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:

sled.jpg

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.

[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.