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how square is square: part deux

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Forum topic by doitforfun posted 04-22-2014 01:47 AM 1464 views 1 time favorited 18 replies Add to Favorites Watch
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doitforfun

199 posts in 1069 days


04-22-2014 01:47 AM

So I decided to retire my trusty crosscut sled when I found that it was no longer trusty. Before I made version 1 I did a lot of research on the internet and didn’t like the standard large sled. It was too big and complicated for me to build at the time so I looked for something simple and took a few different ideas and molded them into this:

The pictures are actually version 2 but the first one was basically the same design.

This time I used oak runners instead of plywood and I paid careful attention to making it as perfectly square as possible. Before I put the face on, I checked and checked for squareness at the front (when it was just the runners and plywood body) and clamped it to my mitre guage and cut a hair off, then checked again with 2 different squares. I must have cut off an inch in 16th increments before I was satisfied that it was square. Then I attached the face.

So I guess the point of the topic is not what squareness is acceptable, but rather how do you get to square?

-- Brian in Wantagh, NY


18 replies so far

View TRHeath's profile

TRHeath

75 posts in 1049 days


#1 posted 04-22-2014 03:43 AM

Depends on how much math you want to do. Try this link:
https://www.youtube.com/watch?v=uE9f4bp_wm8

-- So much to learn....so little time.....

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Paul

721 posts in 1027 days


#2 posted 04-22-2014 04:35 AM

I start with a 30 year old brass finished square and start from there. Click on my projects and you will see the long brass angle I’m talking about. My sled is a monster in that project. A panel sled, so I had even more variance to deal with.

Your new sled has it’s fence already secured. If it’s off at this point then there’s really no going back. You need one pivot point that is secure on your sled before you make measurements to adjust it.

You sound like you are self taught, like I am. I suggest spending a couple hours looking at the 5 cut method to see how square your sled is and how it’s dialed in and start again if your new sled isn’t square.

A dial indicator will save you a bunch of time.

Paul

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OldWrangler

731 posts in 1056 days


#3 posted 04-22-2014 04:56 AM

Woodcraft and several other woodworking supply companies are selling a digital angle finder. It is accutate to hundreds of an inch. I don’t know how I got along without it. I can calibrate my band saw for 90% vertical, my table saw for any angle and my cut off saw for accuracy. It is so easy to use, I check each tool before using it and it has helped my accuracy. For like $25, it is a good tool to have.

-- I am going to go stand outside so if anyone asks about me, tell them I'M OUTSTANDING!

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doitforfun

199 posts in 1069 days


#4 posted 04-22-2014 12:53 PM

I’m going to try the 5 cut tonight! Stupid work is getting in the way of jig making. LOL

By the way, I squared the front (runners and plywood body) before attaching the fence. So hopefully the fence is as square as the body was when I finished my adjustments.

-- Brian in Wantagh, NY

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Stoli

57 posts in 2829 days


#5 posted 04-22-2014 01:08 PM

It looks like your runners extend above the flat bed. How will you put stock down for cutting?

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doitforfun

199 posts in 1069 days


#6 posted 04-22-2014 01:39 PM

Stock goes in front. I can also use the dado and do bevel cuts with this setup.

-- Brian in Wantagh, NY

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Stoli

57 posts in 2829 days


#7 posted 04-22-2014 07:31 PM

Ok, now I see. I was looking at the sled backwards. The stock is pushed forward with the sled, but it rides on the table saw surface.

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doitforfun

199 posts in 1069 days


#8 posted 04-22-2014 07:50 PM

I like that it’s small and lightweight. I hang out on the wall next to the saw.

-- Brian in Wantagh, NY

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doitforfun

199 posts in 1069 days


#9 posted 04-22-2014 10:42 PM

Well I got home and immediately went to do the 5 cut thing and boy was I disappointed. I didn’t think about any of this before but my sled will only cut about 10” width. Also, I don’t have any measuring tools capable of that kind of accuracy. So it is what it is, I guess. All my squares look perfect on freshly cut corners so I guess I should just be happy with that result and leave it at that.

-- Brian in Wantagh, NY

View NiteWalker's profile

NiteWalker

2735 posts in 2038 days


#10 posted 04-23-2014 06:30 AM

Brian, your design is less of a crosscut sled and more like a dedicated 90 degree miter gauge.

A crosscut sled can be extremely simple; the key is to build in a way to adjust it. I just finished up a sled for my new table saw; I’ll post pics tomorrow.
Basically I used a piece of plywood for the base as usual, the rear fence was a scrap of ply. The front fence is L-shaped (literally an “L” from the side). The vertical portion is screwed into the horizontal piece and is what the workpieces rest against. The horizontal piece has 3/8” holes drilled into it to mount to the sled base, which has four holes I tapped with 1/4-20 threads. WIth the bigger holes in the fence I can easily adjust the fence square.
I don’t bother with any 5 cut methods or anything like that. The way I check for square is take a board with flat and parallel edges, crosscut it, and put it back together with the cutoff flipped over. No gap = good. With the L shaped fence, adjustments are very easy. I just loosen 3 of the 4 bolts, adjust as necessary, then tighten the outer bolts until the sled is confirmed square, then tighten the other two.

Another advantage of the L fence is that it will keep the main face straight as long as the edge of the horizontal piece is straight.

-- He who dies with the most tools... dies with the emptiest wallet.

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doitforfun

199 posts in 1069 days


#11 posted 04-23-2014 11:08 AM

Nitewalker, that sounds good. There is definitely no adjustability in my sled. It’s glued and screwed. But I’m hoping that it will simply be perfect forever so I don’t have to think about it again – just grab it when I need it. I know that won’t be the case but at least the version 2 improvements should make it last much longer than the first one I built.

How often do you find yours needs adjustment?

-- Brian in Wantagh, NY

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HorizontalMike

7143 posts in 2375 days


#12 posted 04-23-2014 11:26 AM

Adjust-ability is nice… ;-)

http://lumberjocks.com/projects/57667

-- HorizontalMike -- "Woodpeckers understand..."

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doitforfun

199 posts in 1069 days


#13 posted 04-23-2014 12:05 PM

Very nice.

-- Brian in Wantagh, NY

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Knothead62

2581 posts in 2423 days


#14 posted 04-23-2014 02:00 PM

HM, sheer genius! I like it!

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NiteWalker

2735 posts in 2038 days


#15 posted 04-23-2014 06:18 PM

”How often do you find yours needs adjustment?”
This one is a new one, but my previous one used the same adjustment system.
It stayed true once set. The key to a square sled that stays that way is good runners and a flat, straight fence. For the runners, a hardwood like oak or maple will work as long as it’s quarter sawn. Even better, and what I used is metal runners. No movement at all.
For the fence, the L shape works great. What has also worked for me in the past is a double lamination of 3/4” MDF and even a single piece of 3/4” plywood.

-- He who dies with the most tools... dies with the emptiest wallet.

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