Introduction: Giant Saw Blade Table!
While visiting a friend in another town, I came across a quite large concrete saw blade in a salvage yard down the road from his house. I was mostly looking for scrap metal to keep around the shop as extra material for whatever comes up, but my friend said, "you know, that thing would make a really cool table." He was right! I got to work as soon as I got back home. The evening after I started, I was browsing Instructables and stumbled on the Trash to Treasure Contest, and decided to make this my first Instructable! I'm very excited to finally contribute to the site after lurking for so many years.
-Cutting Torch (optional)
-Metal Lathe (optional)
-Milling Machine (optional)
-3D Printer (optional)
-Aluminum Foundry Setup (optional)
-Electric Hand-Held Drill
-Drill Press (optional)
-Hacksaw or band saw to cut up aluminum castings
-4" Round Steel Tubing
-Large Saw Blade
-Steel C Channel
-Bed Rails or Steel Angle
-Scrap Aluminum (any shape, cut into melt-able sizes)
Step 1: Create Patterns for the Aluminum Endcaps
One of the key things I was designing for with this table was that I wanted it to be able to be easily moved without the use of a pickup truck, so I wanted make sure it could be taken apart. These endcaps solve that problem. Now, you can easily weld thick, flat plates to the ends of the tube and drill holes in them and it would serve the same purpose. If you choose to go that route, feel free to skip to Step 4! However, since I'm not great at welding round things and didn't have any thick steel plate lying around, I decided to sand cast them from aluminum.
The first step is to design and 3D Print a pattern to make the mold. The pattern can be made from wood or other materials as well, but 3D printing is preferable if available. Just be sure to add draft!
If you wanted to go with my design, I've included Fusion 360 files as well as STL files here. Note that I had to print the flat part in two pieces in order to accommodate my printer's small build volume. They don't need much infill - I used 20%, but I did make sure to use the finest resolution possible. This helps when pulling the casting from the mold.
Step 2: Make the Endcap Molds
The next step is to make the molds for the endcaps. Before beginning to ram up a sand mold, I always coat my parts with as much baby powder or talc as I can get to stick to the surface. This helps release the patterns from the mold.
Starting with the flat part of the pattern, ram up your mold with two 1" dowels (or other round thing you have) on either side of it (these will be our sprue and riser). If you're using my design, be sure the recess where the tubular half nests into the flat half is facing the ground as you ram. This is the recess shown in the second picture of Step 1.
This may be bad practice, but in order to make the molding process easier, I covered the open end of the tubular portion with tape to prevent any sand from getting in. This makes it easier to pull out after ramming that half of the mold.
Once the flat side is rammed up and the tubular end is taped off, flip the flask over, and place the tubular end of the pattern in the recess in the flat half. Coat the sand in the flat half of your mold and the tubular pattern with baby powder, and ram up the rest of the mold.
Pull the halves apart, and very carefully remove them from the sand. To make this easier, I like to use small wood screws drilled into the surface of my patterns to make them easier to grab. If they're being extra stubborn, give them a few taps with the end of a screwdriver to help loosen them up.
Now that the tubular portion is out, you can remove the tape and use the hollow area of the pattern to make a "sand castle." If you pack it tight and your sand is tempered well, you should be able to use this as a core which you can drop directly into the hollow left in the mold by the tubular pattern.
At this point, all that's left to do is cut gates from the dowels to the inside of the mold, and you're ready to put the mold back together and pour!
Step 3: Pour the Molds
OBLIGATORY CAUTION STATEMENT
This part is pretty dangerous. Wear eye, face, hand, foot, body, EVERYTHING protection when handling molten metal. Or just don't do it at all. But if you're dead set on doing it, this is how I would do it (safely!) -
Put your aluminum scraps in a suitable container, and stick them in your furnace! I used a small pottery kiln my buddy gave me as a furnace.
As for containers, graphite and other ceramic crucibles can be found for cheap on amazon and ebay, and they work great! I unfortunately didn't have one on hand that was big enough, so I used a heavy-duty cast iron pot I found at an estate sale. If you do end up using an iron or steel container, make sure its walls are at least 1/4" thick, as the aluminum can burn through thin steel. Speaking from experience, this can be an absolute disaster.
Once your aluminum is nice and molten (I usually heat to about 800C), pour it in the molds you made in step 2 and let it cool for about an hour before digging it out (I'd recommend wearing gloves while digging unless you let it sit over night).
Step 4: Cut the Column to Length
For the column, I used... well, a column. It was salvaged from a carport that was being demolished in my neighborhood a few years ago. It's about 4" in diameter with walls about 3/16" thick.
I used a ball peen hammer to chip away most of the old paint (put down a tarp to catch the paint chips!), then I cut off a section about 19.5" long and squared off the ends with an angle grinder. Protip: to get nice square ends on pipe, wrap a piece of tape around it twice, making sure the edges align on both wraps. This gives you a nice guide to go on.
If you're skipping the castings, feel free to skip to Step 6!
Step 5: Clean Up Endcap Castings and Fit to Column
Remember those castings? We're not done with them yet.
We want them to nest neatly inside of the column we just cut, so we'll need to machine them down. Cut off the sprues and risers, chuck the endcaps up in the lathe, and go to town! The inside dimension doesn't need to be an exact fit, but it shouldn't be too loose either. Just enough for a reasonably snug fit so it doesn't wobble too much. Be sure to face the back of the flat side as well so things mate up nice and square later.
Once the endcaps are fitting nicely inside the column, we want to connect them. I decided my best option here was to match drill holes, then tap threads into the aluminum endcaps. I had recently come across a bunch of 5/16-18 allen screws after disassembling some metal thing I had salvaged a few weeks ago so I used those, but the exact size isn't extremely important.
Once everything is screwed together, there's just one thing left to do with the column assembly!
Step 6: Drill and Tap Circular Hole Patterns in the Castings
If you opt to skip the castings, the same steps here apply to the plates you cut to replace them. I'd recommend doing this before you weld them to the column to make handing them easier.
We need tapped holes for both the saw blade and the truck rim to bolt into. You could do this by lining up the castings with the holes and carefully center punching the hole locations by eye, but I got a rotary table a while ago and haven't had the chance to use it yet so I decided to set it up on the mill.
The saw blade has a 6-hole pattern, and the truck rim has a 5-hole pattern, so I spot drilled each casting accordingly on the mill. I then started to drill pilot holes in the same setup, but realized my mill had run out of Z-travel with the rotary table setup and I could not remove the collet without tearing everything down, so I just took the castings over to the drill press and drilled them out there. After that, I tapped each hole for 1/2"-13 on the rim side (the biggest tap I had on hand) and 3/8"-16 on the saw side. These sizes were determined strictly by what I had on hand and the size of the existing holes in the saw and truck rim, so be sure to adjust to the materials you're working with. That being said, if you have a tap large enough to fit standard size lug bolts for your truck rim, I would recommend doing that so you can use lug nuts and studs in the final assembly (more on this later)
Once you're done here, take a moment to bolt everything together and admire how far you've come! This is also a good time to check for anything you might have missed along the way. Now, onto the base!
Step 7: Prepare the Base
For the base, I used some scrap 4"x1" c-channel sections (picked from the dumpster at my old job) and an old truck rim I found under my house when I moved in (there was also an aquarium left under the house that I've been wanting to work into a project, but I couldn't find a place for it here). The c-channel had these tongue-like features cut into the ends of them, so I decided to work that into the design.
Using the cutting torch (angle grinder also works), I made a few cuts into the rim so that the tongues would slide in and the channel would sit flush against the edge. I unfortunately lost the pictures of my torch cuts, but I made a quick model in Fusion 360 to illustrate what they should look like. You just want an area for the tongue to fit in, plus relief to allow the channel to sit flush with the rim.
After making the cuts, slide the channels into their slots and check for levelness on the rim, and on the upper endcap. Make any adjustments needed with shims and clamps, and weld the tongues in place. When setting everything up for welding, also be sure your c-channels are all touching the same plane. If you don't have a flat surface like I did, the saw blade makes a decent enough reference surface for these purposes. Once you're ready to start welding, I recommend tacking the corners on each slot before welding a full bead. That way you can go back and make any adjustments to keep things level.
My c-channel had some pretty thick powder coating all over it, but I was able to remove the majority with the heat from my torch. It can be removed with a grinder too, but it may take a bit longer. Regardless of the route you take, be sure to do it outside, and wear a ventilator! Ideally, your metal would already be clean so hopefully you won't have to deal with this like I did.
Step 8: General Cleanup
Take some time to remove loose rust and any remaining paint from the column and saw blade. This will be necessary in the finishing step. I used a wire wheel and flap disc on the grinder to do most of this work, but a lot of the paint on the column was removed with a ball peen hammer. Be sure to wear a respirator when grinding off rust and paint!
Step 9: Stiffen Up the Table Top
While grinding off the rust from the table top, I noticed it was a tad bendy. Not flimsy, just a little springier than I liked.
To remedy this, I cut off a few sections of bed rail I had laying around and welded them to the bottom. This stiffened it up significantly. The lengths aren't critical. I just eyeballed the first one and used it as a guide to cut the remaining 3.
Step 10: Final Finishing Work
Your table is done now if you want it to be, but I plan on keeping this uncovered outdoors so I want to give it a little protection.
I decided to keep the column and saw blade looking mostly raw, but I wanted to prevent additional rust while sealing in the pitted look, so I applied two coats of Penetrol to each. Penetrol is technically a paint additive, but a lot of rat rod owners use it to seal in the pitted, beat up look on their vehicles while preventing rust from spreading. The finish is like matted gloss. If you hold your hand up to it very closely, you should be able to see a slight reflection in the right light, which I really love.
It can be a little tricky to apply, but I've gotten good results by just wiping it on in thin layers with a clean paper towel. Be sure to clean the metal with acetone or mineral spirits before applying!
The base was pretty ugly after I removed the powder coating, so I opted to spray paint it. The rim got a flat black paint job, while I gave the c-channels the "Billy Eilish Hairdo" treatment. You want to pull the spray can away from the surface as you near the middle of the channel somewhat abruptly, and you'll achieve kind of a gradient finish. If you mess up, no big deal! Just switch to the opposing color and try to smooth it back out. Just happy accidents here!
Step 11: Putting It All Together
We're finally ready to assemble the table for the last time. We've done this a few times already up until now, but this one is for real!
To attach the base to the bottom casting, I would recommend using actual lugs and lug nuts because they will seat better. This is what I should have done, but I didn't feel like going to the hardware store for the right sized tap. Instead, I made some screws with tapered flanges on the lathe using some steel cutoffs I had in the scrap bin.
Next time I'll just go out and buy the right tap, because this ended up taking up an entire afternoon on my old machines! The material was also a good bit larger than what I needed so I spent some time turning it down to size. The process was fairly simple though - once you turn the threads on your part, set the compound over to about 45 degrees to cut the tapered flange and part it off. After that, you can use a hex nut (or better yet, a collet block) to index the part on the mill in order to cut the flats on the head.
Once the bottom casting and base are in one piece, you can attach the column to the bottom casting via the screws we drilled and tapped for in Step 5. I used a cordless drill to make this go a little faster. Do the same thing with the top casting. Be sure to snug everything up nice and tight so the table doesn't wobble! A little loctite might not be a bad idea here since you can still disassemble it via the attachment points between the castings and the base/top.
To attach the saw blade to the top casting, I finally broke down and bought some 3/8"-16 countersunk phillips head screws from the hardware store. They don't necessarily NEED to be countersunk screws, but the holes in my saw blade were countersunk so it just felt right.
Now that everything is together, there's only one thing left to do...
Step 12: Take a Load Off!
Your table is done! Grab yourself a drink and enjoy this lovely springtime weather!
Runner Up in the
Trash to Treasure Contest