Help evaluating old blade

[tony359]

Hi all,

I have recently purchased a second hand DeWalt 745 and after spending a few days educating myself on what to do (and what NOT to do) with a table saw, I have today attempted my first cut.

I made a couple and something didn't feel right: I had to push the wood quite a lot through the blade. My understanding was that the blade was going to do all the work and that I would not need to push too much. The table came with a blade which the previous owner fitted. It looks a bit rusty, not sure what he did with that. He also gave me the original DeWalt blade - which seems barely used as all the labels are still readable - so I decided to give that a go.

With the DeWalt the wood goes through the blade like butter so my question is: is the other blade worn out and to be disposed of?

Attached some pictures. I was told that it was a better blade for wood as it has more teeth.
Thank you for your help!

 

[Trevanion]

Yeah, that looks pretty well used going by the resin build up! It may help to clean that off with some form of cleaner like methylated spirits but it may be just the blade is dull and you need a replacement. Don't dispose of the blade, keep a hold of it and once you've got a few you can send them off for sharpening at the fraction of the cost of a new blade.

Have a look at my thread, it might help you out: A Guide to Circular Saw Blades

 

[PAC1]

It needs a good clean. Also it is a fine toothed blade for either cross cutting or cutting sheet material. It is not a rip saw blade

 

[Droogs]

the first blade you tried is probably blunt and in need of sharpening. if its the one in 2203 then it needs a good clean as well to get the gunk off of it. Put it in a tray with water and a good splash of liquid laundry detergent and clean with a plastic toothed brush. then try again. if it is still pants then it needs resharpening. You can find a postal saw doctor who will sharpen it for you.

the number of teeth are more to do with the type of cut you want to make. A RIPCUT made longways along the grain on the board or a CROSSCUT going at right angles to the grain of the board.
A dedicated crosscut blade usually has between 60 and a 100 teeth) more means a neater cleaner cut
A ripcut blade has up to 48/50 teeth

a general purpose combination blade covers the middle ground sort of being able to do both cuts with 50 0 60 teeth.

the teeth can be shaped at the very edge to give different kinds of finishes depending on the job at hand.

The table saw is very useful tool but remember at heart it wants to kill you and slice you up. Before you start using it please make sure you do some research on safe operation and the dangers to be had. Try to stay away from American demo videos as they have a very different safety culture to the UK

 

[marcros]

also fine tooth blades will struggle where there is a lot of saw dust produced- eg the thicker the timber the more they will struggle and the cut deteriorates. There is not enough room between the teeth to clear the dust, compared with a lower tooth count blade. equally applicable to bandsaw blades too.

 

[tony359]

@Droogs
Both pictures are of the same blade

The DeWalt I am using now has only 24 teeth - I still haven't read @Trevanion guide (thanks!) - it's a DT1158 what would that be for?
Indeed I started with some 1" MDF but I then tested it with a mitre cut of a 2x4 birch stud and it really struggled with that. It left burn marks on it even though I did not stop in the middle of the cut.

I will clean it as you recommend and I will report back!

BTW @Droogs - Appreciate your comment on safety. I am indeed quite scared by the TS but I have to admit that the cuts it deliver are second to none. I have asked advice on this forum (Are Grippers much safer than push sticks?) and watched videos and I am definitely treating this tool with lots of respect. I now cringe when I watch a video where a woodworker is using his TS without the riving knife and end up guiding the piece with bare hands....
Thanks for pointing that out!

 

[Droogs]

you're welcome. I am no expert on the tablesaw but there are plenty here who are and use one far more than me. Never be afraid to ask questions as there will be someone here able to answer it and happy to do so

 

[PAC1]

When you have cleaned it, before using it check all the teeth have crisp edges and no chips or are missing if they are worn or damaged it will need Togo to the doctors.
the 24 tooth saw is a rip saw. If it is sharp and clean it will rip your 2x4 birch studding

 

[tony359]

Done! It took A LOT of scrubbing and a few areas just refused to come clean - silly me I thought it was rust!! I'll test it tomorrow.

The teeth are all good and they feel sharp to my skin - but I do not have much experience on blades.

I'll post an update tomorrow - thank you very much for all your help!

 

[Trevanion]

It's hard to tell from photos but that blade does look pretty well worn, the very tips of the teeth should come to a very sharp point but in the photos they look ever so slightly rounded/chipped.

Wouldn't hurt to give it another try though, just bare in mind a blade like that is better suited to cross-cutting and cutting plywood than ripping timber down with the grain.

 

[tony359]

Thanks. I'll test with some plywood offcuts tomorrow.

 

[tony359]

I have now tested the cleaned blade and while I feel it is much better, I also feel it still struggles with any wood I try. Comparing the DeWalt and the pictured one I can clearly see that the very tips of the one I cleaned are indeed rounded while the DeWalt tips are perfectly sharp.

I guess it'll have to go to the doctor then - MANY thanks for your help on this