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Undercut Saw Blade

GeorgeP's picture

I need to rent an undercut saw to undercut a brick fireplace in preparation for instaling a 3/4" strip floor.  The saw available at the local rental plae is a Crain but it doesn't have a masonry blade.  do Crain sawas have to take Crain blades or can I pick up a blade at the local big box store that will worlk? 

thanks, George

George (post #207118, reply #1 of 19)

God knows I wouldn't want to use my undercut saw with even a diamond blade, to cut brick and morter.

If I had to cut into the brick I'd use my angle grinder and tape a gallon milk jug (with the bottom cut so there's a full bottom flap) to my vac hose.  If your helper can hold that to the rear of your cut (if you direct the angle grinders "exhaust" of dust properly) you will capture most dust.

Still, you'd best tent off the area and try to exhaust that tent area to the outside.

The thinner the diamond blade the better (for dust).  You'll still have to chip out the remainder of the brick and risk damaging the surrounding brick.

Good luck.

Can't help you with the crane saw blade "hole".  My undercut is just a bastard size blade (5-1/2 or so).

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


If it was only a little bit (post #207118, reply #2 of 19)

If it was only a little bit (maybe 4" total distance) I'd use my MultiMaster with the abrasive blade.  If it were a lot I'd find another way to deal with the problem.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

The other way (post #207118, reply #3 of 19)

Several times when running into a hearth we've found another way.

For one, which direction is the flooring running?  Ends at the hearth need not be gapped.

Widths at the hearth might not need to be gapped.  In the event you want the gap, a shoe or other "trim" can be scribe cut if you find it necessary to fill in at the morter joints.

or

Fly on by the morter joints, tape the top of this trim and fill in with morter to erase the gap in the morter joint.

If painted brick, caulk will do the same.

 

I don't think I would ever cut into the full brick front of a fireplace.

Just some other ways for the poster to think.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


Thanks Calvin.  I need some (post #207118, reply #4 of 19)

Thanks Calvin.  I need some clarification.  

"For one, which direction is the flooring running?  Ends at the hearth need not be gapped. "

The boards are runing end on to the hearth.  What do you mean by "gapped"

"Fly on by the morter joints, tape the top of this trim and fill in with morter to erase the gap in the morter joint."

I don't know what you mean by this.  One thing I am coinsidering is to picture frame the hearth so that the ends butt into the frame rather than the brick.

george (post #207118, reply #6 of 19)

GeorgeP wrote:

Thanks Calvin.  I need some clarification.  

"For one, which direction is the flooring running?  Ends at the hearth need not be gapped. "

The boards are runing end on to the hearth.  What do you mean by "gapped" 

The space normally allowed for expansion-later covered by base or shoe mold.  Most of the expansion will be the width of the boards, not the lengths.

"Fly on by the morter joints, tape the top of this trim and fill in with morter to erase the gap in the morter joint."

I don't know what you mean by this.  One thing I am coinsidering is to picture frame the hearth so that the ends butt into the frame rather than the brick.

Apply your picture frame over the top of the flooring and scribe or fill at the brick/morter joints

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


I agree that you should use (post #207118, reply #5 of 19)

I agree that you should use an angle grinder and diamond blade with shop vac for dust.

 

Beer was created so carpenters wouldn't rule the world.

Well, an angle grinder gives (post #207118, reply #7 of 19)

Well, an angle grinder gives me the excuse to buy a new tool but would I be able to cut flush to the floor?  According to what I could find out, the way to do this is to make two cuts.  One at the height of the flooring and one flush to the floor.

Look at some angle grinders (post #207118, reply #8 of 19)

Look at some angle grinders (and the blades) and make up your own mind.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

george (post #207118, reply #11 of 19)

I still don't think I'd be cutting into the brick,

but.......

the only way to use the grinder would be to  cut the perfect top cut  trying to get the same depth continuous. Then, work your way down maybe half way-cut again, then angle the bottom cut down at an angle.  This might make it chip out.  If you do just two cuts, you'll have the pcs trapped, not enough room to get them out.

I have both a thin blade and a thicker segmented masonry cutter (1/4-5/16ths) wide.  I'd cut the top line, the angle line, then grind out as much of the waste and that cutter could do.

Doing this had generated a great mess-hope the vac and enclosure work like a charm...........

The corners could be the hardest not to damage.  Take it easy there.

 

Best of luck.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


If using a grinder, make a (post #207118, reply #9 of 19)

If using a grinder, make a jig for the grinder to ride on.  It looks like even a flat ply plate under the motor housing would work.

Drilling out holes first would make the cutting easier.  Keep the holes well below the finish edge.  Diamond edge blade will be easiest and cleanest, but it is smaller wheel and may not adapt to your situation.

k (post #207118, reply #10 of 19)

A thin segmented diamond blade is the cutter of choice for both a nice cut and pretty good chance of accuracy.  The drilling of holes b/4 cutting will not help you keep the blade in a straight line.

Drilling that close to the floor will not be possible with most drill motors.  if you could, I think it best to score the lines and then maybe drill the holes to remove waste.  It will help keep from fracturing the brick rather than chipping out with a chisel...........but boy, there's no gaurantees it won't happen anyway.

The jig would have to be pretty stable and maybe the nut on the shaft is what could be set to ride on.  Getting it back on the motor housing leaves it too far from the cutting blade. 

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


Thanks for all the (post #207118, reply #12 of 19)

Thanks for all the information.  I decided that a grinder will not give me the cut I want and has more of a chance of damaging the surrounding brick.  I am going to order a diamond blade for the Crain (Model 812) and undercut with that.  I will make the bottom cut first then a scoring cut at the flooring height (it just seems like a good idea) then cut the full 3/4" depth.  That way anything that chips out will fall away from the blade.  I'll post a picture after it's done.

Thanks for all the (post #207118, reply #13 of 19)

Thanks for all the information.  I decided that a grinder will not give me the cut I want and has more of a chance of damaging the surrounding brick.  I am going to order a diamond blade for the Crain (Model 812) and undercut with that.  I will make the bottom cut first then a scoring cut at the flooring height (it just seems like a good idea) then cut the full 3/4" depth.  That way anything that chips out will fall away from the blade.  I'll post a picture after it's done.

not groovy.... (post #207118, reply #14 of 19)

I'm with Calvin only more so on not grooving the brick.  Of all the options mentioned I think that is the worst option.

Besides the big hassle masonry dust is unhealthy. I have little bright spots in my chest xrays where stuff like that has [luckily]  become encysted.

.

So, there you have it. (post #207118, reply #15 of 19)

Two geezers wondering why they didn't work safer when young.

 

 

What's that?   speak up.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


geez talk (post #207118, reply #16 of 19)

I can't hear it thunder myself but can still count to 10.

.

So I rented the saw and (post #207118, reply #17 of 19)

So I rented the saw and bought a blade to undercut the hearth.  It was a lot more work than the videos you can find online lead you to believe but the result is worth it.  The floor is coming out great.

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So I rented the saw and (post #207118, reply #18 of 19)

So I rented the saw and bought a blade to undercut the hearth.  It was a lot more work than the videos you can find online lead you to believe but the result is worth it.  The floor is coming out great.

George (post #207118, reply #19 of 19)

Nicely done!

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/