When does a rip cut become a cross cut on ts?

[SteveF]

maybe this is a dumb question
I know along grain is rip
across grain is crosscut
but if using mdf \ plywood there is no grain
so back to my questiion
if i take an 8 x 4 and rip down to give a 4 x 4
when does it get to the dangerous stage?
2 foot would still run along the fence safely so is a rip

should i back away from the tools and take up golf?

Steve

 

[transatlantic]

Not sure what you mean. As far as I am aware, whether you use a rip or cross cut blade is to do with the quality of the cut, and perhaps how easy it is for the motor. So in regard to plywood, as it's both cross and rip at the same time, you'd use a hybrid cross/rip blade, but you don't have to, any blade will do. You'll just get different results in terms of quality. For MDF, I think any blade will do, but you'd want to aim for something with more teeth.

 

[SteveF]

sorry i should explain better
I understand the blade types I hope
and assume that a crosscut blade would be safe and give a clean cut to rip plywood
and use a rip blade to cut along the grain of a real timber
it was more of a question of how narrow the sheet material is before it is not safe to rip
say my plywood is now 8" x 24", this is now not safe to rip along the 8" dimension but perfectly safe along the 24"

I just wondered if there is a rule of safety

Steve

 

[woodbrains]

Hello,

There is no rip or crosscut per se with man made boards. You can cut it all with a fine toothed blade for better finish, but it can be done along the fence as though it were a rip cut except you do not need to use a short fence, in fact a full lenght fence is best. The only danger is cutting across a long board against the fence. As a rule, the board should have its longest edge against the rip fence. A sliding table or such is best cutting a long narrow board across the shortest side. There is a danger using the rip frence, when registering an edge that is much narrower than the length. As a rule, I would say if the edge against the fence is less than about 2/3 the length. I would hesitate to cut it.

Mike.

 

[Peter Sefton]

Not sure if I fully understand your question but my general advice is always have the longest edge against the fence.

Cheers Peter

 

[andersonec]

Your work piece MUST be long enough to go past your riving knife (which should be fitted at all times) and be in contact with the fence at the same time, if it doesn't then don't cut it, your fence should only go just past the gullet of the teeth of the blade so every time you raise or lower the blade you should adjust your fence and as Mike says, if it is hanging out over the side of your table saw then maybe you should cut it rough with a handsaw first leaving a small bit which you could then finish with your table saw for a nice square edge.

Andy

 

[SteveF]

thankyou all for response
i never worded correct i am sure and title was carp
answers made more sense than the question
i guess it should have been,,,,,when to stop ripping and switch to a sliding table

Steve

 

[Adam9453]

With mdf or plywood etc the best way to think is long edge should be 'ripped' i.e. Running long edge against the fence.
And short edge should be 'crosscut' on the sliding table.
When cross cutting ensure your fence is far enough out the way to avoid binding on the offcut which could result in kickback (even with riving knife in place).
There are some good videos on YouTube about safe tablesaw usage, but not often demonstrated very well by American presenters as they tend to be a bit less concerned about cutting off limbs than us brits

 

[SteveF]

i do like to completely ignore american youtube madness (they voted Trump)
my first job will be to make a shorter fence to attach to my TS fence
i have had many cheap ts in past
but first time having something that could really bite me
so I thought it best to ask dumb questions here, than pay for it later
much rather look stupid and nooby, than make a life changing messup

Steve

 

[RobinBHM]

If you cut something in landscape shape you increase the risk of twisting leading to a chance of a kickback. It can be done but only on stuff thats slightly wider than square and needs careful hand placement and pressure direction.

Generally, for sheet material a rip fence can be long and extend beyond the rear of the blade.

Sheet material is generally considered not to have tension and wont move like timber. Not true in the case of OSB! it can really bind!

For timber, the fence should stop about in line with the gullets at the front of the blade, that way the exiting timber wont get pinched.

If using a sliding table or mitre fence dont use that and rip fence together. You can use a sliding table to support a big sheet as its pushed through for length cuts, but only use thr rip fence for guiding not both fences.

If cutting small repeat pieces with a mitre guide never use the rip fence as a stop unless it can be taken so far forward that the timber leaves the stop before the cutting starts.

 

[Steve Maskery]

I'm really glad that you are so safety conscious. It's a good sign!

In general, man-made boards do not have a rain direction, not beyond their surface veneer. So you can cut in any direction you like. More or less. A tripple chip blade is good for veneered board, BTW.

The long/short fence issue is to do with cutting wood, not sheet materials. Wood can, and does, move, much moreso than sheet materials.

General rule:
Short rip fence for ripping timber
Long rip fence for cutting sheet materials
No rip fence for cross-cutting!

S
Edit - no rip fence for cross-cutting unless it is pulled right back, forward of the blade, and is just acting as a length stop.

 

[SteveF]

thanks Steve
much appreciated
and that "general rule" will go on a chalkboard above my saw
I have been destroying wood for over 30 yrs
but I feel with every new piece of equipment, regardless of how competent I feel, that a few questions is worth it's weight
my new saw is a year younger than me
hopefully it will survive another 50 yrs

Steve