Miter Bar that won't tip over

[Alan Lightstone]

I've seen these before (actually have a miter gauge that has one built in), but I need to find these.

Anyone know who makes miter bars that can't pull vertically out of the track. I have a very large crosscut sled ( the full size Woodhaven one - it's a beast). It's actually so big and heavy (made out of 3/4" MDF), that I built a ceiling hoist to lift it out of the way and lower it to the table saw.

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Anyway, back to the problem. When I'm cross cutting wide pieces of boards (>20" thick or so), the crosscut sled tries to lift up in back and tip down in the front - a real safety hazard.

Now it I had miter bars that couldn't lift up in the back, the problem would be solved. I could slide the sled out from the back to free it up when I want to return it overhead.

[Dave Richards]

My Incra sled as a little tab on the front end of the guide bar that prevents the sled from tipping when I have it pull back toward me. It fits into the grooves on either side of the slot. Depending on your bad, maybe you could add something similar or possible use a flat washer. Here's a picture of the tab on the front end of the bar: http://www.incra.com/images/mitergauge_1000hd_pic2_zoom.jpg

[Greg Hines, MD]

As seen above, Incra makes miter bars with keepers fitted to the ends, I have one of their miter gauges, and it works very well. It also allows you to fine tune the fit with the nylon washers seen in the above photo. I would ask, given how big your sled is, why do you not use two miter bars? It looks like it would be much safer to use two.

Doc

[Art Mann]

I have actually thought about building an infeed table in front of the saw to prevent the sled from tilting toward the floor in the front. I recently replaced my old sled that used 3/4 inch plywood as a base and went with 1/2 inch plywood instead. In addition to being lighter and easier to handle, it provides a little extra saw height capacity. I can not imagine using a sled that requires a hoist to get it on and off the saw.

[Lee Schierer]

Does your saw table have T slots? If not, then there is no cure for your problem shot of machining T-slots into your table.

[Alan Schaffter]

Buy one- INCRA parts and components- you can get an INCRA steel miter bar with their glideLOCK expansion disks and removable T-slot retaining clip. Go to the Incremental Tools website.

http://www.incrementaltools.com/v/vspfiles/assets/images/pc-miterv27_body1_b.jpg

Or go to a metal or welding supply shop and buy 3/8" X 3/4" cold rolled steel bar and fabricate a T-slot retaining clip for it. I use 3/8" X 3/4" cold rolled steel for miter bars on all my sleds and jigs.

[Art Mann]

I'm not sure it will be very easy to use the T slot design since the bar must be slid into place from the edge of the table. The OP is using a cable hoist to drop his sled down into place. The mechanical geometry might not work out to swing the sled that far over. I could imagine a custom machined bar that has a retainer that you would rotate into place with a removable knob from the top after the sled is in place. That would be an interesting piece to design and machine.

[Jerry Miner]

I have actually thought about building an infeed table in front of the saw to prevent the sled from tilting toward the floor in the front. I recently replaced my old sled that used 3/4 inch plywood as a base and went with 1/2 inch plywood instead. In addition to being lighter and easier to handle, it provides a little extra saw height capacity. I can not imagine using a sled that requires a hoist to get it on and off the saw.

That's what I did. I have a "regular" sled and an "extra large" sled for bigger panels. When I pull out the XL sled, I also pull out the "infeed table" which is not much more than a 1 x 4 with a leg. The 1 x 4 has a hook that hooks over the front fence rail and the leg keeps it co-planar with the saw table. The "infeed table" keeps the XL sled flat on the table well in front of the blade, even with a 36" panel on it. I hinged the leg so the whole thing folds up and hangs on the wall til I need it

[glenn bradley]

I would lean toward roller stands or some other support rather than apply that torque to your t-slots. They are made for gentler things although if what you are after is just a little support for when you go just past the balancing point, I have seen t-bar from various suppliers (http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/miter_t-slot_accessories.html?zoom_highlight=t-track) but, only in aluminum (http://www.ptreeusa.com/ttrackproducts.htm#1033).

[Dave Richards]

In the case of the Incra bar, the tab is on only one end of it. The sled would only need to be pushed forward enough to get the end of the bar over the rear edge of the table. That shouldn't be a big deal. With an outfeed table, leave a small gap for the tab to drop through.

[Alan Lightstone]

Does your saw table have T slots? If not, then there is no cure for your problem shot of machining T-slots into your table.

It's a SawStop, and I'm pretty sure it has T-Slots.

I'll have to look into the Incra miter bars.

Greg, I'm not sure that using both miter bars would make it less susceptible to tipping. It might add friction, but the Incra solution looks better.

[Alan Lightstone]

That's what I did. I have a "regular" sled and an "extra large" sled for bigger panels. When I pull out the XL sled, I also pull out the "infeed table" which is not much more than a 1 x 4 with a leg. The 1 x 4 has a hook that hooks over the front fence rail and the leg keeps it co-planar with the saw table. The "infeed table" keeps the XL sled flat on the table well in front of the blade, even with a 36" panel on it. I hinged the leg so the whole thing folds up and hangs on the wall til I need it

I do have a removable infeed table (actually, rollers that pull out on tracks then move inwards as the wood goes towards the blade. A nice space intensive solution, but the sled weight overwhelms that.

[Alan Lightstone]

In the case of the Incra bar, the tab is on only one end of it. The sled would only need to be pushed forward enough to get the end of the bar over the rear edge of the table. That shouldn't be a big deal. With an outfeed table, leave a small gap for the tab to drop through.

I already have that, fortunately. I'm rebuilding the outfeed table, so I'll keep that in mind for the future.

[Dick Mahany]

For my crosscut sled, I made a simple infeed extension that attaches quickly to the front rail. I have Incra sliders, but did not use the T-slot tabs because I like to be able to place the sled on the table with out having to engage the T followers. So far this has worked well and was quick and inexpensive to make ( the attachment bolts are a square U-bolt from my local hardware store cut in half).

BTW, I've since removed the Aluminum miter guide shown below which makes it much easier to position the table with the clamping bolts. Since my sled uses double miter sliders, it was only important to provide surface support. I overthought this when I built it (not the first time :o)
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[Dave Richards]

Dick, that's pretty cool. Thanks for sharing.

[Phil Thien]

Another technique I've seen is attaching a long piece of wood or aluminum or whatever to the left side of the saw. The piece extends past the back and front, and provides additional support to prevent tipping of the sled. You can often do this by drilling/tapping holes in the extension.

[Prashun Patel]

I had a clip on my miter bar. I found that it bound up or made the bar hard to begin the slide. It felt awkward to me.

For bigger panels, I use a different kind of cross cut sled, one with ONLY a front fence. I register off that face, and use toggle clamps to hold it down. It's probably not theoretically as safe as a rear-fence sled, but I have not had any issues with it. It allows me to put pressure near that front fence, which will always be on the table, so even if the panel is wide, it doesn't tip. Then again, I only cross cut things that are about 30" or less. Any larger and I take the saw to the piece.

[David C. Roseman]

It's a SawStop, and I'm pretty sure it has T-Slots.

I'll have to look into the Incra miter bars.

Greg, I'm not sure that using both miter bars would make it less susceptible to tipping. It might add friction, but the Incra solution looks better.

But won't you likewise have a friction problem with either the Incra tabs or conventional T-slot discs on the tracks? Sounds like the rotational force that currently causes the sled to lift will cause binding against the upper surface of your T-slots. And the point load would seem to be even greater due to the smaller bearing surfaces. JMO

David

[Alan Lightstone]

But won't you likewise have a friction problem with either the Incra tabs or conventional T-slot discs on the tracks? Sounds like the rotational force that currently causes the sled to lift will cause binding against the upper surface of your T-slots. And the point load would seem to be even greater due to the smaller bearing surfaces. JMO

David

Interesting.

I just spent a ton of time making the sled accurate to 0.002 using the 5-cut method. I do hate the concept of having to remove the miter bar and start that process again.

I'll have to look into a variation of Dick's idea. It's pretty interesting.

Dick, can you share a few more pictures of that? Especially the bottom and back.

[Dick Mahany]

Interesting.


Dick, can you share a few more pictures of that? Especially the bottom and back.


Alan,

Additional pics attached. A couple of notes:
1. The rear piece (maple) needed to be planed to ~.650" to fit between the tube rail and the rail mount (on my saw).
2. Even so, there is still plenty of material to drill for the 5/16" dia square U-bolt halves
3. The base and front clamp board are made from 19mm Baltic Birch scrap material.
4. The space between the clamp boards on the underside of the platform was shimmed with ~0.090" veneer scrap to level the infeed table top flush with the saw table.
5. The front clamp board is attached with only one screw approximately in the center so that the clamp board isn't over constrained. Probably better ways to do this, but it works.

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This works well for me as is, however if the sled is extremely heavy, a simple support leg would make it a stable as ever needed. Hope this helps.

[Alan Schaffter]

Interesting.

I just spent a ton of time making the sled accurate to 0.002 using the 5-cut method. I do hate the concept of having to remove the miter bar and start that process again.



The next time you build a sled or jig with a miter bar, mount the bar in a shallow, snug dado, then square the fence. If you ever need to replace the bar just set the new one in the dado and you are good to go!

[Chris Fournier]

You don't nave to remove your mitre bars to install fixtures that work in a t-slot. A little metal lathe work, some well sorted tolerances and careful installation and away you go. Very simple if it's well planned out!

[Alan Lightstone]

Had a minor epiphany, using a combination of the above suggestions.

I can install one of the Incra bars in the second miter slot. That way, I won't throw off the accuracy of the present sled.

If that presents too much friction, the infeed extension idea of Dick's is on my to do list as well.

BTW, Dick, why are the cutoff U-bolts necessary? Couldn't it be just built using tight tolerances? Sort of how the Biesenmeyer fence attaches? Or use that same fence clamping mechanism (not sure where I'd get one of those) to tighten it down.

[Alan Lightstone]

The next time you build a sled or jig with a miter bar, mount the bar in a shallow, snug dado, then square the fence. If you ever need to replace the bar just set the new one in the dado and you are good to go!
Good idea, Alan. Unfortunately this came pre-made, and not perfectly square.

I'll use it in the future. How shallow do you make the dados?

[Alan Schaffter]

Good idea, Alan. Unfortunately this came pre-made, and not perfectly square.

I'll use it in the future. How shallow do you make the dados?

It is not critical, but 1/8" works fine. I attach the bars using flat head machine screw through the sled into tapped holes.

[Dick Mahany]

BTW, Dick, why are the cutoff U-bolts necessary? Couldn't it be just built using tight tolerances? Sort of how the Biesenmeyer fence attaches? Or use that same fence clamping mechanism (not sure where I'd get one of those) to tighten it down.

I wanted to use toggle clamps or mag switches mounted to the underside of the table, but my local hardware store had the U bolt in stock for ~ $3. I decided on doing it quickly and inexpensively as I needed to use it the same day. I'm sure there are many elegant ways to accomplish the same.

[Alan Lightstone]

Well, I got the Incra Miter Bar SE, and installed it on the bottom of the sled. More than a slight pain to do so, but it's done.

Interestingly, it does significantly increase the friction of sliding the sled. Perhaps it's not perfectly aligned, or perhaps the adjustments on its width are slighly too tight, but it's on, and the sled no longer tips over.

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Here's it way out, and no longer tipping over, so far safer now.

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Dick's idea would have been far quicker, as it turns out, and far more interesting. Might still do that in the future.