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Hard lessons #4: In Search of the Perfect Miter

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Blog entry by mhawkins2 posted 10-16-2008 04:25 AM 4477 reads 1 time favorited 8 comments Add to Favorites Watch
« Part 3: Tools I did not realize I can't live without Part 4 of Hard lessons series Part 5: Step Away From the Random Orbital Sander! »

I am beginning to think that a dead on PERFECT miter is about like big foot or the Loch Ness monster. We’ve all heard of it, a few claim to have achieved it, most of us probably don’t believe it. I am an engineer in occupation and by nature, so when I say perfect; I mean PERFECT. Dead on 45 degree not 44.99 nor 45.01. The vertical face of the wood is completely vertical as is the blade so the sides don’t tilt. And the wood is absolutely of consistent thickness so the resulting 90 degree joint is PERFECT. I doubt I have ever seen that miter joint. I KNOW I have never made that miter joint and probably never will.

Thankfully wood is a forgiving material and the angle doesn’t have to be accurate to 1/100th of a degree. Thankfully it can be sanded if the mating boards aren’t the exact same thickness. Etc.

So while I have never and will never cut the PERFECT miter I am getting better and no longer cutting the WORST miter.

What I have learned so far in pursuit of the PERFECT miter.
Make sure the blade is perpendicular to the table.

Make sure the miter fence is perpendicular to the table. For that matter make sure you use a fence with your miter gauge.

Carefully calibrate the miter gauge. Especially at the angle you intent to cut. If you’re cutting a 45 pick up a decent drafting square and use that against the blade and miter fence. I have several and found the one made in Germany that was part of my original drafting kit to be the most accurate.

Test cut, and then test cut again. That nice piece of white pine is still much cheaper than that piece of Jatoba wood that you have spent the morning edge profiling.

Try and cut any edge profile first. You don’t want to carefully cut miter and then have tear out at the router table.

Use clamps to hold the piece to the miter fence instead of your hands. A photographer I like once wrote a that “the greatest challenge is keeping that trembling big bag of water we call a body still enough and straight enough to get the shot.” The same goes for miter cuts you hand moves and the piece slips ever so slightly. I prefer to clamp it with wooden clamps in case I goofed and cut the clamp.

Sneak up on the length. For my most successful frame to date I started with the pieces about 1/8” to 1/4” to long (not intentionally mind you). Then I trimmed the ends very very carefully no more than 1/16” at a time till each one was the right length.

This post was longer than expected; I suspect because miters challenge me even more than I knew. So I am off to either further fine tune my miter gauge or try to get that picture of big foot :).

As always thanks for reading.

- Mike

-- mhawkins2 - why does my wife keep parking her car in my shop :)?



8 comments so far

View Betsy's profile

Betsy

2914 posts in 2554 days


#1 posted 10-16-2008 04:36 AM

Mike – miters will drive the most sane person to looney bin if you let it. Miters are just simply tough to get right, that’s why you see so many articles about them.

One question when you say “For that matter make sure you use a fence with your miter gauge.” Are you suggesting a fence on your miter gauge or are you talking about the fence that you use to rip lumber? I ask because I am of the opinion that one should never use the miter gauge with the rip fence.

Just wanted to make sure what you intend to say here.

-- Like a bad penny, I keep coming back!

View mhawkins2's profile

mhawkins2

51 posts in 2226 days


#2 posted 10-16-2008 04:44 AM

I mean an auxiliary fence on the miter gauge. I have a couple beefy one from MDF when I want to support both sides of the wood all the way through the cut. Then I have the one that came with my Incra miter gauge. The ONLY time I will use the table saw fence with the miter gauge as a stop when cross cutting when the fence is set forward of the blade (it’s a unifence) or when the cut is not a through cut such as dado or rabbit. Otherwise you risk kick back.

-- mhawkins2 - why does my wife keep parking her car in my shop :)?

View Betsy's profile

Betsy

2914 posts in 2554 days


#3 posted 10-16-2008 06:09 AM

Whew—- that’s what I was hoping for. I think I just read the post the wrong way. Glad you cleared that up for me.

By the way – welcome to Lumberjocks!

-- Like a bad penny, I keep coming back!

View Mario's profile

Mario

902 posts in 2710 days


#4 posted 10-16-2008 01:37 PM

Wood is an inperfect material so you will never get a “perfect” miter. It is one of the challenges ( or joys) of working with wood.

-- Hope Never fails

View ratchet's profile

ratchet

1291 posts in 2445 days


#5 posted 10-16-2008 05:05 PM

Very good lessons here! Yes, bad miters used to drive me NUTS!!! I decided to solve it with a dedicated miter sled that I can calibrate before use. I use one of those German made drafting traingles as well and find them to be very accurate (not perfect but better than me).

See here for that jig:
http://lumberjocks.com/projects/6269

Clamping the work helps as well….good tip.
Test cuts should be mandatory whenever cutting miters.
One place we differ is sneaking up on it. I don’t. I use stop blocks to make exact cut lengths the first time. If your angles are perfect and your lengths equal on opposing sides it all will come together. I think my miters are now very impressive and some of my WW let me knwo that I have it dialed in.

View mhawkins2's profile

mhawkins2

51 posts in 2226 days


#6 posted 10-16-2008 05:30 PM

Actually I did use a stop block to make sure that each piece was the same length. In this case I had cut dados in each of the pieces so that the panel would sit in a consistent recess plus hide the edges of the veneer. While I used brass setup bars to set the depth of the cut I was not positive that it would be exactly 1/8” deep so my trig for calculating the inside length would still be ever so slightly off. If my dado was a little shy of 1/8” it would have shown with gaps in the corners. Plus I find that unless I step back from the equipment a moment and think more carefully I often make obvious mathematical errors. I did not want to end up with an sightly gap at the corner and did not want to turn a nice piece of wood in fuel so I chose to sneak up on it. You can always cut a board a little shorter but I have yet to successfully stretch one :). This method was fairly tedious but I did get very tight corners. I think it would be possible to get equal or better accuracy without the repetitive process.

-- mhawkins2 - why does my wife keep parking her car in my shop :)?

View Steve2's profile

Steve2

75 posts in 2229 days


#7 posted 10-18-2008 05:57 AM

The problem is you are using an adjustable miter gauge – should cut both sides as complimentary angles. See /www.incra.com/images/jfcmitersliderpic1_zoom.jpg

-- Regards, Steve2

View daviddoria's profile

daviddoria

50 posts in 597 days


#8 posted 06-03-2014 12:12 PM

Steve2, I get a page not found with that link.

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