Table saw - scorch marks - advice please?

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RogerM

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I've been getting scorch marks on timber for some time and today spent some effort to ensure that the fence was exactly parallel to the blade. Still getting scorch marks tho' and the blade seems pretty sharp, and hasn't had a lot of use. Its an 8" TCT general purpose blade that came with the saw (a Scheppach TS2010).

Any ideas? Is is purely a case of re-sharpening, or using a different blade for ripping (don't really want to have to keep changing blades). Here's a piccie of what I mean. This is 1" english oak, and as you can see, the scorch marks appear on both sides of the cut, which was made from top to bottom.

Any advice greatfully received.

DSC02826.JPG
 
Blade not at 90% Or timber not square enough.
Damp wood and grabbing.
You might have to use a pukka rip blade on this piece of timber.

Take your pick :wink:
 
i only noticed that one of my saw blades was dull when i was ripping some maple, time for a sharpen me thinks.


JHB
 
devonwoody":12jc9fda said:
Blade not at 90% Or timber not square enough.
Damp wood and grabbing.
You might have to use a pukka rip blade on this piece of timber.

Take your pick :wink:

Blade definitely at 90 deg and parallel to fence. Face is sawn board. Moisture content is 13.5%, which is pretty much par for the course for air dried timber in Devon. Even some kiln dried American White Oak that has been turned in to a table and indoors by a radiator for 2 years is 11%.

I have quite a lot of this to rip from 1" sawn boards, so would you go for a dedicated ripping blade?

And if so, which make? And would you then just use a GP blade for cross cuts and general use on oak?
 
How many Teeth on the blade?

Are you using a steady moderate feed rate?

If it's just the stock blade, I'd swap it out. I've never had problems with Freud 40t blades for ripping\multi-purpose. Atkinson and Walker blades from Workshop Heaven are also first class

If youre doing a lot of ripping then I'd suggest a 30t blade, more for speed.
 
How many teeth on that blade Roger? If it's more than about 20 it won't be very satisfactory for ripping. I have the 10" version of your saw and use a 24T for ripping, and a 60T for crosscutting. The supplied 42T Scheppach blade is still going strong (been sharpened quite a few times now) despite being about 8years old, and is a great general purpose blade for board materials, but you wouldn't want to rip with it unless it's been recently attended to by the saw doctor.

Is it really that much trouble to change blades? I don't know how different the setup is on your's, but I can swap blades in about 90 seconds.

I have to admit though, I don't do much ripping on mine these days, as the bandsaw is a much better tool for the job.
 
wizer":3g4k54hb said:
How many Teeth on the blade?

Are you using a steady moderate feed rate?

If it's just the stock blade, I'd swap it out. I've never had problems with Freud 40t blades for ripping\multi-purpose. Atkinson and Walker blades from Workshop Heaven are also first class

If youre doing a lot of ripping then I'd suggest a 30t blade, more for speed.

This is a GP 24 tooth 8" blade - so that's about 1 point per inch. Equates to 31 points on a 10" blade. I have a large(ish) quantity of 1" English Oak to rip for a blanket box and a tall bookcase with drawers below. Plus a small quantity of 2" Oak. In an ideal world I would have a 10" saw. I don't have a band saw - so this is a case of making best use of what I have rather than what would be ideal.

Just found this threadwhich is very useful for others having similar problems. Maybe I should have done a search first!
 
There's only one other thing I can think to suggest and that's blade wobble! :shock: You may have nothing to worry about but, you could always check the blade for run-out.

Put a combination square in the mitre slot, set it to one of the teeth and slowly rotate the blade (with the machine isolated!!). If the blade drifts toward or away from the end of your square then, you may have an issue...

If this was the case then, it could just be that the blade isn't seated correctly on the arbour. Otherwise, you could try fitting a large washer (blade stiffener) on to the shaft before the nut (assuming you have sufficient thread length).

I only thought of this because I used to own a cheap Fox saw that gave this kind of finish.
 
If it happens on a sharp 24T blade, then i'd say it is, indeed, run out.
 
A common cause of this is overfeeding a blade with too many teeth (not enough gullet space to clear the waste) but with a 24 you shouldn't be having that problem.

Another issue, as mentioned above, is run out. It is of some use to check the blade whilst it is cold, as this will show any serious warping. However it is also worth considering that when you are using it you are heating the perimiter to serious temperatures - clearly enough to burn the face of the timber in the split second that the two are in contact - but the centre of the blade is spinning in fresh air and being cooled. This temperature difference can cause a blade that is flat whilst cool to take on the shape of a pringle when working.

This is exactly the issue that hand smithing sorts out. The plate is hardened and tempered under pressure which makes the crystalline structure of the steel form flat in the first place. It is then smythed by repeatedly hammering the plate and obsering how it falls away from a straight edge, so the internal tensions within the plate also make it want to remain flat and round. The result is a blade that will expand very slightly in its circumferance when differentially heated, but it will not warp or twist. They are precision ground rather than merely polished, and fitted with big fat micrograin tungsten carbide teeth that can be resharpened.

I was lucky enough to be allowed not only to watch the smiths at Atkinson Walker in action but also video them on a recent visit to the factory in Sheffield (available on youtube as soon as I find time to upload it). Not so long ago they would have downed tools and folded their arms the moment I walked into their shop. The only way you learned how to smith a sawblade was by doing a full 5 year apprenticeship, there's no 'tricks of the trade' malarky in this game thank you very much!

Thankfully things have relaxed as the trade is now in danger of being lost - there are only a handful of qualified smiths left in the country so the Sawsmiths are keen on anything that will encourage youngsters to take up the trade.
wayne3x4r.jpg

All of the industrial blades that we sell are treated in this way and can be returned to the factory for resharpening up to ten times. In most cases, by the time you take into account how many ordinary blades you would get through in the lifetime of an industrial blade, the savings run into hundreds of pounds - and that's on top of the performance benefits.
 
matthewwh":3nihlg2l said:
industrial blades that we sell are treated in this way and can be returned to the factory for resharpening up to ten times. In most cases, by the time you take into account how many ordinary blades you would get through in the lifetime of an industrial blade, the savings run into hundreds of pounds - and that's on top of the performance benefits.

Can you run the economics of that by me. Are those free sharpenings?
 
All the sharpening prices are listed in the saw sharpening service section on the Atkinson Walker page here.

As an example a 20 tooth 200mm ATB blade is £41.32 + £6.35p&p, resharpening for the same is £11.96 each and this price includes posting it back to you.

Add say £4 for posting it up to be sharpened (re-use the original packaging) and the total cost over 10 sharpenings is £41.32 + £6.35 + (10 x £15.96) = £207.27

The same spec ProTrade blade is £15.66 + £6.31p&p, so 11 of them to cover the life expectancy of an industrial blade comes to £241.67.

As the blades get bigger the difference does too, it probably isn't worth having a 200mm blade re-toothed, but by the time you get up to the larger diameters this becomes a viable option as well.

The main reason for choosing industrial blades is their superior stability and accuracy, which is reflected in the quality of the cut. As you can see, the higher initial purchase price gets clawed back over time, and you get a consistent, reliable, high quality cut rather than having the sorts of problems Roger is facing at the moment.
 
Thanks for all your contributions guys. I've ordered a 20T industrial blade and I'll let you know how it goes. Thinking about the use I've given the existing blade, it's cut a lot of chipboard and OSB as well as American White Oak, so maybe not as sharp as I think it is. I think I'll get it sharpened and reserve it for cutting man made boards and keep the new blade for "real" wood.
 
matthewwh":1r5viqvw said:
All the sharpening prices are listed in the saw sharpening service section on the Atkinson Walker page here.

As an example a 20 tooth 200mm ATB blade is £41.32 + £6.35p&p, resharpening for the same is £11.96 each and this price includes posting it back to you.

Add say £4 for posting it up to be sharpened (re-use the original packaging) and the total cost over 10 sharpenings is £41.32 + £6.35 + (10 x £15.96) = £207.27

OK, that's a bit more than using a local saw-doc for sharpening a blade, but nice to have it done by the manufacturer, I guess - should remove any doubt about reliability.

The same spec ProTrade blade is £15.66 + £6.31p&p, so 11 of them to cover the life expectancy of an industrial blade comes to £241.67.

Oh, I see, so the comparison you are making is between an A&W non-resharpenable blade, and the resharpenable industrial one, rather than an A&W industrial blade and any other ordinary industrial blade?

That makes sense, buying a non-resharpenable blade is always going to be a false economy.
 
Very interesting thread.

This may be a silly question :oops: but how do I know if my blade is resharpenable? Is it only industrial quality is resharpenable?

Thanks

Dave
 
Hi Dave,

Industrial blades have much bigger carbide tips on the teeth to allow for multiple resharpening.

There is a closeup of an industrial blade on the right here.

If your blade looks like this then it probably is resharpenable, if it has tiny specs of carbide right on the very end of the tooth then it's a throwaway and start again job.
 
Matthew thanks for the advice - but still confused :oops: :oops:

saw2.jpg

This is part of "your" image - it is not my blade, the comment on the image refers to my blade. The length of what may be carbide (?) is about 3mm. What do you think?

(If it helps I can post a pic of my blade tomorrow?)

Dave
 
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