Problem New saw, problems with open corners when joining...?

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azoq

CGF, Certified Grumble Framer
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May 16, 2011
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Needham, MA
Hello Grumble,

I was wondering if any of you may have some good suggestions for a problem we're having with the new clearmount saw that we purchased recently.

It's been chopping great (and a heck of a lot easier than our old foot-operated chopper), but we're having issues when joining our chopped frames. Although the top of the join looks great, we have some problems with there being a gap at the bottom of the join that we then need to fill in with putty.

Do you guys have any ideas about what this is caused by and the best way to fix it? The problem is most pronounced on taller mouldings, but it's present regardless of the height of the moulding.

Thanks for any ideas you can offer :-D
 
Sounds like the moulding is either rolling forward or sliding as the blade is dropped. If you cut with the rabbet away from you rolling could be the issue. If sliding is an issue you can affix a piece of sand paper to the table near the blade wich will prevent it fom sliding while cutting. Use the thinnest sand paper you can find to avoid new issues.
 
What kind of saw(s) is(are) attached to the Clearmont measuring system?

Are you using a blade specifically designed for cutting miters? More to the point, are you using an inferior blade?

Have you checked to make sure that the fence on the saw is perpendicular to the bed? (this one is my guess as to what is wrong).

These tools are set at the factory, but they can go out of whack in transit. You will probably need to make adjustments to the saw to insure that the 45's are true, the fence and bed are at 90 degrees, and that the extensions are true to the fence.
 
wpfay said:
What kind of saw(s) is(are) attached to the Clearmont measuring system?
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It's a makita.

wpfay said:
Have you checked to make sure that the fence on the saw is perpendicular to the bed? (this one is my guess as to what is wrong).
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The gauge reads that it's ok. Is there a better way to ensure that besides relying on that?

Thanks for all your suggestions :-D
 
How+to+Use+a+Framing+Square.jpg
 
I would use something a little more accurate than a speed square. A machinists square would be preferable. I use a Shinwa brand square. Accurate to .10mm over 300mm on the 45 and no allowance on the 90. http://www.shinwa-measuring.com/Squares1.html
 
Janet has the right idea. I would like to recommend that you use a 45 degree gauge with greater accuracy. While ones that Janet shows is great for ordinary constructions, we should use one with the best accuracy available.

There are many good gauges out there. Most are advertised as "engineering" and most have an accuracy within .001"

measur_angle_main.jpg


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In addition, stay away from thin-kerf blades. Most blades sold in the home centers are thin kerf and will deflect easily when used to cut miters.

The bottom line: make sure your saw is really cutting a true 45 degree angle and make sure you blade isn't deflecting. The gauge above can also be used to check the your vertical cut is a true 90 degrees.
 
We had similar issues even after making sure everything was square... also the moulding might be slightly warped.

We have started hand sanding the chops to ensure a snug fit and it's made quite a difference.
 
Jeff Rodier said:
Sounds like the moulding is either rolling forward or sliding as the blade is dropped. If you cut with the rabbet away from you rolling could be the issue. If sliding is an issue you can affix a piece of sand paper to the table near the blade wich will prevent it fom sliding while cutting. Use the thinnest sand paper you can find to avoid new issues.
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I'm with Jeff on this one.

I have the same set up as you. My set up is with the rabbet away from me. In the beginning I used little build up blocks that slid over the side, to support the rabbet and keep the moulding from rolling.
Now I am so used to my saw; I rarely use that anymore, except for very high profiles.
 
Jeff Rodier said:
Sounds like the moulding is either rolling forward or sliding as the blade is dropped. If you cut with the rabbet away from you rolling could be the issue. If sliding is an issue you can affix a piece of sand paper to the table near the blade wich will prevent it fom sliding while cutting. Use the thinnest sand paper you can find to avoid new issues.
Click to expand...

Yes, I'm almost sure that is what it is too -- we've had the same issue. Jeff's sandpaper idea is a good one. The table can be slick, and the moulding can easily slide on it. In my experience, as I got more accustomed to using the saw, it was a lot easier to compensate and avoid the sliding issue.
 
My guess is that the moulding is sliding.
If it was rolling, surely the top of the joint would be open?
 
osgood said:
My guess is that the moulding is sliding.
If it was rolling, surely the top of the joint would be open?
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Not neccesarily since we tend to force the top closed while joining. That would leave the bottom back open.
 
Jeff Rodier said:
Not neccesarily since we tend to force the top closed while joining. That would leave the bottom back open.
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And I guess that would also depend on the clamping system on the vee nailer and the angle of the fences, if they are adjustable!

My guess was influenced by the fact that the problem didn't exist prior to the new saw being used. I was guessing that the joints were being slightly undercut. Just a guess!

Maybe we should all turn up at Azoq's shop and diagnose the exact problem? ;) ;)
 
Azoq describes the problem in a way that suggests a vertical misalignment of the blade. If the moulding were moving, it's likely that the top would be open. Movement wouldn't cause an undercut. Sounds like the saw is not square vertically when set to 45 degrees that's where it should be measured. It could be square at 90 and off when at 45s.
 
Pat Murphey said:
Azoq describes the problem in a way that suggests a vertical misalignment of the blade.
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I agree, Pat! This should be checked first!

Pat Murphey said:
Movement wouldn't cause an undercut.
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As the blade is lowered into the wood it can pull the wood along slightly, then when the wood is cut right through, hand pressure could move the wood back out again. I had this happen years ago when cutting a moulding that I could not use my clamps on.
 
If the blades are tipped pressure in the direction of the blade will allow the lower portion ot the moulding to be cut shorter than the upper portion. I can feel it sliding in that direction at times on my Pistorius so I recut the end before sliding it through for the opposite miter.

Problem is we have no pictures of the saw set up or the mouding being cut. We also have no feedback on our suppositions so we are all just guessing here. I get a lot of phone calls for troubleshooting and find most times on the phone it only takes a few minutes to correct an issue.
 
If it's a typical swing-head DIY chop saw then it isn't accurate enough for picture frames. Any deviation from 45deg will be culmulative. There are 8 faces on a frame. Three corners -fine. The last one will manifest all the inaccuracies. Wider the frame, the bigger the gap.
If you do manage to tweak it to a true angle, every time you swing the head it will disturb the calibration. And tightening the locking screw can move it out of true.
 
prospero said:
If it's a typical swing-head DIY chop saw then it isn't accurate enough for picture frames. Any deviation from 45deg will be culmulative. There are 8 faces on a frame. Three corners -fine. The last one will manifest all the inaccuracies. Wider the frame, the bigger the gap.
If you do manage to tweak it to a true angle, every time you swing the head it will disturb the calibration. And tightening the locking screw can move it out of true.
Click to expand...

Amen to this. Most of the drop saws sold in Hardware shops are only good enough for cutting door frames and architraves - not picture frames. Another problem with single bladed saws is that as soon as the pivoting/locking mechanism wears a bit your 45% calibration gets dodgy.

Best buy a proper double mitre saw which is designed for framing.
 
I have a great (standard) mitre saw that I've used since 2003....so I wouldn't say you can't do that. It does an excellent job. My "side to side" angle adjustment had a locking mechanism and left went out of true. The saw itself has never been a problem.

From time to time to my fence would get out of square. It was mounted onto a wooden table, not a metal one and over time would be affected. But my saw? Pretty perfect.

For fine tuning if ever I needed it, I used a mitre sander.
 
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