Question
As always, I'm looking for a better way to get stuff through the spray room. What's your favorite way to handle batches of around 50 cabinet doors/20 drawer fronts? I've tried the Pivot-Pro system, but that's all piled up in the corner now.
Right now we spray everything one at a time on a lazy susan and stack the doors on Hafele drying racks. We shoot two coats on the back then two coats on the front. Lots of handling going on, but the process keeps moving. I have a finisher spraying and a helper sanding/handing parts. I'm not sure, with our physical layout, that I'm going to come up with a better process.
I've seen shops that lay all their doors out in rows on sawhorses, then spray, sand, spray, turn, repeat. My room size would require me to spray my doors in two or more batches to get everything done. My finishing area is away from my shop, so there's the issue of what to do with the guys while the batch is drying. Is it even worth trying this?
Forum Responses
(Finishing Forum)
From contributor M:
Racks that roll around easily (i.e., won't tip over) can be built in-shop with plywood strips on a 2X4 frame, mounted on casters.
However, as far as the spraying MO, here is how I do it. I use conversion varnish. Two coats is all you need if you are using a good AAA like the Kremlin or CAT. Spray back 1 coat, let cure, flip and spray face. Sand both sides. Spray back final coat, let cure. Flip and spray face. Done. Aside from UV-cured processes, kind of hard to beat that system. The only problem is if you have a heavy hand spraying, you might get overspray on the backside when spraying the final on the face. I only had problems with it if I was spraying at too flat of an angle on the edges (allowing it to flow under the door too easily) and spraying too heavy.
My spraying procedure is essentially the same as yours, only I spray both coats on the back first and then flip. Your method allows you to handle the door just once for sanding. I have to handle it twice my way. We're using a Kremlin rig and spraying Magnamax. Those 50-door Hafele racks can't be beat, particularly when you get them on sale.
I used this idea to make plywood beds with screw points sticking up. A door is placed gently face down, the back is sprayed first, not the edges, flipped over and sprayed the face and edges. This plywood bed and door is set on the drying rack. Both sides are drying at the same time, cutting finish time in half. An occasional down side is a very small dimple on the back side because of the pin point, but generally, the finish flows into the area and is very difficult to see. At the very least, do the priming and first topcoat with this system, then do the final coat one side at a time to ensure perfect finish.
1) Clean finishing room well. Sweep and/or vacuum floor beginning at back of room moving towards the booth (with the fan on). If vacuuming, make sure to use a HEPA so the fine particulates are not just coming out the backside. Blow off any drying racks that will be used. Then starting at the back of the room again, use compressed air to move the airborne dust towards the booth. (The importance of this cleaning will be evident when you reach the sanding operation.) (20 minutes)
2) Set up the rows (sawhorses), nail boards and doors onto nailboards, backside up. (10 minutes)
3) Starting from the back row, final blow off of dust from items to be sprayed. (Most all dust is first blown off before items enter the spray room!) Blow the dust off yourself well while standing in the booth. (8 minutes)
4) Starting at back row begin spraying the backs (only, not edges) starting first at item farthest from the pot and moving towards the pot (hose behind you). Move to next row, repeat until complete. (This will vary based on your equipment and personal speed. I spray very fast and robotic. You will be able to also once you get used to the system.) (5 minutes)
5) Flip the doors starting at first one sprayed. (3 minutes)
6) Repeat spraying edges first, then fronts. (8 minutes)
7) Tiptoe away, let doors flash.(5 - ? minutes) (Your flash time may be longer depending on your coating and conditions - you want it dry enough that it won't stick to the rack.) I also allow longer for a final coat.
8) Move doors to rack (first sprayed first) and remove rack to sanding station outside finishing room. (5 minutes)
If you have more doors, lay them out, blow them off, and repeat spraying. *You do not need to reclean the room.* (Always clean the room if you are switching projects from a pigmented coating to a clear coat project.)
Key here is to limit the amount of movement in the room during spraying and flash off. (Anyone tries to enter when I'm spraying will experience death by bunga bunga!)
Very little (if any) junk should show up on the finish using this method and sanding time is drastically reduced. If you have sanding helpers, sanding on the first batch can usually begin (outside the room) while the second batch is still being sprayed. So, in approximately 1.75 - 2 hours, 60 door fronts and backs are sprayed and 30 of them are almost done being sanded and are ready for a second coat. With the sanding helpers you can keep a finishing room in near constant production mode. With the reduced handling of this method, would this production time beat your current schedule? If not, then your current system isn't broke, so don't fix it.
My spray room is 16'x18' with a 23'x25' drying area (these are actually two garages at my house, but it's dedicated finishing area). I figure I could get 24 doors sprayed in one batch in my room. I just need to try this once and see if it makes me any money. The way we're doing things now keeps the sprayer on the gun constantly, and I guess that's the issue.
Contributor Y, go to the Hafele website. The part number you're looking for is 007.91.141.
I have a 4 sided rack that holds 80 doors. It is on wheels and can be moved easily. I have worked at shops using the lay-out-everywhere-and-spray method, and was not impressed. Usually there were missed spots and overspray. And when the inevitable - this has to be done right now! - comes in the door, you're screwed.
Spraying one door at a time, you tend to focus more on technique for each door. The lighting is perfect for every door and the rack is right behind you, so as you spray you place the wet door at the top of the rack and get the one below it to do next. As an added benefit, less dust falls on things placed in a rack.
Usually by the time you have gone through all of the doors in the rack, the first ones you sprayed are ready for either scuffing or spraying on the other side.
I have seen people place their wet doors on the bottom of the rack and go up. This is a mistake, as you will knock dust onto the wet door below when you put in the door you just sprayed.
Perhaps it is simply your personal enjoyment to spray one widget at a time, treating each as if it is a one-of-a-kind artifact. Maybe you just like the break in stride afforded by hanging up the gun and stretching a bit as you place a wet item onto a rack and reset another. Everyone does have to find what works for them.
Either way, I agree that racking from the top down is a no-brainer, and I have also seen others make the mistake of racking bottom up. But you have made my point about dust in a wet coat.
Whenever there is excess movement during a finishing operation, dust will be kicked up, knocked down, etc. And when you pick up a freshly wet item and move it through the airstream taking place during a fan on session, you are directly causing the particulates in the air to collide with the wet coat. Hence the reason to allow some flash time before moving the item or movement in the room.
As for the "inevitable, this has to be done right now... you're screwed" problem you have stated as additional reasoning, my reasoning on that is "a lack of planning on so and so's part does not constitute an emergency on mine." If they can't wait an hour for a switchover, they are screwed.
To the original questioner: Having the gun in action full time is not what will determine your increase in production and profits. You can have two helpers picking up, racking and feeding items to keep a gun in constant motion, but that still requires additional handling steps and man hours times "X" per man hour. Whereas batch finishing can be performed by one person.
Additional throughput can be achieved with other warm bodies (less skilled lower wage) if you have them, performing the sanding operations. You have to do a calculation of all these factors to determine the payoff and if this would work for you.
Another benefit of batch finishing is that it also eliminates the tracking requirements as to which piece is ready for sanding first. The whole rack was sprayed within a few minutes of each other, rather than a 40 minute or whatever spread, and are all ready for the next operation at the same time. I know most people should be able to track a first on, first off rack method, but if you ever have to relay directions to prep personnel who don't speak or understand English, this cuts down on any confusion.
Your two-room garage setup sounds fine. A lot depends on what your coating properties are. If your coating has a much longer flash or dry to sand time, then you have parameters which could make batch finishing reach a point of diminishing returns. You have to find out for yourself.
Another consideration is a large crossdraft booth sitting at the end of the finishing area. This is very common and is designed for optimum air draw at the very front of the booth. As you extend outward from the front of the booth, the draw is more turbulent or at least inconsistent. Obviously it is not a problem for some, but it wouldn't work for me, as my room the booth sits in is too large with 14' ceiling height, so the air flow 20' away from the booth is not adequate to carry overspray.
Another issue is NFPA code. To get my occupancy with city building inspectors, I had to sign a statement saying I would not spray objects out in the room area away from my spray booth. All spraying is to be done at the front face of the booth or inside that limit. If you comply to this, then all lighting and electrical outside 3' or 5' from the booth can be standard. If you spray in the area well outside your booth, then all your lighting and electrical has to be up to tighter code for inside a spray booth, which is quite a bit more expensive and is necessary for good reason.
The most obvious thing that stands out to me in the original post is that his room is small and would require two or more batch runs if he were to go this way. Seems to me that is a deal killer, but sure, give it a try and find out.
They pick up a fairly healthy percentage of the finishing profit for doing the marketing and selling the job. I make an almost sinful amount without having to cover the overhead costs. It is a deserved sinful amount, seeing as I will pull a 20 hour shift (maybe with a catnap on the office sofa), and get up at 4 AM to spray the final coat before their staff shows up for their daily shift.
They get a project done that they may not have the expertise or schedule to produce with their staff, pick up pure profit (but for electricity/heat) and get all the credit for the end product. Sometimes it gets them out of a real bind they are in. They know they can count on me to get it done right (I usually produce the samples in the first place).The faster I get in and out, the more money I make.
I also can rent the spray room time for my direct sale jobs I land. I do a lot of on site kitchen and bath finish jobs (waterbased), and like to pull the doors and drawers out to spray those. It is win/win.
There is no end to the variables in finishing. Being able to quickly identify and adapt to which is the best method for any given project is key to enjoying the process and the profits.
I spray, move and buff by myself and this is the fastest, most efficient system for me, with excellent results. Using this method, a batch of 50 doors/20 drawer fronts takes me about 3 1/2 - 4 hours from start to finish. I've tried other methods and was not satisfied with any of them. What works for me may not work for somebody else. Trial and error!
That being a given, the second easiest way to reduce finish time is to use better equipment and materials.
1) Using a good air-assisted airless (or perhaps a pressure pot with HVLP gun). Very hard to beat the sheer output and high quality of finish these guns produce, not to mention greatly reduced overspray.
2) Spray the fastest-curing stuff, which for us is normally conversion varnish, but at times we'll use 2K poly. Most brands of either of these will cure quicker then pre-cats and NC lacquers.
3) Eliminate color-squabbling with customers by being clear to them that color will vary a bit because we are working with wood. Stain color does not equal paint color. Have a "wipe-on, wipe off" policy, none of this "wipe it on, wait for X minutes, wipe it off," because it's really aggravating to be timing how long the stain's been on all those doors.
It seemed that most were looking for 50 to 60 parts at a time. Why not invest in a small overhead conveyor? Hang the parts on the conveyor after white wood sanding, and start the conveyor. Apply the stain on both front and back, and the edges at the same time. If the conveyor were 20 by 20, that is 80 feet of conveyor. If the parts are on 2 foot centers, you can stain 40 parts. When the first stained part returns to the booth, stop the conveyor, change to your sealer, and then seal coat all 6 surfaces at one time. This is the front, back and four edges. As the conveyor continues to run, the parts will be finished on all 6 surfaces at the same time. This will provide the best edge coverage.
If you have a helper, he can sand the parts before they get back to the spraybooth. The conveyor will then bring the parts back to the spray booth ready for the topcoat. The denibbing of the sealer coat needs to be blown off, but the parts are ready for topcoating. The gun is then filled with topcoat, or left if it is a sealer/topcoat dual material. The conveyor will continue to bring the parts into and out of the booth, which will allow one sprayer to apply the finish to the entire batch of parts.
The sealer top coat should also be a water reducible coating. This will allow for a green coating, which will allow you to provide a kitchen and meet the CARB requirements.
The conveyor system will allow you to finish the parts without touching them except for the denibbing after the seal coat. If the conveyor runs at 3 fpm, this is almost 30 minutes of dry time between coats. This means that one person would finish 40 parts, stain, sealer and topcoat in about 1 1/2 hours. If you were alone, it would be 2 hours, as he would denib the parts on line after the sealer coat. 40 parts with three coats and sanding in 2 hours is productive.
Monorail conveyors are inexpensive, and allow the operator the keep spraying. As far as the thickness, I like 1/2 mil for stain, or as required to get the correct coverage, and then 3 1/2 mils of sealer and topcoat. Most of the sealer topcoats have a volume solids of 30%, so this will provide a 2 mil dry film build on all surfaces, which result is a great finish package.
Comment from contributor B:
I wouldn't recommend using the method where you spray one side and flip it immediately onto screws (or pointy dowels). I have tried this before with poor results. It seems the underside doesn't have enough air to dry. I let the piece sit overnight. I used screws that stuck out about 1.5" - maybe that’s not big enough. Either way I wouldn't recommend trying to cut corners on dry times and sanding like this.
