New Sled

[glenn bradley]

My current sleds have given me good service for many years. I just wanted a little more versatility for hold downs.

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[Aaron Rosenthal]

Glenn, that sled looks really skookum (west coast Canadian native word for “cool”).
I’m going to save your pictures to my drive. I just built a prototype sled based on the King Woodworking multiuser sled, but it appears you went further, with the versatility shown in the Katz-Moses unit.
Sweet build.

[Jim Becker]

That is REALLY well thought out, Glenn! Bravo!

[glenn bradley]

Thanks guys. Each sled seems to take the things that have worked well forward to the next. Adjustable fence, replaceable ZCI's for fence and base, stop block and clamping solutions, etc. The material was scrounged from a cabinet shop that had left some material out in the rain and gave it to me. There is some staining which I don't care about and some edge damage which got cut off. After a few years of use everything will blend right in :D

[Dan Cameron]

Here's what I don't understand: You have a solid fence front and back which guarantees that the left and right sides of the sled move as one unit. Why do you think you need two miter slot runners? Wood movement limits just how precisely the bar to slot fit can be if one is to ensure that the sled will not bind under varying humidity conditions.

[Charlie Jones]

Nicely done. I wondered how well those Microjig clamps worked.

[glenn bradley]

Here's what I don't understand: You have a solid fence front and back which guarantees that the left and right sides of the sled move as one unit. Why do you think you need two miter slot runners? Wood movement limits just how precisely the bar to slot fit can be if one is to ensure that the sled will not bind under varying humidity conditions.

I will first say that living in this nice dry desert basin allows me to get away with things that wouldn't last one season in Nebraska :D. Single and double are both good. In my experience two runners are more stable under load than one. I know lots of folks use single runner sleds and I have no issue with that. I find two runners to be more reliable with larger loads. For lighter stuff I pretty much just use the miter gauge. Always more than one way to skin the cat.

[glenn bradley]

Nicely done. I wondered how well those Microjig clamps worked.

They are like any fixture I suppose. I have a lot of t-track and t-track items. I have a lot of MatchFit stuff as well. Most commercial fixtures are going to use t-track. The Micro Jig clamps let you slap a dovetail slot on just about anything so there's the advantage. I also have the bits to cut a t-slot in just about anything. When using ply you want to have a clamp that provides a mechanical compression force as opposed to a lifting force that may de-laminate the plywood. That being said I have used the same router fence faces made of MDF with a t-slot cut into them for over 15 years(???). I think both have a place in the shop.

[Jacques Gagnon]

Great job Glenn,

Very versatile and keeps the fingers away when handling smaller material.

Your approach will surely inspire many others.

Regards,

J.

[Alan Lightstone]

That's really impressive, Glenn. Made on a CNC machine, or the old fashioned way?

[glenn bradley]

That's really impressive, Glenn. Made on a CNC machine, or the old fashioned way?

LOL! The old fashioned way I'm afraid.
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You must remember that I am a bit of a troglodyte despite decades in the I.T. industry. I still have vinyl and CD's.
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I think "old fashioned" is my escape from all the years of high tech :D.

[Dan Cameron]

I will first say that living in this nice dry desert basin allows me to get away with things that wouldn't last one season in Nebraska :D. Single and double are both good. In my experience two runners are more stable under load than one. I know lots of folks use single runner sleds and I have no issue with that. I find two runners to be more reliable with larger loads. For lighter stuff I pretty much just use the miter gauge. Always more than one way to skin the cat.

Glenn, I am sensitive to the 2 vs 1 runner situation because I had a sled bind up to the extent of being unusable due to humidity variation. This was in the San Fernando valley out of LA. It was a sled made of high quality plywood. When this happened I questioned why many woodworking magazines touted sleds with two runners, Compression of the runner material? Nah. I tested a piece of .75 x .75 poplar in a fancy machine we had at work. It took about 800 lbs to squeeze it down .001 thinner So, if two (identical) runners were attached say .001" farther apart than the miter slots, the inside edges of the miter bars would come into contact with the miter slots only under immense sideways forces. Highly unlikely. Similar situation exists if bars are mounted narrower than slot spacing.
All that being said, if one has a pair of runners, each of which would be considered too narrow to use singly (ie too much slop), a pair of runners could be mounted with spacing that is intensionally greater or lesser than the miter slots, and this will reduce the amount of slop. This configuration has ZERO precision or stability advantage over a similarly fitted single runner. That is, if there is .005" of side to side play, it makes NO difference if the two guiding edges are .75" or 10" apart. (unless your runners are sponge rubber)

[Roger Davis]

What is the spacing in inches of the dovetail squares?

[Ken Fitzgerald]

Well done, Glenn!

[glenn bradley]

What is the spacing in inches of the dovetail squares?

4" on center. This dimension was taken from a Micro Jig video. The guy doing the video seemed like he was very familiar with the Match Fit clamps so I followed his lead.


Well done, Glenn!

Thanks Ken. Different strokes :) I couldn't resist and so cannibalized the old sled and made it into a new narrow stock cross cut sled.
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The only downside is the re0used hanging hole is off balance but, I think I can live with it :D

[Wes Grass]

This configuration has ZERO precision or stability advantage over a similarly fitted single runner. That is, if there is .005" of side to side play, it makes NO difference if the two guiding edges are .75" or 10" apart. (unless your runners are sponge rubber)


My gut feeling on this is that it's only true in terms of lateral displacement. But the wider the spacing the greater the angular error. So I modeled it up to see.

It's true, the wider the runner spacing, the greater the angular error. However, with any reasonable length of runner, like 12", the error is 5 decimals out ;-)

The bigger issue *could* be racking and binding. But again, unless you're trying to use 3" long runners in slots spaced a foot apart, I doubt it's going to be noticeable. Differential expansion from heat or moisture is the only thing to worry about.

[Mike Kees]

I think you guys just need to buy a slider.... :D

[glenn bradley]

I think you guys just need to buy a slider.... :D

:D:D:D Too true. I didn't know single versus double was so controversial. Use the method that works for you and be happy. :)

[Jim Becker]

I think you guys just need to buy a slider....

Funny you should mention that... ;)

While I've been "making do" with a very nice cabinet saw in the temporary shop, I did order a replacement slider this past week that should arrive a few weeks after the building is up. I have missed it "big time".

Glenn, I'm in the two runner camp but I can certainly see the other point of view. So far, my quick and dirty sled is working without binding, but it will be interesting to see if that continues as the humidity builds even more in my unconditioned temporary "gara-shop".

[glenn bradley]

. . . my unconditioned temporary "gara-shop".

Let's have some respect for the temporary digs . . . "Garag-Mahal" if you please. :D

[Jim Becker]

Let's have some respect for the temporary digs . . . "Garag-Mahal" if you please. :D
Just. because I (mostly) put a fresh coat of paint on it does not a 'Garage-Mahal" make. :) :D But I appreciate the thought. I'm very thankful I have the space I have, however. It's not adequate for big work, but I can do the smaller projects that come up if need be. It's just horribly uncomfortable with the heat and humidity in full swing right now.

[Johnny Barr]

Every time I make a matchfit sled like Glenn's it sags slightly in both directions. I'm sure that's due to the large amount of material removed when routing so many slots. That's one advantage of T Track. I've tried 15mm and 18mm MDF and 18mm ply. Do I simply go for a thicker board eg 25mm (about an 1") or is there something I'm missing.
Does you see any sag on your sled Glenn?

[glenn bradley]

Does you see any sag on your sled Glenn?

These two actually had a tendency to cup. It took a few days to get around to adding the fences and by that time they had settled down. I attributed this to the stock removal and the weather damaged ply. My experience with good BB ply for previous sleds is that if it starts out flat it pretty much stays that way for years . . . unless the sled gets wet but that's another story for another time :D. 3/4" MDF with the grid pattern cut in could become pretty flexible. The bulk of the sled is supported during use so this may not be a problem in use(?). Cutting a 3/8" deep dovetail in 15mm ply doesn't leave much behind so 18mm would be my choice.

[Dan Cameron]

These two actually had a tendency to cup. It took a few days to get around to adding the fences and by that time they had settled down. I attributed this to the stock removal and the weather damaged ply. My experience with good BB ply for previous sleds is that if it starts out flat it pretty much stays that way for years . . . unless the sled gets wet but that's another story for another time :D. 3/4" MDF with the grid pattern cut in could become pretty flexible. The bulk of the sled is supported during use so this may not be a problem in use(?). Cutting a 3/8" deep dovetail in 15mm ply doesn't leave much behind so 18mm would be my choice.

My sleds have also tended to stay flat even with the humidity swings I have experienced. I have been careful to use the same material for my fences as the sled base (e.g. plywood/plywood) lest differential expansion and contraction cause warping. Also, I have not cut groves for tracks. If I need a hold-down or miter guide I just screw it to the base. After many years I have an ugly sled (from screw holes) which works just as well as the day built.

[glenn bradley]

After many years I have an ugly sled (from screw holes) which works just as well as the day built.

The VERY best kind IMHO :)