Ripping Problem

[Sawyer]

I'm ripping a load of 3 1/2 inch thick dry oak and am having problems.
The machine is an Axminster TSCE 12R 305: 3 phase and reasonably powerful, but clearly being tested to its limits.
The saw is struggling and I'm getting overheating and burning, with the blade having acquired 2 'black eyes' in the process. Blade is also picking up black, slightly sticky deposits on the fence side only. Although not newly sharpened, I would not say that the blade is dull, either. It's a good quality (CMT/Orange) 305mm 28t. rip blade.

I've checked the following, but still getting the problem:
Ensured blade is vertical in relation to the table.
Checked fence alignment, which is correct.
Cleaned the aforesaid black deposits off the blade.
Using a wedge behind blade if kerf closing (case hardening).
Riving knife is correctly adjusted.

Any suggestions on what the problem might be - or is it just that I'm asking too much of the machine and blade? Or do I just need to use a newly-sharpened blade for such tasks?
Does anything need to be done to remedy the 'black eyes' on the blade?
I'd be very grateful for any pointers..

 

[Waka]

Sounds to me that your need a sharper blade.

 

[stev]

There's some interesting discussion on this thread in relation to fence setting for ripping and the problems caused by ripped timber flexing as the cut is made. It might be helpful. Ignore the title of the OP it rapidly ends up being a discussion about how to set a fence for effective and safe ripping.

https://www.ukworkshop.co.uk/forums/push-stick-t52519.html

 

[Richard T]

What might be sharp enough for softer stuff might not be sharp enough for dry Oak.
Could the black marks just be what Oak usually does to steel, and vice versa?

 

[Sawyer]

Could the black marks just be what Oak usually does to steel, and vice versa?

I don't think so, Richard - it's a thick, gummy deposit and the blade has been smoking.

BTW, I've also been ripping some thinner oak, about 1 3/4" which the saw has been handling without any problem. Perhaps it is just a question of sharpening. I've revisited the other thread suggested by Stev and should add that I am not using a full length fence. Rather, the full length one provided has been moved forwards to end just past the gullet of the tooth at table level.
Orthodox procedure (followed by myself) is to use a short fence for ripping; as advocated by the HSE and large trad. ripsaws always have a short fence.

 

[Richard T]

'scuse my ignorance but you say the blade is 28t - what is that? Just wondering if it might have too many teeth for 3 - 1/2" especially if it's ok with thinner stuff...

 

[Sawyer]

'scuse my ignorance but you say the blade is 28t - what is that? Just wondering if it might have too many teeth for 3 - 1/2" especially if it's ok with thinner stuff...

That's 28 teeth. Not sure if coarser blades are available in 305 mm.?

 

[moz]

If the room is filling with smoke as well, you have the phases reversed (DAMHIKT )

But seriously, I guess you are using the universal blade supplied with the machine. The saw has plenty of power at 5HP. The blade is the problem. You need a proper rip blade. The tooth formation is different, it will have about 14 teeth and deep gullets. The dust can't get away fast enough. e.g:

http://www.felder-tooling.co.uk/werkzeu ... hrung.html

John

 

[Benchwayze]

+1 for Moz

John

 

[cutting solutions]

Firstly 28T for 3 1/2" oak is too many teeth.

The Felder blade looks a bit expensive to me :wink:

The "black eyes" are where the blade has become too hot and damaged the plate on the blade.
It has almost certainly become "dished" as we call it in the trade.
It can probably be recovered by the saw doctor but do tell him when you send it in for servicing/sharpening.
they can "hammer" the hot spots out and reflatten the blade.

Doug

 

[Richard T]

I still don't get how 28t relates to TPI (Teeth Per Inch) - if I were to rip 3 - 1/2" I'd use 3tpi.
If 28t means 28tpi then by my reckoning it's about 25ttm (Teeth Too Many).

 

[Jacob]

If not a blunt blade it could be pinching as tension is released. Tap in a little wooden wedge to keep the kerf open after you have started the cut perhaps? And make sure the fence end is as far back as possible - close to front edge of the blade, to avoid wood moving and jamming.

 

[Harbo]

Richard it doesn't mean tpi.
As I understand it, T is the total number of teeth around the circumference though I have never bothered to count them myself.
But like tpi the smaller the number the fewer the teeth.

Rod

 

[doorframe]

I still don't get how 28t relates to TPI (Teeth Per Inch) - if I were to rip 3 - 1/2" I'd use 3tpi.
If 28t means 28tpi then by my reckoning it's about 25ttm (Teeth Too Many).

I think Richard is thinking that it's a bandsaw blade, in which case it would be TPI.

As I understand it we are talking about a circular saw blade, where its 't' as in total number of teeth.

Or is it me that's not reading it right?

Roy

 

[moz]

I still don't get how 28t relates to TPI (Teeth Per Inch) - if I were to rip 3 - 1/2" I'd use 3tpi.
If 28t means 28tpi then by my reckoning it's about 25ttm (Teeth Too Many).

I think Richard is thinking that it's a bandsaw blade, in which case it would be TPI.

As I understand it we are talking about a circular saw blade, where its 't' as in total number of teeth.

Or is it me that's not reading it right?

Roy

Correct, whatever nomenclature a particular manufacturer uses, circular saw blades are always described with the total number of teeth. The ideal number will, of course, change depending on the diameter. My comment above assumes a diameter of 315mm or thereabouts.

Doug, your prices look good. I'll be giving you a call when I need to replace.

John

 

[Guggs]

There are many factors that can cause a blade to 'blue' , Firstly have you got the correct blade for the job intented ? I would always go direct to a saw supplier for advice and not a commercial woodworking store . There are so many factors that can cause 'burning' .Rake of teeth ,saw blade has enough tension ,is the riving knife of the correct arc and thickness.fence alignment ,gullet shape etc and how are the teeth of the saw set i.e are the teeth swaged(set) less or greater than the gauge of the blade body ? All food for thought !

 

[Richard T]

Yup - I've never had any sort of circular saw so the calculation of how big teeth/gaps are by total number and circumference seems very difficult to visualise indeed.

 

[cutting solutions]

and how are the teeth of the saw set i.e are the teeth swaged(set) less or greater than the gauge of the blade body ?

On TCT circular saw blades there is no swage (or set).
there is a clearance between the actual tungsten tip and the body of the blade
on a 300 mm diameter blade I would expect to see 3.2 mm tip and 2.2 mm saw plate for good quality blades.

to OP....
I assume that the blade being used is 3.2/2.2.......otherwise ripping with a thinner kerf at the height you are would certainly cause heating problems which would blister the blade.


For all.
The "T" number on circular saws refers to the number of teeth (just to confuse you all German Industrial blades refer to them as "Z=" IIRC the German word for teeth begins with Z

 

[Sawyer]

Thank you everyone who has posted on this. The conclusion seems to be that I need a coarser blade: for a 305mm blade, does anybody supply something coarser than 28 teeth? I can't seem to find any listed.

Another alternative might be to upgrade my bandsaw for something big, capable of resawing. The Axminster AP5300HD3 at 3 hp looks a bit nifty and I'd expect it to rip 3 1/2" oak with relative ease.

 

[moz]

Whoa, hold on there! I cut thick oak on my 5.5HP saw with the blade I linked to. What is the maximum size of blade it will take? I would be surprised if you couldn't get 315mm on it like the one I posted. Also 300mm is close enough not to make any meaningful difference to the speed at the tip, or the capacity. Widens the choice. Regardless of that, I suggest you give Doug a ring at Cutting Solutions, he will certainly be able to help.

John