Tablesaw Crosscut Sled problems

[Sportique]

I'm no expert, but it seems to me that if the blade and slot are not parallel then, when using the slot, you have two issues (in addition to the "coving" effect):

1. The kerf width is increased, and
2. Increased threat of kick-back.

For (2) above: if you imagine the blade has "toe-in" then the leading edge of the blade is cutting on the slot side, but the trailing edge of the blade is cutting on the side away from the slot - this trailing edge is the rising edge of the blade and could (will?) lift the workpiece off the table?

In my view, the way to deal with these issues is to firstly square the blade with the slot, then set everything else up wrt the slot??

Dave

 

[newt]

Tom the only parameter to worry about to ensure you cut at 90 is the relationship between the slot and the fence this must be 90. The relationship with the blade is not critical, however it is highly desirable to ensure a clean cut, with no vertical errors. the diagram below is just to illustrate clearly not practical, but this will still cut at 90. Demonstrated this at a recent bash. Red is the blade.

 

[jasonB]

Tom,

You will find the the ONLY parameter that is important to square cutting is that the table slot and the blade are totally parallel.

Bob

OK I have dusted off my sledge, the slot & the blade are parallel, made this cut and the bit of MDF is indeed cut at 90deg

I have now inserted a wedge to simulate a fence that is not at 90deg to the direction of travel (pencil line drawn with a square)

I think we all can see that the workpiece has now be cut at an angel but THE BLADE & SLOT AR STILL PARALLEL

So the relationship between the fence and direction of travel is critical. NOT the blade & slot, unless you can convince me otherwise.

Jason

 

[jasonB]

Just read Newts post which is totally correct.

slot and the fence this must be 90

Was this a different bash to the one 9 fingers mentioned or has he just got the parameters muddled up, a little knowledge is a dangerous thing :wink:

Sportique is also correct in saying that if the slot is too out of parallel the workpiece will catch the upwardly moving teeth on the back of the blade and if its a wide board the riving knife will attempt to pull the wood away from the fence (as viewed in Newts sketch) both of which are potentially dangerous.

Jason

 

[ondablade]

This is Woodpecker's version of your gauge Jimi. gauge It uses a nice system of cylindrical rollers to line up instantly off different sizes of mitre slot.

It's remarkable as you say how cheap dial gauges have got too. I've bought here, they also do a well priced magnetic stand so you can use the gauge to set up your planer: chronos

A complicating factor in all of this is the question of the few thou toe out relative to a rip fence that many recommend. In that case (i've not played with this yet as i always did OK for my so far approximate purposes set parallel) i guess you set the blade up parallel to the slots, but offset the fence a whisker so that the trailing teeth don't cause kickback or scar the workpiece.

There's another layer of set up with a sliding table saw. There you can toe out the blade a few thou relative to the line of movement of the sliding table (for clean cuts off it), and toe out the rip fence another few thou relative to this blade setting to give clean cutting and less jamming off it......

 

[Digit]

the fence and direction of travel is critical.

And the 'direction of travel' is controlled by the slot!
Dave, yes the kerf is increased in width, as regards kick back, not necessarily so as the kerf is now wider, therefore less chance of 'pinching', and a blade will cut perfectly well on the 'up stroke'. What I will guarantee is that you would get a lot more saw dust in your teeth! :lol:

Roy.

 

[9fingers]

Just read Newts post which is totally correct.

slot and the fence this must be 90

Was this a different bash to the one 9 fingers mentioned or has he just got the parameters muddled up, a little knowledge is a dangerous thing :wink:

Jason

Gents
I'm ashamed to admit two cases of muddling on my part now that I have re-visited my original post.
Firstly I mixed up mitre fence and mitre slot - No excuses just wrong!
Secondly it was Newt who demonstrated at his bash last year and Paul Chapman who was an active participant in the ensuing discussion.
I knew what I was talking about but wrote something different. :lol:

I'll crawl back under my stone for a bit and hope I'll be forgiven

Bob

 

[Digit]

You are hereby forgiven! :lol:

Roy.

 

[9fingers]

You are hereby forgiven! :lol:

Roy.

Thank you Roy!

 

[ondablade]

Go easy on yourself Bob....

ian

 

[9fingers]

Go easy on yourself Bob....

ian

Cheers Ian,

Maybe I'll stick to motors and machine modifications
The f*ckup fairy has yet to creep into those replies - so far!!

Bob

 

[newt]

Bob completely forgiven

 

[jasonB]

I'll let you of Bob and even Digit for agreeing with you though he hasn't admitted it yet :wink:

Jason

 

[Digit]

???

Roy.

 

[jasonB]

Though many won't believe it what Bob says it is quite correct.

!!!

Jason

 

[Digit]

Guilty as charged! I mis read his post, now I need forgiving!

Roy.

 

[jasonB]

Oh all right then.

Its been a good discussion anyway and no one throw a wobbly

Jason

 

[Digit]

no one throw a wobbly

Yep! Even though I dropped a clanger a discussion as it should be, and hopefully helpful to Tom and others.

Roy.[/quote]

 

[9fingers]

Oh all right then.

Its been a good discussion anyway and no one throw a wobbly

Jason

This is one of the best things about this forum. Ranting and wobblies are incredibly rare compared to Usenet Newsgroups and some other forums around.

Bob

 

[devonwoody]

I'll let you of Bob and even Digit for agreeing with you though he hasn't admitted it yet :wink:

Jason

I'll let you of ??????????????

Those who live in glass houses shouldnt throw stones. :wink: