Angle grinder questions

	Angle grinder questions

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Subject

Author

Date

Angle grinder questions

MiamiCuse

03-27-2008

Re: Angle grinder questions

Dave Martindale

03-27-2008

Re: Angle grinder questions

Frank

03-27-2008

Re: Angle grinder questions

Jeff Wisnia

03-28-2008

If you were Registered and logged in, you could reply and use other advanced thread options

Posted by MiamiCuse on March 27, 2008, 3:27 am

I previously posted a question about a Harbor Freight 4.5" angle grinder I
got which is this model:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=31309

regardless of the quality of Harbor Freight tools, and since I bought it
just to work on a small part of a project I did not want to spend too much
on it.

I wanted to use it to cut some concrete blocks and it came with a depressed
center metal cut off disc, so I went and got a 4.5" diamond blade (which
turns out to be about the same price as the grinder itself!) I ran into
difficulty installing the diamond blade because with the center not
depressed there is no room to put in the locking nut.

Here is a picture of the ginder:

http://i173.photobucket.com/albums/w67/143house/temp/P1010674.jpg

You can see there is a "backing flange" and the locking nut removed.

Closer view of the body showing brand/model:

http://i173.photobucket.com/albums/w67/143house/temp/P1010676.jpg

Now I put back in the backing flange, you can see it is quite deep and
almost the same depth:

http://i173.photobucket.com/albums/w67/143house/temp/P1010677.jpg

Now I put on the locking nut:

http://i173.photobucket.com/albums/w67/143house/temp/P1010678.jpg

Some of you suggested that I flip the locking nut around. This will not
work, because the tool that tightens the nut needs to be applied to that
side with the four small holes.

I then went to HD and looked at their grinders and I do not see a backing
flange like the big one I have. I did find this:

http://i173.photobucket.com/albums/w67/143house/temp/P1010679.jpg

a special backing flange.

So it seems like I could use this flange and the diamond blade instead of
the original backing flange?

Question #2: why are some blades "continuous" and some are segmented? What
are the pros and cons?

Thanks,

MC

Posted by Dave Martindale on March 27, 2008, 5:16 am

>I previously posted a question about a Harbor Freight 4.5" angle grinder I

>got which is this model:

>http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=31309

>Here is a picture of the ginder:

>http://i173.photobucket.com/albums/w67/143house/temp/P1010674.jpg

>You can see there is a "backing flange" and the locking nut removed.

That particular sort of large backing flange is intended only for use
with depressed center grinding discs. It's not appropriate for a flat
diamond wheel, because it won't grip it in the center

(By the way, this looks exactly like what Makita used to include with
their 4.5 inch grinders maybe 5 or more years ago. Makita has now
switched to a smaller flange and larger nut, both about 45 mm in
diameter, and that's what new grinders come with.)

>I then went to HD and looked at their grinders and I do not see a backing

>flange like the big one I have. I did find this:

>http://i173.photobucket.com/albums/w67/143house/temp/P1010679.jpg

>a special backing flange.

>So it seems like I could use this flange and the diamond blade instead of

>the original backing flange?

This is closer, but may not be appropriate for your grinder. The flange
is cut in some way to ensure that it doesn't rotate on the grinder
shaft, but the method isn't standardized. For example, that DeWalt
flange won't work properly on my Makita grinder. So you need something
that fits properly on *your* grinder's shaft. I can't tell from the
photos what exactly your grinder does to key the flange to the shaft.
Makita and Hitachi use two flats on the shaft and a slot in the flange.

Since your HF grinder's flange and nut looks like old Makita gear, they
may be a copy of Makita right down to the dimensions. If that's true, a
new Makita flange and nut set ought to fit it.

Here's a photo of Makita flanges. You want something like the leftmost
one for flat discs like your diamond wheel:
http://www.makita.com/menu.php?pg=accessory_tbl&tag=acc_grinder_flanges&cat_tag=136&tbl=1&f=

You also want a larger nut, one that's the same diameter as your new
(smaller) flange - not the small original one in your photos. Here are
some Makita ones; looks like the leftmost nut probably matches the
flange in the previous paragraph:
http://www.makita.com/menu.php?pg=accessory_tbl&tag=acc_grinder_lock_nuts&cat_tag=137&tbl=2&f=

To find something that will work, go to a real tool store, one that
carries spare parts for name-brand grinders, and find a flange+nut pair
that fits your grinder that holds a thin cutoff disc properly.

(Or just buy another grinder with the correct hardware. I have a cheap
"Superior" brand 4.5 inch grinder that cost all of $20, and it comes
with the correct flange and nut for thin discs. The Makita flange+nut
would cost me $10 or more, so a second grinder for $20 isn't a bad
deal.)

Dave

Posted by Frank on March 27, 2008, 1:53 pm

>I previously posted a question about a Harbor Freight 4.5" angle grinder I

>got which is this model:

> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=31309

> regardless of the quality of Harbor Freight tools, and since I bought it

> just to work on a small part of a project I did not want to spend too much

> on it.

The HF grinder quality is fine, I say its as good as mine Craftsman or even
mine Bosch. The only thing is the Bosh looks much nicer but I couldn't say
it works better - from a serious homeowner/handyman perspective ( I use mine
14" wet gas saw for cutting), not a pro.

> I wanted to use it to cut some concrete blocks and it came with a

> depressed center metal cut off disc, so I went and got a 4.5" diamond

> blade (which turns out to be about the same price as the grinder itself!)

> I ran into difficulty installing the diamond blade because with the center

> not depressed there is no room to put in the locking nut.

The depressed cup is used for grinding not cutting, so don't use it for the
diamond cutting blade.

I have 7 grinders from various companies, including HF, and all thin cutting
blades fit right out of the box without anything more to buy. Don't use the
depressed cup for this. There might be a big thick flat washer for the
backer plate used for the cutting blades or maybe already build into the
grinder. From the picture, looks like the blade could fits in without the
depressed cup or you're missing a backing plate. I would guess you're
missing a backer plate from HF. The DeWalt backer plate you show will not
work.

BTW, three 4" diamond blades for $10 at HF:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46152

> Question #2: why are some blades "continuous" and some are segmented?

> What are the pros and cons?

Continuous for wet and segmented for dry cutting.

Pros and cons: The wet cutting blade last longer but its messy either wet or
dry with any cutting blades. You could get a nice adjustable speed grinder
with a water kit for wet cutting and wet polishing, but HF doesn't have it.
I try to use wet cutting whenever possible to save my 14" Hilti blades which
cost $125 a pop. Forget about wet cutting when you're cutting tile on the
roof. Dry cutting is convenient and no water to fool around with but do ware
dust protection.

Posted by Jeff Wisnia on March 28, 2008, 5:59 pm

MiamiCuse wrote:

> I previously posted a question about a Harbor Freight 4.5" angle grinder I

> got which is this model:

> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=31309

> regardless of the quality of Harbor Freight tools, and since I bought it

> just to work on a small part of a project I did not want to spend too much

> on it.

> I wanted to use it to cut some concrete blocks and it came with a depressed

> center metal cut off disc, so I went and got a 4.5" diamond blade (which

> turns out to be about the same price as the grinder itself!) I ran into

> difficulty installing the diamond blade because with the center not

> depressed there is no room to put in the locking nut.

> Here is a picture of the ginder:

> http://i173.photobucket.com/albums/w67/143house/temp/P1010674.jpg

> You can see there is a "backing flange" and the locking nut removed.

> Closer view of the body showing brand/model:

> http://i173.photobucket.com/albums/w67/143house/temp/P1010676.jpg

> Now I put back in the backing flange, you can see it is quite deep and

> almost the same depth:

> http://i173.photobucket.com/albums/w67/143house/temp/P1010677.jpg

> Now I put on the locking nut:

> http://i173.photobucket.com/albums/w67/143house/temp/P1010678.jpg

> Some of you suggested that I flip the locking nut around. This will not

> work, because the tool that tightens the nut needs to be applied to that

> side with the four small holes.

> I then went to HD and looked at their grinders and I do not see a backing

> flange like the big one I have. I did find this:

> http://i173.photobucket.com/albums/w67/143house/temp/P1010679.jpg

> a special backing flange.

> So it seems like I could use this flange and the diamond blade instead of

> the original backing flange?

> Question #2: why are some blades "continuous" and some are segmented? What

> are the pros and cons?

> Thanks,

> MC

If you happen to own a hand cutoff saw ("Skilsaw") you can buy masonry
cutoff wheels which will fit it almost anyplace that sells power tools.

That's what I use.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

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