MFTing my Sawstop

Motivation

I recently replaced my pimped out Ryobi BT3K with a Sawstop PCS. My BT3K setup had 2 sets of rails with an extended table to the right of the blade. The extension table included a woodpecker PRL router plate.

However, there were 2 aspects of my extension table that I did not like.

1. there was no way to clamp or fix workpieces to the top,
2. the top was built into the cabinet and was not replaceable (and I had mistakenly cut into it multiple times). 

 The Sawstop PCS shipped with a simple flat extension table.  The motivation for this project was to regain the router plate while correcting the 2 issues above. 

Full Goals

1. Create router table
2. Clamping/fixturing options
3. No new holes in sawstop hardware
4. Modular/replaceable top
5. Flatter than sawstop table
6. Minimize cost
7. Allow for future expansion (dust box and router bit storage)

Creating the top

The original sawstop table seemed like a good size, so I cut a piece of 3/4 MDF to 27x40. It was straightforward to create the recess for the router plate. I just had to remember that I will be adding laminate later,  so the depth of the recess needs to be adjusted. 

For extra clamping, I decided to duplicate the festool mft table idea of having a grid of 20mm holes. For my purposes, a rough grid of holes would suffice to give clamping options.

I do not need to have a perfectly spaced set of orthogonal holes, but I still gave it a try. I do not have an LR-32 system, or even a holey rail, so I had to make do with my OF1400, the 20mm router bit, and flat clamps. I will be referencing all holes from the front side. 

I broke the problem down into three parts: get the clamp square to the front side, set the router at repeatable distances from the front edge along the clamp, and relocating the clamp along the front edge at repeatable spacings

Clamp square to front edge

It was pretty straightforward to get the clamp square to the front edge using a woodpecker triangle. 

Repeatable router placement along clamp

This was the most complicated part of getting a good grid. I started by creating a simple jig that slides along the clamp and butts against the edge of the MDF. 

I made use of the guide stop attachment to squeeze the router solidly against the clamp. This ensures that the router moves perpendicular to the front edge along the clamp, and by butting the router against the jig, it gives a repeatable start position. 

I then cut a series of MDF spacers to get repeatable spacings along the clamp. Doing this I should be getting fairly repeatable placements, but the exact distances between the holes is only as good as the exact lengths of the spacers. 

Relocating the clamp

Relocating the clamp was fairly easy because I actually have 2 clamps that can be used. So I simply created a spacer to move the front edge by 96mm each time it was used. I only used the spacer for spacing - the clamp was squared each time. Additionally, the jig was reset to the front edge each time since it had to be relocated to the other clamp. After the clamp was repositioned, a series of holes was created down the clamp.  Move the clamp to the next position, repeat. 

Attaching the rails

I tried making a grid structure for under the table, but wasn't satisfied with the resulting flatness and stiffness using MDF, and any grid structure would interfere with clamps coming through the holes. I purchased some 1.25" aluminum angle from a big box store, and was about to start cutting it when I saw a post about 8020. I had actually just purchased some 10 series for fences for soon to be made sleds, and discovered that the 15 series is nearly the perfect size, and would actually be cheaper than the simple aluminum angle (there was a set of 4 38" 1515 for auction that I won). 

If I attached the 1515 using the 8mm holes already drilled in the rails, the table ended up slightly too high. It turns out that the location is mainly set by the bolt width in the slot, so I decided to widen the slot at the three bolt location. Again using my OF1400, the edge guide, and a home made edge guide, I was able to guide the router parallel to the length of the extrusion, for just enough for the bolt to clear. 

The 1515 rails attach to the sawstop rails using 8mmx16 flat head cap screws and 8mm tnuts. 

The top attaches to the 1515 with 8mmx25 flat head cap screws into 8mm tnuts (they have not yet been drilled in the pic below)

Attaching the legs

The legs originally attached to the sawstop rails. For various reasons, I choose to attach a third piece of 1515 to the outside edge of the table. The legs attach with a right angle bracket using an 8mmx12 hex head bolt into an 8mm tnut and an 8mmx25 bolt. No new holes needed to be drilled into the legs. Not the most stable, but my original idea of mounting into both open tslots didn't work out because there was not enough extension of the adjustable feet in the supplied legs. 

Attaching the supplied adjustment device to the table

At the inside of the table, I dominoed a 1.5" piece of MDF and installed 2 6mm tnuts.  The included adjustment device attached as before. 

Evaluation of design against goals

1. Create router table: success, router plate mounts fine. I had a combo t-track/miter slot before, but never used the miter slot, so I just used a simple t-track. 
2. Clamping/fixture options: success. I now have a grid of 20mm holes. I have already used them to help complete this project. Currently I only have a set of woodpecker delrin pegs, but the table clamps will work if I decide to purchase. I have checked the orthogonality of the grid. Most of the pattern is spot on and I get no rocking. However, there are some that give up to a 0.010" gap over 24". But that does not diminish the utility for me - a perfect grid was just a stretch goal. 
   
3. No new holes in sawstop hardware: success. Used the 6 holes in the rails that were used for the original table. Used the 4 holes in the legs that were used in the original table. 
4. Modular/replaceable top: success. top is attached to 8020 and completely replaceable. 
5. Flatter than sawstop table: partial success. The sawstop table had dip of 0.043", my table has dip of 0.005". The only concern is that the table is one piece of MDF thick and may sag with the weight of the router lift. The third piece of 8020 was attached to the end of the table to mitigate this concern.  I score this as a partial success since somehow my t-track is 0.020" too high towards the end of the table.  I know I checked that the slot was deep enough the whole length of the channel.  I must have screwed up when epoxying it in place.  I plan to take a router and flush the channel at some point.
6. Minimize cost: success. I used scrap MDF and laminate. The 8020 was cheaper than equivalent aluminum angle. T-track was already purchased. The only cost was in the mounting bolts. 
7. Allow for future expansion (dust box and router bit storage): success. There are 2 open channels in each of 3 pieces of 8020 that can be used to attach whatever I need in the future. I have already attached the router power switch and will be hooking up the main saw power box soon.

Now it is time to make some deliverable projects!