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Help with crosscut sled.


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#1 philwillette

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Posted 26 August 2011 - 07:28 PM

Hi Everyone, I built a crosscut sled following Mark's video. After 3 tries with the 5 cut method I got to a respectable .003. Everything has been going great but today I started cutting some 3/4 birch ply for the sides of kitchen cabinets I'm building and they just are not coming out square. I ran the the pieces 24" in the TS and then crosscut one side and then the other to final. The problem is when I make the final cut some times they are off up to a 1/16. I did the 5 cut again and verified that it is still at .003. I have clamped the pieces down to eliminate any movement and sometimes one comes out right on and another one is off again. The sled is solid in the slots so there is no side to side slop. I checked the width of the boards and the sides are parallel. The only thing that bothers me is the stop block is extended 7 inches with a board screwed to the back fence on the sled but I don't perceive any play there either.

I'm getting very frustrated. I have no problem shorting the boards to just under 31" but I don't want to start that until I figure out what is going on.

Anyone have any ideas.

Thank you for any help.

Phil

#2 higtron

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Posted 26 August 2011 - 08:54 PM

Maybe saw dust, or wood chips are getting against the fence which would hold your piece out of square. If it's 1/16" different on the diagonal measuerments your only 1/32" out of square which isn't horrable for cabinets. When you grab opposite corners of the sled one hand on the leading edge on one side and the trailing edge on the other, and rack the sled back and fourth can you feel slop at all. some times the runners get loose. Wood runners dry and swell. If you are getting better results on certain pieces try remembering your body mechanics when you push the piece through, and try and copy those movements on another piece see if that helps. Good luck.

#3 philwillette

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Posted 26 August 2011 - 09:36 PM

I thought of the dust so I was blowing off the sled after each piece and there is no racking on the sled. You're right about the body mechanics that is why I clamped it down, but still got messed up results. I thought this was going to go easy since I got the sled tuned in so nicely. Tomorrow is another day hopefully I figure things out after a good nights sleep.
Thanks for the help.

#4 philwillette

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Posted 27 August 2011 - 08:22 AM

Well I figured out it was my form. Still not sure what I was doing wrong but I did come up with a solution.
I cut 2 strips exactly the same length of what I'm cutting. I then attached extended my sled with some 1/4 ply and used the strips registered on the front and back fence of the sled in line with my kerf cut on the sled. I then clamped a straight edge tight against the two strips creating a fence that ran the entire length of the sled. Perfect cuts every time. It is probably that the piece I'm cutting are 24" deep that I had a problem. Now I can get to making these cabinets.

#5 rmac

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Posted 27 August 2011 - 10:12 AM

I'm glad you solved your problem but from your description I can't figure out what you did. Can you post a picture?

-- Russ

#6 Dan S

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Posted 27 August 2011 - 10:51 AM

Check you fence, if it has any cup or bow in it, it will cause this problem.

#7 philwillette

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Posted 27 August 2011 - 04:30 PM

I knew my description was difficult to imagine. Here are some pics.

No way this baby is moving now. It worked perfectly, assuming the piece you will be cutting is at a perfect right angle so it sits against the sled fence and the extension fence.

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#8 rmac

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Posted 27 August 2011 - 04:39 PM

Okay, thanks for the photos. I see what you did now.

assuming the piece you will be cutting is at a perfect right angle so it sits against the sled fence and the extension fence.

But therin lies the problem. How do you make the original piece square to begin with? That's what the crosscut sled is for. You should be able to make a square cut using the crosscut sled even if the original piece is not square.

Your jig and the extra fence may have solved your immediate problem, but I think you should keep fussing with it until you find out why you were having trouble in the first place. I had the same thought as Dan S ... is the rear fence on the sled perfectly straight? If not, that could be at least part of the problem.

-- Russ

#9 philwillette

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Posted 27 August 2011 - 08:27 PM

The rear fences is straight, that was my first thought and I have checked it about 4 times with my straight edge.
I only had the problem when I tried to cut a 24" deep piece. If the piece is say 10" the cut is perfect. I think I'm having an issue preventing the larger piece from moving.
When I made my first cut it was on a long piece that spanned the entire fence on both sides of the blade so those cuts were right on. The second cut there was 31 inches on the left side and only 1/2 on the right that is when I had problems. But again if the piece was smaller even if it was all on the left it still cuts square.

#10 nateswoodworks

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Posted 27 August 2011 - 11:04 PM

To me it sounds like it is because on your wider stock you are having to have your sled hanging off the front of your TS further, and because of this the runners aren't in the slots as far allowing the sled to skew just a smidge. This would explain why on your narrower stock you didn't hav any problems. For situations like this I always use my panel sled. Since the stock is placed against the fence on the front of the jig it doesn't have to hang off the front of the saw making it more accurate and much safer. There are a couple benifits of this sled, the width of your stock isn't restricted by the sled like on a crosscut sled and the sled is very light. Figure out the average width of stock you think you will be cutting in the somewhat near future and make your runner accordingly. If you need to you can always make a longer runner if need be. Just for refference my sled is about 24" wide by about 30" and I can easily cut 36" wide panels with a 30" runner. Now it isn't very often I need to cut pannels this wide but I recently had to so I made the longer runner, I will probably cut the runner shorter soon just because it doesn't fit as nicely in it's home now. This may not be your problem but sure sounds like it to me. Hope this helps and good luck.
Nate

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#11 Beechwood Chip

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Posted 28 August 2011 - 04:33 AM

I'm with nate - for material over 24", use a panel sled that has a longer runner and a longer fence.

#12 philwillette

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Posted 28 August 2011 - 05:13 PM

That makes sense. I'll have to go make a panel sled.

Thanks for the advice.

#13 TimV

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Posted 29 August 2011 - 06:37 AM

Bingo, I think Nate has it. Ditto here although my changeover point is 19" just because that's what I made the crosscut sled at.

One thing I don't feel comfortable with on your setup is the fence you're using with the sled. I think you're using that to make repeatable length pieces. I see a couple of issues with that. One. There is likely play in the slots and it likely won't be square to the rear cross member. If you accidentally align the edge against the whole fence you could be off of the back cross member. That back cross member is the one that should hold the full length of your workpiece. This is especially true since your workpiece isn't going to be square to start with. The second is safety. You never want to use both a mitre and rip fence together which is what you are essentially doing with your setup. This is very risky because you could get some rotation of the workpiece and catch between the back of the blade and your fence. Dangerous. I will typically only use a 3/4" stop block that I clamp to the back cross member or the table saw rip fence to set distance.

#14 Beechwood Chip

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Posted 29 August 2011 - 08:04 AM

You never want to use both a mitre and rip fence together which is what you are essentially doing with your setup.

I think that what's unsafe is to restrict the movement of both sides of a through cut, which is what usually happens when you use a miter gauge and a rip fence together. You want to allow one piece to fall away from the blade on a through cut, As long as the piece is held to the back fence on the same side as the rip fence/stop, and the other side is free to move, it should be safe.

I agree that a smaller stop would be more accurate because you don't need to worry about angles.

(Another safe way to make through cuts is to keep both pieces locked so neither can fall into the blade. This is what the GrrrRipper does, and is essentially what happens with a dado cut.)

Simple version: if the piece can fall into the blade, it has to be free to fall away from the blade.

At least, that's my understanding.
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#15 philwillette

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Posted 29 August 2011 - 08:22 PM

I don't see the safety issue. The fence on the left is part of the sled so it moves with sled/piece as opposed to the piece sliding against it as it would with a miter gauge and a rip fence.
I did make sure that the piece was totally against the back fence and I could tell if the piece was square to the left fence. If it wasn't I didn't run the piece. But I don't think I will be using it again. I'm going to get right on making the panel sled, I just wish there was a way to crosscut a full sheet. Thanks for all the input, every little bit helps.

#16 rmac

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Posted 29 August 2011 - 08:29 PM

I just wish there was a way to crosscut a full sheet.

A normal table saw is the wrong tool for working on 4 x 8 sheets of anything. For that, you need a panel saw, or a track saw, or a circular saw with some sort of guide.

-- Russ

#17 Beechwood Chip

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Posted 29 August 2011 - 08:57 PM

I usually use a circular saw to rough cut a panel into pieces, and then do final cuts on the table saw. One of these days I'll build a nice track saw guide to make long, clean cuts. I use Board Buddies on the table saw when cutting larger panels. The table saw is nice for repeated cuts.

Somewhere there's a video of Marc ripping a full 8x4 sheet of plywood on a table saw, without a helper. But in recent videos he breaks it down into manageable pieces using a circular saw or jig saw. I asked why a jig saw and not a circular saw, and he explained that the jig saw is safer because the blade movement is perpendicular to the "table", so less risk of kick back, etc.

#18 LoneRider

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Posted 12 October 2011 - 05:39 PM

Yeah, I'm late on this. And my Festool was a lot of money, and I don't use it a lot, but, when I do .....

I used to cut 4x8' on the saw, but trying to get a piece of plywood that is saw 23"x60" on the table saw is fools play. I will use the Festool for the 60", and the table saw for the 23" sides. As well I will use the Festool for jointing 2 boards to each other.

I spent a lot of money on the Festool saw and Domino, but they have definitely help me make better projects, safer.

#19 Particle Board

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Posted 13 October 2011 - 07:15 AM

Also check your table saw fence. If it's off the ripped edges won't be parallel then when you cut with your sled even if you reference off the same edge the other two will not be square. Always reference off the same edge for all cuts.

Don

#20 GarageWoodworks

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Posted 09 November 2011 - 04:42 PM

Hi Everyone, I built a crosscut sled following Mark's video. After 3 tries with the 5 cut method I got to a respectable .003. Everything has been going great but today I started cutting some 3/4 birch ply for the sides of kitchen cabinets I'm building and they just are not coming out square. I ran the the pieces 24" in the TS and then crosscut one side and then the other to final. The problem is when I make the final cut some times they are off up to a 1/16. I did the 5 cut again and verified that it is still at .003. I have clamped the pieces down to eliminate any movement and sometimes one comes out right on and another one is off again. The sled is solid in the slots so there is no side to side slop. I checked the width of the boards and the sides are parallel. The only thing that bothers me is the stop block is extended 7 inches with a board screwed to the back fence on the sled but I don't perceive any play there either.

I'm getting very frustrated. I have no problem shorting the boards to just under 31" but I don't want to start that until I figure out what is going on.

Anyone have any ideas.

Thank you for any help.

Phil



Skip the 5-cut method. The 5-cut method relies on trial and error (make 5-cuts - adjust - make 5-cuts - adjust - etc). Get it right the first try with NO test cuts.

See how here
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