Lousy cuts with compound miter saw
PamelaMilewski
| Posted in Power Tools and Machinery on
The bad cuts are really obvious on a thick block of wood. I have the stock to the left of the blade when I cut. The freshly cut face is not flat, but bulges in the middle. (This is looking in the direction of the blade’s travel) (It’s a Dewalt DW705 12″). BTW, I’m new to the forum, but hopefully I won’t let that cut too much into my prectious shop time!
Replies
Try clamping the peice down. I have had problems with the blade pushing the stock away when held by hand alone causing an uneven cut. (Usually more noticeble when the blade starts getting dull.)
Charlie
Just how thick and what wood? No matter the type of saw, if its portable I tend to schuck up on cuts until I discover the true capacity rather than listen to the advertising. Two passes good better than one bad, Kema Sabe.
Hi Pam,
Welcome to KNOTS.
What Mufti said. And use a stop block to the 'keeper' side and rotate (roll) the piece 90* or 180* to complete the cut on thick materials. Do check your blade for sharp, make sure the arbor nut/bolt is tight, and that your blade is not warped or cracked. Don't force it. Let the saw do the work. Better to spend a few extra $ on a good blade, you'll never reget that investment.
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Rotating the stock works well if the piece is square, flat and the end against the stop is square. If any of the above is out, you compromise the cut.
The first thing I would do is make sure I have the best chop blade. The Forest Chopmaster is the blade I use and I also have the DW 12" SCMS.
If I had to buy a SCMS today, I would certainly look at other saws. That, however is another subject for another day.
is your blade dull? A dull blade can cause the saw to wobble...
Pamela
what they said about clamping the piece. The blade (especially if not sharp) wants to pull the wood in and down due to rotation and will make the cut uneven. Also, push the blade slowly through the cut, and let it come to a stop before lifting up. I was used to slamming the blade through two-by-fours, and it took a while to figure out that wasn't a good idea when cutting miters in hardwood.
Pamela, in addition to what's mentioned above, this link will give you some tests to do to make sure your saw is set correctly for all the 90° and 45° stops and fence adjustment. Probably doesn't have anything to do with your "bulge" but thought it might be helpful.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Pamela Milewski,
Well I haven't experianced that and I saw 4 inch thick x 12 inch wide white oak on a fairly regular basis.
I do a lot of timberwork and the cuts have been consistantly clean and square.. Timbers that big would really show flaws if there were a weakness.. I hold my stock by hand but I certainly don't have a death grip. I do ensure the blades are sharp and I use the proper blde for the task at hand.. no sense in using a 60 tooth thin kerf blade if I'm making a sixty degree cut.
I did make the mistake of using some thin kerf blades on my tablesaw. (it's a 12 inch too) major mistake, the blade flexed all over the place You'd a sworn that a drunk drew the line and a monkey used a bandsaw to cut it out..
Dear Pamela,
I have experienced what you are seeing and it is almost always a dull blade. Put a good Forrest or Freud blade on (No Thin Kerfs) and you should be fine. If it continues, it could be the bearings or the arbor, but I would lay my money on a dull blade.
Best,
John
Ditto what jmartinsky said. A dull blade will heat up and warp. Add this to the lateral forces involved with a miter cut, and you can forget a straight cut. My guess is that if you throw on a new blade, your problem will disappear -- at least until the new blade dulls as well. ; - )
Mike HennessyPittsburgh, PA
Looks like it has to be the blade, I guess. I hadn't really considered that, since I don't think it has that many miles on it. Maybe when my sister borrowed it she chopped up a cord of ironwood? Anyway...thanks everyone!
Cleaning the blade will often times solve the problem.
John White, Shop Manager, Fine Woodworking Magazine
My SCMS came with a nice thin-kerf Tenyru blade which even when brand new would flex when cutting compound scarfs in my custom milled 4 1/2" beech baseboard. Cutting 8/4 wht oak was even worse. I'm extremely happy with the FS Tools full kerf mitre saw blade I relaced it with.
John O'Connell - JKO Handcrafted Woodworking
The more things change ...
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Edited 3/16/2007 3:00 pm by Elcoholic
A very easy way to realign the blade in the linear direction is to measure the kerf of the sawblade itself, then measure the kerf it cuts. They should be the same to all intents. If there is a difference the saw is not tracking true, and you need to change the blade and / or adjust the saw.
How old is your DW705 ?
It sounds to me that the saw needs to be checked for squareness comepletely.
I would first start with making the blade sq to table by adj.the tilt stop screws .
On the back of arm where it pivots ar two set screws. These are to adj the arm so it rises and falls perpendicular to table.See pic .These too pointed scrs bear against the pivot pin .AS you can see in pic one is slightly higher than the other. So you tighten one and lossen the other there by making the arm square in its full range of travel.I would suggest using a dial indicator to check this .
Last, adj fence square to blade with blade all the way down.
On some of the older 705's the set scrs in the pivot arm were not put in offset to adj arm,They were there but they were in line, doing no good at all.So there was no way to adj srm .It was pot luck what you see is what you got.
Also with the early models there was excessive end play in the spindle.
Chris
Pics 1605 and 1606 are the orginal arm with the two scr holes in line . it 1607 yo should be able to see that set scrs offset
chris
Edited 3/16/2007 10:32 pm ET by cmiller231
here are pics Chris
Thanks for those handy pics--those are some adjustments I never knew about (those owner's manuals are so useless sometimes).My model is about 10 years old, and has allen screws set down in that part, and there are 2 on the left and on on the right side.I had a TK blade on there, as it turns out. Didn't realize that was a problem (thanks, those who mentioned it!) and switched back to the factory blade. It cuts better, but still not great. Your post prompted me to get a dial indicator, which I used to measure the runout on the standard blade. It's 8/100 inch. Hmmm. Looks like time to buy a decent blade. If that doesn't fix it, I'll mess with those screws in back.
Edited 3/17/2007 11:10 pm ET by cmiller231
Blade choice can be a big factor. If you've read any of my posts about blades, you'll know that I'm a supporter of high quality 10" thin kerf blades on smaller table saws, but a 12" blade is a different matter. The span is much too large IMO for a TK...I think you're better off with a good full kerf with the 12". Chances are good that the stock blades isn't real good whether it's a TK or a full kerf...you might want to consider an upgrade.
Also, if the cut is close the end of the board, the blade will have more of a tendency to flex too.
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