NOTE: Furniture Grade in this case meaning a dolly that does not have to make a living at working.
The skills that this makes use of is:
- Dimensional layout
- Use of power tools and some hand tools
- Precision assembly
Step 1: Safety and My Background
BACKGROUND: My background is that of what I would call the average guy that enjoys putting things together and is willing to tackle most any project - with the exception from the "average" in that I spent almost 3 years as a short run production commercial custom cabinet maker in college. Next to my dad, the "Bigger Hammer Principle" crew of Dean U. (owner), Al S. (foreman) and Tom B. helped to instill the craftsmanship I bring to any project. Let's keep in mind that college was 30 years ago and more than anything else the cabinet shop spoiled me in that I remember how little time it took to produce high quality work using very expensive precision tools. The TechShop goes a long way in reproducing that environment! If you are lucky enough to live near one check them out.
Step 2: Notebook
Step 3: Measurements and Materials
B. Thus, the base of the unit was 36 inches wide by 19 inches deep. I decided upon 2x lengthwise pieces 6 inches wide and 2x crosswise (front to back) pieces 4 inches wide. There was no "engineering" that went into this. When I was at the lumber yard they had a pair of 72 inch long and 1 inch thick planed and edged red oak that were 6 and 4 inches wide. I could get the two lengthwise pieces and 2 of the crosswise pieces out of them.
C. They also had 4x hard rubber casters (2x each locking and non-locking). The casters were just less than 3 inches tall and the 2x planks would be another 2 inches thus I would come in at 5 inches of height - less than the 6 inches maximum I was concerned with. Each caster had 4x mounting holes for a 5/16th diameter bolt.
D. I used the thickness of the caster mounting flange and the 2 inches of the wood plus the thickness of the 2x flat washers, 1x locking washer and the 1x nut and then less the height of one of the flat washers and head of the carriage bolt to determine that I could use a bolt 2.5 inches long. That required then that I have 4 sets of 4 bolt sets, i.e 16x of everything: carriage bolts, top flat washer, bottom flat washer, bottom locking washer and nut.
1. The flat washer under the head had to be one size larger for the bolt head to lie flat against it as the underside of the carriage head has a small square shank that does not allow it to sit flush in a 5/16th flat washer (learned this the hard way).
2. I subtracted the height of the carriage bolt head and one washer so that we would compensate for the recess of the bolt into the top plate of the dolly - the lat file would have to sit flat upon the dolly and not rest on the carriage head bolts instead.
Step 4: Tools
- Sliding Arm Chop Saw
- Drill Press
- Spade drill bits (excuse to buy a set) ...half the reason I start a project!
- Twist drill bits
- Electric (or Cordless) hand drill motor
- Hand drill with rosebud chamfer bit
- Tape measure
- Layout tools: pencil, scratch awl, knife, small adjustable square(s)
- Clamps: I used two speed clamps
- Socket wrench set
Step 5: Cutting Wood to Length: TechShop Detroit
- Since the casters are symmetrical I laid out the hole pattern on the top of the top plate (6 inch wide long piece).
- I used the nut to provide for one nut's width from both the front and side edge.
- Carefully drew the inside "circle" of each bolt hole on the top plate.
- By eyeball I marked the center of each drawn circle with an "X"
- I then pushed an awl into the marked "X" to provide a guide for the spike of the spade bit operation.
- I then repeated this on the other 3 corners.
- I would have brought with me to the TechShop my layout tools: combination square at the minimum - using a single small nut to align the casters was expedient not convenient or easily repeatable.
- I would have marked the same holes on the bottom 4 inch cross plates while I still had the orientation right there in front of me.
Step 6: Recess for the Head of the Carriage Bolt: TechShop Detroit
- When using a flat washer under the head of the bolt the recess hole has to be a little larger than the outside diameter of the washer.
- My washers were 1 inch in diameter and the next larger spade bit was 1.125 inch diameter.
- The depth of the carriage bolt head and its flat washer was about a quarter inch - the same thickness as the 5/16th nut which made for some convenience since I did not have a small pocket depth ruler (I do now).
- Once I had the depth of the drill travel dialed in and locked I centered the spade bit's center spike in the guide hole I made with the awl and clamped the work in place with the bit holding the work till the clamps are set.
- Repeat for the 16 recesses that need to be created.
- Clean up the area.
Step 7: Drilling the Carriage Bolt Holes
From here on out I am at my home "workshop", i.e. that area behind the furnace.
Drilling the 32 holes (4 in each end of the 4 pieces) for the caster mounting was the most tedious of the entire operation.
- The recess holes are already positioned this we just have to drill down the center of the holes using the spade bit center spike as a guide.
- I used a 3/8th inch bit to provide for some play in the assembly when tightening the bolts at the end.
Bottom Plates (Cross pieces):
- We first have to mark the position of the bolt holes then drill them.
- Initially I expected to just lay the appropriate top plate on its corresponding bottom plate and mark the centers through the existing holes. To say that was problematic was an understatement.
- I settled on using the same positioning method as I did when laying out the hole positions with the top plates.
- I changed the procedure only in that I used a combination square set to the same nut width as before and marked the positions.
- Using an awl I crated a guide for the drill bit and drilled the holes.
NOTE: using a drill creates a lot of very small "curls" of wood (oak being hard by nature means these curls will roll) under your feet and on a slick surface (linoleum in my workshop area) will make maintaining a good purchase between you and the floor difficult so I cleaned up the floor after each batch or "end" of 4 holes.
NOTE: I also chamfered both sides of each hole on all boards to eliminate the slight tear-out that is created by the twist drills.
Step 8: Assembly
- Carriage bolt, larger of the flat washers then insert through the cross piece with the recesses then through the short cross piece, then through the caster mounting flange, then the 5/17th flat washer, the locking washer then the nut and make finger tight.
- Repeat for one of the other holes for that caster.
- Repeat that operation for the other 3 corners: 2x bolts each and finger tight.
- Check alignment looking for flush and square.
- NOTE: Flush is less important than square and square is relative to the bottom of the lat file. Our aim was to be reasonable for the purpose at hand...no one's life is hanging in the balance and although you will know its dirty little secrets it is highly doubtful anyone will see any slight offsets underneath the lat file. Life is short - be reasonable.
- Any offsets beyond what you are willing to live with can be adjusted by reaming the appropriate holes in the appropriate direction to allow for adjustment.
- Once the dolly is as square and flush as you like then gently tighten the bolts down a bit more. assemble and insert then tighten the remaining bolts till the heads sit against the washers and the lock washers are flat. No gorilla impersonations needed here - half a rotation past snug is probably fine - remember this dolly will not have to work for its living...it just has to sit there and look pretty.
Step 9: Final
Post project review:
- Although I did not put a finish on the wood it certainly would have been more "furniture grade" if I had.
- Possible consideration is a layer of "non-skid" applied to the top plate: either stair tread grit or bathtub anti-slip application. Even a layer of drawer cabinet foam would work.
- I would have used a template/jig to transfer the bolt hole locations since it was a repeatable sequence and needed precision - I could have made a simple paper jig (similar to the way they mark for installing a door knob or dead bolt). A 4x6 note card with a fold on the short end and then align it flush to the outside and flush with the folded edge and poke an awl through the marked holes.
- I could also have clamped the boards together when drilling through the top plate and eliminated the tedious marking of the boards altogether.
- Lastly, before setting the lat file on the dolly I would have lowered the leveling feet in the back of the file for an added measure of stability.