Finally, a better sled runner

[Phil Thien]

I will be building a larger cabinet and needed a sled that could cross-cut 24" panels. I wanted a single-runner sled (cause my table saw only as one miter slot).

Wish list: (1) A runner that had no seasonal movement. I've used wood. It expands, it shrinks. (2) A runner with no slop. I have used the Incra miter runners, but they are tricky to adjust. The 24" version has only three (I think) width adjustment points and no matter what I do, there is always a little bit of side-to-side play. Plus, the 24" Incra Runner (their longest) wasn't really long enough (my sled is 27" long and I wanted a runner at least 27" long to match).

I decided to try UHMW plastic. I got a boatload of the stuff on sale from Peachtree Woodworking's sale. Included were two 48" long runners.

The stuff is flexible, doesn't glue well, and it was about .003" shy of .75". Great!

This is what I did: I routed a .75" groove in the bottom of my new sled (1/8" deep). I centered six 3/16" holes along this groove (at 6" intervals), and drilled some matching (but slightly larger at 1/4") holes in my UHMW runner.

I inserted special prongless t-nuts into the UHMW plastic (I used my woodworking vise to just squeeze them in). These nuts, BTW, are sometimes referred to as Propell nuts, sometimes as Hurricane nuts, McMaster just sells them as t-nuts. I used the #10-24 size (they have a base that is 45/65" in diameter).

Inserting the t-nuts into the runner made it "bulge" up to .752" around each nut.

I screwed through the top of the sled, through the runner, and into the t-nut. Trying the sled in my miter slot it was a little tight. A couple licks with a cabinet scraper at the "bulges" and it slid perfectly, no play and slides like butter.

The best thing is, I can actually tighten the screws from the top and the plastic bulges a little more (and the runner tightens in the slot). Loosen the screws and it slides like butter again. So, it is slightly adjustable.

And I like the fact that the runner can be removed/replaced, too.

You may wonder how to achieve this with a dual-runner sled (if you're one of the lucky ones with two miter slots). My suggestion is to make two single-runner sleds (one for left of blade, one for right). Then, with the sleds in their respective slots, attach the front and rear fences to join them together into a single unit.

[Dave MacArthur]

Great post! Thanks!

[Mike Goetzke]

Nice job Phil. You post brings back good memories - I had a BT3K of some sort for about 20 years before I bought a Unisaw a couple of years ago.

Mike

[Phil Thien]

Nice job Phil. You post brings back good memories - I had a BT3K of some sort for about 20 years before I bought a Unisaw a couple of years ago.

Mike

:)

I still really like my BT3K. My dream saw is an Inca 10" cabinet saw (280/290 model). It was an Americanized (w/ 5/8" arbor) tilt-arbor cabinet saw with hard-anozied aluminum top. Very few of them got imported, you mostly run into tilt-top and 2100 cabinet saws.

[Michael Panis]

Did you get the 90degree angle bracket at McMaster also?

[Brian D Anderson]

Nice job! Is there any reason you didn't go with the Kreg fixture bar?

http://www.toolmarts.com/kregkms7303.html

They're 30" long and have 6 adjusters. I used two of them for my sled, which is also 27" long.

-Brian

[Phil Thien]

Did you get the 90degree angle bracket at McMaster also?

No, they only had it in 8' lengths and I didn't know what shipping would do to me. I picked it up at a hardware store.

[Chris Padilla]

You're quite the innovator, Phil! Glad to have you aboard and a nice job!

[Phil Thien]

Nice job! Is there any reason you didn't go with the Kreg fixture bar?

http://www.toolmarts.com/kregkms7303.html

They're 30" long and have 6 adjusters. I used two of them for my sled, which is also 27" long.

-Brian

The main reason is that my miter slot is a shop-made fixture itself, using an Incra miter channel. Many of the miter bars out there are hard enough that I worry that they will wear the aluminum extrusion prematurely.

I guess whenever I post I should remind people that my table saw is only a Ryobi BT3000. Many of the issues that I'm confronted with probably are non-issues for you guys. Don't get me wrong, I like my saw and I've modified it pretty extensively. But a saw that doesn't come with miter slots? Get outa here!

If I had a cabinet saw w/ cast iron top, I'd absolutely look at something like the Kreg. The additional adjusters look like they'd allow for better adjustment than the Incra runners allow.

[Lee Schierer]

I've also mounted UHMW with flat head screws and counter sunk holes up from the botom into the sled. You can also drill and tap UHMW with machine screw threads. Just be careful when tightening not to over tighten as the threads will strip out.

UHMW can be worked with woodworking tools without much problem. The shavings are a bit of a pain to clean up.

This is O.T. but I used UHMW to make sacrificial runners for my snowblower and they have already lasted longer than the steel runners that came on the snowblower. I wore through 1/8" steel in one winter. I put on 1/8" UHMW over a new set of steel runners and they look like they will easily last several more years as they are still almost 1/8" thick after one winter.

[Phil Thien]

I've also mounted UHMW with flat head screws and counter sunk holes up from the botom into the sled.

I was gonna do that but when confronted with a choice, I always go for the non-obvious solution. :rolleyes:

When I first examined a piece of this thin plastic I noticed its flexibility. That is why I wanted the groove (to keep it straight). But the groove would further reduce the thickness of my sled, so less holding power for the screws. One thing led to another and I ended up with the solution above.

But now I'm wondering whether, in the future, I'd be better off with a machine screw from underneath into a t-nut from the top of the sled. Perhaps this would give me a wider adjustment range. I don't know why that would be important, but maybe something to play with.

[Eddie Darby]

If you don't have a bunch of UHMW plastic hanging around, Lee Valley sell these runners.

http://www.leevalley.com/hardware/page.aspx?c=2&p=32045&cat=3,43576,43581

2 foot and 4 foot lengths available. I like the "T" nuts!

[Alan Schaffter]

In general I don't like UHMW runners, but they are the only way to go if you have an aluminum miter slot. Steel or cast iron and aluminum don't mix very well as far as friction goes. I never liked the aluminum miter slot on my router table.

As far as miter bars for cast iron tables- I use 3/4" X 3/8" cold rolled steel bar. It is hard, smooth and a few years ago cost only about $5 for 20' of the stuff. I drill and tap it so it can be screwed in from the top of my sled. If you want a really snug fit, you just need to hit is with a center punch or peen it in a few spots.

[Brad Shipton]

I dont think all the UHMW runners are within .003. The ones I bought (from lee valley) were terrible, so I sent them back.

Brad

[Phil Thien]

I dont think all the UHMW runners are within .003. The ones I bought (from lee valley) were terrible, so I sent them back.

Brad

I do know Peachtree offers runners they claim are .75", and other runners designed for Craftsman slots that are .744". The .75" runners I got are a little shy of .75", though. It would be interesting to know the actual size of the Lee Valley units you returned.

I do know that a year or so ago I tried some .75" UHMW plastic at Rockler in a chunk of the miter channel from Incra that I had. At that time I felt they were a poor match, the UHMW plastic had too much play.

Knowing what I do now, I think it would have worked fine had I either used the prongless t-nuts or used the screws from the bottom like others have suggested. The little bulge in the UHMW plastic is really all it takes to firm the fit up.

[Andrew Joiner]

I'm a fan of single-runner sleds too. Just as an experiment I made one with a 3/8''x 3/4'' UHMW runner. It crosscuts 36". It's lightweight because the body is only 3/16" thick. It's still accurate 8 years later. It's my favorite sled cause it's light and stores right under my cabinet saw.

[Bob Wingard]

Since your #1 criteria was that you didn't want something that expends/contract with the seasons, I think you will be sorely disappointed with this stuff over time.

I used to carry armloads of it home from work, hoping to use it for runners & jig parts ... UNTIL I found how much it moved with heat/cold ... I see you've made provisions for adjustment on your ... that is a good idea, because you will use that feature more than you'd like.

These guys provide all the technical properties of the stuff, in case you're interested ... ... ...

http://www.polytechindustrial.com/products/plastic-stock-shapes/uhmw-polyethylene

[Alan Schaffter]

Since your #1 criteria was that you didn't want something that expends/contract with the seasons, I think you will be sorely disappointed with this stuff over time.

I used to carry armloads of it home from work, hoping to use it for runners & jig parts ... UNTIL I found how much it moved with heat/cold ... I see you've made provisions for adjustment on your ... that is a good idea, because you will use that feature more than you'd like.

These guys provide all the technical properties of the stuff, in case you're interested ... ... ...

http://www.polytechindustrial.com/products/plastic-stock-shapes/uhmw-polyethylene

I may be wrong, but I think you will find like nylon, UHMW PE also absorbs moisture! As I said in the original thread, I like 3/4" X 3/8" cold rolled steel for my miter bars. I think it slides easier than any of the plastics.

[Phil Thien]

Since your #1 criteria was that you didn't want something that expends/contract with the seasons, I think you will be sorely disappointed with this stuff over time.


This thread got bumped because a spammer posted a link to what I assume is his plastics reselling outfit. The spammer had three posts over several years, all of them links to his plastics outfit.

The thread was started approx. four years ago, and I have not noticed any seasonal problems whatsoever in that time.

I looked up the coefficient of thermal expansion for UHMW plastic: x 10-5 in./in./°F (http://www.jjorly.com/uhmw_technical_data_sheet.htm).

It would appear that in order to see a change of .001" across the .75" width of the runner, I'd need a change in temperature of approx. 12.12 degrees (F).

Absolutely a ton more than (for example) aluminum. Probably a ton less than what you'd expect from seasonal changes for wood.

My shop is climate controlled, so it really doesn't matter for me.

[Phil Thien]

I may be wrong, but I think you will find like nylon, UHMW PE also absorbs moisture! As I said in the original thread, I like 3/4" X 3/8" cold rolled steel for my miter bars. I think it slides easier than any of the plastics.

Water absorption over 24-hours is stated as NIL:

http://www.jjorly.com/uhmw_technical_data_sheet.htm

[Alan Schaffter]

Water absorption over 24-hours is stated as NIL:

http://www.jjorly.com/uhmw_technical_data_sheet.htm

Thanks, so it is not like nylon.

[Andrew Howe]

I do know Peachtree offers runners they claim are .75", and other runners designed for Craftsman slots that are .744". The .75" runners I got are a little shy of .75", though. It would be interesting to know the actual size of the Lee Valley units you returned.

I do know that a year or so ago I tried some .75" UHMW plastic at Rockler in a chunk of the miter channel from Incra that I had. At that time I felt they were a poor match, the UHMW plastic had too much play.

Knowing what I do now, I think it would have worked fine had I either used the prongless t-nuts or used the screws from the bottom like others have suggested. The little bulge in the UHMW plastic is really all it takes to firm the fit up.

I bought some.from mcmasters and it was too big for my saw slot. Bought cold rolled steel.and it fits perfect with one runner. My sled is big 33" capacity for the workshop cabinets I am making.

[Anthony Diodati]

I wonder if there is somewhere local to get the cold rolled steel. There is some reasonable on e bay, but then the shipping kills it IMO.
Maybe I will check with lowes. Tractor supply had some aluminum and cold rolled, but it was only about 1/8" thick.

[Jacob Reverb]

I wonder if there is somewhere local to get the cold rolled steel.

Markup on metals at the Borgs is probably 5000%. Google or Yellow pages "steel service" or "steel service centers" in your area...they may have short offcut remnants ("drops") they may sell you cheaply (most sticks are sold in 20' lengths). Check also for local welding and metal fabrication shops.

I think I bought my cold-rolled steel for runners at use-enco.com ... look for items marked down and you can do all right. They also have regular specials (20% off, free shipping, that kind of thing) if you get on their mailing list or Google around for Enco coupons.

I do metal fab as well as woodworking, and I have been very happy with their prices/service/shipping speed.

[glenn bradley]

Good stuff Phil. I have runners of wood, aluminum and UHMW. Where I live all perform well but, I do use the trick of tightening the UHMW screws just a bit to tailor the fit. The aluminum has adjustments built in (Incra) but, the wood had to be planed/scraped for a tailored fit.

[Phil Thien]

Markup on metals at the Borgs is probably 5000%. Google or Yellow pages "steel service" or "steel service centers" in your area...they may have short offcut remnants ("drops") they may sell you cheaply (most sticks are sold in 20' lengths). Check also for local welding and metal fabrication shops.

I think I bought my cold-rolled steel for runners at use-enco.com ... look for items marked down and you can do all right. They also have regular specials (20% off, free shipping, that kind of thing) if you get on their mailing list or Google around for Enco coupons.

I do metal fab as well as woodworking, and I have been very happy with their prices/service/shipping speed.

I think every decent-sized town has a place to get the stuff. Here in the Milwaukee area I'd probably go to Speedy Metals. Get the phone book and start calling anyone in there and ask them if there is a local source for cold rolled.

[Alan Schaffter]

It is good to see my suggestion for using cold rolled steel for miter bars is still a good one :) :)

As I went back through this thread one other idea popped into my head when some folks talked about the weight of their sleds. I haven't done it but plan to take a hint from metal aircraft manufacturers (and other metal fabricators)- I'm going to add lightening holes to my sled.

If your sled is made from decent Baltic or other good birch ply, you can cut holes in it to reduce the weight. It can actually have more holes than structure and still do the job its intended job just fine. Grab a fly cutter and have at it!

[Anthony Diodati]

It is good to see my suggestion for using cold rolled steel for miter bars is still a good one :) :)

Well, I went to Lowes anyways to see what they had. 3/4" wide, but only 1/4" thick, X 3 feet long, but it should be OK. It was normally $7.00 something, on clearance for $5.74 each.
I didn't think that was too bad, so I got 2 of them.
Was worried they might be a little loose, but they are actually too tight, but I think I can knock them down with a file a little bit. I think 1/4" thickness will be alright.

[Phil Thien]

Well, I went to Lowes anyways to see what they had. 3/4" wide, but only 1/4" thick, X 3 feet long, but it should be OK. It was normally $7.00 something, on clearance for $5.74 each.
I didn't think that was too bad, so I got 2 of them.
Was worried they might be a little loose, but they are actually too tight, but I think I can knock them down with a file a little bit. I think 1/4" thickness will be alright.

1/4" will be fine.

Let us know how they work out.

[Anthony Diodati]

OK, what is the best way to line up the steel runners once I get them sized?
A have a $25.00 piece of phenolic plywood that I don't want to ruin. Should I drill my holes in the runners, then shim the bottom of my runners in the slots, and use carpet tape on the runners, and lay my board/base on the runners, remove it and screw it down?
I was thinking I want to use 2 runners, not one.

[Bill Huber]

OK, what is the best way to line up the steel runners once I get them sized?
A have a $25.00 piece of phenolic plywood that I don't want to ruin. Should I drill my holes in the runners, then shim the bottom of my runners in the slots, and use carpet tape on the runners, and lay my board/base on the runners, remove it and screw it down?
I was thinking I want to use 2 runners, not one.

When I used steel, I use Incra aluminum now, I drilled the holes in the steel, tapped them and then as you stated shimmed them up just above the table.

Then put the double back tape on them and set the table saw fence so it was just at the correct place for the sled. Then holding the sled against the fence lowered it down on to the bars and pressed it down.

With a smaller drill bit I drilled though the tapped holes and the sled on all the holes. I then turned the sled over and enlarged the holes and counter sunk them and put the screws in.

When I made the sled with the aluminum ones I did it the same way only I used a transfer punch that would just fit in the pre-drilled and tapped holes to mark the sled. Then with a brad point bit I drilled the sled holes and counter sunk them.

[Alan Schaffter]

Frankly putting the runners on last is the backasswards way to make a sled. Cut a very shallow dado for the runner, in case you ever want to replace it then drill and tap holes in the bar and use flathead screws from the top of the sled to attach the bar.

Then, attach and square the fence.

Unless you are really ham-fisted and/or attempting to crosscut/miter really long, wide and heavy stock (which is better cut done on a miter saw) and likely to torque it, there is no need for two runners. Two runners are much more difficult to precisely align so they will slide easily. As I think someone said here, if you really want two runners make the sled in two halves and join them together.

[Bill Huber]

Frankly putting the runners on last is the backasswards way to make a sled.

Then, attach and square the fence.

Unless you are really ham-fisted and/or attempting to crosscut/miter really long, wide and heavy stock (which is better cut done on a miter saw) and likely to torque it, there is no need for two runners. Two runners are much more difficult to precisely align so they will slide easily. As I think someone said here, if you really want two runners make the sled in two halves and join them together.

I agree that the fence is the last thing you install.

I have made 3 sleds and each one has had 2 runners on them, maybe I don't need 2 runners but I have always put 2 on. I have never had a problem getting them to be precisely aligned if I put the sled base against the table saw fence and then lower it like I stated in my post above.

As far as 2 runners go, maybe I don't need them but I like the stability they give and I can place an 8/4 4" board on it and not have to worry about it wanting to skew. Everyone has their own way of doing the same thing and that is just mine.

[Anthony Diodati]

I am stubborn, I am thinking 2 is better, but I may just try one. I can always add the 2nd one if I feel I need to.
You guys that are only using one runner, is this a sled with the kerf in the middle of the base, where there is base on both sides of the blade/kerf, or are you making the kind that only has the base on one side of the blade.
I am making the kind that has the base on both sides of the blade.
The last 2 I made for my contractors saw, just had one runner, but the base only went to one side of the blade.

[Anthony Diodati]

Well, I am working on a smaller one right now, it is only about 23" wide and 13" deep. I used two metal runners, about 12" long.
My red oak fence has a slight bow to it, I had it all dialed in with a shorter piece of wood, but then cross cutting a longer piece it changed.
I have to face joint the fence, but My little delta has the cutter head out waiting for bearings.
I did learn one thing, it was sliding nice then I screwed down the back (back of the saw) fence, and it started to bind. To I marked my runners and worked it, and filled my hi spots again, and it was OK.
But then when I tightened my front fence, it got easier yet. So I think it's best to wait till both fences are screwed down till you fine tune the runners.
I used a screw in the right side of the front fence, and a 1/4" bolt into a threaded insert in the base so I can fine tune the fence. The hole the bolt passes through is over size.

The next one I have a piece of Phenolic coated plywood, it is 24 deep, X 32" wide. I may just go ahead and try the single runner with that one.
http://www.rockler.com/light-brown-phenolic-faced-plywood-sheets