Getting perfect miter joints - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 53 Old 10-15-2012, 04:58 PM
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post #22 of 53 Old 10-15-2012, 06:00 PM
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Quote:
Originally Posted by Rashed
After all the replays and trouble shooting, i recommend to check if your boards are straight and square. It could happen some times. ?de2c
Agreed. If your boards are cupped or warped even slightly it will effect the joint. Also if the wood is not held or clamped firmly in position during the cut it can wander causing the cut to be off.

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post #23 of 53 Old 10-16-2012, 02:07 AM
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An old tradie I knew when I was an apprentice had a little trick on the job. He would tack or clamp his pieces in place and then re-cut the joint with a handsaw. The joint would come up a treat.

As for cutting on a table saw, that would be my last choice unless you have a good quality saw with a sliding table. I just use a 12 inch drop saw. Good sharp blade is a must.

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post #24 of 53 Old 10-16-2012, 08:43 AM
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I can attest to TS being a poor choice. I'm making a small frame for the wife right now and the angles that I am getting from my TS seem like 45, but just aren't. I am thinking that a miter box might even be a good solution. I should mention that I am using a miter gauge for the 45 instead of tilting my blade. I feel like this is a better choice since I don't have any kind of digital protractor or tilt box.

I fiddle with it, curse, leave it for a day, repeat.
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post #25 of 53 Old 10-16-2012, 09:24 AM
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Quote:
Originally Posted by Phaedrus View Post
I can attest to TS being a poor choice. I'm making a small frame for the wife right now and the angles that I am getting from my TS seem like 45, but just aren't. I am thinking that a miter box might even be a good solution. I should mention that I am using a miter gauge for the 45 instead of tilting my blade. I feel like this is a better choice since I don't have any kind of digital protractor or tilt box.

I fiddle with it, curse, leave it for a day, repeat.

Having issues is not the TS's fault. There are things you can do to make good miters using the miter gauge.
You should install an extended fence on the miter gauge, run a strip of sandpaper on the contact side to prevent the work from shifting AND use a draftsman's triangle to set your 45 degree angle.

A clean, sharp blade will make a huge difference also.

Anything less than that and you are asking for inaccurate miters.

You can make a 45 degree "frame" sled, but that will only be as accurate as you make it and you need an accurate triangle to do that. The degree stops on stock miter gauges are not accurate. Some have adjustable stops that you can lock once you get it set up, others have 5 degree stops like the Incras and are much better.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #26 of 53 Old 10-16-2012, 09:32 AM
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Quote:
Originally Posted by woodnthings View Post
Having issues is not the TS's fault. There are things you can do to make good miters using the miter gauge.
You should install an extended fence on the miter gauge, run a strip of sandpaper on the contact side to prevent the work from shifting AND use a draftsman's triangle to set your 45 degree angle.

A clean, sharp blade will make a huge difference also.

Anything less than that and you are asking for inaccurate miters.

You can make a 45 degree "frame" sled, but that will only be as accurate as you make it and you need an accurate triangle to do that. The degree stops on stock miter gauges are not accurate. Some have adjustable stops that you can lock once you get it set up, others have 5 degree stops like the Incras and are much better.
That looks like some helpful advice. I have been using an acrylic drafting 45 to set my angle. It is a stock 80's craftsman miter gauge, so certainly not a device of serious accuracy. I will have to try the extension on the gauge. I think I have one that I already made out of 3/4 MDF that mounts w/ machine screws and t-nuts. The blade is fairly new and sharp. I need to do some measuring I think. I have this crazy theory that perhaps my miter slots are not parallel. I'll have to try attaching some sand paper as well.

It really should not be as difficult as it is some days.
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post #27 of 53 Old 10-16-2012, 11:58 AM
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Cutting mitres on a table saw with a miter gauge is tricky business, only thing I can add is to clamp the material to the extension, holding it by hand even with sandpaper attached will not always be enough as just too much is is going on all at once.

I clamp the material with my miter saw as well.

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post #28 of 53 Old 10-17-2012, 07:49 PM Thread Starter
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So i did another attempt went and bought more lumber.....sigh..

Ya know side rant here. A $40 box has turned into a $100 box heh. Learning curve i guess. Seems like everything i've built for myself came out great but this box for my mom is a pain in the ass..anyways.

I have it glued and i rounded the corners and theres a 1/32nd line at the joint. How tight should the joints get? I dry fit them first to check for tightness and it looked great, I'm happy with it, was just curious. Also, any way to get rid of it or is it just gotta be what it is?

Also, i did the tape method on all the joints then folded it together and some ended up a smidge taller then the others whats the best way to get a flat bottom/top. Surely a planer would tear this thing apart?

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post #29 of 53 Old 10-17-2012, 10:18 PM
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You can set up a TS to make perfect miters but you need to make a jig for best results.
I have a beautiful Delta Unisaw that I have had for 25 years or so. The miter that came with it wiggles in the slot from side to side.
So no matter how much I fiddle with the fine tuning adjustments it's almost impossible to make a perfect miter.

So I made a sled, I made the runners out of plastic from an old cutting board my wife was throwing out.
You know the white plastic stuff. I cut a bunch of strips at one time so they were a slip fit with some resistance.
I screw them to the bottom of my sled which is just a flat piece of plywood, I like Baltic Birch to make this type of jig.
Then I take a block or two of squared up wood to make a fence depending on the type of fence i need.
Using a known accurate tri square or protractor I lay out a line at whatever angle I am looking for on my sled measuring off the tablesaw blade.
Then I screw one end down with a drywall screw short enough not to mess up the table. Keeping to the line I put a nail in to tack the other end and make a couple of
test cuts. I put the two pieces together to make sure I have a 90 degree angle, once I am sure it's exactly correct I screw the other end down, if I need to adjust I pull the
nail out a bit and swing the fence to adjust it. Now you have a dedicated jig for whatever angle you need.

Here is a trick to glue your miters together without clamps.
Get yourself some brown craft paper, you know, the stuff paper bags are made of.
Slather your glue on one pair of the miter cuts, press them together on top of a piece of the craft paper on a flat surface and press together for a few seconds.
Get yourself a wet rag and wipe all the excess glue off right away, don't be shy about getting the wood wet.
Repeat for the other joints and go play golf or something while your waiting for the unit to dry.

What happens is the brown paper acts as a clamp as the cellulose absorbs the glue and holds your pieces together. After its dry just sand off the brown paper.
If you wiped off all the glue thoroughly you will not have anything to clean up or mess up your finish later.
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post #30 of 53 Old 10-17-2012, 10:30 PM Thread Starter
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Quote:
Originally Posted by Flatlander View Post
You can set up a TS to make perfect miters but you need to make a jig for best results.
I have a beautiful Delta Unisaw that I have had for 25 years or so. The miter that came with it wiggles in the slot from side to side.
So no matter how much I fiddle with the fine tuning adjustments it's almost impossible to make a perfect miter.

So I made a sled, I made the runners out of plastic from an old cutting board my wife was throwing out.
You know the white plastic stuff. I cut a bunch of strips at one time so they were a slip fit with some resistance.
I screw them to the bottom of my sled which is just a flat piece of plywood, I like Baltic Birch to make this type of jig.
Then I take a block or two of squared up wood to make a fence depending on the type of fence i need.
Using a known accurate tri square or protractor I lay out a line at whatever angle I am looking for on my sled measuring off the tablesaw blade.
Then I screw one end down with a drywall screw short enough not to mess up the table. Keeping to the line I put a nail in to tack the other end and make a couple of
test cuts. I put the two pieces together to make sure I have a 90 degree angle, once I am sure it's exactly correct I screw the other end down, if I need to adjust I pull the
nail out a bit and swing the fence to adjust it. Now you have a dedicated jig for whatever angle you need.

Here is a trick to glue your miters together without clamps.
Get yourself some brown craft paper, you know, the stuff paper bags are made of.
Slather your glue on one pair of the miter cuts, press them together on top of a piece of the craft paper on a flat surface and press together for a few seconds.
Get yourself a wet rag and wipe all the excess glue off right away, don't be shy about getting the wood wet.
Repeat for the other joints and go play golf or something while your waiting for the unit to dry.

What happens is the brown paper acts as a clamp as the cellulose absorbs the glue and holds your pieces together. After its dry just sand off the brown paper.
If you wiped off all the glue thoroughly you will not have anything to clean up or mess up your finish later.
Thanks for the help bud! I use the tape method, works great it uses the tape as a clamp on 3 of 4 corners so for the last i wrap a ratchet strap around it and clamp er down and check for square and it works great.

I just wasnt sure how tight a mitered joint should be, as i have a teency line at the joints.
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post #31 of 53 Old 10-18-2012, 07:35 PM
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Quote:
Originally Posted by jschaben

Two things are needed to get a good miter. The opposite sides MUST BE EXACTLY equal. The miter cuts must be EXACTLY 45. Other than that, piece of cake
Sure. Easy for you to say! :)

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post #32 of 53 Old 10-18-2012, 07:49 PM
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I'm not sure whether I heard this on TV or read it somewhere.

A salt shaker was found in a very old woodworkers chest along with several vintage tools.

The person who had acquired the chest looked into it and found that adding a touch of salt to the joint after glue application prevented the joint from slipping. The joint strength was not negatively effected by the salt as it was dissolved by the glue.

No mention was made of the type of glue used in this method so I'm not sure how well it would work with different glues.

Have anyone of you ever heard of this?

Jeff

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post #33 of 53 Old 10-18-2012, 08:06 PM
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Salt is used to extend the open time of hot hide glue which would have been the glue used at the time.
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post #34 of 53 Old 10-18-2012, 08:10 PM
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Thanks Keith,

So the application of salt really had nothing to do with reducing workpiece slippage during assembly?

Jeff

"I have never let my schooling interfere with my education"

Mark Twain

When I die, I want to go peacefully like my grandfather did in his
sleep. Not yelling and screaming like the passengers in his car.

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post #35 of 53 Old 10-18-2012, 10:04 PM
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Salt also acted as a preservative for the hide glue as it was an animal based substance.

Wise men speak because they have something to say; fools because they have to say something -Plato

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post #36 of 53 Old 10-18-2012, 10:13 PM Thread Starter
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Anyone care to elaborate on my topic? is a glue line like that normal?
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post #37 of 53 Old 10-18-2012, 10:28 PM
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yeah, probably acceptable

Perfect miter/bevels are harder to get than a miter like on a frame because the bevel has to be exact AND over the entire length.
On a flat frame miter you can immediately see any gaps and make a correction. With the blade angled over at 45 degrees and just the width of the material like 1/2" or so, any deviation will show as a gap either inside or on the edge and you won't be able to tell unless you assemble it. On a flat frame you can lay the pieces down inside a framing square and see how they line up and any gaps will be apparent. On a bevel you have to have some of the parts assembled or have a transparent square box to see the gaps. You can dry fit the pieces overt a known square box with an edge guide on one side as a checking fixture.

I hope I'm making my point clearly ..... I donno?

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 10-18-2012 at 11:15 PM.
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post #38 of 53 Old 10-18-2012, 10:35 PM
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Quote:
Originally Posted by lateralus819
Anyone care to elaborate on my topic? is a glue line like that normal?
Sorry bud,

We got into joint slippage and I thought my post might be helpful to someone.

No highjack intended. This happens sometimes in this forum.

We take it with a grain of salt. :)

Jeff

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post #39 of 53 Old 10-19-2012, 03:01 PM
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1. the miters do not need to be a perfect 45 degrees, they just need to add up to 90 degrees. often a miter gauge is off the same amount on both directions, so if you cut one angled piece on one direction of the miter, cut the other angle mating piece on the other side. this holds true on miter saws also. cut mating pieces on opposite sides of the blade.

2. my trick to close up a glued joint with a gap - sand the joint (med grit) after gluing and clamping. the sawdust fills the gap in the joint and the glue holds it in there, and it will look tight. stains and varnishes fine also.
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post #40 of 53 Old 10-21-2012, 06:33 AM
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Alright, round two. I've built sacrificial extensions for my miter gauge for left and right side usage. I then aligned my miter gauge with my blade (from max height position) using a C-line acrylic drafting 45.



My results weren't perfect, but it is much better. I then glued the miters and secured the frame together with a small amount of tape around the corners and then a ratcheting strap. With the strap tight, I then clamped the frame flat between two scraps of MDF.



The bad news, though, is that my frame is now too small b/c I removed too much material re-cutting the miters over and over.

Last edited by Phaedrus; 10-21-2012 at 07:44 AM. Reason: Image size madness
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