Unifence modified with incremental positioning

[Jim C Martin]

Hello All:
I'm sure some of you have seen Jeremy Schmidt's tablesaw fence (https://www.youtube.com/watch?v=4pudkvHFOfk) with incremental positioning. I had thought about making one but I really like my old Delta Unifence. I spent quite a bit of time trying to figure out how to integrate incremental positioning with my Unifence but was just coming up empty. Then I saw Bob Neumann’s set up on Instructables (http://www.instructables.com/id/AccurizedIncremental-tablesaw-fence/) and that got me going.
My fence ended up being a composite of their two approaches.
I used 3/4-16 because I thought it would be strong enough on its own with support along the whole length like 3/8-16 would need. Nut and Bolt supply sells the 3/4" threaded rod for less than Ace would get for the 3/8". I only supported it at each end with simple blocks made from scraps. I also included Jeremy's feature to rotate the threaded rod as a micro adjust. The nuts grip the support block fairly tightly so it won’t rotate on its own. Its simple to rotate the nut by 1/12 of a rotation (from a flat to a point) which gives a travel of ~0.005 inches. Nuts are held by loctite to prevent coming loose without needing two nuts on each side of the support block.
I followed Bob’s approach of using a piece of spring steel which I screwed to the Unifence head. I attached a half-coupler-nut to the spring steel with epoxy since I don’t have a welder (I'll add screws to reinforce the epoxy). I did not implement a toggle clamp like he did because I can micro adjust and don't need to use freehand positioning. So my half nut and spring are set so that they always engage when I position the fence. If I find that I want the ability to slide it without engaging the teeth I can always modify it later.
So far so good. Of course it took a lot longer than it should have and I drilled several more holes in my fence rail than necessary. Just to see how repeatable it really is, I dialed in the fence for 4" then removed and replaced it. See the pic.
Cheers,
Jim
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Cheers,
Jim

[Ted Reischl]

Nicely done. It is great to be able to move the fence back to an exact known location any time you feel like it.

I do not use the method you outlined above, a few years ago I installed a wixey system on my unifence.

The biggest thing is like I said before, being able to move the fence back to a known location anytime. Once I got used to it I found that I no longer cut "extra" pieces "just in case". Same thing is true for your modification.

Now I am looking at what you have done and thinking if I can incorporate that idea into something for the RAS fence. Right now it has a T track stop system with those slidey tape thingies. I don't usually care if something is precisely 5.000 for example, just so all the pieces that need to be 5.000 are the same length. The gears are spinning in my head, holy smokes, someone put some oil on them!

[Paul K. Johnson]

It looks like you're measuring from the wrong side of the blade. ???

Cool idea and implementation. Kudos!

[Jim C Martin]

Thanks. Yes, it does look like that but I zero'd the caliper for blade width.
Cheers,
Jim

[Jim C Martin]

Now I am looking at what you have done and thinking if I can incorporate that idea into something for the RAS fence. Right now it has a T track stop system with those slidey tape thingies. I don't usually care if something is precisely 5.000 for example, just so all the pieces that need to be 5.000 are the same length. The gears are spinning in my head, holy smokes, someone put some oil on them!

Thanks Ted. Anything Incra can do with their 1/32 tooth racks you can do with threaded rod and half of a coupler nut!
One note of caution: Make sure the threaded rod is really 16 threads per inch. The stuff you can get at Ace, Home Depot, and Lowes will be off by a couple of teeth over a foot or two. The threaded rod at Bolt and Nut supply is really accurate. Cut vs rolled threads I think.

[Charles Lent]

I also have the Wixey gauge, and have learned to use it well, so I don't see a need for me to do this, but it's nice to see someone doing it. Has he implemented a way to make a partial thread step? It would be handy at times. Join Tech was the first to have the ability to rotate the threaded rod whenever a partial thread movement was desired. They had a calibrated knob on the end with detents.

Charley

[Jim C Martin]

Yes, its easy to fine tune. From the original post: Its simple to rotate the nut by 1/12 of a rotation (from a flat to a point) which gives a travel of ~0.005 inches.


Has he implemented a way to make a partial thread step? It would be handy at times. Join Tech was the first to have the ability to rotate the threaded rod whenever a partial thread movement was desired. They had a calibrated knob on the end with detents.
Charley

[keith micinski]

I have never seen a half coupler nut and I just did a Google search for a half coupler nut and can't find anything. Is there another name for it. Also are you saying the fence slides normally when the locking lever is released and then when you tighten the locking lever it sucks this half coupler nut into the threaded rod? My unifence doesn't appear to be loose enough when it slides that it wouldn't be constantly catching on the threaded rod.

[Jim C Martin]

Hi Keith:
Sorry, I should have explained that. Its just a coupler nut cut in half along its length. Actually probably more like a third. Its just cut open so it can mesh with the threaded rod. Both Jeremy and Bob use the term and show pics in the links I provided.
You're right about the sliding. I have to completely release the catch on my fence so I can pull it back slightly. Then I slide it to where I want it and push it forward. I can feel the teeth grab and pull it slightly one way or the other depending on how well I lined up on a 1/16". I was concerned that this might be irritating but I got used to it in a few minutes.
Cheers,
Jim


I have never seen a half coupler nut and I just did a Google search for a half coupler nut and can't find anything. Is there another name for it. Also are you saying the fence slides normally when the locking lever is released and then when you tighten the locking lever it sucks this half coupler nut into the threaded rod? My unifence doesn't appear to be loose enough when it slides that it wouldn't be constantly catching on the threaded rod.

[fRED mCnEILL]

I used a Wixey gauge on my table saw but at some point it would randomly be off by a fraction.So I bought another one and it eventually did the same thing.Not good if your cutting expensive material. So I finally bought an Incra fence.LOVE IT. I make a lot of repeatable cuts so it eliminates the tap-tap-tap you get even with the Wixey. Expensive but worth it.

[Jim C Martin]

Thanks fRED, I had not heard that the Wixey would get buggy after a while. Good to know.
FWIW, the parts I used to modify my Unifence cost less than $15. It might be an affordable alternative for a lot of woodworkers. My sense is that it would be easy to modify a Biesemeyer style fence for incremental positioning as well.
Cheers,
Jim


I used a Wixey gauge on my table saw but at some point it would randomly be off by a fraction.So I bought another one and it eventually did the same thing.Not good if your cutting expensive material. So I finally bought an Incra fence.LOVE IT. I make a lot of repeatable cuts so it eliminates the tap-tap-tap you get even with the Wixey. Expensive but worth it.

[Bill Dufour]

FYI: Metal cutting lathes use a "half nut" to engage the lead screw. They use both halves and wedge them together.
Zoro Tools is probably a good source for threaded rod of different cost and quality.
Bill

[ryan feasel]

Can you please provide some additional pictures of the underside where the rod attaches to the fence? Thanks.

[Jim C Martin]

Sure Ryan, here you go. Not much to it, just two 1/4-20 screws. Note one of the many holes in the rail that was part of my trial and error process.
361231


Can you please provide some additional pictures of the underside where the rod attaches to the fence? Thanks.

[Bill Space]

Hi,

I understand what you have done and think you did a great job. I too love my Unifences. I have two of them.

But I am wondering about the utility of the modification. Seems like I can easily set my Unifence to a 1/32 target, and perhaps to a 1/64 if I am lucky. 😀

Granted, you can be more certain of where your fence ends up by counting partial turns of the threaded rod. But I am just not sure the effort of building a set up like you have is worth it. We're not metal working; wood changes a lot with moisture variations.

I am not not adverse to technology. I love the DRO I put on my planer.

I am just having trouble convincing myself that installing a system like you did would have much real benifit to me.

Still, I like what you have accomplished.

Just wondering if a few thousandths error (OK, maybe 15/1000) is significant when woodworking. I am pretty sure. I can get that close if I need to with my Unifence, as is.

Call me a dreamer...you could be right! 😀

Thanks for sharing!

Bill

[Jim C Martin]

Hi Bill:
All your points are perfectly valid. In fact, I had considered them and asked myself many times why I was doing it. I'll even throw in one more point: I run almost everything over the jointer or through the planer after I cut it so its best to cut a little oversized.
So why do it? I guess it seemed like a fun challenge that might come in useful when cutting several parts the same size but not at the same time. After all some folks spend several hundred dollars on Incra fence systems for this kind of repeatability and accuracy and I've spent less than $15. Worst case scenario is that I don't find it useful and I take it off with a total of 6 screws. Plus I had fun doing it and I'm happy with how it turned out. All part of the creative process for me.
Cheers,
Jim


Hi,

I understand what you have done and think you did a great job. I too love my Unifences. I have two of them.

But I am wondering about the utility of the modification. Seems like I can easily set my Unifence to a 1/32 target, and perhaps to a 1/64 if I am lucky. 😀

Granted, you can be more certain of where your fence ends up by counting partial turns of the threaded rod. But I am just not sure the effort of building a set up like you have is worth it. We're not metal working; wood changes a lot with moisture variations.

I am not not adverse to technology. I love the DRO I put on my planer.

I am just having trouble convincing myself that installing a system like you did would have much real benifit to me.

Still, I like what you have accomplished.

Just wondering if a few thousandths error (OK, maybe 15/1000) is significant when woodworking. I am pretty sure. I can get that close if I need to with my Unifence, as is.

Call me a dreamer...you could be right! 😀

Thanks for sharing!

Bill