Hi guys.
I have not under cut a fireplace yet and want to make sure I can do it right the first time. Looks like the Crain saw can be fitted with a diamond coated blade so I'm wondering if that is what you use .Also wondering what's out there for dust collection if any ?

As far as technique, I found this video .http://www.youtube.com/watch?v=SV2G7gJh2es Looks like he sets the blade height to clear the flooring height and only cuts once. Then busts out the mortar under his cut line with a chisel . I'm wondering if that's the right technique and how you cut out the corners where the crain saw can't reach ?

Thanks

Iv'e done it Paul....it works nicely when just dealing with mortar...when you have to actually cut into stone it gets rough..

get a good cold mason chisel and transform into Fred Flintstone

if its a nice clean line of brick, you can cut it..or picture frame around it nicely for a good finish..

a grinder may come in handy depending on what you are cutting..

no dust collection I know of short of having another guy sit there with vac hose right at cut point..

don't know if its possible to wet it first to help in this..

James, how long would you say it takes on average to under cut a 5' long by 2' wide red brick fireplace ?

Paul, I use this vac http://dustlesstechnologies.com/dustlessvacuum.htm with the prefilter, zero dust with the lower profile Crain sawt hat has a dust port; http://www.craintools.com/fs-more_pages/fs-820.html with the segmented diamond blade . I cut through river rock, concrete, ceramic, porcelain, brick, you name it buddy this package does it.

That fireplace I can do in about a 5 minutes, charge 10 ducats a ft.

Here is a few fireplace hearths I have undercut with that saw, and used to use a regular shopvac with a HEPA filter on it.

http://www.flickr.com/photos/13772863@N ... 231981053/

Don't forget to make 2 cuts, top of wood level and at the bottom, then simply break off whats left with a pry bar.

Hey Guy's glad I found your thread - I have two fireplaces to under cut and have been looking around to rent a saw like that for this one time use but can't seem to find one locally (portland or). Does that Crain saw really cut flush or would a standard grinder work the same?

I believe the Crain under cut saws can cut flush to your subfloor. And thanks Steve for the info

Yes they all cut flush, I like to do the flush cut first, then the top. I have never seen one for rent, probably because they are kinda dangerous if your not used to it.

@ Paul, anytime.

Stephen, the low profile version can be lowered and raised like the 812 super saw .Any advantage to buying the super saw or not really ?

Paul, I had the 810 before and personally I only use the 820 for undercutting hearths. I like the lower profile of the 820 for getting under objects. It has plenty of power to cut through stone. I hate the adjustment screws on all those saws.

I love my 812....Dust free as it gets, and cuts right into the corners To me the base on the grinder type lookin undercut saws aren't as stable..they're narrow compared to the Super Saw, and want to teeter toter..all the weight is on the back end . There not balanced. I hate those adjustment screws on all the Crain saws too. Just don't over tighten.

Anything with a dust port is pretty much dust free depending on your vac, and if using the 820 lean towards the front. It goes under cabinets unlike the 812.

Can't remember ever having to undercut under a cabinet toekick I'll stick with the more powerful, cuts like butter, ergonomic, designed model, ....don't want to deal with leaning and balancing with that narrow base, while undercutting....OOPS, didn't lean the same on that last cut...darn it's 1/4" higher!

You silly man, trixs are for kids. I don't seem to have that leaning problem, just keeper flat. I guess you've never run into areas with objects blocking the saw, I have, just sayin. And if I had to undercut a toekick I can, I can, and you can't neener neener.

Hey, just want to say thanks to this forum and this thread. I just undercut my hearth to accept some pre-finished hardwood flooring. Just a lowly homeowner, first time cutting stone, but was able to rent a Crain 812 saw for $20 at a Taylor rental, bought the 822 diamond blade on amazon for $60 had it in two days.

Did two cuts, one flush then the upper one, nailed the height the first try. Built a tent around the fireplace and had my wife holding the vac next to where I was cutting. This is the right tool, stone cuts like butter, well, kind of hard butter.

I ended up setting the blade depth to about 1 1/4", since the face of the stone isn't very flush, to make sure it would hide any gaps. Seemed to work best if I did a couple of passes, first about 1/2-3/4", then the full depth.

I've seen videos of guys chiseling out the channel by hand but a small hammer drill works really fast if you just stick it in the lower cut so you don't damage the stone above. See pictures and short video clip in link below.

https://photos.google.com/share/AF1QipPJ_RnXeu_6AWeuoNMow4MVt4LEbXRdfiORLbmgNi73YWTfVoDxBk9Mjczg5fcaTg?key=ZDJER05IX3RDZjFHR0d6VWxyN1g0eGhmU1ZIS0l3

Awesome!
alf