SCMS and Table Saw Blades

[Sisyphus]

This may be a silly question, but can anyone tell me if can I use the same blades on my SCMS and my tablesaw?

I have a SIP 1332 10" table saw and I bought a Bosch GCM10SD recently. Both of them take 254 mm blades. The spindle bores are different diameters but I can use bushes to adjust them.

What has prompted the question is that I have been trying to cut some 22.5 degree bevels on the table saw so that I can build a radiator cover from MDF. The table saw blade is a Trend Craftrange 60 tooth top bevel blade but it does not provide a very good cut. The Bosch came with a couple of spare blades one of which says 254x3.2x30. 80HW on it.

I assume that the greater number of teeth gives a better cut but I am always careful to the point of nervousness with these machines. I cannot think why the Bosch should not be OK but wonder if I should just forget about it and buy a table saw blade specifically for cutting MDF.

 

[DaveL]

The blades for use in mitre saws are often negative rake and should not be used in a table saw, so you need to check the spec of the spare blades supplied.

 

[brianhabby]

The blades for use in mitre saws are often negative rake and should not be used in a table saw, so you need to check the spec of the spare blades supplied.

Dave,

Can you explain just what you mean as I have been using a blade in my table saw that says it is for a mitre saw and not had any problems.

regards

brian

 

[Slim]

Normal blade:

Negative rake:

As I understand it, a negative rake blade in a SCMS will reduce the chances of the blade grabbing and riding over the wood. The use of a negative rake blade in a table saw can cause the wood to rise up ove the blade which obviously could be very dangerous.

* pictures borrowed from CMTUK

 

[DaveL]

Thanks Simon for posting the pictures.

The way the wood is being cut is very different for the two types of saw. On the table saw the wood needs to be held down on the table and the front of blades action with positive rake is to push the wood down on to the table, that action on a mitre saw will tend to pick the wood up from the bed and throw it over the fence. Fitting a negative rake blade helps to stop this happening, the force now tends to hold the wood down on the bed, however if fitted to a table saw that action is now lifting the wood off the table. Thus its not recommended to use negative rake on a table saw.

A negative rake blade in a table saw will be more liable to kick back and feeding the timber will be harder to control.

 

[devonwoody]

I assume if crosscutting on a table saw the mitre blade does not have quite the same dangers?

 

[DaveL]

I assume if crosscutting on a table saw the mitre blade does not have quite the same dangers?

It will still try and lift the timber off the table compared to a posative rake blade.

 

[devonwoody]

Thanks for the advice, looks like I have got to spend some more cash, wonder if the wife is going out tomorrow :wink:

 

[brianhabby]

Thanks for the pictures Simon, they certainly explain what's going on. I'll have to have a close look at my blade tomorrow and check if it is negative rake or not.

The reason I bought that particular blade was because it is a narrow kerf blade and therefore puts a lot less pressure on the motor of my cheap table saw.

thanks for the advice.

regards

Brian

 

[Sisyphus]

Thanks for this explanation. Having been hit by a bit of wood coming off the table saw when I first dabbled in woodworking, I have no desire to repeat the experience.

Its a quick raid on the piggy bank and off to the shops tomorrow for me.

 

[motownmartin]

Normal blade:

Negative rake:

As I understand it, a negative rake blade in a SCMS will reduce the chances of the blade grabbing and riding over the wood. The use of a negative rake blade in a table saw can cause the wood to rise up ove the blade which obviously could be very dangerous.

* pictures borrowed from CMTUK

Thanks for the info Simon, I am now quite concerned about the Blade I have fitted in my table saw it looks as though i'll have to spend more money to get the correct blade.