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Why are my cuts so horrible?

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Forum topic by Scootles posted 06-21-2014 03:29 AM 1242 views 0 times favorited 14 replies Add to Favorites Watch
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Scootles

153 posts in 1580 days


06-21-2014 03:29 AM

I’m cutting 1/8” BB plywood at 45” angles and they are HORRIBLE cuts… Does anyone know why? I am using the stock blade… As steady as I am, my cuts have a ‘curve’ to them. No 2 cuts match up. When held against a straight edge the middle touches, but the 2 edges don’t… :(


14 replies so far

View jmartel's profile

jmartel

7143 posts in 1815 days


#1 posted 06-21-2014 03:41 AM

A miter or a bevel cut? Sounds like you aren’t using steady pressure or they are sliding a bit.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

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NoThanks

798 posts in 1194 days


#2 posted 06-21-2014 03:41 AM

Sounds like your not keeping the wood totally flat as your making the cut.

-- Because I'm gone, that's why!

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Scootles

153 posts in 1580 days


#3 posted 06-21-2014 04:08 AM

I’m using my tablesaw, and its slightly warped. I was thinking glue-ups would solve the problem with the warped wood.

I’m ready to toss in the towel. Without the top notch machinery I had when I worked in a cabinet shop, all I can make is trash… :-/

View ColonelTravis's profile

ColonelTravis

1452 posts in 1559 days


#4 posted 06-21-2014 04:45 AM

Top notch machinery is going to have a problem with warped wood, too. Two things come to mind, although I’ve never done it with 1/8 ply, so maybe these won’t help.

Thing 1 – dampen the bowed side, lay that side face down on your driveway or floor or patio or something that gets a lot of sun or warmness. Being summer now should make this easy, unless you’re an Aussie. The concave side is the part that lost moisture, so you’d be adding it there while taking some out of the humped side, resulting in movement toward straightness again.

Thing 2 – Not sure what the size of your plywood is when you cut it, but you could clamp it underneath a heavy board so it’s straight and cut them both, which would give you a straight cut, but when you unclamp it it will still be warped. Maybe during your glue-up you could eliminate that via your clamps and be fine. Not sure, but I have looked at many sheets of it before and always seen warped pieces in the pile somewhere. Seems to be sort of common with that stuff.

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Paul

721 posts in 1230 days


#5 posted 06-21-2014 04:50 AM

1/8” plywood? Getting close to veneer size there as is. Thin plywood wants to warp around itself, cutting it by itself is a losing battle if you have had it in your shop for a while already. When ever I buy 1/4” ply for a project I plan on cutting and using it the same day I get it.

Depending on the end result of said 1/8” ply using a sacrificial 3/4” ply backer on top will help make cleaner cuts. 3/4” ply is much more expensive however.

Just a note of caution cutting warped anything in the table saw ups the anti on a kick back happening.

Paul

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waho6o9

7797 posts in 2242 days


#6 posted 06-21-2014 04:54 AM

A block plane should clean it up.

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Paul

721 posts in 1230 days


#7 posted 06-21-2014 05:00 AM

Waho,

I’ve never had any luck with a block plane on the edges of plywood without terrible chip out. Care to elaborate a bit more on your process on planing plywood edges?

Paul

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waho6o9

7797 posts in 2242 days


#8 posted 06-21-2014 12:48 PM

Maybe cut a couple pieces of scrap at 45 degrees and sandwich

the plywood in between and plane away the problem areas.

Shouldn’t take much.

A wicked sharp blade is beneficial.

View Buckethead's profile

Buckethead

3192 posts in 1534 days


#9 posted 06-21-2014 01:00 PM

Wicked shaaahp cures all. Plane. It. Flat.

-- Support woodworking hand models. Buy me a sawstop.

View InstantSiv's profile

InstantSiv

259 posts in 1260 days


#10 posted 06-21-2014 01:07 PM

Try putting masking tape on both sides of where the cut will be. I got the same results with 1/4” ply and figured I would try masking tape next time I needed to cut thin ply.

View ajosephg's profile

ajosephg

1880 posts in 3226 days


#11 posted 06-21-2014 09:32 PM

I’d recommend an 80 tooth cross cut blade as well.

-- Joe

View TheFridge's profile

TheFridge

7096 posts in 1151 days


#12 posted 06-21-2014 09:41 PM

That’s what she said.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Ted's profile

Ted

2808 posts in 1876 days


#13 posted 06-21-2014 09:43 PM

If you have a router of any sort, cut it square then get your 45 with the router. A router table would be best but if you don’t have that, mount or rig a fence to your router. You may have to deal with preventing chip out by scoring with a utility knife first, or mounting a sacrificial piece… whatever it takes. Basically, use the table saw to get the straight cut, but use some other method to get the 45.

-- The first cordless tool was a stick. The first power tool was a rock.

View Dallas's profile

Dallas

3599 posts in 2152 days


#14 posted 06-21-2014 09:55 PM

Put weight on when cutting to make it flat, you can fix it later.

You can also cut 1/8” with a knife and a straight edge that is going to give you a lot better cut.

-- Improvise.... Adapt...... Overcome!

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