Thinner kerf circular saw blade won't tighten

[OldKettle]

Hi,
I am trying to replace the default blade on this circular saw

https://www.screwfix.com/p/erbauer-erb596cws-2000w-235mm-circular-saw-240v/71604

with this thinner kerf blade (for cutting polycarbonate sheets)

https://www.amazon.co.uk/gp/product/B00DI8RASG/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

but the blade will not properly tighten (can still be spun by hand when the blade is tightened). I've clean it out with compressed air, in case there was any debris, but that hasn't fixed it.

Do I likely need to buy a replacement flange washer and/or bolt? If so, can anybody please advise a source?

Any thoughts would be much appreciated.

 

[Tigercubrider]

Do you have both flange washers on?

 

[OldKettle]

Hi.

Here is before installing the blade, and after. There is nothing else under the blade, once installed. Is there a part missing?

 

[Burnerman]

Your saw is designed to hold a blade of 2.8mm thick, your new blade is 1.65mm thick.
Therefore you need a shim of 30mm bore x 1.15 minimum thickness to grip the blade securely......if you can find one!
John

 

[OldKettle]

Your saw is designed to hold a blade of 2.8mm thick, your new blade is 1.65mm thick.
Therefore you need a shim of 30mm bore x 1.15 minimum thickness to grip the blade securely......if you can find one!
John

Thanks. I had thought that using a thinner kerf was pretty straightforward (and common), as long I kept the same bore size and did not exceed the saw's max blade diameter.

Is it unusual to use a thinner kerf with the same saw?

Do I need something like this?

https://www.accu.co.uk/en/shim-washers/62847-HSHN-30-42-1-A2

A quick search has given me a max of 1mm thickness so far. Can I stack them?

 

[big-all]

ehhh its a 235mm saw fitted with a 165mm blade
you blade gaurd possibly wont work properly and may indeed be rather unsafe
having said that iff any thing would think more teeth and a shallow approach angle may be best

 

[Burnerman]

Most blades that I have bought have had a couple of shims with them to suit various arbors. Exact arbor diameter is vital and the outer diameter of the shim should be at least the diameter of the clamping disc. You can stack shims but naturally enough the blade must be secure and run true.
A shim has a guaranteed uniform thickness whereas a normal washer may not be.
Therefore great care is necessary here.
John

 

[SammyInnit]

That blade you've bought is going to make a right mess of the polycarbonate. You need a blade with more teeth, the one you've selected is for rough cutting soft timber.

Secondly as mentioned you're using a blade that's well undersized for that saw; could have some implications with the speed and lack of teeth.

You can make it fit by using shim washers but I'd reconsider the blade you're using.

 

[OldKettle]

That blade you've bought is going to make a right mess of the polycarbonate. You need a blade with more teeth, the one you've selected is for rough cutting soft timber.

Secondly as mentioned you're using a blade that's well undersized for that saw; could have some implications with the speed and lack of teeth.

You can make it fit by using shim washers but I'd reconsider the blade you're using.

Thanks to everyone.

I had originally focused on the thickness, but now understand that the number of teeth is more important, so I will scrap the idea of using the blade.

The diameter is 190mm vs 235mm for the saw. If that is too low I will just get rid of the blade altogether.

For the polycarbonate sheets, I've decided to get a pack of these blades and just use my jigsaw instead. Do they look OK? (4mm double wall polycarbonate for a greenhouse)

https://www.amazon.co.uk/Bosch-2608631010-Jigsaw-Blades/dp/B0009U7B1W

 

[SammyInnit]

They look fine. Blades for metal work well too. For materials that are hard and brittle like PC you want more teeth with a shallower gullet at a mid to low speed.