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Corner shelf cutting woe

Posted: Mon Oct 18, 2010 12:05 pm
by dougclutter
Am trying to build a corner shelf for a friend. The piece I'm trying to cut is 3/4" oak plywood, 28-1/2" x 13-1/8" square. I'm trying to do a 45 degree cut from the corners...thus leaving a ~2" corner relief.

I can't seem to duplicate the 45 degree cuts. Am using the SS Miter Gauge with squeeze-grip. Have tried adjusting it as follows:
  • Adjusted to blade - checks to 45
  • Cut test piece - comes out fine
  • Adjusted center widening screw till gauge is snug in channel
  • Checked and rechecked all table clamps...everything seems snug and solid
Doesn't seem to matter what I do, I can't duplicate the cut. Something seems to shift out of alignment and then the cussing starts. (I'm very good at the cussing.)

Any thoughts would be greatly appreciated.

Posted: Mon Oct 18, 2010 12:26 pm
by Gene Howe
A few suggestions: Turn the miter gauge around so it's fully on the table at the beginning of the cut. Make a sacrificial face long enough to support the work through the blade. Apply a strip of sand paper to the new wooden face. Or, make a sled with a 45 fence.

Posted: Mon Oct 18, 2010 12:40 pm
by pennview
It's hard to diagnose what's causing your problem from afar, but if you can't get a good cut on the saw, an alternative way to cut the miter would be to cut the plywood a bit oversize with the saw and then use a straight edge clamped to the plywood and use a router and pattern bit to trim the plywood to the exact size.

Posted: Mon Oct 18, 2010 12:56 pm
by dougclutter
Gene Howe wrote:A few suggestions: Turn the miter gauge around so it's fully on the table at the beginning of the cut. Make a sacrificial face long enough to support the work through the blade. Apply a strip of sand paper to the new wooden face. Or, make a sled with a 45 fence.
I hadn't thought about using a sled, but that seems like the best bet. Thanks Gene!

Posted: Mon Oct 18, 2010 12:59 pm
by dougclutter
pennview wrote:It's hard to diagnose what's causing your problem from afar, but if you can't get a good cut on the saw, an alternative way to cut the miter would be to cut the plywood a bit oversize with the saw and then use a straight edge clamped to the plywood and use a router and pattern bit to trim the plywood to the exact size.
Thanks for the suggestion, but I've never had much luck putting plywood in the vicinity of a router. Maybe the high RPMs just scare the plywood into pieces? :rolleyes:

Posted: Mon Oct 18, 2010 1:28 pm
by mickyd
Gene Howe wrote:A few suggestions: Turn the miter gauge around so it's fully on the table at the beginning of the cut. Make a sacrificial face long enough to support the work through the blade. Apply a strip of sand paper to the new wooden face. Or, make a sled with a 45 fence.
If you opt to go with the miter gauge reversed 180 degrees with the sandpaper faced miter gage extension, you can take up any remaining miter bar play by wrapping paper around the bar then putting it in the table slot. Then adjust for your 45 degree.

45 degree miter

Posted: Mon Oct 18, 2010 4:30 pm
by truxton
If I understand it correctly, why not cut it off close then secure it to the saw table at your preferred angle, clearly marked. Then use the disk sander to creep up to your exact spot.

Posted: Mon Oct 18, 2010 6:04 pm
by 8iowa
I've found that as pieces get larger the miter gauge looses it's usefulness. Shopsmith's cross cut sliding table can be set at 45 degrees and can handle larger boards, with greater accuracy, than the miter gauge.

This cross cut "sled" is perhaps my most used accessory.

Posted: Tue Oct 19, 2010 7:06 am
by dougclutter
8iowa wrote:I've found that as pieces get larger the miter gauge looses it's usefulness. Shopsmith's cross cut sliding table can be set at 45 degrees and can handle larger boards, with greater accuracy, than the miter gauge.

This cross cut "sled" is perhaps my most used accessory.
Which sled do you have. I've been looking one from Rockler for $139 and another from Incra for $280. Do you have a favorite?

Posted: Tue Oct 19, 2010 7:47 am
by dusty
dougclutter wrote:Which sled do you have. I've been looking one from Rockler for $139 and another from Incra for $280. Do you have a favorite?
Be aware that not all sleds will work on the Mark V. There is that small matter of the miter track not being the same width and height. I believe Incra is your best bet - but not just any Incra. Make sure it is Shopsmith compatible what ever you get.

Then there is always the home built version.