So I came what I thought was a WRX bucket seat but turned out to be a Celica bucket seat at the Pick and Pull the other week. So I decided to make a new computer chair.
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The Materials/Supplies:Car Seat: This comes down largely to personal choice (I assume because this is WSC that means WRX/STI seats) but there are certian traits one should look out for in the seat that can make your life a lot easier.
1.) How are the rails attached to the frame of the seat? If they're easily removed it will make your life a lot easier. Unfortunately with my seat its all rivets and spot welds so I'm going to have to zip cut them off at some point.
2.) Distance between frame/slider rails on the seat. The farther apart they are the more room there will be to mount arms for your chair if you choose to do so. It will also make the adaptor plate easier to recess into the seat.
3.) Where are the mounting holes for the frame of the seat? On my seat they were directly on the bottom pointing straight down, which made fabricating the adapter plate and doing the layout reasonably easy. If they are on the sides of the seat you will need to make L brackets to be able to attach the seat to the adapter plate. Which is extra work and more of a pain.
The Donor Office Chair: Kijiji as always is generally your friend here though it can also complicate things if you don't have much information on the chair. There are once again a few things to look out for/consider.
1.) Don't buy a cheap quality chair. You plus the weight of the car seat could be too much for a poor quality base to handle. It could break, be unstable, or the hydraulics could struggle.
2.) Width of the outriggers. The wider the better as they will provide more stability.
3.) Easily removable back. Most chairs have an easy to remove bottom, but the back isn't always.
4.) How does the base attach to the seat itself. Here we are looking for three things, for the base to be separate from the seat itself, and for the base to be nice and flat, and have good surface area.
5.) How do the arms attach. Ideally you want arms that wrap underneath the chair so the bracket is horizontal. Also having them be separate from the base will make things easier and give you better end results. If the arms are too close together and attached to the base it could prevent you from mounting the seat.
6.) Adjustability. The sky is the limit here but also recognize that obviously some things will become useless (ie any adjustability to do with the chair back). Two key features I would look for would be locking tilt, and I got lucky enough to find a chair with a base that slides back and forward similar to how the Car seat would.
The Adapter Plate: I chose to make mine out of wood for ease of construction, and not having easy access to metal working supplies. I went to Lowes and bought a 2'x4'x3/4" sheet of maple and had them cut it up into 3 of the dimensions I needed for my adapter plate so I had a couple spares in case I screwed up. Make sure whatever you decide to use is plenty sturdy, I'd suggest using laminated hardwood plywood 3/4" thick. Hardwood is strong, it being laminated makes it less likely to crack along a grain line, and the thickness is added insurance.
The Hardware: This will depend largely on the kind of car seat you pick up. If the bolt holes are on the bottom of the seat facing down I would suggest using my method of threaded rod. Make sure the lengths of rod are nice and long, you can cut them down later. If the bolt holes are on the side of the car seat you will need L brackets. You can either buy premade ones; or pick up some flat bar, bend it, and drill holes in the desired locations.
Ensure you use washers and locknuts/lockwashers at every mounting surface. Especially important to use large "fender washers" on the mounting surface to the adapter plate to distribute the load.
I suggest also using the nut inserts for base and arms of the chair on the adapter plate. It will make life A LOT easier taking the base and arms on and off.
If you're going to be replacing the hardware that came off of the base instead of reusing it make sure you take into consideration clearances. For almost all the bolts on my chair they were all flat and recessed because the base and the arms slide overtop of the bolt locations. If I replaced them with a protruding hex head bolt things would not have worked out.
The Tools:Some things you can get away without, but this is what I suggest having.
1.) Measuring tape
2.) T-Square
3.) Two wrenches to match your selected hardware size(s) (Gearwrench makes life a lot easier)
4.) Large Phillips Screwdriver (most chairs are assembled using large phillips hardware, if you only have a small phillips it will strip them)
5.) Drill
6.) Drill bit set
7.) Hammer
8.) Vicegrips
The Budget:This is the rough breakdown on the costs for my particular project. Your mileage will obviously vary depending on what you source for an office chair and a car seat.
Celica Seat: $30
Office Chair: $30
Adapter Plate: $20
Hardware: $30
Total: $110The Layout:Proper layout is 90% of the job as most of the custom fab here is an adaptor plate. As such all the holes must line up with the hole pattern for each respective peice. Furthermore they must have the correct spacing relative to the mounts for the others. It isn't rocket science; just careful planning, double checking, and taking your time.
There are a few tips to make your layout go smoother:
1.) Did you say "pfft I don't need a T-square" when you looked at the tools list? You're going to have a fun time getting everything lined up without it. It makes things go faster, and massively aids in accuracy.
2.) Don't trust that the board is perfectly square. What this means is not taking measurements from the edges of the wood. Draw a centerline across the board using the T square vertically and horizontally. All of your measurements will come off of this datum line, ensuring everything lines up and is the correct distance apart.
3.) Don't just measure out to the points where you need to drill holes and then only mark that spot. Run a line across the whole length of the board vertically and horizontally through that point. These lines make great reference lines, and if the line isn't parallel to the other vertical and horizontal lines its easy to see if something is wrong. You will see by the end my adapter plate looks almost like a grid with all the lines trough it.
4.) With all the lines running across your board the intersections and the spots where you actually need to drill can become confusing. So make sure when you plot your points to drill you circle that intersection.
5.) Sketch out your plan and write down all the distances and dimension first. Then double check it. This doesn't have to be neat by any means, this is a cocktail napkin kind of thing. I didn't even put in mild effort to freehand a straight line. All that matters is you have a good visualization of what you intend to do, and have the distances worked out between the lines/bolt holes.
6.) Put together the various pieces at every stage to ensure everything is where it needs to be and isn't conflicting with anything else. This is especially important because deciding where to put the various pieces relative to each other is more of a freehand thing. Then you go back to doing the proper layout for their bolt holes.
7.) Speaking of where to put each piece relative to each other; don't forget to take into consideration the center of gravity of the chair. You want to be able to recline the seat without being worried about it constantly wanting to tip over. So be sure to spend some extra time looking at your distance options.
8.) When using the measuring tape avoid using the tang/hook. Use the 10" mark then subtract the 10" off of your total. Why 10"? Because it you went off of another mark, say 1", it would be very easy to screw up and forget to subtract the 1" off the total leading to things being off. Similarly its easier to just subtract 10 off of something than other numbers. It also gives you room to work as the hook/tang is now 10" away from your measuring point.
The Fabrication:Assuming that you got whatever store you bought the wood from to cut the sheet to size for you all the fabrication here is just going to be drilling, bending itshay out of the way on the seat, and in some cases cutting off things on the bottom of the seat for added clearance.
For tips on this theres not really much:
1.) Drill pilot holes. Large drill bits like to wander and start off target when they bite, remedy this by choosing a smaller drill bit and drilling a pilot hole first. I was guilty of forgetting this when I drilled my first hole and it made a little bit of a mess.
2.) Drill the holes a little larger than needed for the threaded rod. I'm not talking like 1/4" of slop, just enough breathing room so that the plate doesn't have to be pushed on perfectly square for everything to line up. The fender washers will more than make up for the loss of strength from the larger holes.
3.) Be careful to ensure you are drilling straight. A hole can get pretty cockeyed over the course of 3/4" and it can throw your carefully planned layout out of whack, and make fitting everything together a pain, or impossible.
