adambaum

Crosscut sled - what's an acceptable error?

Recommended Posts

All,

 

As I go through my trials & tribulations of building a crosscut sled, what is considered an acceptable amount to of error?  .02" over 18"?  More? Less?  I'm actually building a 27" deep sled, but 18" seems to be a nice dividable number and I rarely use the sled for items much bigger than that.

 

My current sled is out about 1/50" over 17".

 

Adam

Share this post


Link to post
Share on other sites

A 27" sled?  That's a big one.  I would also make a smaller one -- say 12" deep (you will use it 90% on the time).  I actually think my small sled is 9".  I almost never use my 24" deep sled.

 

I don't have much experience with inaccuracy in a sled -- my method of making a sled leaves me with 100% dead-nuts-on.

 

We'll wait for others to chime-in?

Share this post


Link to post
Share on other sites

HHH, I have a few sleds I use. They all have a bit of error. What method did you use to get to zero?

 

Adam, I do my final shimming with pieces of paper, so I'd say acceptable error is half the thickness of a sheet of paper over what ever the length of your sled is.

Share this post


Link to post
Share on other sites

==> HHH, I have a few sleds I use. They all have a bit of error. What method did you use to get to zero?

 

I posted my sled method a couple of days ago on a related thread -- take it for what it's worth...

 

Share this post


Link to post
Share on other sites

==> I watched this last night researching a recommended YouTube personality. His method seems fairly no-frills and straight forward for achieving near perfection.

 

TS panel cutter -- not a cross-cut sled...  Different animal...  I used to have one of these, then I got a TS55...

Share this post


Link to post
Share on other sites

The real issue here is the 5-cut method. It essentially puts a magnifying glass on the level of error we experience with our sleds. And truthfully, it puts the error on a scale that few of us really every have to worry about. But because it's so effective, we do it. But it can certainly lead to someone chasing their tail all day long.

 

To me, the acceptable amount of error is right at the cusp of where you might notice it. While assembling a project, if you have a 17" wide panel that is off square by less than 1/32" and pretty close to 1/64", would you notice? Would you even be able to see it with the squares you have access to? My guess is that for most of us, the answer would be no. And for anything smaller, like joinery, that level of error becomes even less impactful. 

 

But, if you CAN get it better (without driving yourself crazy), give it a shot. If you think trying to improve on it will simply make it worse, then stop where you are and start building a project. 

 

Here's a story that might help you put things in perspective. When I got my tablesaw (the PM2000 with the flames), I started to stress about the flatness of the top. I can't remember how much of a dip it had but it was more than most of us would consider acceptable. I'm picky, but not THAT picky. So I asked for a new top and the manufacturer agreed that it was a little too much error. Unfortunately, the second top had the same problem. I lost a few weeks of tablesaw time as a result of this fussing around and decided I had enough. I needed to get back to work. I bolted the top down, calibrated the saw as well as I could and started on the next project. It was bugging the heck out of me that I was going to "live with" this error but I pushed forward. Over 6 years later (or something like that), I have yet to notice ANY negative impact in my work. The final fit and finish of my projects is as good as I expect it to be. So the moral to the story is, it's only a problem if it's a problem. Your sled's error is not yet a problem, it's a number. If you start using it and you find that your work quality is diminished by the level of error you're experiencing, then you know for you in your situation, it's an issue that needs to be fixed. If you never notice a thing, then there really is no problem at all and the sled is accurate enough.

  • Like 1

Share this post


Link to post
Share on other sites

>TS panel cutter -- not a cross-cut sled... Different animal... I used to have one of these, then I got a TS55...

Methodology is the same.

Share this post


Link to post
Share on other sites

I use a sled to mill out my wooden A/C vents and return panels. The sled has to be dead on or it comes out dead wrong. Even a fart-skin out of square will result in the parts not lining up. That being said, it's an extreme situation compared to most woodworking requirements. Marc is right....if you can't tell it's off, then don't fix it.

Share this post


Link to post
Share on other sites

I use a sled to mill out my wooden A/C vents and return panels. The sled has to be dead on or it comes out dead wrong. Even a fart-skin out of square will result in the parts not lining up. That being said, it's an extreme situation compared to most woodworking requirements. Marc is right....if you can't tell it's off, then don't fix it.

 

 

Right!

 

And small 8-9" wide sleds are a lot easier set up, and to lift on and off the saw, so build several, and stress where it's really warranted.

Share this post


Link to post
Share on other sites

William Ng has a great YouTube video on making and squaring a tablesaw sled. He actually has a simple mathematic formula that tells you exactly how much to adjust the rear fence and in which direction. However, it is my belief that his method only works if you build your sled centered between the miter slots. Personally, I built mine with more of the sled to the right of my blade, as this suits my style best. I completely understand your frustrations. I chased my tail for quite a while before I finally got it dialed in. Just be patient and step away when you start to feel like you're gonna explode....."Hulk hate crosscut sleds for tablesaw!!!" <-----this was me on multiple occasions.

Share this post


Link to post
Share on other sites

Glad to have inspired you.  Good article.  I'll build something and see how it comes out before passing final judgement on my sled.

 

Adam

Share this post


Link to post
Share on other sites

I have made several sleds over the years but the last couple I made have been the easiest, this is what I do- tuning your saw first is a must, and getting the fence exactly in line with the miter slots is key. I then place washers in the miter slots to shim the runners just proud of the saws top, put the runners (quatersawn Maple is my preference) in and align them with the front edge of the saw. I then spread glue on the runners (wax your saws top first so if there is squeeze-out it wont stick or discolor your saws top) and then place your plywood firmly against the fence and the front edge of your saw and place weights over where the runners are and walk away for an hour or so. Now since your fence is perfectly in line with your slots which is perfectly in line with the blade (this is where tuning your saw perfect to start with comes into play) you can use a square register the fence of your saw to the one your attaching to the sled. I spread glue on the bottom of the fence and place it on the sled, then I then slide the sled just far enough off the front of the table saw to be able to shoot a few brad nails up from the bottom. Then I push the sled back onto the saw and double check the alignment, tap the fence one way or the other to get it perfect (the nice thing about brad nails is they allow you to tweak it a bit) place weights on the fence and walk away again. When you come back then put screws up from the bottom to re-enforce the fence, attach a front fence and your done. With doing it this way I have gotten perfect cuts right away every time and passed the 5-cut test with flying colors. It takes longer to build the sled because of waiting for the glue (if you try to screw before the glue dries its going to slide) but not having to spend the time adjusting it and having no frustration is worth it. I prefer using 1/4" plywood and laminating up a 1 1/2 thick fence as it is very rigid and will never move on you. Like I said this has been a huge improvement over all the other sleds I have made through the years not only because of the ease of building but also since the fence is glued and screwed down it doesn't get knocked out of whack like the ones I made that you could adjust the fence.

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.