprotected spot. Let's say it's raised lettering on a valve cover? Now.... it's best to take a die grinder,file or some other means to "round off" the 90 degree edge in this instance. Sort of like creating a transitional phase in the surface much as it would be done with a 3-angle grind on a valve seat. from a 90,then to a 45 degree, back to the 90 therefore creating a machined "round" if you will. Your part will thank you for this in the end. The finished preocess will have a smoothed over effect and therefore better adhesion overall.

        Also.... I strongly suggest investing in Lab-Metal (sold right here on this very website) for filling ANY hole or divot, no matter how minor. This is especially good for cast aluminum which has pock marks. Keep in mind that whatever you coat will retain that profile and only be enhanced due to the gloss of the powder involved. I.E. - It will stick out like a sore thumb! Invest in the Lab-Metal. It's a tough durable product that will withstand the rigors of powdercoating. Quite difficult to sand smooth so be forewarned! If any of you has used Bondo in the past, it's a like minded experience. Funny story actually..... in my younger days of powder coating I was doing a customer's Harley Gas tank. From the factory they come with Bondo on the extreme lobes of the tank to give it that big round "hump" we all are familiar with. Well.... I fancied myself quite the bondo worker as a young'n and I figured that I would do the same with the Lab-Metal (called something else back then). BOY! Was I ever wrong. Stop laughing at me, I was young .I hand sanded and massaged that lump of filler for 3 days straight to get it back to the point where it looked stock. THIS STUFF IS AS TOUGH AS IRON! Go easy with it and please....don't put a big amount on planning to just sand it down later. Take my words for it......you'll be sorry. Baby steps with this stuff,ok? It works, and works well. I highly suggest using it on any metal surface to "ckean it up" before that initial coating. It's also great for scratches or gouges in the metal that will telegraph through to the finished result.
        Another area that I wanted to touch on in this post is plugging threaded holes. I cannot stress to you all enough how important that is. If you coat inside a threaded hole, you WILL be chasing it out with a thread-tap. I promise you that. Get some masking tape from Caswell here and block it off. Some cut a little circle and tape over the hole while others roll a piece into a tube and simply stick it in there. They make silicone plugs and such to be used and if I bug Caswell enough....they will carry those as well. In the mean-time....I suggest just putting a bolt in the thread with perhaps one or two threads screwed in. It blocks the hole and keeps everything clean. Heck...you can even attach a wire to hang your part from in there and have a ready made ground (that's done all the time in industrial powder coating shops around the world).

        Again....there will be more posted about this subject and others in the future. I hope what I've written so far has helped somebody. Take care and have fun with it......Russ

        Comment


        • #5
          Good trick and suggestion with the circular motion with the gun. I've been doing this lately, and believe it or not it gives much more even and uniform coats. Using the hot coat pro cup gun, i often leave powder in the spare cups i have. I always make sure to shake them to fluff the powder up before using them aswell. It just gets rid of any clumps and gives me a better spray pattern. Also, those of you concerned about larger blasting cabinets, may i suggest making them out of wood. Most of us do not have access to metal working equipment to make them out of metal, and lets face it they cost more money. I have made 3 out of wood, only because it is much cheaper than metal. They work greak, cost less, and are easiar to make. Most of us have circular saws and caulk guns (make sure you silicone EVERY seam), so its more practical for us. Just my 2 cents on little things ive managed to pick up on and or do to save money and time.

          Comment


          • #6
            Oh yes, another thing i've picked up on. I NEVER coat over a existing coating, unless its a coating I personally applied via powder. I find that once heated, the older coatings peel and decinigrate, not giving a good adhesion to the subtrate. Also when you do blast off the old paint from say a valve cover, make sure you get it all, even that little tiny bit in the corner you missed. Once heated that piece will flake up, and give you bad adhesion. In the long run it will cause your powder to flake, and give grease and oil a place to get under the coating, which is not good.

            Comment


            • #7
              Outgassing and it's dilemma's

              I've been asked this question a million times and no doubt, will be asked about it a million more. It's just one of those things that's always going to be there in the field of powder coatings. I'm talking about outgassing,folks.

              To understand the "why" this is happening....you must first understand the basic principals of metallurgy. For this excercise we will classify our main goal in the non-ferrous family (aluminum,copper,lead,zinc,nickel,tin,aluminum alloy etc. Basically....anything that isn't magnetic). While ferrous metals tend to be magnetic by nature and have a tight knit bond after heating (steel is a prime example).

              Now....with that said, an aluminum metal is our basic focus here. Aluminum is one of those lovely "white" metals that likes to be very moldable and for it's weight, quite strong in a great many applications. Is it the best to hold a coating though? Not really. By nature (unless alloyed with another metal or super heated in a treatment process) it's very porous by nature. That is to say.... it allows or admits the passage of gas through pores. You'll notice that I didn't say "contains gas". Because basically...it does not. Whenever you have something that "outgases" such as your big-block intake manifold...the gas that escapes is nothing more than the air you have surrounding you. Basically the holes open up a little more due to the fact that heat expands metal and air pockets are more easily acceptable to become free of thier bonds as a bubble. What does this mean to you and how can it be dealt with,you ask? Well.....read on.

              For this example we'll be taking a common part such as an intake engine manifold and coating it. Something we can all basically associate with,right? We'll be using the hobbyist gun and say..... your basic black poly powder to coat with. Sound fair?(7-10 PSI and 20 KV on the volatge side)
              First steps first....I'll assume by now you have prepped your part accordingly and have it all ready to coat. At this point is our first "tip" to coating aluminum. If you have degreased the manifold....make sure you have all the solvent out. "Solvent popping" looks exactly the same as outgas and needs to be taken care of in the same manner. Pre-Heat the manifold to a temperature of 250 degrees before coating to work it all out of the pores. Remove the piece and coat as you normally would any other metal....the pre-heat will not only solve the solvent dilemma, but attract the powder you are spraying to the part. All while this is happening, the pores of the metal have pretty much "gassed" themselves out by now and are willing to be filled with coating as opposed to air. Work quickly! Once aluminum reaches a point below 200 degrees, it likes to take the air back in, as it were. Put your part back in the oven and bake for the low temperature guidelines (lower temperature and longer time as per your directions). Lower temperatures for longer mean less of a chance of any other pores that havn't opened up yet to stay that way. Higher heat = more open pores. Plain and simple. Let the manifold sit in the 250 degree oven until the PMT has reached that point as well. Keep raising the temperature by 25 degrees and waiting a good 5-10 minutes (depending on thisckness of the metal) until the PMT itself matches the ambient air in the oven. You'll keep doing this until the point of your lowest cure temperature has been reached. Good..... now cure as per your directions (300 degrees for basically 22-28 minutes PMT sounds about right on a poly).

              So far we have blasted and prepped aluminum, pre-heated then coated. In the oven slowly up to cure temperature and now we are about to remove. If this were a convection oven I'd just say shut the heat off and crack the doors (for all you advanced hobbyists), but for all the kitchen oven users out there....removing and letting air cool at this point is just the same. The point is to get that PMT down rapidly. Enough to where the pores of that metal will want to close up quickly and take the coating with it. (side note....this is where coatings on cast aluminum done properly will have superior adhesion. A pleasant side-effect for us, the powder coaters of the world) What you should have in the end of it all is basically a well coated piece of cast aluminum. Sure...there's tons of other methods of coating and primers involved but for you guys....this is where you start. Second coats should pretty much be treated the same way but with more comfort in knowing that you can raise the temperatures quicker if you like without fear of further outgassing. Keep in mind...if you cure a part at 300 degrees for the first coat, you should do the same for your second coat as well! Anything else and it will no doubt create a gas bubble underneath your coating and eventually failure down the road. Once the coating is cured however.... it can be treated like any other part you've done. Just as durable, just as sexy a finish

              Sorry that got long winded...but like I've said in the past....some of these things need to be at times. Hope that helps somebody out there (and thanks to user "tomg552001" for the information request that sparked this post). Take care all.....Russ

              Comment


              • #8

                Comment


                • #9
                  Reclaiming Powder

                  Another hopefully useful hint from yours truly....

                  Powder from coatings is meant to be reclaimed. Theoretical coverages for certain types of polymers are quite staggering due to the fact that there are 100% solids at play here. Just to put it in perspective, a typical pound of polyester powder is good for 25 square feet of coating (I know the book tells you otherwise, but I'm telling real world expectations here) at 1.2 mils. To get that type of coverage from a spray can....you'd have to use 14 common size spray cans at roughly 3.99 each. Do the math. One pound of powder at an average price of say...10 dollars versus 55.86 for the spray cans. Not too shabby a deal if you ask me considering liquid sprays contain VOC's and all sorts of other nasty things. So how do you get the most out of that powder? Well, I'm glad you asked....read on!

                  First of all, I don't even bother with the stuff that gets caught in the shop-vac (cyclone seperator and canister or bag type filters for all those about to turn "pro"). It's a waste and can be dumped in your garbage. Unless of course...you just want to practice spraying to get a feel for the whole process. If that's the case, be my guest. It's basically a "gimme" at that point for no cost training.

                  To screen powder of it's impurities you will need (and more than likely Caswell will be offering these to you in the very near future). A set of "filters" to sieve your powder through. These are nothing more than wire mesh screens with grades on them in the following forms. 60/80/100/120/160/200/240. These numbers signify nothing more than the holes per square inch for any screen in particular. 60 has 60 holes per square inch, 80 has 80 crosshatched holes and so on. Each hole getting smaller and smaller as the numbers go higher. Anyways, start with your 60/80 and filter out all the big particles. You'd be amazed at the things you're going to pick out. Lint,hair,wood chips, etc come out at this process. Next is the 100/120 family. Clumps of pigment and most nasty things not deemed sprayable come out at this point. After that we have the 160/200 grouping. This is where you get your "fines" or finely ground particulate back and this will more than likely be your reclaim for pigmented powders. Anything that makes it past the seive at this point is totally sprayable as a coating. Above 200 series screens are really meant for clear and exotic colours. The very finite particles can be found here and give the smoothest flow. All of the powder after the screening process that doesn't filter through is basically worthless in my book and should be tossed in the garbage. I've seen some people actually screen thier powder before they coat with it, which is fine if you need that really smooth home run on an important piece. Some of the industrial guns actually have a 160 sized screen on the pick-up tube before it even hits the gun. However....most powder from the supplier has been through the 160/200 grouping already and can be trusted. Note...when you hear either myself or another coater who's been in the game a while talk about the "grind" on a powder, THIS is the range of which we speak. HB Fuller (the powder that you guys get from Caswell) has a nice grind to it and I've used it industrially for years with no complaints. It sifts well and shelf life is on par with anybody else out there. Remember this though....if you've reclaimed powder from the floor of your booth or elsewhere and you have inexplicable "smut" in it......it's time to sift it. Hope that helps somebody out there wondering what to do with all the excess powder. Take care all......Russ

                  P.S. - keep looking to the Caswell products for new listings in the very near future for these screens and other helpful coating tools and products coming soon, hopefully.

                  Comment


                  • #10
                    a note about safety

                    Just me again with some more ramblings about safety in the powder coating forum.

                    Let me start off by saying that you should ALL be wearing some sort of breathing protection when coating. Mind you, seeing as how powder coatings contain no harmful elements in thier natural form, they are classified as a nuisance dust by OSHA and should be treated with respect as such. While I wouldn't recommend and oxygen tank and hazmat suit, a particulate or dust mask at the very least is highly recommended. Make sure it fits snugly around your nose area especially! If you are coating something blue, and then step outside to blow your nose and it comes out blue...... you are not wearing your device properly. Some (like yours truly) wear a chemical cartridge type mask with the elements replaced by particulate filters. After all, I've sprayed a lot of powders before and worked on a lot of nice things. Not a single one of them is worth damaging my lungs over! Most of the coatings you guys encounter will be of the "organic" variety. That is to say.... they have some sort of carbon molecule within thier structure and will not harm you unless you burn them. Here's a fun fact. Burning butter from a frying pan contains many of the same harmful elements that burning powder does. Perhaps not to the same extent, but they are there nonetheless. Why is that so? Carbon. Burnt or cintered carbon will create a nasty gas called isocyanate. When inhaled, it will give you a grim little condition called (and I want you all to remember this) Glyco-Toxemia. It's a very fancy way of saying "blood-poisoning". What basically happens is the isocyanate eneters your blood stream through aspiration (you just breathed it in) and makes you sick as a dog. Ever had the worst ever flu of your life just come on you in 30 minutes or less? Breath in those vapors and you will. I'm not talking the "my tummy hurts" kind of flu either. I'm talking doubled over wishing you had remembered this post because you feel like somebody just kicked you repeatedly flu. Not a nice thing. Is there another way you can get this function to happen to you when not even close to the ovens if it's burning? You betcha! Go ahead and grab a smoke from the pack in your pocket that you've been holding in there while powdercoating. Now....when the head of it burns and you force the burnt powder into your lungs go and lay down immediately. I bet even money that within 3 minutes you will be sick as a dog. What if you didn't have the smokes in your pocket but neglected to wash your hands? Same thing,my friend. Powder that is charged clings to you and everything around it. As soon as you hold that cig, it's prone to get on there and you're a gonner as well there. Keep the smokes far away from the powder. Wash your hands very well after you coat and before you smoke. Wear a good dust mask at the very least and watch what you do..... your lungs will thank you for it Hope that was a good "word to the wise" for somebody out there who hasn't thought of it yet. Probably one of the most important lessons I'll ever teach ever. Be respectful, but have some fun at the same time. Take care all.......Russ

                    Comment


                    • #11
                      I'd also like to to this topic. For me, the smell of curing powder for too long of a period gives me a bad headache. If this happens to any of you guys, or the smell makes you feel sick at all pick up a particulate dust mask with a activated carbon layer. It helps reduce if not kill the smell, and lets me continue my day without a violent headache.

                      Comment


                      • #12
                        The Color Wheel Explained

                        From time to time maybe you've wondered what colours go with what. Perhaps, somebody has asked you in confidence as a powder coater "what do you think, you've been doing this a while" only to find yourself as confused as they are about available choices. The link below explains (sometimes in great boring detail) how colours go with one another and how to effectively use the color wheel to it's fullest. Who knows... you may just surprise yourself with odd recommendations of an orange ochre with a linen taupe! lol. Anyways.... here's the link and I hope you not only learn something useful from it, but it makes your decision in exactly which powder to buy from here easier for you...... Russ

                        http://www.hypermaths.org/quadibloc/other/colint.htm

                        Comment


                        • #13
                          Job Pricing

                          As time goes by, some of you hobbyists will be doing things for your friends and accepting "donations" to your hobby fund (assuming you havn't done so already,lol). I have no idea what you guys are charging to compete with the "pro's".... but here may be some simple guide-lines to help you out and get that winning bid for your parts.

                          Professionally..... we work on a 6.6 hour day. By the time the worker gets in and does his morning routine of talking to his buddies,has a break in the mid-morning, another for lunch, and then another at mid-day and drags his or her backside to the timeclock... it works out to 6.6 workable hours in a full shift. Now... with that said, the business owner has to get the most production of of the worker and price accordingly to make up for labor/taxes/insurance/etc. Assuming the standard powder coater makes $15 dollars an hour, we double that for taxation and add another 10 for insurances (worker's compensation and health). This equals to $40 dollars. *MOST* bosses pad the amount by 75% to make up for dealing with paperwork and lost time,energy expense, etc therefore leaving us with a $75 dollar per hour labor rate. This is a very general figure as the higher salaries go and more technical research one warrants... the higher the fees go. So technically speaking... the labor for an average worker looks something like this
                          8hrs X $75 per hr = $600 dollars USD.
                          Mind you.... to break even the boss has to charge for at least $420.75 (6.6 workable hrs @ $75 - 15% (for profit) to make up for ultimate loss). Therefore leaving us at the mark of $52.59 per hour that the boss HAS TO make in order to do the job at cost. This is a good thing for you because you are not at this level. Your structure may look like this......

                          1 workable hour @ $15 dollars (under the table tax free) plus energy and materials cost ($25 dollars per hour) = $40 dollars per hour. Therefore a saving of 12.59 per hour that the "pro's" can't even come close to. When compounded by the day, it equals a $100.72 dollar loss for the day, and $503.60 dollar loss for the week.... per worker! Most small job shops have an average of 6 workers so that leaves us at $3021.60. See how much you look better now? Let's use this in a "real world" example now, shall we?

                          Instead of my infamous "widget"... we'll use a set of valve covers from a small block Chrysler product ( just because I don't like the groans from my widgets,lol).
                          Typical "over-all" work hours are broken down like this.....

                          15 Minutes receiving of parts
                          1 Hr sandblast and prep (inludes hanging and cleaning)
                          30 Minutes coating
                          1 Hr Oven time
                          15 Minutes wrapping and packaging.

                          Of course.... the more you fit in an oven,do all at once,etc... the more you gain. But that's understood.Also... the more you complete this process, the smaller the time estimates will be for you as a worker.

                          This totals 3 labor hours. For the typical powder coating shop, the amount may be close to $225 dollars ( I know some pro's charge less. We're using textbook logic here). For the "professional hobbyist" however... your fees are approximately $120 dollars. The goal here is this.... to cover for your time, materials, energy useage and foreseeable expenses in one billable hour,$40 is more than fair. For any of you actually past the "professional hobbyist" stage, if your pricing is much lower, you're going to lose. I assure you of this. Sit down and do the math! For the professional hobbyist... this is VERY close to where you need to be. Imagine the part in hand and "pretend" you are sandblasting it. How long did it realistically take? Now pretend to powder coat it? Add that to your time.... imaginary time from a dead-stop in the oven? Factor that in as well. Packaging, and recieving time? it all adds up. Total it all out and multiply by the $40 per hour rule. Professionals will almost invariably try to get an "oven full" of parts to bring the cost down. As well they should! Therefore bringing the process time down by maybe a half hour or so. Volume orders can also be adjusted accordingly. (some as much by 40%!). The simple point is.... in order for the "professional hobbyist" to compete, one must realistically approach the project with time in mind. If you do too many "favors", you will no doubt go broke very quickly. Take your time, get a feel for where you can cut corners (hobbyist and pro alike) and price accordingly. Hope that helps somebody out there.... Russ

                          Comment


                          • #14
                            Picking the right compressor

                            Often times we may be up against a wall in what compressor to choose for our needs. Some hobbyists may require only a 2 HP 10 gallon compressor while others have greater needs for a 50 HP unit complete with air dryers and aftercoolers. The choices inbetween the two are astounding. Rotary screw, piston type,oil-less..... it's enough to make your head spin sometimes. Let's focus on the two main types of compressors first, shall we?

                            Rotary Screw ~ Traditionally cooled and lubricated through glycol, this compressor offers the ability to create massive amounts of compressed air and a rapid response to loss of pressure. The system basically works by taking two rotating shaft assemblies and forcing air via means of constant flux of negative space between the "pattern" or design of the shaft. Another form of this method is seen on "blowers" for automotive use. While they may take slightly more power to produce the volume of air that it's cousin the piston style does... it makes up for it's appetite with noise reduction and low serviceability.

                            Reciprocating Piston ~ You've no doubt seen this compressor everywhere, no doubt. The true workhorse of the industry. This design most resembles that of your common automotive engine in many ways. A motor spins the crankshaft of the air end. One piston draws air down through valves while the other exhausts it into a tank reserved for when you need compressed air. Forever runninf in this fashion, air is moved along at a hefty pace from the intake to the exhaust of the "compressor" until a certain pressure is achieved. Once said pressure is achieved the limit switch tells the elcetric motor to turn off and stop the process. No doubt there are varying types of this compressor in use all over the world, but this is the basic principal of the machine. What the resiprocator lacks in style and grace that it's cousin the rotary screw has, it makes up in longevity. It's not uncommon to see this style of machine in use for well over 3 decades with simple rebuilds along the way. Slightly more noisy, this compressor is like the enrgizer bunny. It keeps going and going and going.....

                            With that said, here are some handy rules for estimating when looking for a compressor:
                            1. Air compressors are normally rated to deliver 4 to 5 CFM per horsepower at 100 PSIG discharge pressure.( non 110V estimates. Lower voltage is approx 1-2 CFM per HP)
                            2. Depending on the the size of the system, compressed air costs about 25 to 42 cents per thousand cubic feet of free air ingested by the compressor (including operating and maintenance costs).
                            3. A 50 horsepower compressor rejects approximately 126,000 BTU per hour for heat recovery.( they make heat. adjust accordingly for your HP needs)
                            4. Motor amperage draw: 1 Phase 115V - 10 Amps per HP
                            230V - 5 Amps per HP
                            3 Phase 230V - 2.50 Amps per HP
                            460V - 1.25 Amps per HP
                            In the general "6 levels of compressed air quality", powder coaters generally fall in the middle at level 3. That is to say you will need : compressor, refridgerated compressed air dryer and an oil removal filter. This system removes 99.999% of oil aerosols and any solid particles larger than .025 microns.

                            A good general rule of thumb to follow when researching your needs for a compressor is as stated : (requirements now + 20% growth) + 20% demand factor. That is to say..... if you need 25CFM (cubic feet per minute) now to supply your needs, add 5CFM for a future growth and 6 CFM for demand of draw. This equals 36 CFM requirement MINUMUM when shopping around for a new compressor (again, these numbers are used for an example purpose only. Your needs will be different). It's often a common mistake that we see something "on sale" only to find out perhaps a year down the road that we should have spent the extra money because you can't operate all of your equipment now that you've expanded. Or even worse.... you can't powder coat when somebody is blasting,therefore creating a loss of billable hours within your facility.

                            After all is said and done, it boils down to "do your homework". A compressor is a tool used to make money with, bottom line. If you buy cheaply made.... it will invaruiably break down on you at the worst possibly moment and you'll have to repair or re-purchase anyways. I suggest you calculate for your needs and abilities and then for your budget. Shop around. Wait for the sale. Ask that friend of your what he's doing with that old compressor he never seems to use . I hope that helped somebody out there in your decision to purchase a machine that will service your needs for quite a while to come. ..... Russ

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                            • #15
                              http://www.oldengine.org/members/billd/electrol.htm

                              http://www.stovebolt.com/techtips/ru..._derusting.htm

                              etyrrany

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