A Quick Look at Micro Jigs

GRR-Ripper and MJ Splitter

 a match made in heaven


Bill Esposito

20 Nov 2004
Updated 8 Jan 2005
Updated 15 Jan 2005
New Features Updated 18 Feb 2005
New Acessory, Deflector/Connector 6 Nov 2005



If you read woodworking magazines or frequent the newsgroups or message boards you most certainly have read rave reviews about both the GRR-Ripper and MJ Splitter from Micro Jig, Inc.  I read them as well but it took me a while to actually pull the trigger on a GRR-Ripper.  Having experienced a minor kickback shortly after firing up my Jet table saw when I first got into this hobby, I have been very safety conscious about everything I do around that saw.  As cool and safe as the GRR-Ripper appeared, I just couldn't see myself using the GRR-Ripper that much because I always use my Biesemeyer splitter...and you can't use the GRR-Ripper as intended with that splitter.

 If you've already read this review and are looking just for the update, skip to the bottom of the document.

About a month ago I purchased a GRR-Ripper 2000 from Lee Valley.  I thought I was missing a couple of O-rings and emailed Micro Jig for replacements (The O-rings weren't really missing; I found them hiding on my bench a couple of days later).  Shortly after requesting the O-rings I got a phone call from Henry Wang of Micro Jig offering to send the missing parts.  Micro Jig, Inc tries to personally contact anyone who has a problem with their products.  We had a great conversation about the GRR-Ripper, splitter and even how to make ZC inserts.  We concluded the conversation with Micro Jig offering to provide another GRR-Ripper and a MJ Splitter so that I could perform a thorough evaluation.  At this point I still wasn't sold on the GRR-Ripper as being anything more than a glorified push block but pairing it with the MJ Splitter I was going to have the added safety I was looking for.


This write-up does not have the normal level of detail and testing I put into my reviews and it isn't supposed to.  This is "quick look report" as to how I felt about using the products.  As I use them more, I'll be updating this with that detail. 


The GRR-Ripper comes neatly packaged in a small box and requires assembly.  The only tool needed is a #2 phillips.   I mentioned O-rings earlier; Micro Jig cleverly uses these O-rings to captivate the hardware on the configurable components of the GRR-Ripper.  This way, when you remove a leg, spacer or stabilizer because the current cut doesn't need it or because you have to reconfigure the placement of a component, there is no loose hardware.  The hardware is captivated in the picture at left. Reading the instructions and assembling the GRR-Ripper should take you about 20 minutes...or 30 minutes if you don't read the instructions. :) You can also log on the Micro Jig web site and watch animations of the assembly process.

The GRR-Ripper is constructed of High Impact Polystyrene and is hefty enough to last forever. 

Ok, so why is the GRR-Ripper more than just a glorified push block?  The main innovative design feature is the fact that the GRR-Ripper is in contact with and pushing both the keeper and waste piece, assuring that they remain parallel to avoid kickback while keeping your hands out of harms way.  The gripping surfaces provide a better grip than anything I've used thus far.  Standard push blocks almost universally use a not so durable, open-celled foam pad while the GRR-Ripper uses a very sticky (that's sticky as in non slip) closed cell or rubbery (not sure just what it is made of) pad.


The GRR-Ripper can be configured to work with just about any type of cut and it really excels with narrow, short rips and hard to hold shapes.  If you have two of them you can use the hand over hand method of feeding longer stock but I haven't mastered that technique yet and I personally would not use that method without a splitter.  Micro Jig calls this technique "leap-frogging".


Ahh, the splitter.  The MJ Splitter is a pretty ingenious little device.  It will take a bit longer to set up the first one than a GRR-Ripper but it is pretty simple and you only have to make the installation Jig once.  The included instructions are simple to follow and again you can log on to the web site and view their online pictures.  The MJ Splitter comes in three flavors, full kerf, thin kerf and their new double thin kerf splitter.  I have all three versions and will be taking a look at them as time permits.  Right now, I'm testing the full kerf version.


The MJ Splitter requires the use of a zero clearance insert (ZCI).  Half inch MDF or birch plywood work great for this.  Because the feather board action of the MJ Splitter works on as little as .003", your ZCI must be tight in the opening.  One way to accomplish this is to run down to your local hardware store and pick up some nylon set screws and the appropriate tap.  Then tap 2 holes into one side of the insert and one into the side on the front.  With these 3 set screws you can adjust the insert to be tight in the saw.  You'll also want to tap 4 holes through the top of the insert in the same place as the OEM insert so that you use these set screws for leveling (see below).

The 3/4" hole in the ZCI is to stick your finger in to remove the ZCI. The cutout next to it was already there as I used these ZCI's with my Biesemeyer as well.

With the ZCI on the saw, you follow the instructions and make the jig.  The required drill bit and screws are included.  You'll need a piece of 1/2" material that is about 15" long and 4" wide.  Once the jig is made and positioned properly over the ZCI, you drill the mounting holes for the splitter.  Next you insert one of the two splitter inserts included in the package.  Which splitter insert you use and which side faces away from the fence is determined by how much pressure you want (in increments of .003) on the keeper piece.   This can in essence act as a feather board pushing the keeper up against the fence, behind the blade.


Using the GRR-Ripper with the MJ Splitter is in my opinion the best way to use the GRR-Ripper.  You get all the safety features that the GRR-Ripper alone offers, plus you get the added security of a splitter to help prevent the back end of the blade from picking up the work and throwing it back at you.  Even using the GRR-Ripper if you have a mental lapse and don't keep the GRR-Ripper up against the fence, you could be in trouble.  The MJ Splitter will help protect you in those situations.  I think that Micro Jig should offer a GRR-Ripper 1500 and 2500 package which includes the MJ Splitter since I think they work best when used to compliment each other.


Even with all the safety features the attribute of the GRR-Ripper that I think contributes most to my safety is the fact that using the GRR-Ripper requires me to THINK about every cut.  No more do I just set my fence and grab a push stick and make the cut.  I have to set up the GRR-Ripper.  I have to know where the blade will pass.  I have to know where the center pad is and where the outer pad will grab the waste piece.  None of this is complicated but it forces me to THINK, and thinking is the most important component of safety.


Again, more to come on these products as I get more time on them.   I see the GRR-Ripper living at my table saw, router table and jointer.


Since the original writing I've used the GRR-Ripper and MJ Splitter while making a table and an aquarium hood. I've used the GRR-Ripper on my table saw, router table and jointer. I've become quite comfortable using the GRR-Ripper for small work on my table saw and have even used the "leapfrog" method. On the router I set up and cut both simple and odd shapes and believe that because of the control I had over the pieces being cut, the quality of the work was better than had I used something else...unless I was to have constructed something exactly like the GRR-Ripper. On the jointer they were used simply as push blocks and I can't honestly say that they worked any better than the other plastic push blocks I have.

On the table saw I used the GRR-Rippers for ripping 4/4 lumber, squaring 2" laminated legs and ripping three foot long 1/4" inch strips of walnut for some bead detail. The GRR-Ripper made it all both easier and safer.

I did run across a problem. On two separate occasions I failed to tighten the knobs on the adjustable middle leg, and the studded knob worked loose and fell off in the path of the blade. On neither occasion did they fall off onto the blade so I was lucky. These studs aren't very long and it wont take much to cause a loose stud to back out.

Microjig is working on a simple remedy for this, and I've got a couple of DIY fixes you can try that work.
The first thing you will need to do is remove the center leg. You do that by removing one of the outer legs and loosening up the center legs knobs and slide it off. Next tighten up both knobs so that you expose the last couple of threads of the studs. (photo left). I then took the assembly over to my vise along with a hammer and a punch and I dinged up the last thread on each stud. This prevents the oval nut from coming off (photo right). An alternative to the peening is to simply put a drop of five minute epoxy on the last thread. All we need to do is to create some resistance so the nuts wont back off.

UPDATE 15 JAN 2005

Ok folks, here's a short term fix. When reassembling the stud, I tried it with and without the steel washer. The pic at right is with the washer, I prefer without as it gives you at least another turn before running into the o-ring. Microjig will be kiting a longer stud and a retaining o-ring like they use on their other fasteners for those who want the fix.

Microjig will continue to investigate this issue and this may not end up as the final solution.

I also used the MJ Splitter the entire time and it proved to work very well. One thing you will want to do with the splitter is make a number of ZCI's and raise the blade for some of your most usual cuts, like 2/4, 3/4 and 4/4 and one with the blade fully raised. Why you do this is so that you can install the MJ Splitter right up near the blade. The MJ Splitter will install about 3/4" behind the blade so if you make only a ZCI with the blade raised to its max height, then when ripping a 3/4" board, the wood won't contact the splitter until it passes about 2.5" past the back of the blade (top right in photo below). Now make that same rip with a ZCI/splitter installed when the blade was only raised high enough to cut 3/4, and the work will contact the splitter about 3/4" behind the blade(top left in photo below)...a more safe condition allowing for fewer things to go wrong and contact that spinning blade.

The only things different in these pictures are the ZCI's. The blade height is unchanged.

You can't use the drilling jig per the instructions when installing the insert for a lower blade height. I simply slid the jig back so that the hole closest to the blade was about 3/4" behind the kerf cut on the ZCI.

New GRR-Ripper Features

Micro Jig has come out with a couple of new features for the GRR-Ripper. You can now purchase the MJ Handle Bridge Kit which includes the bridges and a trailing hook.

The handle bridges are a pair of plastic arches which are attached by T-nuts to the main body of the GRR-Ripper(left). The bridges provide four contact points for the handle instead of the original two and better distribute the pressure on the rubber pads. The handle bridge allows the GRR-Ripper to exert a more even pressure on the work. By using the handle bridge you no longer need to reposition the handle in order to get better pressure on the work.

By adjusting the handle so it is angled across the body of the GRR-Ripper as shown in the photo at right, I'm able to apply both down pressure and force towards the fence. The action of pushing the work naturally applies force towards the fence. This angle is also very comfortable.

The next set of photos will show the trailing hook in use during a number of operations. The hook is simply a piece of the same material as the GRR-Ripper, a T-bolt, washer and knob (left). The hook slides onto the GRR-Ripper (right) using the T-bolt and track and is tightened down.
[edit 2/19/5] One thing I missed on the first go round was that Micro Jig recommends using the included trailing hook as a template for DIY hooks. That way when using them on a table saw, if they get cut up you simply grab or make a new one.

At left you can see the hook being used on the table saw and on the right on the band saw. I think it is especially useful on the bandsaw as it keeps your fingers out of the way without having to apply too much sideways pressure to the GRR-Ripper.

The last picture in the group is using the GRR-Rippers and the hook on the jointer. This aids in feeding the work especially when the top side of the board is still rough.

By the way, don't be afraid to make your own custom hook out of hardboard or ply if you need it to be longer.

All in all I think this is a worthy addition to your GRR-Ripper arsenal and from the looks of the threaded inserts in the handle bridges, more attachments are in the works.



Copyright 2004-2005, Bill Esposito.
All Rights Reserved.