Show me your micro-adjusters for Crosscut Sled

[Andy Sowers]

All,

I've been wrestling with squaring up my crosscut sled today which I noticed (to my chagrin) has somehow got out of kilter recently.

I've been using the 5-cut method, but can't seem to get it close enough. I'm tapping gently to move the fence, but this is just too coarse of an adjustment.

I was considering retrofitting to add some kind of micro-screw adjuster on the fence. Any ideas from the crowd? Pictures would be great.

Here's a view of the back of my sled:

135777

The fence is held down by two bolts with oversized thru holes to allow for fence adjustment. After I get the fence dialed in, I drive additional wood screws in from the bottom help secure the angle.

Thanks
Andy

[Greg Hines, MD]

My sled is very simple, and I just loosen the screws holding it in place to square it, but so far, it has done fine.

One thing that I have seen for adjusting router table fences is to create a fine adjustment using a turnbuckle and pair of bolts which seemed to work well. I forget where I saw it, probably ShopNotes.

Doc

[Glen Butler]

I have no pics because I am still building mine. For you, would it be possible to glue a block on each end of the back of the sled. Tap each block with say a 10-32 screw, that you could butt your fence to as you tighten the bolt. Wick thin CA into the fibers and retap for durability. Then use the screw for a finer adjustment.

[Glen Butler]

I guess no one out there has micro adjusters to help Andy out. Well I finished my sled last night, and it went famously.

Pic 1 below shows the micro adjusters. They are a 5/16-24 x 3/4 set screw. I drilled the fence rail (shown more clearly in pic 2) to accept the set screw, wicked thin CA into the hole, tapped, CA again, retap. This provides exceptionally strong threads in the 1-1/8" MDF rail. I machined a piece of poplar for use as the mechanism that holds the fence straight (pic 3). I don't know why I chose poplar, I probably would have been better off with 3/4 MDF. To get the poplar perfectly straight you'll see in the background of pic 3 that I clamped my level to the TS fence. Pic 4 shows how the MDF fence is attached to the poplar. I left a little space under the fence to allow chips to get out of the way. Pic 5 shows the final assembly

So how did the micro adjusters work? Excellently. I set the fence against the adjusters and tightened the two outside bolts along with one near the blade. Did the five cut method. I ended up with .4915 in front and .4635 in back.
0.4915 - 0.4635 = 0.028
0.028 /4 = 0.007

The fence is 60" inches long. My five cut sheet was 20".

20/60 = 0.007/0.021

So I need to move the right side of the fence foward 0.021. There are 24 TPI in the set screws.

1/24 = 0.0417
0.0417/8 = 0.0052

So every 1/8 turn will give me 0.0052

0.021/0.0052 = 4.03

I adjusted the right side of the fence the 4/8 of a turn. Retested using the five cut method, and I am 0.0005 in 20". No guessing, just mathematic.

[glenn bradley]

I just use the tap method and this has worked fine. I do have four bolts across the length of the fence but don't know that this helps. The bolts fit in very tight holes in the fence so as to allow no movement. All adjustment is via oversized holes and mortises for the t-bolt heads to move within. Did that make any sense. I am able to snug one end and then 'swing' the fence. I notice your two bolts. Do they slide or only pivot?

Early design with bad pics here: http://www.sawmillcreek.org/showthread.php?t=50581

Better pics here (http://www.sawmillcreek.org/attachment.php?attachmentid=59692&d=1173332187).

[Glen Butler]

The poplar is slotted at all six bolt locations. Tapping works . . . surely, but I wanted to eliminate the geussing and checking.

[glenn bradley]

The poplar is slotted at all six bolt locations. Tapping works . . . surely, but I wanted to eliminate the geussing and checking.

I am guilty of missing the micro adjust feature Glen was showing; very cool idea.

[dan sherman]

I finished up my sled tonight, and got it down to .0055" per foot (calculated) using the 5 cut method.

I cut the big back panel for my router table, roughly 32" square and I'm of a little more than a 1/64". Thus real world was a little over the calculated value.

How close is close enough?

over 3 feet how close is close enough 1/32", 1/64", 1/128", smaller?

[Glen Butler]

What is close enough really depends on the application. I needed my sled as near perfect as possible cause I am squaring up panels for line boring shelf pegs, and flipping panels compounds any error. So if I had 1/128 accuracy it would end up 1/64 difference corner to corner on a shelf and thats more than enough to make the shelf rock.

Before I learned of the five cut method, I made a sled that was .007 (1/128) out of square in 24". I crosscut parts for over 100 cabinet doors on that sled but the doors came out square and the customer had no problems installing the doors and lining them up.

[Andy Sowers]

Very cool Glen!

My next sled will incorporate something exactly like yours. I think the one thing that makes adjusting mine difficult is that it lacks the stationary piece along the front of the sled. Thus, all adjustments to square have to be "bumped." In practice, I found that my "bumps" weren't very predictable...

Another idea I had was to use a kreg micro adjuster that I picked up over the holidays as a stocking stuffer. But your setscrew idea is slick!

Thanks for the followup!!!
Andy

[Glen Blanchard]

Well when I made my sled a few weeks ago I did not incorporate a micro-adjuster. However, after each test cut (5 cut method) I clamped a dial indicator to the sled to register the amount I subsequently moved the fence (via tapping). A little math prior to the tapping told me how much to move it. Worked great....this method along with a micro-adjuster would have been awesome.

[Stephen Edwards]

Glen Butler: Very nice sled and a great micro adjustment concept. Is there a set screw on both ends of the sled? It seems so from your description but I just can't see in the pics to be sure. Thanks for sharing your idea.

[Glen Butler]

Andy,

What I was saying above is you can do this on your current sled, just glue some blocks to the front edge of your sled and tap those for a set screw.

[Andy Sowers]

Brilliant idea Glen! I think I will do just that! Andy

[Glen Butler]

Glen Butler: Very nice sled and a great micro adjustment concept. Is there a set screw on both ends of the sled? It seems so from your description but I just can't see in the pics to be sure. Thanks for sharing your idea.

Yes there is one on each end.

[Wayne Jolly]

Glen - Just out of curiosity, how did you measure to .0005" accuracy over 20"???

xeddog

[Glen Blanchard]

Glen - Just out of curiosity, how did you measure to .0005" accuracy over 20"???

xeddog

Wayne - I bet Glen used a set of digital calipers along with the 5 cut method. Glen ???

[Andy Sowers]

Are you familiar with the 5-cut method? If not, check out the link below... should help explain. Bottom line is you can measure this easily with a set of calipers (assumes your calipers can measure down to the ten-thousandths...)

http://www.thewoodshop.20m.com/five_cut_method_swf.htm

[Wayne Jolly]

OK, I get it now. I misunderstood the statement I guess. 5" x 4 sides = 20". I was thinking 1 side of 20". Duh!

xeddog

[Andy Sowers]

My guess is that he really did use a 20" square piece of stock... so he could in fact measure the difference across 20 inches... that's what I did...

--Andy

[dan sherman]

I just re did mine and I used a 18" square, as that was the biggest chunk of scrap mdf I had. You want as large a piece as possible, to magnify the errors.

I got mine down to .0018" per ft. :D The problem was the fence had a slight bow in it, and thus throwing everything out of wack.

[Glen Butler]

Wayne - I bet Glen used a set of digital calipers along with the 5 cut method. Glen ???

That's exactly right Glen.

[Glen Butler]

No longer allowed to edit the post above. Let me also say that you don't need a caliper that is accurate to the ten thousandths. Remember that when you finish the five cut method. The difference between the two ends of the 1/2 strip you cut off is 4 times the actual. My result was .002 so divide by 4 to get .0005.

[glenn bradley]

I'm tapping gently to move the fence, but this is just too coarse of an adjustment.

Tap more gently. I use the handle of the hex driver that I loosen and tighten the nuts with. A tap that to my mind makes no change at all is generally the last tap to get me within a thou on the 5 cut method.

Alternately, some of the screw adjustment mechanisms I have seen here are really cool! :) BTW, I think I see only two fastening points on your fence. Even if the fence were hard rock maple I would expect some deviation during some cuts. I use four positions; two on the end as you show and one a few inches on either side of the blade. I loosen all but one to "tap" and I tighten all four before each post-adjustment test-cut sequence. That way, once it is right, there are no changes made.

[Cameron Reddy]

... Did the five cut method. I ended up with .4915 in front and .4635 in back.
0.4915 - 0.4635 = 0.028
0.028 /4 = 0.007

The fence is 60" inches long. My five cut sheet was 20".

20/60 = 0.007/0.021

So I need to move the right side of the fence foward 0.021. There are 24 TPI in the set screws.

1/24 = 0.0417
0.0417/8 = 0.0052

So every 1/8 turn will give me 0.0052

0.021/0.0052 = 4.03

I adjusted the right side of the fence the 4/8 of a turn. Retested using the five cut method, and I am 0.0005 in 20"...

Impressive! So, when all the other kids in math class were complaining "when are we going to use this..." You were paying attention.

[Glen Butler]

Ha, ha. I paid attention up through trig. I use trig all the time, but beyond that I just didn't care. Calculus, theoretical or imaginary numbers, I just don't care. I want real numbers.:D

[Glen Butler]

:) BTW, I think I see only two fastening points on your fence. Even if the fence were hard rock maple I would expect some deviation during some cuts. I use four positions; two on the end as you show and one a few inches on either side of the blade. I loosen all but one to "tap" and I tighten all four before each post-adjustment test-cut sequence. That way, once it is right, there are no changes made.

I have six. Each of the bolts in the last pic is a fence fastening point.

[Tony Shea]

Great idea Glenn. One could also use some small angle iron or aluminum and mount it behind the fence and tap that. Might be a little easier to go through the tapping process. Use nuts on either side of the bolt to lock the settings. This is the approach I took on me sled and seems to work well.

[ken gibbs]

I am humble in the presence of great mathmatics. However, what exactly in the "5 step" or "5 cut" method? thanks.

[Dan Forman]

Ken---There is a link in post 18.

Dan

[Glen Butler]

I am humble in the presence of great mathmatics. However, what exactly in the "5 step" or "5 cut" method? thanks.

Everything up there is simple mathematics, but it can be hard when it seems someone is pulling numbers out of the air. I have a hard time following someone elses steps that they went through too. Everyone's mind just does the steps in a different way. I can explain in more detail what every number is and where it came from and it surely will make a lot more sense to you. Just ask.

[Joseph Tarantino]

i'm embarrassed to say that i cannot see how glen's micro adjuster works. i'd like to build another cut off sled and would like to be able to dial in the fence easily. glen...any chance for a few more pics that might clear up exactly how the adjust feature works? it would be much appreciated.

[Jeff Bartley]

If you have a set of feeler gauges you can try this: calculate the distance the fence needs to move, place a feeler gauge (whose thickness matches this calculated distance) in front of your fence, now clamp a block against the feeler gauge (sandwiching it between block and fence). Finally, remove gauge and very lightly tap fence to the block, re-secure the fence, and test.
I wish I had tried this when I squared up my last sled. I kept over-tapping. And a side note: remember not to loosen the bolt on the opposite end from the 'block and feeler gauge' or that end could move and throw everything off.
Jeff

[Al Willits]

Yes there is one on each end.


I use the tap method and its worked for me so far but I could see the set screw being much quicker.

I think I'd set the fence up so it was slightly more than 90 degree's and use only one of them though.

Al

[Neil Brooks]

Because I didn't build in a micro-adjuster, when I built my sled, and because I DO like the idea of a finer way to adjust it ....

More than once, I've grabbed a scrap block of wood, drilled a hole through it, and then screwed a long-ish (say, 3+ inches) machine screw through it.

Then, I've been able to simply _press_ the block against the rear fence of my sled, while turning the screw a thread or two at a time.

Particularly if my sled is sitting ON the table, with the runners IN the slots ... IT (the sled, itself) isn't moving -- only the rear fence (with bolts loosened) is.

If the sled WERE moving, I'd simply clamp it to the table, first.

It actually works fairly well ... nudging the fence a tiny, controlled, bit at a time.

Let's just say it's a really crude and cheap version of Rockler's ....

http://www.rockler.com/imageGallery/CustomerComments/16755_60493908_IMG_0006-siz-2.JPG

[Loren Hedahl]

My favorite method for woodworker tool micro-adjustments which I think might work well here is not to tap, but tape!

Scotch brand clear vinyl tape is about 2/1000 inch thick. Garden variety black electrical tape is about 5/1000 inch thick.

Of course doing this isn't entirely proper, but in my mind a practical, elegant solution especially if I need to get some work finished.

Another possibility might be to slightly taper the fence by sanding more at one end than the other, or by painting using heavier coating on one end.

Just ideas. If they help, fine.