My first real project - garage ceiling shelving

[chrispitude]

Hi dusty,

These joists (thanks Tim!) are 16" OC and are also the floor joists for the two bedrooms above.

- Chris

[Ed in Tampa]

What are these joists? Are they 2x stock or manufactured beams. If they are beams you better check with the manufacture before you mount any studs to them.
If they are 2x stock again I caution you be sure you know the load limit depending on size of the joist. You don't want your floor to sag or fail.
Ed

[chrispitude]

Hi Ed in Tampa,

They are real 2x joists and not engineered joists. They are 2x6s or 2x8s.

Hi all,

I appreciate the concerns about my joist strength. I should be clear here that these shelves are actually just a single shelf (not a stack of shelves) suspended from the ceiling, with only 20" between the shelf and ceiling, intended for bulky item storage only. There will not be a heavy load placed on the shelves. If they fall down or sag my floor, I would be surprised (but maybe not too surprised given all of the concern!).

The next step in the project is to cut some dados. I have a Freud SD508 dado stack which is still new-in-box, never used. I've never cut a dado in my life. Let me see if I can describe this:

• I have 32 4-foot pieces of 2x4.
• In each of these 32 pieces, I need to cut a dado on each end, for a total of 64 dados.
• At each end, I must cut a 1.5" wide dado across the 3.5" width of the 2x4, which will allow another 2x4's end to be fastened into the slot.
• The dado will be 3/8" or 1/2" deep (not sure yet).
• The edge of the dado closest to the 2x4 end must be 7 13/16" from the end.

So basically, I need to cut a 1.5" wide dado across the 3.5" width of a 2x4, a precise distance in from the end.

What's the best way to do this? I can't cut a dado 1.5" wide in one pass, so I'll need to do it in two passes. Here is my current thinking:

• Set up the dado to be a hair over 3/4" wide.
• Set up a stop so that the dado will be cut with the far edge exactly 7 13/16" in from the stop.
• Make this dado cut across all of the work pieces, including an extra scrap test piece.
• Move the stop precisely two hairs under 3/4" further away from the blade.
• Dado the test piece and make sure the end of a 2x4 fits snugly into the dado. It should now be exactly 1.5" wide, or as close as my skill can get to it.
• Make this dado cut across all of the work pieces.

For the second dado cut on the test piece, I'll try to sneak up on the desired width rather than overcutting. Does this seem like a reasonable thing to do?

Will I be fine cutting a 3/4" wide dado, 3/4" deep, all at once with an 8" dado stack? Or do I need to do that in successive depths? Do I need to use a certain speed setting with an 8" dado versus a 6" dado? (I haven't looked this up in the manual yet, so I really should do my homework and read the manual before attempting any of this.)

Feedback is greatly appreciated!

- Chris

[paulmcohen]

Max speed of the 8" blade may be lower than the 6" but I don't think so, you would have to check. Since most saws are single speed one speed for both should work.

I would use the rip fence on an extension table to set one edge of the dado and clamp something on the other side of the blade to set the other edge and cut the whole dado on one board before moving on the the next.

If you let the blade come to speed between cuts I don't see and an issue cutting 3/4" deep in one pass. If you cut the whole width in one pass it easy to change depth after cutting all the dado's on all the boards.

[dusty]

Paul has a better dado set than I do. I cannot cut a 1 1/2" wide dado so I would have to do this in at least two passes per piece.

Step 1: Set up per Photo 1 so that the edge of the dado furthest from the end of the 2x4 is right on the desired dimension (left side of blade makes a critical cut).

Step 2: After cutting all required pieces, move the fence toward the blade and align the right side of the blade for the other side of the dado. This too is a critical setup (right side of blade is critical).

(Photos 1 and 2 depict step 1) while (photo 3 depicts step 2)

Photo 4 depicts a wide dado cut with a 3/4" wide dado blade by making two passes..

Set up and cut a test board before cutting anything for use.

[chrispitude]

Hi dusty,

You have succeeded in simply describing what I was attempting to describe with far too many words! Many thanks and I am glad to know I was thinking along reasonable lines. I like Paul's idea of having two stops set up so I can quickly cut the full width. It sounds like more setup work up front to get the stops just right, but less time overall since I can make both cuts with the workpiece up on the table. I'll have to think about it, I don't have any nifty stops made up like you have (but it sure would be nice).

This afternoon I took a break from work and went down to the garage. I followed the never-used Freud dado manual and assembled a 13/16" dado stack from never-used dado plates onto my never-used Shopsmith dado arbor. I used my never-used Shopsmith arbor wrench (got sick of using combinations of slip-joint pliers and finally bought one!) and tightened everything up. Golly, this 8" dado stacks is heavy. I swapped out the saw blade table insert for the never-used dado insert and removed the riving knife. I raised the table and pulled the headstock to the left and removed the saw arbor and attached the dado arbor. Did I mention the dado stack sure is heavy? I slid the headstock back over and realized that unlike the saw blade, the dado doesn't magically center itself. After sliding the headstock a bit away and locking it down, I lowered the table down until (checking - yep, it's unplugged!) my tape measure indicated a 3/4" protrusion from the table to the highest arc of outer tooth travel.

I plugged in the headstock and donned eye protection. At this point I realized the speed control was still set to saw instead of dado. Since everything was all set up, I took the shortcut of turning on the power only briefly enough to get some rotation, and changing the speed down to "dado" as the headstock spun back down.

Well... now my Shopsmith was staring at me with its angry new smile - a sea of hungry dado teeth. It was weird to face such a dangerous-looking implement with no upper guard in place. I grabbed a 2' piece of scrap 2x4 and loaded it into the miter gauge.

I donned hearing protection (in addition to my eye protection) and flipped on the power switch. Golly, those lights sure dim something good when that dado stack spins up, must be heavy... Once it was up to speed, I clenched the miter gauge grip white-knuckled and tentatively advanced the 2x4 towards the spinning carbide jaws. As the workpiece met the dado, my white-knuckled advance slowed to a glacial crawl. Was I feeding too fast? Would it catch the 2x4 and toss it through the ceiling into my guest bedroom, laughing all the while?

About an hour later, I completed the cut. I reached a trembling left hand over and powered down the headstock, eyes locked on the dado stack as it spun down. After waiting a few minutes to make sure the dado was completely still, I unclenched my right hand (hand cramp!!) and took a look at my handiwork. A perfect 13/16" wide cut, a perfect 3/4" deep, and a nice smooth bottom! Wow, that is pretty cool!

Events portrayed above may be slightly exaggerated, but not by much. What happens if you feed a dado too fast - does it just bog down/cut rough, or will it kick? Will I know it when I'm going too fast? Should I feed at about the same rate as a saw blade, or a little slower, or much slower?

Other than gaining experience with feed rate, it seems like my biggest challenge will be in getting the stops and setups right - and making sure I don't replicate a mistake 64 times! Now I see why you guys spend so much time making jigs and slot- and fence-mounted doohickeys and such...

After everything was over, I realized I never fired up the dust collection - fine sawdust everywhere!! (no doubt thanks to the feed rate)

- Chris

[dusty]

The doohickey hanging on my rip fence is a very important safety measure when making the cut that you are planning.

It need be nothing more than a piece of scrap clamped to the fence but it is imperative that you have something. We discussed this earlier in this thread (I think) when you were using the feather board. Anything that results in the cut off not being trapped between the fence and the blade.

To use two stops for this setup, I think you for going to need to use floating tables. If you have 5' tubes that should be no problem.

Don't forget - you want a doohickey at the other end also. This piece is not as likely to be a problem because you have a hold on it with the miter gauge handle.

In cuts like this, I do NOT draw the stock back thru the blade. I take it off the table on the outfeed side. Many will likely disagree with me here; I watch many people who do draw it back with the blade still turning. I don't.

This is one good reason for having something you can call an outfeed table. A few of your cutoffs can accumulate there before you have to make a trip to the other side to collect them.

I hate it when something with a nice, clean, crisp cut falls off the outfeed table to the concrete floor.

[dusty]

when the Shopsmith is turned on is not a good sign. I'm sure you know that but I felt I had to say it.

I'd guess that you are running on a #14 feed that is rated at 15 amps (typical of a garage area). The lights and all outlets are probably on the same line.

It might have been a blessing that you forgot to turn on the DC.

[paulmcohen]

Paul has a better dado set than I do. I cannot cut a 1 1/2" wide dado so I would have to do this in at least two passes per piece.

Don't know where you got the idea I had a 1 1/2" dado blade but I don't. The one pass was refering to depth before changing the table setting, you still need to run the wood over the blade multiple times.

[dusty]

If you let the blade come to speed between cuts I don't see and an issue cutting 3/4" deep in one pass.

If you cut the whole width in one pass it easy to change depth after cutting all the dado's on all the boards.

Guess I read into this statement incorrectly.