Thread: Cross cut sled accuracy.

I would say that's far too inaccurate, and you should be able to get it a lot more accurate than that.

When doing the 5 cut method, if the end result is 1mm off, you need to adjust the fence by 1/4th of 1mm, not 1mm.

Get a sheet of paper and a test piece of timber use one thickness of paper tucked in the far end and use increasing amounts of paper until you find your square.
then place a block of wood with the pieces of paper tucked in, clamp the block, remove the paper and then move the fence until it rests against the block.
no math required method.
cheers

What mpot said - you should be much closer than that.

I use 5 cut method for a square of mdf that is 300mm on a side. After adjustment, my cross cut sled is out by ~0.1mm over a single 300mm long cut. This translates into probably 0.05mm out over the kind of widths I normally cut on it.

I made the runners out of a high density plastic for stability/repeatability, since even quarter-sawn hardwood runners would bind at certain times of the year depending on the prevailing humidity

Go with the shooting board idea. Apart from being able to creep up on the exact angle the resulting planed surface is better for gluing than a sawn one.

Tom McLaughlin has a 3 cut method which still creates a very accurate result but without the math.

3 Cut Method to a Dead-on Crosscut Sled with Tom McLaughlin - YouTube

Maybe see if this is this works better for you.

If you are still getting results, have you considered checking if your saw needs tuning up? Both this and the 5 cut method rely on the mitre slot being parallel to the blade.

Originally Posted by taz01

Both this and the 5 cut method rely on the mitre slot being parallel to the blade.

Unfortunately, mostly we use "budget" table saws from manufacturers who are catering to a price point rather than build quality, with minimal QC / QA.

The quote above is a fundamental condition - IF it is not parallel on your saw then adjustments to the sled will be mute to an extent.

One simple test is to measure the "clearance" between a clamped stop block of dense hardwood to the front then rear of the saw blade as the sled is pushed 'through" the saw. There are numerous clips on the 'web showing technique, measuring to the same tooth etc. In real life every tooth will contact the work piece. I personally believe it's best to take a wide sample of measurements rather than to one reference tooth.

I cut numerous small components (2mm high triangles 75 mm long etc) for the construction of inlay banding blocks. Precision and accuracy are essential as errors accumulate rapidly as you step 10, 20 ... 50 units along the banding block.

I would suggest checking the fundamentals of your saw - arbor float, mitre slot to blade, wear in trunnions etc. and repairing / adjusting as required. Then stuff like free play in sled runners / mitre slot etc. I spent over three days adjusting my Woodfast TS250, to reach a point where further adjustment was not practical due to design / manufacturing quality etc.

Is the base of your sled perfectly flat and sitting evenly on the table top? If it isn't it will effect the accuracy of your mitre cut. Just slightly different pressure on the sled as you slide it through will cause the warped areas to either bear down on the table or lift off it making your cut line change angle.

Originally Posted by Mobyturns

Unfortunately, mostly we use "budget" table saws from manufacturers who are catering to a price point rather than build quality, with minimal QC / QA.

The quote above is a fundamental condition - IF it is not parallel on your saw then adjustments to the sled will be mute to an extent.

...

I would suggest checking the fundamentals of your saw - arbor float, mitre slot to blade, wear in trunnions etc. and repairing / adjusting as required. Then stuff like free play in sled runners / mitre slot etc. I spent over three days adjusting my Woodfast TS250, to reach a point where further adjustment was not practical due to design / manufacturing quality etc.

Agree entirely. If you are using a lower end table saw there could limited ability to adjust your blade so it is parallel with the mitre slots, but it's worth investing the time and filling the swear jar. There are lots of good videos on you-tube on how to do it. Also have a look at who makes your saw and google to see if they have a detailed manual or exploded diagram to show you how to perform the adjustments (sometimes the manuals are hidden away on websites so google it). Also see if there are similar designs of your table saw (most are made in the same factories in China) and see if they have manuals/diagrams.

If you have finances, invest in a dial indicator gauge (tablesaw specific or just a generic one) to see if the blade is out of parallel. Again there's a ton of videos on how to do this. This will be more precise and repeatable than a 5 cut method.

I like Tom Mclaughlin's 3 cut method - a very clear approach to sneaking up on accuracy. But as others have said, there are still plenty of ways for inaccuracy to creep in. I think I will be making myself a shooting board!

In addition to the 3 cut method mentioned there is also a 5 cut method linked here The 5-cut method made easy | Squaring a Table Saw Cross-Cut Sled in 5 minutes - YouTube
This link is a collection of cross cut sled methods to improve accuracy. https://www.youtube.com/results?sear...+crosscut+sled
best of luck have a go
calabrese55

I have made a lot of sleds and the only thing i took out of that 3 cut video was the importance of an accurate square.
I use 16mm White board for the sled base as its flat and smooth, dado cleats are timber and 2mm higher than the table top. I set the dado cleats in place and apply glue then lay the sled base on them and use the fence to get it fairly accurate, put some weights on it and let it dry. For the front and rear cleats i use hardwood 40 x 70 dressed with one edge dead straight, i screw the back cleat on then run the sled not all the way through the blade then apply glue to the front cleat and position it using a builders square against the blade, not the teeth, and leave it to tack enough so it won't move then clamp it and leave to dry. This works every time and the proof is in the number of questions i get on how i get my mitre and square cuts so perfect.

DaveVman if your box stock is just a little bit cupped or twisted it will be hard to get a square cut as well.

Two people who know how to do it properly, get the slot parallel to the blade before anything else.

Quantifying what Wrongwayfirst says, a sheet of A4 copy paper is a smidgin under 0.1 mm. You should aim for an error less than 0.2 mm in 200 mm.

For all fine work like small box making, I prefer to do the final clean up on a shooting board.

This is all a bit depressing because I'm not even getting consistent results from my sled. Thanks to you guys I now realise I need to figure out a way to check and adjust my blade to the mitre slots since it has been moved twice. It is a Sawstop. It is a good table saw. But the balde is burning the wood. Which it didn't do prior to 2 hpise moves in 6 months. so that probably my first clue which I was trying to ignore.

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