Suggestions for Hardie Cement Board rabbit cut
rdy4trvl
| Posted in General Discussion on
I need to make a rabbit cut into Hardie fiber cement lap siding to replace some old cedar installed vertically. The cut is 1/4″ x 1/4″. I have routers (full-size and palm) but I’ve only used them sparingly, for simple projects and I have a decent table saw (large portable Hitachi). I’ll be routing about 72′ of stock.
Three questions:
Can I reliably rabbit-cut fiber cement without blowouts and excessive chipping?
Better to do this on a table saw or with a router?
What type of blade would you recommend given it’s fiber cement?
Thanks
Replies
I don't know about the blow out but I would definitely go with carbide tools on this.
Router or table saw??? Someone suggested an angle grinder but I'm not sure I can do 70'+ with a grinder...maybe in a jig.
They make circular saw blades for cutting fiber cement board which are I believe a special carbide. I think they run 25 or 30 bucks so they aren't too bad. Just search Amazon for fiber cement saw blade. Lowes and Home Depot carry them too at least by me I have no idea how well a rabbet would work.
No too much $ so worth a try.
Buy a good respirator too, that s*** is nasty.
I resided my house with Hardie plank and PVC trim. The only cuts I had to make in the fiber cement that weren’t 90° were extreme angles at the gables. There was a lot of chipping and a a few breaks in the extremely brittle fiber cement. I used special blades in the chop saw and skillsaw (the 7 1/4” blades only have 4 teeth, the 10” have 6, and their fiamond blades, not carbide) but still had some damage. Having said all that, a couple things: Whatever you try do it outside, as someone else said, that dust is nasty, and causes cancer. If you go the router route use diamond cutters. I know they make round over diamond bits for concrete, but not sure about straight cutters (other than CNC mill cutters). One last thing, have you considered any of the other materials out these days? There are competitive products made from fly ash and composite materials that can also be cut with standard woodworking tools. Good luck!
Have you checked with the Hardie Board company to see what type of cutter to use. They should know what is best.
I'd suggest spending about $100 to buy a compact circular saw with a 4 1/2 inch blade (Rockwell and others) and using a diamond ceramic-cutting blade for your cuts. It may come with one in the original kit as mine did; but you can get the blade for under $10 if not. Use a fence. You'll have to do multiple cuts to get a 1/4 wide dado or rabbet, but it should easily cut a 1/4 inch deep kerf. It's what I've used to cut Hardie board and other concrete board projects. As mentioned, there will be lots of dust, so plan to manage that. But it's a useful tool that you will be glad to have beyond this project.
6' only! I would use a circular saw with a diamond blade because I have that, next choice a circular saw with a composite blade for masonry-because I also have that- but about 6 bucks from Ace. But really for 6 feet -1/4" square you can probably do it with a utility knife and no dust! OOOH ---72 ' --- that's different! I'd still go with the circular saw.. 1/4"×1/4" that would be two passes with a composition blade. Flat surface and a saw guide.
KEEP YOUR GOOD POWER TOOLS AWAY FROM FIBER CEMENT. It's next to impossible to get the cement dust out of them once the work is completed. The dust created is micro fine and gets into areas that will cause challenges to normal wear and tear. Unless of course you need an excuse to upgrade your existing power tools. Don't ask me how I know this. I had to say bye, bye to a couple of tools, Miter Saw, Table Saw, etc. As always there will probably be a response or two that conflicts with this advice. I suspect you're going to find that the Hardie siding might crack and split easily once dado'd 1/4" deep. It's not that thick. If you are referring to "Corner Boards" and not planking/siding you might get away with a dado. Be sure to prime and paint the dado before joining the adjacent piece to it. Hardie has pre-primed their product for years now to help protect it during installation to reduce moisture absorption. Good luck. Let us know how you come out with this installation.
I have a specialty compact circular saw with diamond blade and have cut miles of hardy, tile, concrete and granite with it. It's over 30 years old and still going. They have sealed bearings and motor parts to keep the fine dust out. Look in the tile department at the big box stores. About a hundred bucks.