Circular saw blades
 

I have a DeWalt DC390 18v cordless circular saw. This takes 165mm
diameter blades on a 20mm arbour. I can't find any blade finer than
30 tooth to fit this saw. I have seen a Trend 48 tooth blade that has
the same size arbour (20mm) but is 160mm diameter (5mm less).

I have 2 questions. The first of course is if I fit the smaller Trend
blade, will it be dangerous? Secondly, will it give me the fine cut
that the blade is designed for?

Whilst on this subject, am I right in thinking that the smaller the
blade diameter, the fewer teeth are needed for finer cuts? For example,
the trend described above has 48 teeth around its circumference. This
gives 0.095 teeth per centimetre of circumference. On a 300 mm diameter
blade, to get 0.095 teeth per cm you would need 90 teeth around the
circumference. Which is a "fine" or even "extra fine" cut if
you read the adverts. Is this sort of conversion the right thing to do?

Thanks for your reply Grunff. For interest though my maths for the
above is as follows.

Circumference = PI * diameter

so for the 160 diameter trend, we get

3.142 * 160mm = 502.72 mm for the circumference.

Now there are 48 teeth around the circumference so

48/502.72 = 0.09548 teeth per centimetre.

To get this number of teeth per centimetre on a 300 mm diameter blade,
we would need a blade of

300mm * PI * 0.095 = 90

So a 90 tooth 300mm blade would have the same number of teeth every
centimetre as a 48 tooth 160mm blade.

Now my maths may be flawed, but could you expand a little on where I am
going wrong.

Thanks again.

In message .com,
writes
Thanks for your reply Grunff. For interest though my maths for the
above is as follows.

Circumference = PI * diameter

so for the 160 diameter trend, we get

3.142 * 160mm = 502.72 mm for the circumference.

Now there are 48 teeth around the circumference so

48/502.72 = 0.09548 teeth per centimetre.

This is a case of taking a step back and looking at your answer

You're saying the teeth are 10cm apart

you've dropped from mm to cm

--
geoff

Hi Dean
I have a DeWalt DC390 18v cordless circular saw. This takes 165mm
diameter blades on a 20mm arbour. I can't find any blade finer than
30 tooth to fit this saw. I have seen a Trend 48 tooth blade that has
the same size arbour (20mm) but is 160mm diameter (5mm less).

There is a whole lot more to saw blades that just the number of teeth,
pitch, angle, rake etc. I recently replaced the blade on my DeWalt radial
arm saw. Same size, same bore, same number of teeth.

Performance was entirely different. Splintering underneath, blade grabbing
the stock etc. Had the old blade sharpened and it's now a different saw
entirely.

I'm not up on the whys & wherefores but do check it out first with someone
who knows.

Dave

On 20 Jul 2005 04:05:40 -0700, wrote:

I have a DeWalt DC390 18v cordless circular saw. This takes 165mm
diameter blades on a 20mm arbour. I can't find any blade finer than
30 tooth to fit this saw. I have seen a Trend 48 tooth blade that has
the same size arbour (20mm) but is 160mm diameter (5mm less).

I have 2 questions. The first of course is if I fit the smaller Trend
blade, will it be dangerous? Secondly, will it give me the fine cut
that the blade is designed for?

Whilst on this subject, am I right in thinking that the smaller the
blade diameter, the fewer teeth are needed for finer cuts? For example,
the trend described above has 48 teeth around its circumference. This
gives 0.095 teeth per centimetre of circumference. On a 300 mm diameter
blade, to get 0.095 teeth per cm you would need 90 teeth around the
circumference. Which is a "fine" or even "extra fine" cut if
you read the adverts. Is this sort of conversion the right thing to do?

I have had a similar issue, and have a slighlty smaller than designed
blade in my circulr saw, to get more teath, and a finer cut. I did
acheive a finer cut.

I decided that as long as the blade if fimly held in, and the hole is
the right size, that I would not increase the danger level. However I
have no specalist knowledge to back up this decision, it just felt
right.

Of cource the speed at the top of the blade decreses as the diamater
decreases.


Rick

David Lang wrote:
Hi Dean
I have a DeWalt DC390 18v cordless circular saw. This takes 165mm
diameter blades on a 20mm arbour. I can't find any blade finer than
30 tooth to fit this saw. I have seen a Trend 48 tooth blade that has
the same size arbour (20mm) but is 160mm diameter (5mm less).

There is a whole lot more to saw blades that just the number of teeth,
pitch, angle, rake etc. I recently replaced the blade on my DeWalt radial
arm saw. Same size, same bore, same number of teeth.

Performance was entirely different. Splintering underneath, blade grabbing
the stock etc. Had the old blade sharpened and it's now a different saw
entirely.

I'm not up on the whys & wherefores but do check it out first with someone
who knows.

Dave


Codless circs are significantly different to mains circs. Theyre much
lower power, tend to run at slower speed, and use a coarser cut blade,
and possibly a thinner blade too, to make up for some of the lost
ground. Whether theyre ground the same I've no idea, but would not
assume so.

I would not want to replace a codless blade with a mains one except as
an experiment to see what happens. I would expect to get significantly
lses cut per charge - theres good reason they use coarse blades.

If you want something decent, use mains when poss.


NT

In article , PC Paul
wrote:
wrote:

Codless circs are significantly different to mains circs.

Something very fishy about that sentence. :-)

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Owain wrote:
wrote:

Codless circs are significantly different to mains circs. ...

Can you upgrade with an optional codpiece?

Owain

hmmm... What I always wondered is if the codless ones swell for such a
premium, why dont they get mains ones and just take the cod out?

NT