Improve the Accuracy of Your Miters

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I am sure that Incra provided WWGOA all the help to produce this method & video for checking their miter gauge.

But before anyone runs off believing that George has really accurate advice, remember he is the same person who told us how to verify that your bandsaw table was perpendicular to the blade.

Caution is advised. (Well, do so with my advice also. Verify, verify, verify is my advice)

Forrest

I am not familiar with the Incra miter gauge used, but the stop appeared to be an adjustable rod as well as the movable base. I doubt the hidden end of that rod had a 30° end.

In other videos, the 'view' reveals contradictions to what he says not that what he says is also wrong.

Salt grains recommended.


I be real curious 'how' the Incra is 'adjustable' that covers the entire angle range.

I do not see this procedure of much use with a typical miter gauge with three or fewer 'stops'. 45° stops, perhaps.

[beatnik]

By the time you slop glue in those it could end up off the other way. Trim that last end 1/1024 or whatever or just leave it be. I can't see that good myself.

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Aha! Two part 'head'.

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[dusty]

Aha! Two part 'head'.

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I squared to the table as recommended but I did not square to the saw blade. I squared to the miter track rather than to the blade.

The miter track, using a different procedure, is verified to be parallel to the blade using either a dial indicator or:

http://shopsmith.net/forums/showpost.htm?p=116303&postcount=1

[benush26]

I did the 30 degree test with the Miter Express 1000SE combo. It has a long adjustable fence extension. I used an old piece of stock about 2 1/2" wide, that I first cut to 6 sorta equal pieces, then followed the video instruction with cuts on one end, then flipped, the stop set and the next set of cuts made.

The INCRA stop included does a fine job of keeping the angled cut point (aka pointy end ) at a precise place for repeatable lengths.

I used the Nexabond 2600 medium set glue. It is so thin I don't think it would add much to any accumulated error and since most of the cut surface is end grainish I didn't want to use lots of Titebond.

First run through had about 1/16th cumulative error over about 36" of cut, so I plan to add a thin shim and try again with fresh lumber. If the shim causes too much overcorrection, I'll just remove it and go back to the original error. However, most of the shop is in TOTAL disarray as I try and scavenge back the space I lost. so it may be a week or so before I again make any saw dust!

I understand that I used the sled and gauge rather than the table and gauge, however I believe that very accurate results could be obtained by either.

Be well,
Ben

[JPG]

I did the 30 degree test with the Miter Express 1000SE combo. It has a long adjustable fence extension. I used an old piece of stock about 2 1/2" wide, that I first cut to 6 sorta equal pieces, then followed the video instruction with cuts on one end, then flipped, the stop set and the next set of cuts made.

The INCRA stop included does a fine job of keeping the angled cut point (aka pointy end ) at a precise place for repeatable lengths.

I used the Nexabond 2600 medium set glue. It is so thin I don't think it would add much to any accumulated error and since most of the cut surface is end grainish I didn't want to use lots of Titebond.

First run through had about 1/16th cumulative error over about 36" of cut, so I plan to add a thin shim and try again with fresh lumber. If the shim causes too much overcorrection, I'll just remove it and go back to the original error. However, most of the shop is in TOTAL disarray as I try and scavenge back the space I lost. so it may be a week or so before I again make any saw dust!

I understand that I used the sled and gauge rather than the table and gauge, however I believe that very accurate results could be obtained by either.

Be well,
Ben

Shim? To make face of the gauge fence perpendicular to the table top yes, but not a miter angle correction.

[benush26]

Shim? To make face of the gauge fence perpendicular to the table top yes, but not a miter angle correction.

Presume that a fence or extension attached to the miter gauge and that when the gauge displays 90 degrees that it is supposedly at 90 degrees but after making a long test cut you find that the actual angle is other than. By placing a shim near the end of the gauge between the vertical face of the gauge and extension/fence you can change the angle, with the idea that you reduce the perceived error such that when the gauge indicates 90 degrees it is as close as you can make it using mechanical means.

With a Shopsmith miter gauge you can adjust it to 90 degrees to the bar, then move the pointer to reflect your chosen position. With the INCRA, since the angle indicator positions detents or v grooves are fixed within the structure of the gauge, the simplest option is to adjust the extension/fence which adjusts by placing shims between the gauge and extension. If you have an INCRA miter gauge and are not using an attached extension, you may be SOL if the indicated miter angle on the gauge is not accurate enough for you personal tolerances.

Separately, if the vertical face of the gauge is not perpendicular to the table and you want it to be, then shimming the top or bottom of both attachment points will get you closer to perpendicular.

So, though there is no crying in baseball, there is shimming with INCRA!

Clear as mud?

Be. Well,
Ben

[dusty]

Presume that a fence or extension attached to the miter gauge and that when the gauge displays 90 degrees that it is supposedly at 90 degrees but after making a long test cut you find that the actual angle is other than. By placing a shim near the end of the gauge between the vertical face of the gauge and extension/fence you can change the angle, with the idea that you reduce the perceived error such that when the gauge indicates 90 degrees it is as close as you can make it using mechanical means.

With a Shopsmith miter gauge you can adjust it to 90 degrees to the bar, then move the pointer to reflect your chosen position. With the INCRA, since the angle indicator positions detents or v grooves are fixed within the structure of the gauge, the simplest option is to adjust the extension/fence which adjusts by placing shims between the gauge and extension. If you have an INCRA miter gauge and are not using an attached extension, you may be SOL if the indicated miter angle on the gauge is not accurate enough for you personal tolerances.

Separately, if the vertical face of the gauge is not perpendicular to the table and you want it to be, then shimming the top or bottom of both attachment points will get you closer to perpendicular.

So, though there is no crying in baseball, there is shimming with INCRA!

Clear as mud?

Be. Well,
Ben

Ben, On the Incra, if you loosen the four screws that secure the "protractor" to the miter bar, does it not adjust (for fine tuning). Refer to post #13 this thread.

[benush26]

Ben, On the Incra, if you loosen the four screws that secure the "protractor" to the miter bar, does it not adjust (for fine tuning). Refer to post #13 this thread.

First I apologize for the picture!! Camera phone zoomed in, with an unsteady hand from too far away, but can't get closer for a few days!!:mad:

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If you mean those three bolts, yes, I could adjust using those and it is what is in the manual

However since the gauge will, for the foreseeable future be used exclusively with the sled, I was told to just adjust the swing of the fence. Quicker, easier,and all that was necessary or so I was told . I don't move the fence laterally. Ordered the correct tape, so when things get sorted out will install and zero it.

Unfortunately, other peoples mega errors have thoroughly screwed up my schedule so I am not in a mood to spend more than one go round trying to adjust the miter gauge. If the quick and dirty fix doesn't work then I will have to live with the results for at least a month (probably closer to 3 )

But, yes you are correct in how the gauge should be properly adjusted.

Be well,
Ben

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So this is what precipitated that apology.

I agree that your shimming will alter/correct the angle maybe easier than the 'correct' way. More than one way to achieve the same result.

Nothing you posted you posted to this thread is inaccurate, but does deviate from the 'official' method.

So what! Independent thinking is something I admire! Just make sure it is thinking!;)