Homemade Spray Booth

[BETAQDAVE]

    It’s about time that I got going on my spray paint booth as I need to paint the copper bottom of the Wanderer.  I need a little break from ship building anyway.  What follows will be somewhat of a building log for my booth.

     The components have been cut for some time now, but (as they say in advertisements) some assembly is required.  As far as the design goes, I had come across an article in the Jan/Feb 2004 issue of Ships In Scale magazine written by Don Stauffer for a homemade lighted spray booth that looked promising.   While a bit too small for my use, I decided that with a few modifications to enlarge it, I could make it more useful to me.

    I decided to base my overall size on the use of a pair of 14” x 20” furnace filters.  So I sketched a plan for it at 1 ½”=1’-0” as shown below.

    So now I had all of the components cut to size and laid out on my “handicap” workbench shown here with an eight foot length of 1” vinyl “J” molding that would be used to hold the filters in place.  To eliminate using the wrong panels in the wrong place, I wrote the sizes and names of the parts right on the panels.

    Once I had the design finished I took some graph paper and made up some cutting diagrams for cutting up one 4’ x 4’ sheet and one 2’ x 4’ sheet of ½” particle board to economize my cuts.   I liked Dons idea of a front-to-back air flow design and I decided to increase the fan capacity from 100 CFM to 130 CFM by using a pair of 65 cfm rated fans as shown here.

    The two fans needed to be mounted on the right side panel, so I laid out their placement.  Contrary to the listed size of four inches, they actually required a four and a half inch hole.  The mounting holes were then marked also.  Again to eliminate dumb mistakes, the front and back edges were labeled with F and B respectively. (Who would do that????)

    I will be starting the construction by cutting the holes for the fan and drilling the mounting holes, but that’s all the time I have right now.  So, that’s all for now folks.

[BETAQDAVE]

    As I said in my last posting, the right side panel first needed to be drilled for the fans.  Using a two inch hole saw installed in my large capacity drill press in the garage,  I set one edge of the hole saw up against the inside edge of the drawn 4 ½” dia. circle for both fans and cut entrance holes for my jig saw blade.

  Things seemed to be going smoothly until I encountered the dreaded: You can’t find the right tool when you need it syndrome.  Finding my jig saw wasn’t a problem, (since I have two of them) but my package of blades for them seemed to have sprouted legs and run off somewhere. Usually my accessories for my portable tools are stored either in the tool case or right next to it, but there was no sign of them.  When this was discovered a house wide search ensued that wasted a good two hours.

    Looking high and low, the frustration level kept steadily climbing until I finally gave in to the: You won’t be able to find it until you give up and you will find it later when looking for something else altogether syndrome.  Oh well, there is usually more than one way to skin a cat.

    Installing a 3/8” brad point drill bit in the drill press, I proceeded to drill many, many, many (Did I mention many?) slightly overlapping holes around the inside perimeter of the drawn circle until the waste finally dropped out.  It made for a very crude hole, but by switching to a two inch sanding drum installed in the drill press it was sanded smooth right up to the drawn circle.

  

    You will notice in the photo below my equally crude setup for sucking up the heaps of saw dust created by this operation.

    Between the house wide search and the much modified procedure, this turned out to be a full day’s work on the spray booth.  It felt sort of like trying to make a silk purse from a sow’s ear, but I guess if the end result turns out all right then it’s all good!  Hopefully things will work out easier on the rest of this project.

[BETAQDAVE]

 

    Positioning the fans carefully over the holes, the fan mounting holes were located and marked by firmly tapping a 5/32” drill bit thru the holes on the fan frames into the face of the board.  Rather than mounting the fans with screws, I decided to use some 5/32” full threaded bolts about 2 ½” long with washers and lock nuts (as the thin particle board wouldn’t give a regular screw very much purchase) so these holes were drilled clean thru the panels and countersunk on the inside face.

    All of the panels will be both glued and screwed together except for the top panel to ensure that the air will only be drawn through the filters for maximum fan efficiency. The top edges of the booth panels will have self-adhesive foam weather-stripping applied to seal that joint.  

    I decided to add another upgrade to the original design, rather than screwing down the top panel it will now be hinged to the top of the back panel to allow easier filter changes.  The three hinges will need some of the screw holes relocated and the hinge itself will be mounted somewhat backwards to function properly above the weather-stripping as shown in the sketch below.  Two latches will also be added to pull the top down tight.

    So before starting the assembly of the booth, numerous holes needed to be predrilled for all the screws.  To be sure that I didn’t forget any holes, the sketch below was made to show the location of all the screw holes needed to assemble the basic frame.

    As you can see by that sketch, the left and right side panels need five equally spaced holes on the face of the bottom edges to attach to the bottom panel, and six equally spaced holes along the face of the back edges for attaching to the back panel.  I used the drill press because the holes needed to be exactly ¼” from the edges and perfectly perpendicular to the surface so that when the screws are driven into the edge of the back and bottom panels it will help them go straight into the center of the thin ½” particle board.  With a guide fence on the drill press as shown below, this is easily accomplished.

    In addition to these holes, the front face of both the right side panel and the baffle needed six equally spaced holes on the front edges at 3/8” from the edge for attaching the ¾” thick front panel which fits between them.  Along the back edge of the bottom panel, nine equally spaced holes needed to be drilled ¼” in from the back edge of the bottom panel for attaching the back panel.  The bottom panel also needed five equally spaced holes drilled in a line exactly 2 1/4” from the right end starting at 1½” from the front side to attach the baffle.  Once all of these holes were drilled, the holes needed to be finished with a counter sinking bit on both faces as shown below. 

       While the countersinking allows the screw heads to fit flush on the exposed front faces, the hidden back faces also need this to be done.  That’s due to the fact that when screwing parts together the surface of the part being pulled tight tends to mound up around the screw making it hard to pull the joint up tight.  That is especially true when screwing into particle board.  The detail shown below shows that the countersinking leaves room for this excess material to mound up without interfering with the joint.

    Upon temporarily setting the components together with clamps to test the fit of everything including the filters, it became evident that I had made a couple of dumb mistakes.  First, when buying the furnace filters, I should have realized that the 14” x 20” x 1” filters were actually labeled on the box in what they call nominal sizes.  The actual dimensions of 13 11/16” x 19 11/16” x ¾”, caused some consternation on my part to find a way to accommodate the new sizes without having to re cut everything.

    Having already revised my design to use 1” vinyl “U” channel in place of the wood and hardboard assembly used in the original design by Don Stauffer in his magazine article, at ¾” the filters would now be a very loose fit.  However, with the addition of some narrow strips of 1/8” hardboard glued to the inside of one flange of the channel, the filters can fit a little tighter and still be  easy to install with 1/8” of play.

     Thankfully the flanges of the “U” channel are fairly wide and can help me cover some of the remaining gaps.   Having already planned on using two filters butted together in the middle with a strip of tape over the gap, there is a little play there also.

    The second mistake was that I overlooked cutting the front cover for the plenum. Since I didn’t have any more of the ½” particle board I will just cut it from a scrap of ¾” pine. (The pine is lighter and will provide more purchase for the screws anyway.)  The part’s just a 2 inch wide strip approximately 22 inches long with the two ends cut at a bevel to match in with the top and bottom panels.  The bevels are important in order to give an airtight seal to the plenum, so I left it at 22 inches until I got the booth partially assembled. 

    Having a little extra length to play with, I marked the bottom bevel directly from the bottom of the baffle onto the bottom of the front cover.

    After cutting the bottom end bevel, the front cover was just be propped in place to allow marking the top bevel even with the top of the right side panel to help ensure a tighter joint there also.

    This whole situation just reminded me of a saying used often by Marine Gunnery Sargent Tom Highway (AKA Clint Eastwood) in the film Heartbreak Ridge: “A Marine needs to improvise, adapt, and overcome.”  While I’m not a Marine, that quote could still apply here.  As a matter of fact that quote was a motto that I readily identified with anyway, thanks (??) to my lifelong adventure (??) with MD.

    On that note, I think I'll take a break. (To see if I missed anything else.)

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[Roger Pellett]

Dave,

 

A nice project!  I am concerned with your fan if you plan to use solvent based paints as it does not appear to be explosion proof.  

 

Roger

[BETAQDAVE]

12 hours ago, Roger Pellett said:

A nice project!  I am concerned with your fan if you plan to use solvent based paints as it does not appear to be explosion proof.  

The fans are brush-less and supposed to be good for this application.

[BETAQDAVE]

    The assembly of the booth started out with the right side panel being attached to the right end of the bottom panel.  The two pieces were propped in place temporarily to use the predrilled holes in the right side panel to locate and guide an 1/8” brad pointed wood drill bit into the edge of the bottom panel for pilot holes for the 1 5/8” square drive drywall screws. 

    Once the holes were drilled, the parts were laid out on a movable assembly table for application of the wood glue.  I drew a line ½” in from the edge of the right side panel and laid painters masking tape along that line to keep most of the heavy layer of glue confined to the area of the actual joint.  The glue was spread in a continuous thick layer with a stick to ensure that the joint would be sealed from air leakage.  When I finished applying the glue, the tape was removed.  Once again the panels were set into place and two of the screws were partially driven in by hand to locate the pilot holes.  I used the baffle panel with a clamp on the top to help hold the panels in place and to make sure the joint would form a good right angle joint.  

    The other three screws were partially driven in place to check the alignment.  When satisfied that everything was properly aligned, all five screws were driven home with my impact driver to get a good squeeze out of glue.  Now that it was held together by the screws, the baffle was removed just long enough to take a damp rag to the joint to both remove the majority of the glue squeeze out and to form somewhat of a fillet of glue to make sure the joint was well sealed.  The photo below shows this glue fillet.

    Now the baffle was re-clamped in place to maintain the right angle joint while the assembly was set aside to let the glue set up properly.  I felt that this joint was the key to my assembly to allow the other components to be braced to them and not flex enough to break the seal of the glue fillet joint. Once this assembly sets properly I will use a similar procedure to attach the back panel. The following photos will show some of the details and how things stand at this time.

    We are leaving for a short vacation to Door County now, which should leave plenty of time for this key joint to set up properly.  At this point I can readily see that this booth will be quite heavy and with my limited strength I may need some help to wrestle the rest of this thing together.  It's a good thing that I planned on having a roll around stand to mount it to! 

[BETAQDAVE]

    Now that I’m back from vacation, it’s time to get back to work on the booth.  The back panel was the next part to attach and it’s the largest part to work with.  I could have used more hands here, but I made do by balancing things on the roll around cart and some various clamps as shown below.

    Once everything was secured with clamps, I proceeded to drill through two of the predrilled holes in the right end panel into the edge of the back panel and drove in two screws to help hold it together while drilling the remaining holes.  

    Then the assembly was flipped over to expose the bottom panel with its edge resting on the cart.  Once again a couple of holes were drilled through the predrilled holes in the back panel into the edge of the bottom panel to help hold things in place to align and drill the remaining holes as shown below.

    Now the fun really began by unscrewing the back panel in order to apply the glue.  Luckily the yellow wood glue I used has an extended set up time to allow me extra time to wrestle the parts into place and drive in the 15 screws required.  The gluing was done similarly to the previous parts, but of course there was a much longer joint to glue up along the surface of both the bottom and right end panels.

    Once the glue was spread properly, the back panel needed to be placed in the glue on the face of the bottom panel and slid into the glue that was on the face of the right end panel.  With the part precariously balanced on the cart with one hand, I took one screw in the other hand and screwed it partially by hand through the top of the right end panel to help steady the parts.  Then while still holding the back panel in place with one hand, I put a miter clamp on the other end of the back and bottom panels with the other.

     Now that things were loosely held in place with the one partially driven screw and the clamp, I turned the cart around so I was facing the right end panel and placed the remaining five screws in place and drove them all with my impact driver to pull the joint up tight.  The whole assembly was then flipped to place the face of the back panel onto the cart, being very careful not to dislodge the miter clamp that was the only thing holding the other end together. 

    Finally, I was able to place and drive home the nine remaining screws.  The glue squeeze out on the inside of the booth was a bit thin, so a little more glue was spread on the joint to allow me to make the fillet on the joint as shown below.

    All that remained to do now was clean up the glue that squeezed out on the backside.  Here is the backside of the booth as it stands now.

    Once again everything will sit awhile as the glue cures.  The fact that the glue was spread so thickly, I thought giving it a little more time to set up would be a good idea.

[BETAQDAVE]

    The previous step in the assembly has had a couple of days for the glue to set up, so it’s time to add the left side panel to the booth.  I don't have much time today, but here is a short update.  The procedure was similar to the previous steps: temporarily clamp it together, drill the holes through the predrilled holes into the edges of the bottom and back panels, disassemble it to slather on the glue, reassemble and clamp it back together, and then install and drive in the screws.  Once the glue was given the fillet on the inside and the outside was cleaned up, it gets to sit for a day or two again.  

    Here is a current status photo below.

                                                            

[BETAQDAVE]

    Once again, I was short on time for the booth today.  Given the fact that particle board is notorious for reacting to changes in humidity, I really don’t want it to warp out of shape. The fact that this is a portable booth and will probably see a lot of humidity changes it will be given a few coats of paint to seal it.  Since all of the joints to be glued are done, I thought today would be a good time to get at least one coat applied. I had some left over white satin enamel paint, so I thought this would be a good way to use up some of it.  Only had time for one coat today so this is its’ current status.

[BETAQDAVE]

     There have been many things keeping me away from this project lately including the elevator problems, the downed tree, a couple of funerals, and just life in general, but I did get a break yesterday to get at it again.  The fans were bolted to the right end panel with a bit of caulk around the edges to maintain a good air seal.  This had to be done before installing the baffle as the inside end of the stove bolts would be very tough to access in the 2 inch space once that was attached. 

    The next step was to clamp the baffle panel in place to allow me to align the holes in the bottom panel with the bottom edge of the baffle and drill into the bottom of it.  It was becoming too difficult to wrestle the heavy assembly around on the assembly table from the wheelchair to allow me to tilt it back on its backside, so I just clamped it in place as shown.

  

    It did however; make it a bit awkward keeping the drill perpendicular to the surface of the bottom panel while drilling straight up through the bottom so the bit would stay in the center of the baffle panel.  The clamps were removed at this point to allow me to countersink the holes that I just drilled in the bottom edge of the baffle panel.  Next, I buttered up the bottom edge of the baffle with a heavy coat of yellow wood glue.  The assembly was clamped together again and the screws were driven home.    The Plenum cover was slid into place and that was clamped as shown here to sit overnight for the glue to set up.

[BANYAN]

Hi Dave, following your build with some interest as I am making a version for use with my 'Air Eraser'.   

 

I have read that the fumes from paint can be a fire hazard and that the extractor fans should be well away?  I note though that many manufacturers have them on the booth body as well so can't be that much of a problem, especially if there is a filter ayer before the motor?  Have you investigated this?

 

cheers

 

Pat

[BETAQDAVE]

On 6/30/2019 at 8:54 AM, BETAQDAVE said:

The fans are brush-less and supposed to be good for this application.

 

[BETAQDAVE]

    Now that the glue has had two days to set up it was time to put in the plenum cover.  Once I got to this point, I realized that the cover should have been attached to the right side panel during the last step when I would only have needed to glue up the bottom and one side of the cover.  Now I have to butter up both sides and the bottom at the same time!  To keep from scraping the glue off while sliding the cover in place, I planed about 1/16” off one edge.

    I clamped the cover in place so that I could drill through the baffle and right end panel into the cover.  Taking the cover out, those holes were countersunk as before to allow for a tighter fit.  Going to the yellow carpenters glue bottle again, the edges and bottom end were buttered up with a heavy coat and the panel was slipped back into place.  Two of the screws on each side were driven into place with a hand screwdriver to seat into the predrilled holes and get everything properly aligned.  The remaining screws were then driven home.  The excess glue that squeezed out was removed with a damp cloth to finish the installation. Here is a photo at this point below.

    Now I decided to test fit the filters and their plastic supports.  I found that the filters were actually a tight enough fit that the 1/8” hardboard shims were not really necessary after all.   All of the plastic U channels were then trimmed for a tight fit for later installation. 

    Cutting the plastic U Channel was difficult at first until I realized that there was an easier way to do it without having the saw chatter its way through it.  Marking the cut with a pencil and a small square, the piece to be trimmed was clamped in my vice with two scraps of ½ inch particle board in the gap.   The scraps were lined up with the cut line even with the mark and the line was placed very close to the end of the vice jaws.

 Now with a hack saw, the blade just used the end of the scraps for a guide. The chatter was minimized and the cut was square.   

    While still in the vice, a sanding block was used to smooth the cut.  I also decided to fit a section of T channel to fit between the filters in the center.  At this point everything was fitting properly as shown below.

    Taking the filter assembly out, I used more glue to make the fillet for the bottom of the baffle.

    Now using a pencil, I marked a line three inches in from the back panel on the bottom and both sides to locate the inside edges of the filter assembly.  As the baffle still needed to be painted, a small drill was used to make an impression in the panels so that when the line was painted it could still be used as a guide to relocate the face of the filter frame. 

    Hopefully, I can get back into the shop tomorrow to paint the booth assembly and begin making the top.

Edited August 17, 2019 by BETAQDAVE
typo

[BETAQDAVE]

    Not much time today, but did manage to finish painting everything on the booth with the exception of the top panel which needs a lot of work yet.  I managed to tip the booth onto its backside to paint the bottom side of the bottom panel and took this photo from the top.  You can see the layout of the plenum from this view.

[BETAQDAVE]

    My booth wiring setup will be somewhat changed from the original design, due somewhat to being wheelchair bound, I will mount the power strip on the forward edge of the left end panel. (If I put it on the top as in the original, the switch would be out of my reach.)  Modified extension cords will be run from both the fans and the light fixture back to the power strip.

   Here are photos of the LED twin light fixture that will be used.

    As you can see, the fixture needs to have a plug with a ground wire, so I have taken an old three wire extension cord and cut the wire off at about 18 inches from the male plug end. (Using a replacement fitting to terminate the wires is something that is hard to assemble and leaves a lot to be desired anyway.)  The other end will be spliced and anchored inside the fixture.  From there the cord will be run out of the back of the fixture towards the back edge of the top, anchored there and run loose around to plug into the power strip.

    As in the original design, I will need to make up a pair of metal brackets to attach the fixture to the top panel that will allow the LED bulbs to sit down in the cutout for the light.  

    Putting the power strip on the opposite end of the booth, means that the wire leads to the fans will have to be run all the way around the backside of the booth.  To do this, I cut a pair of two wire extension cords off at 36 inches from the male plug ends so the plugs could be used as is with the cut end spliced to the fan leads.  Since the terminals inside the fans are not accessible to connect the extension cord wires to, I need to splice them directly to the lead wires extending out from them.  I don’t want to leave the splices out in the open, so I will make the splices inside a junction box and clamp them in place.  From there the cords will be anchored to the back of the booth, leaving enough slack to allow them to plug into the power strip.

    All of the splices will be twisted into wire nuts and coated with liquid electrical tape that I picked up from Micro-Mark.  At present I am modifying the hinges for the top panel and contemplating modifying one of my rolling carts to use for making the booth portable.   

[BETAQDAVE]

    This is the cart that I’m thinking of using for my portable paint spray booth.

    It is quite light and somewhat shaky, but with the weight of the booth itself and a little reinforcing I think it would work OK.  It is similar to the cart that I am currently using to make the booth, but it has a drawer section on the right side with five removable pull-out plastic drawers.  There is an easily removed protective cover panel that prevents the drawers from sliding out, so anything inside should stay put.  The bottom drawer could readily be replaced with a shelf to accommodate my sprayers’ compressor.  The only reservation that I have with it is the height.  I feel that since I am in a wheelchair, it may set the booth too high for convenient spraying, not to mention opening it up to change the filters.

    Unfortunately, shortening the legs could prove to be unfeasible.  So I guess I am curious to know how the fortunate ones that can stand up use theirs.  Does your booth sit just above your waist or higher?

    The cart that I am using to make the booth has no drawers, but the legs can be readily shortened to whatever height would work the best.  I will continue to be open to any thoughts on the mater since I can still work on the other facets of this project.

    Meanwhile, I am working on the electrical features.  The light fixture shown here is next.

    Using an old three wire extension cord, since the fixture needed a ground wire, I cut it off at roughly 18 inches from the plug.  The other end was stripped back to expose the three wires. The cord was run through a 90 degree cable clamp and securely clamped it in place. 

     If you notice in the photo, the fixture wires are solid, while the cord has stranded wire.   The solid wire had about ¾” exposed, so I left about 1 ½” of the stranded wire exposed.  That allowed me to twist the stranded wire tightly around the solid wire with my fingers.  Then I trimmed the end to fit into the wire nut and twisted that until it was tight.  Once all of the wires were joined together the nuts were turned down to allow me to seal the connection with the liquid electrical tape shown here.

    Now I proceeded to mount a switchable power strip on the front left side of the booth.  As you can see, it mounts with the keyhole system, so locating the screws to match needs a technique that I learned long ago.

    Using a strip of painters tape stretched over the holes on the back, I rub a soft leaded pencil over the holes, which gives me the location of the holes.

    Now the tape is applied to the location selected for the power strip.

    Now holes are drilled through the tape and the appropriately sized flat head wood screws are installed.  The tricky part is to adjust the amount of screw exposure to give a firm attachment.

 

    Once the strip is attached, I have learned through experience that an additional screw needs to be installed to prevent the power strip from slipping out of the keyhole slots as shown here.

    I got a start on the fan wire hookup.  A plastic electrical box was screwed to the booth between the two fans.  The wire between the box and the fans was wrapped heat shrunk plastic wrap to protect the wires and I nailed some cable staples to anchor them just before entering the box.

 

    Times up, so I guess I’m done for now.

[mtaylor]

Dave,

How heavy will the booth be?  I'd be worried about it being top heavy and easily knocked over.

[BETAQDAVE]

    Mark, despite its rickety appearance, it is quite stable and easily capable of supporting the booth.  After all, I have been using this four legged version of the cart shown below here to build the booth.  

    The primary advantage of this four legged cart is that the legs can be fairly easily shortened with a pipe cutter.  However, it doesn't have the drawer section for storing all of the air brush accessories.  If push comes to shove, I could probably fashion some sort of shelving to attach to it, but there's quite a bit more work involved for that. 

    Essentially, my choice depends on the optimum working height for using the booth.  If I do have to shorten it, it can only lower the center of gravity and thus make it even more stable.

 

[BETAQDAVE]

    Taking my hinges for the top panel to my shop drill press, I clamped it in place to drill additional holes for all of the hinge leaves.

    You can see from the sketch below that the holes nearest to the hinge pin would be too close to the edge of the top panel and would end up in the foam weather strip on the top edge of the back panel.

    Since the hinges came in pairs of two, I decided that four hinges would be better anyway.  The hinge pins are a rather sloppy fit, but by using all four of them it should help to reduce some of the slop.

    Returning to the electrical hookups, the fan wires were spliced in the plastic electrical box with wire nuts and given two coats of the liquid electrical tape. 

    The cords for the fans were encased in some flexible plastic cord organizer to further protect them.  The organizer was securely attached to the booth with several staples running across the back and left end panels of the booth to the power strip.

     Once the second coat of liquid electrical tape in the splice box set for 24 hours, the wires were pushed back inside the box and a blank cover panel was installed.

    The next thing to tackle will be making the top cover.

 

Edited September 13, 2019 by BETAQDAVE

[BETAQDAVE]

    I managed to start on the top panel by cutting out the opening for the light fixture.  Holes were drilled in the corners for using my saber saw, and I did use it to cut about two feet.  But, I noticed that the saw wasn’t following my line even though a guide was clamped to make it do so.  Upon closer inspection, I found that the blade was bending off to one side.  I assumed that is was due to the blades alignment being out of whack.  Since the procedure to get it realigned was rather tedious, I decided to just use a short bladed hand saw to complete the cut by twisting the blade a bit to force it back in line.

    I still used the saber saw to make the short cuts on the end and make a kerf enabling me to use my hand saw to complete the cut, but I guided it along the line by hand without the guide.  It turned out that I was able to cut faster and straighter with the hand saw anyway.

    Still, the cuts were a little ragged and needed to be evened out with rasp and sandpaper.  The back side of the cuts was especially rough, so I just eased the edges a bit.  I took out a sheet of 1/8” thick Plexiglas and laid it over the cut–out to size it with about ¾” overlap.  Using a felt pen the size was marked and it was set aside to cut later.

    Now I marked the location of the hinges evenly on the top side of the panel and numbered both the location and the hinges, as the hinge hole locations varied a bit.  The hinges were then set one at a time on the panel with one leaf hanging over the edge and I used them as a template to locate the holes for the stove bolts.  Those holes were then countersunk on the inside face of the panel to reduce interference with the air flow.  The hinges were then temporarily attached to make it easier to locate the hinge holes on the back panel. 

    Since my foam weather-strip was incorrectly shipped as ½” wide by ¼” thick rather than the 3/8” thick that I ordered, I needed to reduce the gap between the top and back panel.  Luckily the hinge holes had not been drilled yet so I just used 1/8” spacers rather than the 3/16” that I planned on using.  The weather-striping would thus be compressed when the top was closed to provide a tighter air seal.

    Returning to the Plexiglas panel for the light fixture, I decided to use my band saw to make the cuts to reduce the tear out on the backside of the cut.  Once the panel was cut out, I used a sandpaper block to finish the edges and round over the corners.

    Tomorrow, I plan to continue working on the top panel.

[BETAQDAVE]

    I gave the edges and top surface of the top panel three coats of paint yesterday after removing the hinges.  A final coat was also given to the inside of the booth and a bit of touch up to every hole that was drilled.  I think that it should be pretty well sealed to protect it now from humidity changes.

    I set up my drill press with a guide fence to locate 18 evenly spaced holes 3/8” from the edge of the Plexiglas panel.  I will be using some ½” long 9/64” pan head wood screws with flat washers to attach it to the inside face of the top panel.  The holes were drilled oversize with a 3/16” bit to allow for any movement between the particle board and the Plexiglas.   Things went along smoothly until I got to the last hole (of course), when the bit caused the Plexiglas to fracture and break off a large chip from the edge.  Apparently I must have used a little too much pressure with the drill.  Luckily it was in one piece and I just glued it back onto the edge with plastic cement and set aside to cure so I could finish drilling the hole later.

    The repair to the Plexiglas worked just fine and I finished drilling the holes today.  I decided to increase the size of the holes to ¼” to allow a little more room for expansion and contraction.  My guide fence on the drill press was still in place, so it was an easy adjustment. (I was very careful drilling them this time however.)

    Here is the current status of the booth.

 

[BETAQDAVE]

    Once the booth is in operation, the spray from the booth would cover the Plexiglas eventually so I decided to take Dons suggestion to use a trick used by dirt racers and motorcyclists referred to as: the tear-off.  This is accomplished by using a piece of transparent packaging tape stretched over the Plexiglas light window with one end doubled back about ½” to form a pull tab.  When the light cover gets too opaque from spray paint, you simply grab the pull tab and peal it off.

    You can put multiple layers of tape on the window to allow you to rip off the topmost layer one at a time.  This allows you to repeat this operation several times before having to open up the booth to put on a new set of tear-offs.

    On Dons booth, he had a single bulb light whereas my booth has two, thus making my light window a bit wider.  The tape only comes in a width of slightly less than two inches, but I will simply overlap two pieces of tape for each tear-off.  Applying these strips is much easier to do when the Plexiglas is removed from the top panel and laid out on a flat surface, so to avoid doing that too often; I plan on making four tear-off strips for mine.

    My next step will be to position the Plexiglas window on the inside face of the top panel and predrill some holes for the mounting screws.  Then I will proceed to make some mounting brackets for the light fixture.

[thibaultron]

I like the tear off tape idea! Thanks for the tip!

[BETAQDAVE]

    I positioned the Plexiglas over the opening on the bottom side of the top panel and traced around it to make it easy to re-position when removing it to install the tear-offs.  Using a center punch, all of the screw holes were located in the exact center of the Plexiglas holes so it would be able to expand and contract once it was screwed down.

    The Plexiglas was set aside and I used a 5/64” bit to pre-drill the pilot holes for the screws. (I purposely drilled them well under sized to allow the screws to get a tighter grip in the particle board.)   Once all the holes were drilled, the Plexiglas was re-positioned and all 18 of the ½” long 9/64” pan head wood screws were installed with flat washers.

    By flipping the top panel over and setting the light fixture into the opening you can see that the light fixture housing sits almost ½” proud of the particle board. Since this would allow light to leak out where it’s not wanted, strips of ½” particle board will be added to fill this gap and serve as a raised mounting board for the brackets. (It will also stiffen the front edge of the top panel.)  I fashioned a prototype of the bracket from a piece of galvanized tin shingle into this 1 ½” wide Z shape to mount the light on this raised mounting board.

     Using the remainder of the shingle, I fashioned the four light mounting brackets.  I applied some 1 ½” wide painters tape on the shingle for each bracket so all of the brackets would be a consistent size and would make the cut line easy to follow.

    The locations of the two bends from the prototype were then marked on each piece and one leg was shortened for use on the raised mounting board.

    The pieces were the marked for the mounting screw holes. Each long flange was drilled with a 1/8” bit for two Philips head bolts for attaching to the fixture.  Each of the short flanges was then drilled with a 9/64” bit for a pair of wood screws for attaching it to the raised mounting board.

    Using my machinists vice, the flanges were bent over on the marks previously drawn on the tape.  Unfortunately I don’t have a bending break, but the tin was thin and bent readily.

                                                        

    I placed the brackets where the bolts wouldn’t interfere with anything inside the fixture.

    The fixture was opened up and the brackets were clamped to the fixture so I could use them as drilling guides for the bolts.  I drilled eight 1/8” holes and the 3/8” long 7/64” bolts were then installed from the inside out, with a flat washer, a lock washer and hex nut on the outside for each.

    Despite my efforts to keep the particle board straight and flat, I discovered that when the top panel was test fit, the panel was no longer covering the entire width of the front opening.  Measuring the overall width of the booth at the bottom was 31 11/16”.  However the same measurement at the top was now a full 32”!  Checking the upper corner of the left side panel closer, it was found to have warped.

    Taking out a bar clamp, I tightened it until the top and bottom measurements were equal.

    The only easy solution seemed to be adding a wood brace across the opening at the top.  I found a scrap of 5/4 clear pine that was long enough to fit and I trimmed it down to 1 1/2'’ wide on my band saw.  It was a rather rough cut, but a block plane, a scraper and a little elbow grease cleaned it up just fine.  Measuring the space with the bar clamp still in place, it was cut to length and put in place.

    The fact that my booth is wider than the original probably contributed to the need for one.   While the brace wasn’t a feature that I had planned on having it will certainly make it stronger and prevent the top panel from sagging.  The brace, being as slim as it is, shouldn’t detract from the view-able area very much.  I’ll just give it a coat or two of paint and anchor it in place with some small angle braces. 

[BETAQDAVE]

    Not much accomplished today, but I managed to get the brace painted and attached.

    Not sure how much I will be able to do on the booth for a bit, as I need to get started on preparing for the holidays which includes the Xmas displays.  Here is the current status of the project.

[BETAQDAVE]

    Since it's raining today looks like I get to work indoors again today, so back to the shop.  I ripped down some of my scrap ½” particle board into several 1 ½” wide strips to make the mounting board for the light fixture.  These were then cut to length, tightly butted together (to screen off any extraneous light) and screwed into place with some ¾” Philips flat head wood screws.   I set the light fixture in the opening and used the pre-drilled holes in the brackets as a guide to locate and drill 7/64” holes for some ½” long 9/64” Phillips round head wood screws that were then driven home.

    The lines were redrawn inside the booth to mark the face of the vinyl filter brackets.

    I ran a bead of glue where the vinyl bracket would seat to help seal the gap somewhat.

    Before the glue could set, the vinyl strip was placed and I drilled five 7/64” holes into the bottom of the booth for some more of the ½” long 9/64” wood screws to draw it down tight.

    Using four screws apiece, this procedure was followed for the two vertical vinyl brackets.

    Once the vinyl brackets were all installed, I did a test fit for the rest of the filter assembly and was satisfied with the fit.

 

 

[BETAQDAVE]

    Continuing my rainy day posting.

    While contemplating my next phase of the build, I discovered while reviewing post #20, that the hinges were placed in error on the top side of the top panel, which in itself was not a big deal as far as the placement of those holes, but it caused another problem elsewhere. The original idea was to have the pivot point of the hinges half the thickness of the compressed weather-strip above the top edge of the back panel as shown in post #19.  That was to prevent the weather-striping along the top of the back panel from being displaced when opening the top of the booth.   Since the hinges were used as a template for drilling the holes on the back panel, those holes were now 5/8” too high.  OOPS!

    Flipping the top panel over to expose the correct side of the panel, the Plexiglas window was removed and set aside for installing the tear off sheets later.  The hinges were then temporarily attached to the bottom side of the top panel and the outline of the hinges was traced onto the panel as shown here.

    Since this will now be the inside of the booth, I decided that making the hinges flush with the surface would improve the air flow.   Taking the hinges off again, I took out a fresh sharp blade and put it into my scalpel handle to go over the marked outline several times.  I took a ¼” wide wood chisel and gave it a good sharpening.  I roughed out the majority of the material with that chisel and one of my small modeling chisels.  I then finished up with my Dremel tool mounted in a homemade router attachment and smoothed out the bottom of the recess to the proper depth.

    Since the screw holes in back panel would no longer line up, those holes needed to be plugged.  I took a length of 3/16” square basswood, rounded off the corners, coated with wood glue and tapped it into those holes until the far end was slightly beyond flush with the inside of the booth.  I cut off the remaining length on the outside slightly proud of the outside face.  This was repeated for all of the remaining holes.  Once the glue was allowed to set, the remaining ends of the plugs were sanded flush.

        A quick dab of paint and no one is the wiser.

 

        The recesses for the hinges were also given a coat of paint to seal the particle board and the hinges were reattached to complete the repairs.

    The inside of the plugs were also painted and a heavy coat of paint was applied to the seam of the vinyl brackets to give me a tight air seal around the filter assembly.

    The final item to be completed today was painting the light mounting boards sealing all joints to completely eliminate all the extraneous light at the joints.

 

[BETAQDAVE]

    Just a quick note here.

    Now that the hinges are correctly attached to the bottom side of the top panel, the hinges need to be re-attached to the back panel.  Since the weather-stripping came in ¼” thickness rather than the 3/8” that I ordered, I was a bit concerned about the air seal at the top of the booth.  So I checked the fit of the top panel and found that some of the top edges were a little too uneven for my taste where the panels met.  Since the weather-stripping is so thin now I don’t think that it would be able to bridge the gap enough, so I need to trim down those high areas.  The most efficient method available to me would have been my belt sander, but I don’t think that I would be able to handle that anymore from my wheelchair.   (Not to mention the clouds of saw dust that it would produce!)

    Edge trimming ½” particle board will take some ingenuity on my part keeping the edge square and smooth by hand without breaking up the edges.  I guess that I will have to think on that for awhile.

[thibaultron]

Sharpen a wide chisel, buy a couple of lengths of square metal keystock. Then clamp or screw then to the top, and run the chisel along them to flatten the top edge.

 

Before I catch heat about running a chisel edge across metal, use a cheap chisel.

[BETAQDAVE]

    Hold the phone there dummy!  What was I thinking?  Why try paring down the tough particle board when it’s much easier to add some softwood shims that can then be lightly sanded down even?  Having a large surplus of 1/16” thick basswood strip wood in various widths, that’s just what I did!

     I took a long flat metal bar and laid it along the top edges of the booth to locate and measure the problem areas.  The biggest discrepancy occurred where the top edge of the baffle panel sat a hair over 3/32” above the right side panel and about 1/16” above the back panel.  The back corner of the left side panel sat about 1/16” shy of the top of the joint with the back panel, so I can use a tapered shim there.  The back corner of the baffle was actually a little low also and needed a bit of shimming.

    I took a length of ½” wide 1/16” thick basswood and glued it to the top of the right side panel for the first of two layers to go there.  Not having any edge clamps available, I resorted to taping it in place. 

    The low corners of the baffle and the left side panel were also given short lengths of tapered shim to correct those areas and were glued and taped down.

    You can see here that the front brace was also depressed a bit, and while there is no concern of air leakage there, if left shy the top panel would not sit flat.  So that needed to be shimmed too.

    A single layer of the 1/16” basswood sufficed to shim up most of the errors, and an extra layer handled the remaining areas.

    A second layer of 1/16” shim was now added to the right end panel and applied.  The back panel and brace were then done similarly. 

    Now with all areas shimmed and taped down, I just needed to set the booth aside for the glue to set up for 24 hours or so before starting sanding operations.

  

Edited October 26, 2019 by BETAQDAVE