Masonite Hardboard - which blade to use

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I "lucked into" thirty or more five foot by nine foot Masonite boards - dark dense 1/4" thick.
I cut a few with a thin kerf carbide blade and then started having troubles - blade (on worm drive skillsaw) would warp and could not cut a straight line - it got "wavy."
I set the depth of cut shallow so as to save the saw horse/support boards from a through cut. I go slow against an edge guide.
The replacement blade I tried was a 150 tooth steel "Plywood" blade from Lowes that just aggravated the problems.
Does anyone have any experience cutting this stuff? I'm planning on covering sixty linear feet of shop wall with it and each board will reguire at least two cuts to "fit."
direct suggestions, advice, replies to gooeytarballs ATSIGN gmail.com please
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Hoosierpopi wrote:

I've had good experiences cutting it with a 10"x100T carbide blade on my table saw and cutting it with a carbide end mill in a router.
Hm, I should add: "You suck!"
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Morris Dovey
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The biggest problem is that the board is probably not laying flat and is supported on the bottom. If is is not it can bind and pinch the blade. Masonite is not particularilly more diffucult to cut than any other thin material. I also suggest you stick with carbide tooth but not the thin kerf.
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Thanks. I did switch to a new HFT 24T or 40T Carbide blade and found it a bit easier. But still getting some smoking and wander. Its not a thin Kerf.
I'll have to run down to Lowes and see if I can get a (7.25" blade with more teeth as running these sheets through my table saw is not an option now absent a helper and a large saw table. I've one more sheet to cut for this wall, then eight more to cut for the other and I'm done. Maybe I ought try building a saw table for the task after this wall. Hmmm.
Thanks again.

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Hoosierpopi | 2009-08-26 | 11:57:40 AM wrote:

Make yourself a circular saw cutting guide, like this: http://wayneofthewoods.com/circular-saw-cutting-guide.html
I put my Masonite on three or more sawhorses (to support both pieces after the cut), then clamp my guide on and cut. I've never had any trouble with wandering, binding, or smoking, and I'm using the stock blade that came with my Hitachi saw.
When you make the guide, the only piece you have to get absolutely straight is the wooden guide block. If you use a router, set up your guide so your saw works on one side of the guide, and your router works on the other.
I used a piece of MDF molding for the guide block. It's nice and straight off the shelf.
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Steve Bell
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SteveBell wrote:

Maybe I read it too fast, but I didn't see where it mentioned that the guide strip needs to be straight. Good for you for mentioning that.
I found that it's best to just use a piece of 3/4 finish plywood as the guide strip, and make it several inches wide. That way you can screw it down to many sacrificial under-side pieces, or move it back and forth on the same under-side piece.
This way, when you switch saws, blades, tools, or whatever, you won't have to realign the guide strip to a straight line, as the plywood guide strip will stay straight.
--

-MIKE-

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-MIKE- | 2009-08-26 | 4:33:35 PM wrote:

I don't trust factory edges to be straight. I used an extruded aluminum straight-edge to align the block on my jig before I glued it down.
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Yeah, tell me about it. See my "crappy plywood" post from a couple months ago.
I actually bought one of those $20 Johnson aluminum cutting guides. The two 4 foot sections are nice to have around and I used one on a strip of hardboard as a four foot and under cutting guide. I keep the other piece for quick clamping to whatever for use with any tool.
I would never trust it (with the two pieces attached end-to-end, as designed) to cut 8 ft. Even if you can get the two sections clamped together perfectly straight, the slightest pressure against it, pushes it crooked.
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-MIKE-

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I use a third behind the other two to make sure the pieces aren't crooked. This guide is on my list for projects as soon as the weather gets better.
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snipped-for-privacy@gmail.com wrote:

They only come in two's. :-)
Did you buy two packs, or find the aluminum on your own?
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-MIKE-

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Two packs (lost the connector on the first during a move).
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snipped-for-privacy@gmail.com wrote:

That's a great idea, and it's still worth 40 bucks. The fourth comes in handy to just have on the wall for whenever you need one.
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-MIKE-

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I did make such a guide/ I used some very good 7/16" 11-ply plywood for the guide strip and glued it to a piece of Masonite (the length of the boards I was to rip) and cut using the worm-drive skill saw I am using for the job. (I actually made two of these - one long and another shorter one for cutting the width).
The idea of screwing the two pieces together warrants a revisiting of the guide making as does the idea of using it with a router and making one guide serve the two tools.
I do know of a place that sells aluminum extrusions of up to twenty feet and will look into getting an extrusion to serve as the guide bar/ strip. Maybe some 3/16 C channel about 1/2 inch by 2 inches would do. But it will be expensive I'll bet! Maybe, with a router, I cut bevel the edges so each sheet would mate up better with the previous sheet. Nah, I'm not that good.
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Haven't had this problem myself but I typically use a table saw. If I was having this prob, I would first get something sacrifical I can put under it, maybe an old piece of 3/4 ply. Then make a zero clearance cutting runway I can lay on top. Again, maybe a 6" wide piece of anything with a fence of 3/4 stock screwed along one side. One cut with the worm saw sets the width. Now drop the runway on top of the masonite, on top of the sacrificial. Set the depth to cut maybe 1/8" into the sacrifical. Now the masonite is sandwiched between those and the cut should be clean.

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I built one of those guides by gluing a lone 4" strip of 11-ply wood (some expensive scrap found outside a sign shop [trash] in Florida years ago) onto a strip of 15" wide Masonite, then running the worm drive along the plywood edge to create a saw guide as long/longer as the boards to be cut.
The first time we tried this, I laid several rough cut 2 by's across two saw horses and laid the Masonite on top of them. This time, the saw horses were arranged so that too much of the Masonite hung unsupported and I added OSB under the sheet to be cut as both a support and sacrificial board.
I didn't recall as much difficulty the first time as I had this time. But the wife says we had smoke then, too.
Thanks for the Feedback.
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The saw blade is taper ground. Set it deep and it'll be hitting at just the front and back edges. Set it shallow, and it will hit all along the buried edge. So it heats up, which is what made it wavy. Expansion slots would help, but I'll bet it doesn't have them.
Good part is that once it cooled down it was probably as good as new.
Run it deeper, and try to keep it in a straight line.
John Martin
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Run it deeper, and try to keep it in a straight line.> John Martin
Makes sense. I'll definitely try that on this last cut with the carbide blade.
Thanks
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On Tue, 25 Aug 2009 11:56:15 -0700 (PDT), Hoosierpopi

I don't think the blade has anything to do with a "wavy cut." Most likely, your tablesaw would benefit from a tuneup. Make absolutely sure the miter slot is parallel to the blade and to the fence. If it is off 1/64", that's too much and you will get poor cuts and increase the chance of kickback. Also use an outfeed table, rollers or another person at the back to support the stock. Always keep your eye on the fence, making sure the boards are tightly against the fence at all times.
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Phisherman wrote:

He's not cutting with a table saw--he mentioned a worm drive Skilsaw.
If he's going to cut Masonite that way I think he needs to clamp it between two stiffer boards if he dosn't have a flat table to lay it on.
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If he's going to cut Masonite that way I think he needs to clamp it between two stiffer boards if he dosn't have a flat table to lay it on.
He sure is - no other reasonable option.
The sheets at 63" wide and about nine feet long.
They were free, but show some wear and tear at the edges.
They are heavy, bulky and difficult to move about - now in top garage, cutting in barn, my TS is in basement, finished boards are for the barn.
I think that "deep cut" advice may prove the solution. It was avoided because I had stacked all eight sheets onto the sawhorses used to support my cutting operations (cut the short dimension of all eight at once since all were to be cut to the same length) and worried about nicking the second sheet as I cut through the first. I set the depth of cut as shallow as I could.
Like I said, I'll have to reset the depth and have another whack at the task.
Thanks for the feedback.
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