The paint booth project progress continues to slowly take place. As usual I continue to be bombarded with side projects which always end up slowing down the main projects. The goal was to have the booth completed before the New Year. FAIL!!!!!! I figured out how to solve that problem, no longer set any goals. There we go…right back on schedule.
The main frame of the booth was previously finished. Before I can start to tarp the entire structure I needed to fabricate the intake air assembly. The plan is to create a pressure booth therefore a fan, and duct work, need to be mounted on the intake side. I had previously calculated out the air needs of the booth. Total booth volume is approximately 936 cubic feet. I want to ensure I can double the air exchange every minute meaning I need to find a fan capable of at least 1900 CFMs. My fan options open up since the fan will not be mounted on the exhaust side and therefore will not be exposed to combustible fumes. Unwanted explosions should not be too much of a factor. Of all the fan and motor assemblies I looked at none of them were perfect for my application. So I decided to build a fan assembly that would suit my specific need.
After flipping through pages of a local appliance parts supply catalog I was able to find a 22” 4 blade aluminum fan with a pitch of 27 degrees that was capable of producing 3640 CFMs of air movement. The horsepower requirement for the fan was rated at .37 horsepower with a max speed of 1420 RPM. I was able to find a surplus 1 horsepower treadmill motor with an RPM of 1750 for $20. This was going to work perfect. Since the rated fan CFM was overkill I would be able to pulley down the fan rotation to get the spec’d RPM. Once the paint booth is completed I will then be able to do further testing. If the CFM movement needs to be tweaked all I will need to do is re-pulley the system.
So I stated the ventilation portion off by welding up a collapsible aluminum frame to support both the fan and the duct work. The frame will fold in flat to the main frame in order to accommodate storage. The idea is that the fan assembly will need to be removed and stored separately from the main frame. With the frame built it was on to the fan assembly. Using some 11 gauge sheet metal a circle was cut and then lined with 1” ring rolled flat bar. With some spare aluminum and a couple of flange mount bearings I was able to fabricate a fan support. The treadmill motor has no case to it as it is designed to mount inside a treadmill assembly. Using some muffler clamps I was able to build a mount for the motor that allowed it to be suspended by its rubber end mounts. Hopefully having the whole assembly rubber mounted will reduce my main frame from rattling apart.
Since I am unsure of what final RPM I will be running I built the mount for the motor out of a length of angle iron. Since different pulley sizes will also impact my V-belt lengths having the extra bit of angle iron will allow me to customize my belt tension adjustment.
I have yet to build a shield for the fan blade. As it sits now I am sure it would do some serious damage to human body parts should something decide to get in its way. Before I finalize the fan assembly the rest of the booth will need to be completed and performance testing will be required.
Next step on the road to completion will involve having to secure a tarp to the main frame assembly. I am dreading this part simply because I am a one man operation that is going to be wrestling a 30’ x 40’ tarp over the skeleton and then having to trim it a fasten it. I suspect a calm demeanor and deep breathes will be involved.