Crosscut sled issues

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Forum topic by PNW_Steve posted 08-25-2017 06:01 PM 1799 views 0 times favorited 12 replies Add to Favorites Watch
View PNW_Steve's profile


50 posts in 1154 days

08-25-2017 06:01 PM

Mornin’ Everyone,

I have been working on a crosscut sled for me new (to me) Unisaw. I started a week or so ago and followed one of the many designs out there.

I cut and fit two inserts for the miter slots from oak. I fit them to slide easily in the slots with little side play, shimmed them up from the bottom of the slots and sat the sled on top of them using glue & screws to attach. Then removed the shims.

For as long as the humidity stayed around 16%-20% it fit beautifully. This morning the RH in my shop is 46% and the sled was pretty well stuck in the miter slots.

I know that I need to remove some material from the miter slot inserts but am braindead when it comes to figuring out where to start removing material. As I did glue the rails on I have one shot to fix it properly. If I foul up the whole sled is wasted.

Any suggestions as to how I should proceed?



12 replies so far

View buckbuster31's profile


256 posts in 1367 days

#1 posted 08-25-2017 06:05 PM

watch the wood whisperer video. he addresses that but basically you need to run the grain of the the runners where it expands up and down vs left to right

View Kazooman's profile


1540 posts in 2804 days

#2 posted 08-25-2017 06:13 PM

Since you glued the inserts on your options are pretty limited. I would try a piece of sandpaper glued to the side of a block of wood so that you can run the block along the bottom face of the sled while sanding the edge of the insert. Go slow to avoid removing too much wood.

However, if you get the sled dialed in at the now higher humidity you will be facing the opposite problem when the runners dry out when the humidity goes back down. Then the fit in the miter slots will be too loose and the sled will not fit well. That is the nature of the beast when you choose to make table saw jigs with wooden runners.

You have a high quality saw. If it were up to me I would invest in a good set of commercial metal miter slot inserts. They work great. Most have adjustable bearing points so you can fine tune the fit to your saw’s miter slots. Well worth the investment, IMHO.

View ChefHDAN's profile


1730 posts in 3701 days

#3 posted 08-25-2017 06:43 PM

I agree with Kazoo, either look to buy some runners or go to a product that wont be affected by RH. I’ve got loads of solid surface counter tops that I salvaged when one of my cafe’s was renovated and it mills fine with carbide, so I just mill it to use for my runners.

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

View fivecodys's profile


1647 posts in 2488 days

#4 posted 08-25-2017 08:00 PM

I had this happen to me. What I did was to take a sharpie and run a line down each side of the runners and then place the sled back in the miter tracks. I shoved it back and forth and then checked to see where the sharpie had been rubbed off or smeared. I took a cabinet scraper and sandpaper and worked on that spot a little and then started the process all over again until I had it moving smoothly again.
Go easy or you will take off too much and then when the humidity goes down it will be sloppy lose.

Next time I will use LDPE or an old cutting board to make the runners.

-- A bad day woodworking is still better than a good day working.

View Carloz's profile


1147 posts in 1443 days

#5 posted 08-25-2017 08:08 PM

1. Mark the runners with a black marker. If you do have black use red, if you do not have red use blue.
2. Insert the sled into the slots and move several times, You might need a good push if the wood swelled.
3. Take the sled out and see where the marking is gone. Remove the material in those spots.

The best tool that works, but you are unlikely to have is a shoulder plane. A piece of rough sandpaper on a wood block works too.

View EricTwice's profile


248 posts in 1385 days

#6 posted 08-25-2017 08:35 PM

First you have to find out if it is one inset that is tight or both, or they may fit fine, and they swelled to push in or out. Once you know exactly what the problem is, You can adjust with hand tools as discribed above, of if the runners are square to the side of the sled you can trim them with the table saw. (You have to be careful with this, we are talking microscopic amounts)

UHMWP works well as an alternative to wood also, (but I usually use wood, and they work perfectly in winter but when the summer humidity comes they stick, or the other way round and are sloppy in winter)

Go slowly and have fun,

-- nice recovery, They should pay extra for that mistake, Eric E.

View PNW_Steve's profile


50 posts in 1154 days

#7 posted 08-25-2017 09:18 PM

THANK YOU Everyone!!

I had considered the “sanding block” but not the marking to find the high spots. I have Marsh stencil ink that should work for marking. I will give it a shot.

I see Sled V2.0 coming soon with metal or synthetic inserts. I wish that I had not glued these in place…..

Thanks again for the suggestions.


View MrUnix's profile


8212 posts in 3051 days

#8 posted 08-25-2017 09:27 PM

I’ve made them out of oak… then sealed them with poly and given a good couple coats of wax. Your humidity swing is small compared to what we get down here, and I’ve never had a problem with them yet. If the moisture can’t get to them, it can’t effect them :)


-- Brad in FL - In Dog I trust... everything else is questionable

View PNW_Steve's profile


50 posts in 1154 days

#9 posted 08-25-2017 09:32 PM

I ve made them out of oak… then sealed them with poly and given a good couple coats of wax. Your humidity swing is small compared to what we get down here, and I ve never had a problem with them yet. If the moisture can t get to them, it can t effect them :)


- MrUnix

If I can get them to play nicely, I’ll give that a shot before I tackle V2.0.

Thanks for the input.

I still have Dilbert on the brain…..

View patcollins's profile


1687 posts in 3717 days

#10 posted 08-25-2017 09:53 PM

Using two runners is always risky, if your sled itself expands any it will no longer slide.

I found when I had a two runner sled it helped if I stored it on the saw in the miter slots.

View PNW_Steve's profile


50 posts in 1154 days

#11 posted 08-25-2017 10:16 PM


You guys officially ROCK!

Marshes black stencil ink, sanding block and beezewax. It slides like a dream!!

Thanks again.


View Robert's profile (online now)


3950 posts in 2333 days

#12 posted 08-26-2017 01:00 PM

I bought a stick of Azek to use haven’t done it yet but don’t see why it wouldn’t work.

I’m thinking plow a dado since the material is quite flexible.

-- Everything is a prototype thats why its one of a kind!!

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