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-   -   Issues arising from straightedge + circular saw (https://www.woodworkingtalk.com/f2/issues-arising-straightedge-circular-saw-8969/)

bzbatl 03-10-2009 01:13 PM

Issues arising from straightedge + circular saw
 
I don't get what's happening here, and I'm ruining my awesome MDF sheets that I've *never* had an issue with before.

I'm using a 100" straightedge to rip 4x8 sheets of MDF down to make my bench top. Problem is, the saw keeps pulling AWAY from the straightedge, no matter how much pressure I put towards it.

I've tried 3 different blades (Freud ripping, Dewalt framing, and Dewalt plywood) and keep getting the same result. After about 20 or so inches of cut the saw just starts drifting away from the straightedge.

Granted, this is a heavy 7 1/4" saw, but I've never had this issue before on crosscuts - and this is MDF we're talking about!

Anyone have any ideas? I'm just about ready to break some stuff ;)

Gene Howe 03-10-2009 01:25 PM

My saw is a Skil worm drive and the only time I've had the problem is when the power cord catches something. Since you have tried different blades I can't imagine anything else that would cause it to drift.

Oh, wait.....what sort of support are you using? Is it possible that is causing the drift? I use 3/4 insulation board. I offers NO resistance.

Kudzu 03-10-2009 01:33 PM

Sounds like you shoe of the saw is not longer square with the blade.

I bought a DeWalt saw after ruining a door like that. I bought the DeWalt just because it had adjustments for this.

GeorgeC 03-10-2009 01:57 PM

Quote:

Originally Posted by bzbatl (Post 70740)
I don't get what's happening here, and I'm ruining my awesome MDF sheets that I've *never* had an issue with before.

I'm using a 100" straightedge to rip 4x8 sheets of MDF down to make my bench top. Problem is, the saw keeps pulling AWAY from the straightedge, no matter how much pressure I put towards it.

I've tried 3 different blades (Freud ripping, Dewalt framing, and Dewalt plywood) and keep getting the same result. After about 20 or so inches of cut the saw just starts drifting away from the straightedge.

Granted, this is a heavy 7 1/4" saw, but I've never had this issue before on crosscuts - and this is MDF we're talking about!

Anyone have any ideas? I'm just about ready to break some stuff ;)

Does it pull awaw REGARDLESS of the direction in which you are cutting?

George

bzbatl 03-10-2009 02:30 PM

Gene - I lifted the sheet onto two sawhorses and two rollers. The piece I'm cutting off it's only 24" wide x 48" long, but it's kind of "balanced" on the roller section. I might need to try to pick up a big sheet of the foam to try that.

Kudzu - I checked the blade for square, it seems to be ok. It cuts a straight line for a little while, but it just pulls away eventually.

George - I didn't even think to try cutting the other direction. I've had the straightedge on the left side of the saw because I'm right handed... Maybe I'll try pushing it away from me instead of pulling it in.

Garibaldi 03-10-2009 04:10 PM

How old is your saw? It could be that an aged/stressed spindle is heating up and flexing as you saw.

bzbatl 03-10-2009 04:34 PM

About 6 years old. That'd be disappointing - I just made some real easy cuts through 1/2" BC that were nice and straight, but this MDF is giving me all kinds of grief.

I really need to just pony up the $100 or so for a nice 5" plywood cutting saw.

Gene Howe 03-10-2009 04:37 PM

I've read that those 5" blades, when you can find them, are a little spendy...like $30!!!

bzbatl 03-10-2009 04:45 PM

Yeah but at least they cut straight and the saw is far easier to handle ;)

woodnthings 03-10-2009 05:03 PM

Try This
 
Just draw a straight line on a scrap piece of mdf, you might have a few by now!, and see if you can saw a straight line "freehand" with the saw and blade you normally use. Try to sense if it's "pulling" to one side or the other after the blade and saw warms up. After sawing 24" or so stop the saw and trace the base plate on the wood to see if the base is parallel to the saw cut. This may tell you one way or the other. If nothing seems wrong try a different blade, or conversely if it Does pull change the blade, and try again. Let us know what happens. bill

gregL 03-12-2009 11:03 AM

Try taking another straightedge of 1/2 inch or 3/4 inch plywood and clamp it as a second straightedge on the other side of your saw's baseplate with the saw in between your regular striaghtedge and the plywood one. Clamp one end and then move the saw to the opposite end and use the baseplate as a clamping position guide. I have done this for years in conjunction to my 100" aluminum straightedge and get excellent results. Your saw cannot veer of course this way. I also apply a coat of pastewax to the edges of the saw's baseplate and the aluminum straightedge to reduce friction. This works fine whether using my poter cable 110v circular saw or my makita battery powered circular saw.

Gene Howe 03-12-2009 01:26 PM

BZBATL,

Were you ever able to get a good cut? Did you find out why the saw wandered?

bzbatl 03-12-2009 02:31 PM

I haven't had a chance to get back in the shop (er, I mean garage) to try again yet. But the above suggestion about the second straightedge is brilliant!!

Thanks everyone, I'm going to try this weekend - new baby gets in the way of projects ;)

Gene Howe 03-12-2009 04:59 PM

Be sure and let us know. Babies come first...and second, and third....

GeorgeC 03-12-2009 05:31 PM

The second straight edge will solve your current problem, but you need to find out the basic cause.

G

Garibaldi 03-12-2009 06:52 PM

Yes, you need to determine why - if you're losing a straight line that quickly due to to a mechanical defect, it could be very dangerous. Especially since you say it's just started doing this. Either you have a brain tumor you don't know about :eek: or something has changed in the saw.

bzbatl 03-16-2009 11:18 PM

I tried freehand and the blade pulled to the left after about 10". Then I tried the two straight edges on both sides. Result:

http://photos-c.ak.fbcdn.net/hphotos..._3430734_n.jpg

End result: Skil Saw RIP, welcome new PC 18V kit from Lowe's. I'm quite impressed with the Porter Cable - it ripped through this BC board like butter and left a nice clean edge with the Freud blade.

Came with a 6 1/2" circular saw, 24T blade, a drill, two batteries, a one-hour charger, and a tool bag for $109. Not too shabby. Picked up a 6.5" Freud Avanti 40T blade for $19.

Gene Howe 03-17-2009 07:04 PM

So, it was the saw. Glad you "buried" it. Coulda been dangerous as well as infuriating.
Sounds like a good deal on the new stuff, too.

bzbatl 03-18-2009 11:03 AM

Maybe the spindle that the blade mounts on finally went? I'm still unsure exactly what was wrong with it - but thank you all for your suggestions. I couldn't believe the amount of chipout I was getting on that BC ply.

My wife wanted me to donate it to Goodwill, but I'd rather it just get melted down and recycled instead of someone else going through these troubles.

I'm incredibly happy with the Porter Cable 18V set, just disappointed that I have to have a whole new set of 6.5" blades now :D

ScottyB 03-18-2009 06:19 PM

Gee, a story that ends without injury AND you get a new tool? I guess that'll work most days. :yes:


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