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HELP with my cross cut sled

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Forum topic by AngieO posted 08-04-2012 04:25 PM 1690 views 1 time favorited 19 replies Add to Favorites Watch
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AngieO

1172 posts in 813 days


08-04-2012 04:25 PM

Topic tags/keywords: cross cut sled sled moisture question problem table saw

I was excited to get outside today after it rained yesterday and I couldn’t really get any work done. As a reminder… I store all my tools in the garage. Garage has an AC unit that is set to about 75-78. (probably the higher end). When it’s time to work… I pull everything out and work in the yard.

I’ve been working on a cross cut sled. Here is how far I had gotten two days ago. Yesterday… didn’t do anything

So, as I was putting this together I obviously tested the rails before I attached to them to the board. They slid very nicely through the slots. I attached one and tested it. I sanded a little and tried again and it slid nice. I attached the second and did the same. I was going to put some wax on and add the rest of my pieces today. I had put the sled in the slots and left it there. Today when I went out I couldn’t get it out. Finally with my sons help I was able to get it off and I sanded away. I didn’t really get very far so I took one of the rails off and tested the one left. It wouldn’t go through. I guess I need to start over.

I guess I’m wondering if it was moisture that expanded the wood or what? My table’s slots are kind of a “t” groove so I had to put it on my router and add some rabbets. Like I said… worked great the day I made it.

I guess I have to start over. But what can I do differently? Different material? Different method? We live in a river town. Our whole area is known for it’s humidity.

You guys have been such a great help. So I appreciate everyone that responds.

And until then… I’m going to go play with my miter saw and router and make some sawdust! :)


19 replies so far

View guitchess's profile

guitchess

82 posts in 2374 days


#1 posted 08-04-2012 05:27 PM

Look at the grain direction of the runners. It should be pointing up and down, from the sled to the table. This will make the expansion contraction happen in the vertical direction instead of side to side.


You could also make slits in the runners and countersink a screw in the middle of each. This will make the runners adjustable.

View Alongiron's profile

Alongiron

402 posts in 1359 days


#2 posted 08-04-2012 05:59 PM

It is tough to see but are your runners made of hardwood? Hardwood will move alot less then that of softwood. I god choice would be Oak or Walnut…another good choice would be a good 8 ply plywood..that would not move the least of the 3

-- Measure twice and cut once.....

View boxcarmarty's profile

boxcarmarty

9346 posts in 1026 days


#3 posted 08-04-2012 06:50 PM

Remove 1 of the rails and cut your sled down. Your sled only needs to run on one side of your blade, otherwise you’ll be cutting it in half. With the sled running in only 1 slot, You’ll cut the resistance of them pulling against each other. Also use a hardwood or quality ply and watch your grain direction as guitchess and Alongiron said…..

-- My mind is like lighting, one brilliant flash, then its gone.....

View nwbusa's profile

nwbusa

1017 posts in 952 days


#4 posted 08-04-2012 06:56 PM

Depending on how much you want to spend, there are options other than wood for the runners.

http://www.leevalley.com/en/wood/page.aspx?p=65247&cat=1,43455

http://www.leevalley.com/en/hardware/page.aspx?p=32045&cat=3,43576,32045

I used the UHMW material, and it worked great for my sled.

-- John, BC, Canada

View Tomj's profile

Tomj

204 posts in 1048 days


#5 posted 08-04-2012 08:19 PM

One of the problems I had when making a sled for my Craftsman portable was the T-grooves/T-tracks. You could buy T-track that would be the easiest, I’m just not sure if the Craftsman is a off size so you have to buy it from them and if I remember correctly they aren’t that long. I’m sure there are other ways of dealing with this. Also the humidity/weather changes absolutely can effect the tracks. Good luck.

View AngieO's profile

AngieO

1172 posts in 813 days


#6 posted 08-05-2012 02:52 AM

I’m not sure what kind of wood that I used. I thought I used the piece that my friend told me was oak. But since I didn’t buy it and I don’t know how to identify the woods… I’m not positive.

When I went to Lowe’s today (only place open), I talked to a really helpful guy. He suggested that after I get everything cut, before I attach the rails, that I should put a sealer on all the pieces. He said that would seal it and keep the material from swelling and contracting. What do you guys think?

I’m not really in a position to buy pre made runners.

Boxcarmarty… I thought about doing that. I was also going to add a “handle” to it that would keep the two pieces together once I cut it in half. But I did see one that was just on one side of the blade. I may still do that.

Tomj… YES. those dang T-grooves were a pain in my butt. Maybe I’d be done by now if it wasn’t for them. But I did use my straight bit on my router and added the grooves so it would still go through.

I gave up for today and made a box and a picture frame. It was fun until I ran out of light. :)

View boxcarmarty's profile

boxcarmarty

9346 posts in 1026 days


#7 posted 08-05-2012 03:38 AM

We’re gonna need to see pictures of the box and frame. Then you can run up here to Martinsville and get another piece of oak or walnut from my stock and try it again…..

-- My mind is like lighting, one brilliant flash, then its gone.....

View AngieO's profile

AngieO

1172 posts in 813 days


#8 posted 08-05-2012 03:51 AM

Really? Did I know that you were in Martinsville? That’s where my friend lives that has hooked me up with most of my tools.

View AngieO's profile

AngieO

1172 posts in 813 days


#9 posted 08-05-2012 03:54 AM

nwbusa… I’ve been thinking about that plastic as well. Didn’t know what it was called. Thanks for the link.

Boxcaramrty… I’m planning a trip to Martinsville in the next two weeks. You are only about an hour and a half or so away.

View HerbC's profile

HerbC

1175 posts in 1525 days


#10 posted 08-05-2012 06:10 AM

Angie,

There are plenty of sleds with two runners in use.

The problem was almost certainly due to expansion of the material in the runners due to the weather.

You could use runners cut from the plastic they use in commercial cutting boards (like the ones sold at Sam’s Club or Costco…). The material machines well with normal woodworking tools (just keep it moving so it doesn’t overheat and melt while cutting) and in addition to not “moving” with humidity changes, it is also slick and slides well. You can’t use normal glues on it and would have to attach it with screws. When you do so, be sure to countersink the screw hole and don’t use too much pressure with each screw or it will distort the plastic runner.

“Sealing” the wood runners might help but there’s some question as to whether it would really help. Oil finishes which penetrate into the wood do not “seal” the surface. Film finishes such as polyureathane do seal the surface to some degree but the finish would change the width and thickness of the strip by whatever the thickness might be. The best thing to use on wood runners would be a good wax such as Johnson’s Paste Wax. Be careful not to use any wax that has silicone in it (as many car waxes do) since silicone can transfer to the wood you’re using in your projects and cause problems with your finish, such as “fish-eye”...

Good Luck!

Be Careful!

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View Rob's profile

Rob

122 posts in 1653 days


#11 posted 08-05-2012 12:03 PM

Angie, I had the same problem as you when I built my cross cut sled and I fought with it so much I was ready to toss the whole thing. Then I decided to spend a few dollars and bought a piece of miter track from Rockler and screwed it to my sled. No expansion or contraction. Works perfect every time. If you continue to have problems, you may want to try the method that worked for me.

http://www.rockler.com/product.cfm?page=21651&rrt=1

View bondogaposis's profile

bondogaposis

2544 posts in 1017 days


#12 posted 08-05-2012 01:37 PM

I think part of the problem is that you are rabbeting the runner to fit in the T-slots. That just gives more opportunity for binding. I recommend that you try runners that are straight in profile rather than rabbeted and use 1/4 sawn material. I like to use maple or birch for my runners as those woods are fairly stable and it is easy to get slick finish on them.

-- Bondo Gaposis

View AngieO's profile

AngieO

1172 posts in 813 days


#13 posted 08-05-2012 08:17 PM

Herb… I have some Johnsons Paste Wax that I’m going to try. Since I have more time than I do money I’m going to try and see if the sealer will work.

Rob… Thanks for the link to the miter track. If the sealing doesn’t work I may give that a try. Gotta get more money though to throw at it.

Bondogaposis… Actually the first runners I made were straight. But when I ran them through they allowed the base of the sled to move back and forth too much. Since my slots had the “t” in them… as soon as the slots got past that part of the miter slot… it would just allow the base to twist.

View boxcarmarty's profile

boxcarmarty

9346 posts in 1026 days


#14 posted 08-05-2012 10:44 PM

Let’s see if this helps any. I went back and looked at the picture of your saw. Have you considered grinding the tabs off of the slots so that you can use a solid track?

I also found a blog here on LJ’s with the same situation. He gives the dimensions of the t-slot which maybe helpful if you want to mill it in a plastic.

There is also a member that commented that he ground the tabs off of his saw.

Here is LegendInMyOwnMind’s blog….. http://lumberjocks.com/LegendInMyOwnMind/blog/23230

-- My mind is like lighting, one brilliant flash, then its gone.....

View bondogaposis's profile

bondogaposis

2544 posts in 1017 days


#15 posted 08-06-2012 12:04 AM

Ok, well I didn’t know about the tabs in my suggestion. What a stupid design, if it was my saw they wouldn’t last long. Sorry, Angie O, I didn’t fully understand the problem you are dealing with.

-- Bondo Gaposis

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