Cross-cut sled

[Mark & Juanita]

Yep, what he said.

[Mark & Juanita]

... snip

That's how I did it

I made this easier by putting more than two screws in the runners before removing from the saw (I used 4 along the length of the sled on the table).

I took a slightly different approach. I did attach the one end with a single screw. I then made the initial cut in the sled, cutting to about 1" from where the back fence would be attached. Using a machinist's square, I then moved the back fence to as near square as detectable with fingernail and feeler gauge. I then clamped down the back fence and used a single screw to hold the fence down. I made a test cut and measured the deviation with the machinist's square and feeler gauge. The first cut was off a bit, so I used a rubber mallet to "adjust" the fence in the correct direction. After a couple of tries, I got the measurements I alluded to in my original post. After getting that precision, I then screwed down the back fence with multiple screws to keep it in place.

... snip

[Mark & Juanita]

yep, what both Bruce and AgkiS said. That is exactly what I was describing.

As further clarification, My only concern was with side B of the board, a piece that had been jointed flat only moments before performing these tests.

... snip

What I meant. ... snip

As I responded in another post, I used a machinist square and feeler gauge. Actually, the error is slightly under 0.0015, but my feeler gauge set doesn't have anything smaller. I'm certainly hoping this is sufficiently good such that only slight planing or sanding will be required for any boxes built using the Leigh jig.

BTW, the error was in the other direction, but, as you say, the effect is the same, I just had to apply the mallet in the opposite direction :-)

[Agki Strodon]

Yep. I misread the table. I need one of those fancy calculator things.

Agkistrodon

[B a r r y]

Thanks!

Send 'em to nospam @ snet dot net.

Barry

[K. B.]

Thank you all for your comments and insight on sled making!

-- Karl B

[Gregory Jensen]

I used Eds P's advice and got mine down to 0 .00000015 outta square in 5 inches ( whew! I though I would have to do some sanding..) My Gawd,,, my wood expands and contracts more than that from day to night

Serously the proven method for making a crosscut sled is just what Ed stated... make the thing then screw on the back platform try and try and try when your happy GLUE IT.. I remember my first one I made it so perfect so I guled it together,,, then had to knock it apart, lose an inch to re-align the thing thanks

PS I use "SLIPIT" lube ( Non silicon) to lube the sliders--- great stuff ..

[Bruce]

3.8 nanometers. Not bad :) That is less than the width of 2 hydrogen atoms. I'm impressed.

[Edwin Pawlowski]

Is there a way to get those hydrogen atoms out of the way for a closer fit? Ed

[Test Tickle]

Sure, but you need a shop-vac. It's simple physics, right? After all, nature abhors a vacuum.

tt

[dale austin]

[Pat Barber]

[Mark & Juanita]

How: Machinist's square and feeler gauge

Why: Take four pieces that are out of square by 1/32" (or even 1/64" -- normal high-precision wood measurements), assemble into a frame. How well-crafted will that frame appear? Just because it doesn't make sense to measure some things to better than 1/32 or 1/64 (or even 1/16) -- there are other times when getting something cut square (or mitered at 45 degrees) to high precision is essential. Another example, take 4 pieces of wood and dovetail all ends to assemble into a box. If all sides of the box are out of square by 1/32, how well will those dovetails fit?

[Pat Barber]

I grant you that careful measurements are required for any woodworking but when I hear folks talking about somthing that's .0005 out of square, that's getting a little silly.

I own a LOT of measuring devices and I believe I only have one ruler that even shows 1/32" marks, which I can barely see, little less make a correct mark to.

I do have a Incra ruler my wife bought me several years ago that has 1/64" and I can say without a shadow of doubt, I can NOT measure anything using that ruler.

I do all the normal joinery including a few dovetails and as a general rule, most of the joints are tight and quite fine.

I have seen these silly "measurement" things for several years here on the rec and I think it really must make people crazy cause they can't measure and cut a board at some of these "extreme" tolerances.

I go to GREAT lengths to "not measure" if at all possible.

I use story sticks and templates if at all possible.

Mark & Juanita wrote:

[Charlie Self]

Pat Barber notes:

And the older you get, the more it becomes "barely see".

Ayup.

Just talked to a major woodworking tool manufacturer, hand tool division, and we spent time discussing how measurements were taken and checked in ye olden days. Mostly, they weren't. Story sticks did the job, as they'll do it today. Simple, quick, repeatable almost unto infinity, and CHEAP!

Charlie Self "Bore, n.: A person who talks when you wish him to listen." Ambrose Bierce, The Devil's Dictionary

[bridger]

well, yeah, of course, but depending.....

I do some metalworking too, so I have tooling to measure WAAAY tighter than is needed for woodworking. I do my designwork on the computer, and sometimes I can't avoid having things come out in 64ths, as much of a pain as that is. I do avoid it where possible.

I've never used incra stuff. it seems to me to be well made and cleverly designed. My uneasiness with it is around the closed system thing- their stuff seems like it's designed to have you "need" another gizmo from their high priced line to do pretty much any next process.

But there is one very notable exception to the "32ths is all we need for woodworking" thing: toolmaking. This should be obvious to you, Pat. Shopmade tooling should be as accurate as you can make it, especially something as much used as a crosscut sled. It's not unreasonable to hold tooling to an order of mgnitude better tolerances than cabinets or furniture that are the actual product of the shop.

but you do want your crosscuts to come out nice and square, right? And without having to worry about them....

[Pat Barber]

I'll go along with the "tool maker" needing to use 1/64" where practical, but that comes into play very rarely for most folks.

In the construction of a cross-cut sled, measuring isn't really needed as much as being able to produce a "square edge", which can be done, with very little in the way of measuring....

[e-mail] wrote:

[bridger]

yabbut.... the guy has some nice machinist grade measuring stuff and likes to use it. there sure ain't no harm done by dialing in a crosscut sled and the method he described is easy, fast and accurate....

[Mark & Juanita]

That certainly may be the case, a methodology for adjusting a sled to square without measuring is certainly possible. The result and final precision will probably be very close to the same as obtained by using precise measuring tools and a couple of fine adjustments. The methodology I used with a few relatively inexpensive measuring tools was one I found to be relatively fuss-free, requiring only two tuning taps to the back fence to get the precision I desired.

As Bridger indicated, this effort was expended on a tool that I plan to make extensive use of in the future. I certainly do not use such measurements for assembly of furniture; my use of these precise measurements is reserved for setting up the equipment.

[bridger]

Barry- I made up a little PDF about my table saw sled. it's posted to ABPW. you're free to use it as is on your website, or if you would prefer I'll send you individual pictures. bridger