Adjusting a miter saw

[Mrs.B]

I'm having a REALLY big issue with my miter saw. It's a 12" DeWalt with a Phaedra system. I've tried everything I can think of and I still can't get a great cut. I need some advice. This is what I've done so far:
Installed a freshly sharpened blade.
Checked the fence to blade with a machinist's square. That's okay.
Checked the blade to table. Okay.
Checked right side and left side. Both are okay.
Made sure square wasn't reasting on a tooth.
I lock the stop when I cut. Straight cut the frame rails so that I don't have to keep moving the saw back and forth for each cut.
Miter seems to be off 1/32 or so. Can't stand that little gap at the rabit. Multiply that by 4, that's a HUGH gap.
What am I dong wrong?

[JFeig]

from top to bottom of the cut

or

front to back

Do you have balance washers on the blade to prevent wobble? Are the bushings properly packed and free of movement.

[Jerry Ervin]

Your 45 degree detent is not a true 45 degree. That is a drawback to using regular contractor grade chop saws. A fixed position saw gives a much truer cut.

You are going to have to tweak that adjustment somehow. A tiny amount, and I mean tiny. You are probably no more than 1/2 degree off.

Hopefully Framerguy will jump in and give you pointers on the adjustment. He knows a lot about fine tuning chop saws.

[Mrs.B]

The gap is from front to back. How would I tell if there was any wobble in the blade? My son is the machinist, I will ask him to help me and we'll check the bushings also. Thanks.

[JFeig]

front to back gap of 1/32" is an indication of a fraction of a degree off of the preset 45° knotches .........

if the gap is at the front... the angle is too small - less that 45°

if the gap is at the back... the angle is too large - more that 45°

Have you considered a sanding disk for adjusting this small difference in angles if you can't adjust the saw. Knowing that there is a gap - work with that info rather that the triangle... the triangle can be lying.

[Framerguy]

Mrs. B,

We recently purchased a Ryobi TS1552 12" compound miter saw to do some cleanup on some of the less than average chops and those that are freight damaged on the ends. I checked the saw out and, surprisingly, it was pretty well calibrated. I did have to set the 45 degree left and right but they have come up with a really neat adjustment now for that.

Check the back of your saw fence and see if there isn't a couple of bolts or large allen screws holding the left and right sides of the fence onto the table. You can actually loosen these and, with a drafting right triangle that you know for a fact is true to the 45 degree angles, you can set the angle of both cuts pretty danged close. If your son is a machinist, he will be able to come up with a highly accurate 45 degree block for you. You will be moving your blade to the left and right 45 degree mark and locking it down and actually adjusting the fence to the blade rather than the other way around but it works and is alot easier than what I had to do with my saws about 18 years ago!!

Regarding your blade "wobble", called runout, most 12" blades suffer from this to one degree or another. It is an inherent problem with a flat blade that is carrying 80 to 100 little pieces of carbide and spinning a such a fast speed that the blade will have some vibration or slight wobble to it. The easiest way to minimize this condition is to put a blade stablizer on the left side of the blade before bolting it back onto the shaft. This isn't a cure-all as it puts a limitation of how tall a moulding you can chop but it will cut down on the vibration. There are other influences that cause runout but this is the only way I know to minimize it if yoku are experiencing any vibration or wallowed out chops.

Hope this helps you get those chops the way you like them, Mrs. B.

(Every time I see your name it reminds me of Aunt B from Mayberry!!):)

[Mrs.B]

I have been thinking about buying a sander but didn't want to spend the money if it wouldn't fix the problem. United has one on sale for 269$. It seems like everything goes on the fritz at the same time. I'm having printer issues and router (computer) issues also. Sometimes it's so hard to keep up with everything and frame too!

[Jerry Ervin]

If United still has any of the Barton electric sanders, that is the one I would want. I have had one for years. They are/were built like a Mack truck and should last forever.

I use mine next to never now that I have a Ledsome saw.

[artfolio]

One thing I learned early about mitre saws is that squares of any kind are useless for fine tuning the mitres. Once you have the cut close to correct (as you have by the sound of things) cut a mitre in the widest piece of moulding which will fit in the saw and test it in your V-nailer or against your guillotine blade. Make minute corrections until both methods show a good result then join a 12" x 12" frame in the same moulding as a final test.

If your saw can't be calibrated accurately enough to pass this test it is probably a "handyman" job and really not up to scratch for serious work.

[miterbox]

that your stops are set and that each piece of moulding (top/bottom) (left/right) are exactly the same size???

[Framerguy]

I have been thinking about buying a sander but didn't want to spend the money if it wouldn't fix the problem.

I thought the problem was with the miter saw?? I don't see how buying a sander would fix any problem with the saw! That would be like buying a life raft to "fix" a leak in your boat!!

You have a few things that you must ensure to have your saw cut true accurate miters.


You have to ensure that your saw blade is perfectly vertical to your saw table in all settings
You have to ensure that your blade is cutting a perfect 45 degree angle on both sides of your fence
You have to be very sure that you do not feel any vibration or shaking of any kind in your saw when it is at full speed and cutting woodIf you can honestly say that you have checked and the saw is cutting perfectly in a vertical alignmnet to the saw table and your angles are so close to 45 degrees that you can't measure the deflection with common tools, and the saw doesn't feel like it is shaking or vibrating and the cuts are consistently smooth and both horizontally and vertically square (flat), then you probably will be experiencing pretty tight chops.

Years ago I had to completely tear down my Makita LS1030 chop saws to the table and, using shimstock and engineer's rules and scales, calibrate all the things that I have mentioned here by hand!

I disagree with whomever said that squares aren't adequate for calibrating chop saws. Yeah, some squares like a carpenter's framing square or a roofing square probably won't be accurate enough for your needs in calibrating a chop saw. And most chop saws aren't calibrated from the factory closer than the accuracy of a mitered door trim or straight chopped 2x4 for framing in a house. But you CAN calibrate most any saw that isn't an off brand if you use the proper tools and take your time and do things in sequence. Look in a good quality woodworker's supply catalog and spend a little money to buy some accurate squares and angles and you should have a good start to calibrating any name brand saw if everything else is in good working order.

[Mrs.B]

Framerguy,
Didn't read your post until late this morning. You must be a real night owl!
My son brought over another one of machinist's tools last night and we did some more tweeking on the saw. I cut up some white pine I had laying around and got a pretty good miter. Then I cut a scrap of LJ Kenya and I know the saw is set right, got a very good miter. Whew!
Thanks to you G's for all the advice. I still think I may buy a sander if anyone has an opinion which brand and where to buy it. Ha, as if Grumbler's didn't have opinions!