New Table Saw Fence

My table saw is an old Rockwell 10″ contractor saw, which is an excellent saw, but one of the first things people tend to do with these saws is upgrade the fence.

The factory fence tends to be difficult to keep parallel to the blade, easy to push out of alignment, and has a limited capacity (the maximum distance between the fence and the blade is about 24″, so longer cuts require using the miter gauge or making the cut freehand).

One of the previous owners of my saw knew this, and so upgraded the fence… to a factory fence from a different saw. I’m guessing his buddy had a saw with a slightly better stock fence, and gave him the stock fence when he upgraded to a better one. The “upgraded” fence on my saw had a better cut capacity, but was still difficult to square and easy to push out of alignment, and the rails were too tall, causing them to interfere with my miter gauge (the top of the guide rails were higher than the bottom of the miter slot). So upgrading the fence was still on my to-do list.

I had been researching tables saws ans fences and I knew that the gold-standard for accurate fences was the Biesemeyer T-Square fence, but these are expensive, and although I use my table saw often, I am not a professional cabinet maker, so I couldn’t justify buying one of these fences.

After reading reviews and comments on all the t-square style fence systems I could find, I settled on the Delta 36-T30 30″ T2 Fence System, and found the lowest price on Tools-Plus.com.

I used the new Amazon.com Universal Wish List plugin for Chrome to add the fence to my wishlist, and my lovely wife bought it for me for my birthday.

Some of the negative reviews for the new fence had complained about having to drill new holes in the fence rails to install it on their table saw because the pre-drilled holes did not line up, so I was expecting to put some effort and ingenuity into this installation, but first things first, I had to remove the old fence.

The old fence was fairly simply installed. Its rails consisted of parallel tubes on the front and the back of the saw, separated from the table with spacers (the spacers came in to play later in an unexpected way) and bolted directly into threaded holes in the edge of the cast iron table top. I think just removing the old fence was a significant improvement.

Upon removal I noticed that the holes in the table top were significantly larger than the remaining original holes. The previous owner had drilled out the original holes and re-threaded them to fit the “upgraded” fence, so I now had holes that were too large for the mounting screws that came with the new fence. But I figured I could find a way around this.

The new fence came with a large number of screws, washers, nuts, and bolts, and when I read through the directions, I couldn’t find a need for all of them, so I decided to just use them as I saw necessary and see if I could make the fence work without drilling any new holes.

Luckily, although the holes in my table top were too large for the mounting screws, they did line up with the holes in the fence, and I was able to put a nut of the back side of the hole in the table top in place of the threads in the cast iron itself.

I then adjusted the rail until it was parallel to the table top and started working on the back rail.

 

On the back, for whatever reason, the bolts for mounting the rail were the correct size to thread directly into the larger holes left by the old fence. I was happy about this but ran into a new problem: I didn’t have the required 8mm Allen wrench to tighten these bolts.

I dug through my tools and scraps and eventually found a small nut that perfectly fit in the head of the bolt. I mounted the nut onto a small bolt and tightened it down with a slightly larger nut.

This assembly acted as an adapter: the 8mm nut fit into the 8mm Allen bolt, and the 9mm nut fit into a 9mm socket, so I could ratchet the bolt into place.

After finally installing the back rail, I checked it for parallel before moving on to the next step.

 

I had intended to re-install the extension wings, but at this point I realized that the spacers (mentioned earlier) that held on the old guide rails, were not used with this new fence system, and so the distance between the front and back rails was too small to fit extension wings.

This was disappointing, but I have been considering making my own extension wings, so I figured I’ll just make that my next project and set the old ones aside for now (I may add some washers to the rails as spacers to allow the wings to fit, but I haven’t decided yet, since I don’t really like the open aluminum wings much anyways.

The next step was to install the guide (square tube) for the fence itself. This was fairly simple, but the trick is to make sure it is parallel to the rail it is bolted to (and thus parallel to the edge of the table top). By tightening down one end, and taking a measurement, and then adjusting the other end to match, getting the guide parallel to the rail.

 

The remaining steps were fairly quick, and involved setting the fence in place, adjusting the various set screws in the fence until the fence was parallel to the miter slot and blade and square to the table top, and calibrating the measurement indicator. On this last step, I realized that my fence system was 2″ too far to the right for the attached measuring tape on the guide, so that when the fence was against the blade, the indicator was 2″ to the left of zero. The only way to fix this is to move or replace the measuring tape, and since I’ve seen adhesive measuring tapes before for pretty cheap, I’m not to worried about this for now… but it is a little sad.

 

Despite the various complications, I was able to complete this installation in about an hour, and the result is a sturdy, accurate fence that is easy to adjust and a big improvement over the fence the saw had when I bought it.

Zero-Clearance Insert

After completing the riving knife modification, I needed to replace the blade cover insert to accommodate the knife’s position behind the saw blade.

I had been using the stock insert, which has a full opening to accommodate a dado stack. This setup does not support the wood fibers along the edges of the cut, and will allow tearout along the ends of the cut pieces, resulting in a frayed edge on the final product, particularly when cutting across the grain.

A zero-clearance insert has a slot that is only as wide as the blade itself, and thus the wood fibers are fully supported all the way up the the blade itself (almost as if with a pair of scissors), making for the cleanest possible cut.

Not only are zero-clearance inserts preferable to factory inserts, they are the easiest type of custom insert to make since the slot for the blade is created by simply cutting through the blank insert with the blade installed in the table saw.

I started with a set of phenolic zero clearance kit from Rockler. This kit is about $30 and contains two rectangular blanks from which you can cut inserts to fit your saw. I could have purchased a pre-shaped insert but they are more expensive ($30 for one insert) and this seemed like a fun project.

Per the instructions that came with the phenolic blanks, I started by tracing the stock insert and cutting the the blank close to the final size. The instructions recommend using a band saw for this cut, but I don’t have one yet (regularly refreshing my search on Craigslist) so I used my scroll saw. This was marginally successful, but I burned up a good blade and the blank was jumping all over the place. Honestly I think this step would be better handled with a hacksaw if a band saw is not available, or at least by switching the blade on the scroll saw to one without any reverse teeth.

The idea of the first step is to leave minimal material for the the router bit to remove in the next step, which is to use a copy-bit and the stock insert to finalize the shape.

I used turner’s tape (fancy double-sided tape) to attach the stock insert as a template to the rough-cut blank and used a 1/4″ copy-bit on my router table to remove the extra material and bring the outer diameter of the phenolic blank to its final shape.

I almost had a minor disaster while doing this. I noticed a slight change in the sound coming from the router bit, so I shut off the router and realized that I the bit was slowly lifting out of the collet and was begining to cut into the metal of the stock insert. There was no visible damage to the router bit (Carbide is tough!), so I re-seated the bit and really tightened it down. I was able to finish the routing without any other issues. On a side note, I’m now convinced that I need to set up some dust collection on my router table…

The phenolic blank is thicker than necessary for my saw, so I set up my drill press with a large forstner bit to remove enough material for the insert to sit flush.

Once I had achieved the correct thickness, I drilled out and countersunk the holes for mounting the insert.

I stripped out one of the screws while testing the fit, which gave me a chance to use a screw extractor bit that I had never tried before.

The extractor worked well enough, bit it really guts the screw so I cut a slot in the screw to re-use it as a flat head until I find a replacement.

After this, I re-installed the blade on the table saw and cut the slot in the new insert. This had to be done in 3 stages:

      • I very cautiously lowered the insert on to spinning blade to remove enough material be able to set the insert fully flush with the table top with the blade installed. Since the insert is unsecured, it is very important to do this slowly from BEHIND the saw. This way if the insert is ejected it flies away from you. since, at this point in the process, the top of the insert is completely symmetrical, I actually started cutting with the insert backwards and had to flip it around and start the cut over:
      • I secured the insert and raised the blade with the table saw running until the blade reach its full depth:
      • I extended the cut to make room for the riving knife. I actually did this with a hand saw, Stanley FatMax:

With everything finally installed, I quickly cross-cut a piece of rift-sawn white oak to see what sort of cut quality I would get. I made the cut freehand, with the blade set too deep,, but still got a decent quality cut with minimal tearout.

I’m happy with the results, and I am done with this project.

Table Saw Riving Knife modification

A few months ago I picked up an old Rockwell 10″ contractor saw that needed some work which I got up and running pretty quickly. Up until this point I has only used cheap portable table saws (my current saw was a $250 Ryobi), so moving to the 1.5 HP, belt-driven, cast iron contractor saw was a big upgrade; but even though it was a more stable and accurate tool (and thus less dangerous to use), I found myself nervous about using it, fearing a catastrophic kickback despite never having having this problem with any prior saw (perhaps my fear was due to all of the horror stories and warnings I read while researching how to restore the Rockwell).

I’ll make another post that goes into a little more detail about the saw and the repairs I made, but for now I’ll focus on my most recent modification: adding a riving knife.

A bit of background: A riving knife is essentially a fin behind the blade that rises and lowers with the depth of the cut. It is approximately the same width as the blade and helps to keep the material in line with the blade after it is cut.  It also helps to prevent the freshly cut material from pinching the back of the blade, which can result in dangerous kickback and serious injury. Most American saws have featured a “splitter” type system, which places a fixed fin a few inches behind the blade. Riving knives have been standard on European saw for some time, and are now standard in high-end table saws (American or otherwise). Splitters are better than nothing, but since the original splitter was missing from my saw, I decided to see if I could add a riving knife instead.

I started by tracing my saw blade onto a piece of 1/8″ aluminum plate and drawing a knife shape that would closely follow the blade and then cut it out with a jigsaw.

My saw is set up with a thin kirf blade, that measures about .0925″, so I knew I would have a bit of metal to remove before the blade would be the correct thickness.

kirf width

I worked on it for a long time with my grinder, sander, and hand file, but was still too thick, and was having trouble maintaining consistent thickness along the blade

.knife thickness

At this point I did a little more research on the appropriate width of a riving knife and found out that the goal is not to necessarily match the kirf width, but rather to land somewhere in between with kirf width and the blade plate width, since the purpose of the knife it to keep the wood from grabbing the plate. My blade plate width is .0745″ so anything in between .0745″ and  .0925″ would be fine.

Blade plate thickness

I went to the local metal supply and picked up a new piece of aluminum that id 0.09″ thick, that I will be making the new knife out of.

Since, at the moment, my wife and daughter were taking a nap and I couldn’t use any loud tools (i.e. the jigsaw) to cut out and shape the new blade, I used the existing blade to finish the construction of the mounting bracket for the knife within the saw itself.

I had already cut the basic shape of the mount out out 1/4″ aluminum and refined the shape by clamping it in place with a pair of vise-grips and raising and lowering the arbor assembly to see if the mount interacted with and of the other saw components. My final shape is shown below:

Riving knife mounting bracket

This right end is designed to mount to a flat surface on the arbor assembly that is parallel to the blade. I drilled (using my cordless (read: “quiet”) drill) and tapped the flat surface in the arbor assembly to match the three holes in the right end. The two holes on the left end are placed to thread in screws to mount to blade itself.

A test fit showed everything to work properly:

Mounting bracket test fit

I then removed the bracket and attached it to the knife using a couple of nuts as spacers to bring the knife directly behind the blade:

Riving knife assembly

I was then able to install the full assembly and test the movement:

I am happy with the movement overall, of course I will need to finish the second knife before I can test it, but since I won’t need to adjust the thickness of the new knife, I should be able to finish is pretty quickly.

I may also revisit the knife length. You can see in the video that the blade comes up before the knife, and if only parallel to to the top of the blade when the blade is at full height. This means that the knife will not be present in shallow cuts. This is not a problem on newer saws because they are designed with a fairly complex system of linear slides that keep the riving knife in the same position relative to the blade.

Since my saw raises the blade by swinging it along a radius, and my riving knife if effectively an extension of the arbor assembly, it is moving on a larger radius, so each degree of movement is exaggerated in the riving knife relative to the blade.

I can resolve this my making the riving knife longer, but with the consequence that the riving knife will be over the top of the blade when the blade is at full depth. I haven’t decided which problem is worse, so I’ll have to update you with the results of further experiments.

Video of the full process below:

Hello World

My friend told me last week that his new year’s resolution was to start blogging. Since I didn’t have any resolution of my own, I stole his.

I am a Husband to a wonderful wife, the proud Dad of the cutest 7 month old girl in the world, a project manager at Qualcomm, a homeowner in San Diego, and a somewhat compulsive and ADD tinkerer.

I’ll be posting mostly about the projects I’m doing around my house and in the garage, sharing tips, tricks, and screwups.

I’m currently working on:

Other projects I will be starting/continuing will be:

  • The Backyard
    • Applying stone veneer to my BBQ installation
    • Building planter surrounds for the palm trees
    • Installing sprinklers and drip irrigation
    • Laying grass sod
    • Installing lighting
    • Building a pergola and childproof railing
  • The Front Yard
    • Installing sprinklers
    • Laying Sod
    • Installing lighting
  • The Inside
    • Making a cabinet for our printer and office supplies
    • Making a barn door type sliding door system for the master bathroom
    • Installing a ceiling fan in the second bedroom
    • Figuring out how to configure my gaming setup (xbox and projector)
  • The Garage
    • Figuring out how to store a wheelbarrow and a lawn mower and get them out of the way
    • Making shelves and drawers under my workbench
    • Making room for my wife’s car and my workshop to coexist in a 2-car space

Overall, I should be able to manage to keep myself busy…