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Michael Ginsberg
01-12-2012, 5:25 PM
I am attempting to get accurate 45 degree miters for a 3 x 3 oak frame I am making for a sign I made. The little gap I am getting is driving me nuts! I know that it can be filled with dark putty as I am staining the frame a dark brown color. But, I want to do it right!!
I tried using my new Bosch chop saw. I got a small gap on the angles. I used my table saw with my miter attachment from Incra. That gave me a smaller gap, but still a gap! I seem to remember a trick from high school shop. Put both pieces of the frame in a miter clamp. Keep cutting on the miter joint with a back saw until the opening is gone (cutting both pieces of wood at the same time).
Has anybody tried this trick? If I keep playing around I will have to trim my sign to fit the frame that I keep monkeying with.
Any suggestions welcome. Thanks

scott vroom
01-12-2012, 5:33 PM
Can you post a close-up photo of the gap? It sounds like you have a calibration problem with your Bosch saw. Which model Bosch do you have?

Lex Boegen
01-12-2012, 5:54 PM
I was just coming to tell you that "trick". It works well, but realize that you will be reducing the length of both pieces slightly, so you may fix one problem and create three others. If you're going to paint it, you can fill the gap with a slice of veneer to restore the original dimensions. If it's stain-grade, good luck. It's always best to test your miter joints with same-dimension scraps first, before committing to the expensive stock. Here is a good instructional video (http://www.youtube.com/watch?v=QzV-o4_kacc) from the Woodworkers Guild of America on fine-tuning your miter gauge.

Michael Ginsberg
01-12-2012, 6:30 PM
The Bosch saw that I have is the new one with the articulated arm, not the slides. I realize a machine like this is not exacting as I may need. I think it has limitations.
I realize the "trick" will shorten the length of each piece slightly. As long as they shorten equally, I can make the sign a smidge shorter in length and height. I also think the problem I had with the Incra miter guage is that I did not install sandpaper strips to a wooden subfence as was suggested by Incra. I just used the aluminum fence and perhaps it creeped up on the cut a bit.
I think I will try the miter clamp trick. I hope it cuts them to match better.

Michael Ginsberg
01-12-2012, 6:33 PM
I know this sounds silly... I am not very computer savvy. I am not sure exactly how to upload pictures on to SMC. I can take the shot, save to my computer. But I don't know how to proceed from there :(


Can you post a close-up photo of the gap? It sounds like you have a calibration problem with your Bosch saw. Which model Bosch do you have?

Michael Peet
01-12-2012, 7:04 PM
I have had the best luck with a 45° shooting board.

219490

Mike

Harry Hagan
01-12-2012, 7:23 PM
I watched a recent episode of the Woodsmith Shop titled Picture-Perfect Miters (#511). They showed how to build a table saw sled to cut perfect miters. If you can catch that episode you’ll be in business.

Michael Ginsberg
01-12-2012, 7:51 PM
That clip was great! I will try that this weekend. After setting up the wooden subfence that Incra suggested, I will check to see if it is right on..



I was just coming to tell you that "trick". It works well, but realize that you will be reducing the length of both pieces slightly, so you may fix one problem and create three others. If you're going to paint it, you can fill the gap with a slice of veneer to restore the original dimensions. If it's stain-grade, good luck. It's always best to test your miter joints with same-dimension scraps first, before committing to the expensive stock. Here is a good instructional video (http://www.youtube.com/watch?v=QzV-o4_kacc) from the Woodworkers Guild of America on fine-tuning your miter gauge.

Rick Thom
01-12-2012, 8:10 PM
Two essential jigs for me.
Miter sled makes exact 45 deg cuts every time. Use a stop block to ensure opposing sides are identical in length.
Cross-cut panel sled. Cuts exact 90 deg. http://thewoodwhisperer.com/the-cross-cut-sled/ is a good one and easy to make IME
Worth the hour or so to make them, and then use them with confidence for years to come.

Michael Ginsberg
01-12-2012, 8:25 PM
Thanks. I am going to make them both in the near future.


Two essential jigs for me.
Miter sled makes exact 45 deg cuts every time. Use a stop block to ensure opposing sides are identical in length.
Cross-cut panel sled. Cuts exact 90 deg.
Worth the hour or so to make them, and then use them with confidence for years to come.

Dave Anthony
01-12-2012, 8:49 PM
I use a Jessem sliding table, but you should be able to get accurate 45 deg cuts with the Incra.
1. use stop blocks to ensure pieces are the same length
2. sand paper on the fence will help with stock creep, clamping the stock to the fence works better.
3. make sure the saw blade is set to exactly 90 degrees

David Hawxhurst
01-12-2012, 9:11 PM
shooting board and hand plane.

Pat Barry
01-12-2012, 9:19 PM
Rick, I agree with the sled approach. I could never get them right until I made a jig like you pictured here. Cut the joint pairs using the left and right side of the sled maintaining the proper orientation of the pats for best results.

Darrin Davis
01-12-2012, 9:31 PM
The problem with miter saws, even if you have them set to a perfect 45 degree angle, is that unless you clamp the piece tight and make a very slow cut the wood will always move due to the vibration of the cut. The blade with also flex and bend during the cut enough to make it nearly impossible to get a perfect miter cut. If I have to have a perfect miter I use the miter sled I built for my table saw. I used to have a guillotine that was great but I was worried about someone losing a finger so that has been removed from my shop.

Jerome Hanby
01-12-2012, 10:48 PM
I saw an episode of Saint Roy where he had some miter type saw build specifically for picture frames. It would let you clamp the joint together and saw through the intersection in order to make them "perfect". Cool solution if you had such a gizmo. Building a shooting board and using a plane would probably be more practical.

Then again, i recall seeing some Craftsman Miter saw that would let you set the fence to a right angle. Let me see if I can find a link... Here it is (http://www.sears.com/shc/s/p_10153_12605_00921226000P?sid=IDx01192011x000001&srccode=cii_17588969&cpncode=30-21893244-2). Be cool to know if it was any good...

Lee Schierer
01-13-2012, 9:47 AM
I use a jig like the one shown by Rick and cut pieces on the left and right side. After purchasing my Kreg miter gauge, I tend to use it as the cuts come out accurately. I usually cut them intentionally about 1/4-3/8 inch longer than needed. If I need to adjust the angles a bit, the extra length allows me several adjustments. I check the length of pieces on opposite sides by standing the sharp corner on my saw table and putting them back to back to see how close the tips come to each other. You can easily see differences as fine as 1/64". It is critical to proper fit up that opposite sides be exactly the same length. Once I verify that I have the angles right, I can trim the pieces to the correct final length.

Jeff Monson
01-13-2012, 10:12 AM
I use a sled very similar to the one Rick built. I need some help remembering from some older members here. There was a gentleman that used to post alot of jigs and techniques, he has unfortunately passed away....I cannot remember his name. He posted the build process for a 45 degree mitre sled. I built one a few years ago, it took maybe an hour to accomplish. This sled is deadnuts accurate for building anything with 45 degree corners. I used it for table tops, picture frames, square frames, rectangle frames, it never let me down.

Stephen Cherry
01-13-2012, 10:18 AM
I think that the idea with the miter sled it to cut one board on one side, the other on the other side, so that as long as the boards of the sled are at 90 to each other, the miter will match up even though the angle may be slightly off of 45.

Will Winder
01-13-2012, 12:06 PM
Here's another video about making a 45 degree miter sled for the table saw
http://www.youtube.com/watch?v=lXLeMVAkSIY

Rick Gooden
01-13-2012, 12:11 PM
Millers-Falls miter box with Disston saw. Perfect every time.

Michael Ginsberg
01-13-2012, 12:13 PM
Rick,
When you use a miter sled like this, Do you put both mating pieces on the sled at the same time so the blade cuts on the joint on both at once. Or, is each piece done seperately? I figured if you do both at once, each hand can hold one piece in place on the support as the sled is pushed through the blade.



Two essential jigs for me.
Miter sled makes exact 45 deg cuts every time. Use a stop block to ensure opposing sides are identical in length.
Cross-cut panel sled. Cuts exact 90 deg. http://thewoodwhisperer.com/the-cross-cut-sled/ is a good one and easy to make IME
Worth the hour or so to make them, and then use them with confidence for years to come.

Lee Schierer
01-13-2012, 2:48 PM
Rick,
When you use a miter sled like this, Do you put both mating pieces on the sled at the same time so the blade cuts on the joint on both at once. Or, is each piece done seperately? I figured if you do both at once, each hand can hold one piece in place on the support as the sled is pushed through the blade.

You cut one piece at a time, just make sure that you cut the mating corners on opposite sides of the jig. If you tried to do two at once the waste would interfere with the other piece you are trying to cut.

Jeff Monson
01-13-2012, 3:19 PM
I will try to explain this as best I can. I drew up a quick sketch to try to help. Lets say we want to build a table top frame that is 12" square and the frame is 3" wide.

The colors that are represented
Green is the workpiece.
Yellow is an offcut that MUST be the same width as your workpiece (in this case 3", any length)
Purple is just a thin scrap that is glued or pin nailed to the yellow offcut.

219574

1. Start with 4 pieces of stock 12 1/8" long by 3" wide. The 1/8 is added as this is the width of the blade kerf, 1/16" will be removed on each cut, as a result you will loose 1/8" of your desired dimension.

2. Lay out the 4 pieces and number the corner joints (I also like to draw a 45 with the pencil and color out the area I want to remove, makes it easier to keep everything in order)

3. Your cuts will be made with all the number joints facing up, every corner will have 1 cut on the left side and 1 on the right, results in a perfect 90 degrees.

4.Slide your workpiece and the offcut to the top of the triangle, the scrap you have attached to the offcut will stop the workpiece exactly in the middle of the kerf. This will result in the loss of the 1st 1/16".

5. I attach 2 toggle clamps to the triangle 1 for left cuts and 1 for the rights. Once you have the workpiece referenced you can clamp it down and remove the offcut, now make your cut. I will make all my left cuts 1st and then the rights.

This system has been very reliable, very accurate and very simple to do, just remember to add 1/8" to the overall dimensions and you are good to go.

I hope this helps you out.

Rich Engelhardt
01-13-2012, 3:51 PM
I need some help remembering from some older members here. There was a gentleman that used to post alot of jigs and techniques, he has unfortunately passed away....I cannot remember his name. He posted the build process for a 45 degree mitre sled
Nissim Avrahami (Nikki)?

A true creative genius.
Sadly, a lot of what he posted was done with links to an online service that hosted the pictures. Quite a bit of his hard work has been lost.

Don Jarvie
01-13-2012, 3:56 PM
There was an article in FWW a few years ago where the guy made the frame going clock wise or counter and then fitting the last miter by hand if necessary. Never tried it but it seemed like a good plan.

Jeff Monson
01-13-2012, 5:46 PM
Nissim Avrahami (Nikki)?

A true creative genius.
Sadly, a lot of what he posted was done with links to an online service that hosted the pictures. Quite a bit of his hard work has been lost.

Bingo, thanks Rich!!! I had his links saved on my old computer as he was truly a creative genius. I miss his posts and kindness. I built a couple of his jigs and sleds, all worked like a champ.

Gary Kman
01-13-2012, 10:52 PM
Look very closely at your joint. A miter cut side loads a blade, pushing it away where the load is greatest resulting in a concave cut line. If so, use a sharper, stiffer blade. Also check for vertical squareness to see if the joint is making contact on the back and leaving as gap at the face. Third, seasonal humidity can change the width of a 3" board enough to open a miter. Draw it full scale, increase the width of each board 1/32" while leaving the length the same and watch the gap open at the outer corner big enough for a dime to fall in.

Rick Thom
01-13-2012, 11:55 PM
Look very closely at your joint. A miter cut side loads a blade, pushing it away where the load is greatest resulting in a concave cut line. If so, use a sharper, stiffer blade. Also check for vertical squareness to see if the joint is making contact on the back and leaving as gap at the face. Third, seasonal humidity can change the width of a 3" board enough to open a miter. Draw it full scale, increase the width of each board 1/32" while leaving the length the same and watch the gap open at the outer corner big enough for a dime to fall in.
Gary, just a few additional thoughts for miters on wider boards...
- one of the advantages to the miter sled is the defined saw kerf in the bed of the sled. If you only use blades of the same kerf width... either thin or regular kerf, and always ensure your blade is set exactly on 90 deg ( I use a digital angle gauge fwiw) it is quite easy to hit your cut line for length on your stock right on because you can clearly see the intersection of the stock and the edge of the blades kerf.. no guessing required.
- for any stock where a fine cut is required, isn't it a good idea to sneak up on the final cut?.. maybe you make several miter cuts to relieve any internal tension/movement with the last one being the money cut.
I like the idea of the kerf cuts on the backside of the wider stock to help control seasonal movement (see pic). In some cases it would be unacceptable appearance-wise but others, ok.
Maybe some of these ideas would help.

Michael Ginsberg
01-18-2012, 12:25 PM
Thanks for all your input!!!