micrometer adjustment for Unisaw

[Eric Anderson]

I built a micrometer adjustment for a Unisaw with a Unifence. It uses a Starrett micrometer and works pretty well. It is compact and stays out of the way until needed.

[phil_ordway]

I like it. Nice pix. I think I have a mike barrel around the place.

[TeamCasa]

I'm not sure how useful - but sweet! Dave

[eganders]

[David]

My micrometer is my finger going tap, tap, tap against my Bies.

David

Eric Anders> I built a micrometer adjustment for a Unisaw with a Unifence. It uses a

[igor]

micro-adjustments for the fence. Unfortunately, I cannot figure out from your photos how the micrometer moves the fence. I s'pose if I had a Unisaw I might understand.

Now, maybe I do see if I am right about this: Does your gadget just push the fence to the left and serves as a stop if you push the fence to the right? -- Igor

[Mike Marlow]

materials I use as well. I cut mostly wood on my table saw. But... that doesn't stop me from appreciating a really nice job all the same.

[John]

When wanting extreme measures on my Unisaw with Bessy fence, I have use a digital micrometer and Lee Valley rare earth magnetics to hold the micrometer in place. Reads to 0.001 and is very repeatable, but getting it to be EXACTLY a certain reading can take a good bit of bumping and fine tuning the fence guided by the micrometer

I have also been know to take my Incra Jig off the router table and clamp it's fench to the back of the Bessy fence AND then clamp the plywood platform the Incra is attached to the the table extension - gives me much easier positioning and when it is right I just lock the Bessy fence down with it's clamp and off I go

John

[eganders]

Right!!

igor wrote:

[JMartin957]

work do you do?

John Martin

[Eric Anderson]

[igor]

[Larry Jaques]

On 09 Dec 2004 06:33:56 GMT, [e-mail] (JMartin957) calmly ranted:

The more precisely you cut the wood, the more professionally it fits together (for fine woodworking) and the better it looks. It can also mean the difference between a bad glue joint and a good one. If you CAN cut more precisely, why not do it? It's also good for shaving off those RCHs of wood which causes interference fits.

Consider the width of a dado slot. Adjusting the fence for that makes it cut perfect openings. Ditto tenons, sliding dovetails, etc.

========================================================== CAUTION: Do not use remaining fingers as pushsticks! ==========================================================

Comprehensive Website Development

[Swingman]

I still wonder just how useful one would be on a Uni-Fence? Every one I've ever used had a very slight movement, toward the blade, when being locked. Although small, it would sure seem to be enough to throw off any measuring in the "thousandths" range.

[igor]

Amen! And well said. As I've written here before, where I can achieve precision I try to do so, subject to some cost-benefit. It's akin to reducing the number of variables in any problem. If I were to figure out the least precise operation in any part of a ww project and use that degree of precision in all measurements and other related steps ... -- Igor

[JMartin957]

First of all, a micrometer is a tool for measuring, not for pushing large assemblies such as a table saw fence. The threads simply aren't designed for that. Since it was free, however, I can't complain too much.

Second, what do you think a change of .001" on the micrometer means to the cut? Try putting a couple of DROs on the fence - one at the front and one at the back - and see what the movement really is.

Lacking the DROs, a better tool for the job would be a much heavier screw - say a 1/2" x 20 tpi. One turn would be 50 thousandths. A sixteenth of a turn would be about .003" - which is about what a typical hair is. Need to be any more accurate than that? I never measured a RCH.

I do appreciate the need for accuracy - it its place. I do a lot of metalworking as well as woodworking. There are times when I have to hold accuracy to "tenths" (.0001", tenths of thousandths) for such things as bearing fits. But I don't work to that accuracy unless the part requires it. And, frankly, I can't think of any woodworking operation that would require working to thousandths.

If I need a dado to a precise size I set the head to that size to begin with, making a few test cuts until I get it right. I'm willing to bet I get a more accurate cut that way than you do by moving the fence for a second pass. Same goes for tenons. Sliding dovetails? Straight or tapered? I guess I've always just found a plane to be the best tool for any final adjustments.

In short - since the micrometer head was free, it's fine. But I wouldn't encourage others to run out and buy micrometer heads to make similar adjusters. Because it's the wrong tool for the job. It doesn't give you an accurate reading of fence position. And I can't conceive of any normal woodworking operations where micrometer accuracy is necessary.

John Martin

[Bob G.]

==================== I tend to agree... . I do like the looks of it.. Nice job...

BUT I have never wished for a micro adjustment in the 15 years I have used my Bies...just never NEEDED one... The original poster may have and he solved his problem pretty nicely I think...

Bob Griffiths

[eganders]

Sort of like the philosophy you use when you test or measure something. You want the device you are using to do the measurement to be 10 X as accurate as the thing you are testing is to be.

As far as the movement of the Unifence -- don't know yet. I hope that I can push the fence against the micrometer while I am clamping the fence and keep it from moving.

[eganders]

Oh, I wouldn't encourage anyone to do that either! And it would not greatly surprise me if the threads gave out if I get aggressive with it. But...any other thing I do will be more expensive--free, you know. And, this way I will be taught first hand how many thousandths make a difference in a fit.

[Guess who]

That's a good idea, but how do you make it happen? Have you measured the wobble in your blade while it cuts? I'm not being funny here. I want to know. Accuracy of cut also depends on the material, not just the cutter. I've always known that such accuracy [say ten thou] was useful in mechanical assembly, but in woodworking? Wood is compressible. There has to be variation in *any* saw cut. What I'd like to know is the measured accuracy/precision of the cut after you are finished using the micrometer. What difference is there from tooth to tooth measured from a distance away? Are all teeth in a blade lined up to the same accuracy? What if you measure to one tooth and there is another that will cut a shade further out? Blade wobble would be a primary consideration for me in judging if the accuracy set up is retained. You could set up an electron microscope to line up the blade, but not cut to that accuracy by a long shot, so what makes the micrometer so useful then? What I'm driving at is whether or not you've made a cut on one piece, then moved the micrometer a thou and made a cut on another, then actually measured that thou difference in the materials. But still and then, when you glue and clamp all that will change.