Using an Incra miter gauge to set the angle on the Shopsmith miter gauge

[algale]

I have an Incra (Shopsmith edition) miter gauge as well as the original Shopsmith miter gauge. The Incra, once set up, is dead on accurate and, conveniently, has positive stops at every 1 degree. The Shopsmith has a stop at 90 but it isn't all that repeatable because there's slop in the pin that serves as the stop.

I recently had to reset the Shopsmith miter gauge to 90 degrees and I did it the old fashioned way, with a precision combo square, base against the miter head and blade against the miter bar.

Then I got curious. How closely did that set up agree with my Incra?

As seen in the photo, I put the Shopsmith miter gauge in one of the slots on top of my 520 fence. From the opposite direction, I put my Incra gauge in the other slot.

IMG_4216.jpeg (323.54 KiB) Viewed 45075 times

Then I brought the heads of the two gauges together. The faces of the two miter gauges butted up against each other perfectly with no gap.

IMG_4217.jpeg (453.49 KiB) Viewed 45075 times

It occurs to me that by setting the Incra gauge to any angle, I can use this set up to set the angle on the Shopsmith gauge. Sort of an alternative to the miter set Shopsmith used to sell.

[DLB]

...Sort of an alternative to the miter set Shopsmith used to sell.

This is a great idea if the Incra is that accurate and repeatable. Shopsmith should sell these Incra miter gauges! Shopsmith does still carry the Miter Sets made for the SS miter gauge, $119 each or $225 for the pair though. I'd like the Incra, but rarely see them for sale and usually require the purchase of an entire used Mark V.

- David

[algale]

Shopsmith should sell these Incra miter gauges!

They used to. Must have had a falling out. I just checked the Incra website and they no longer sell any of the Shopsmith "editions", either. No spare parts, i.e. Shopsmith-sized miter bars, either.

In addition to the Shopsmith edition v120 gauge, I have a Shopsmith edition Incra Miter 5000 sled. I prefer to use one of the Incra's for most operations versus the Shopsmith miter gauge. But the Shopsmith miter gauge can be locked into position in the main table saw miter slots or the the belt sander table miter slot and when there's an operation where that is useful, I reach for the Shopsmith miter gauge.

[dusty]

Neat but I have one question. Is the miter track on the fence "dead on parallel" to the miter track in the table? If not.....well, you figure.

Another though. Is the input table rail at 90 degrees to the miter slot. Mine is. Use the front rail as the reference surface and flip the miter gauge upside down on the miter slot to set it to 90.

[dusty]

Neat but I have one question. Is the miter track on the fence "dead on parallel" to the miter track in the table? If not.....well, you figure.

Another thought. Is the input table rail at 90 degrees to the miter slot. Mine is. Use the front rail as the reference surface and flip the miter gauge upside down on the miter slot to set it to 90.

I want a procedure where the "reference surface" is not dependent on an independent alignment.

[algale]

Neat but I have one question. Is the miter track on the fence "dead on parallel" to the miter track in the table? If not.....well, you figure.

Another though. Is the input table rail at 90 degrees to the miter slot. Mine is. Use the front rail as the reference surface and flip the miter gauge upside down on the miter slot to set it to 90.

Keeping the fence parallel to the miter slots and the miter slots parallel to the blade are very important for accurate and safe cuts and I've just checked mine and everything is bang on within a few thousandths.

But none of that actually matters for setting or checking the angle of your Shopsmith miter gauge protractor using the method illustrated in my post. In fact, I could take the fence off the table and move the fence over to my bench for this purpose. As long as the head on my Incra miter gauge is accurate relative to its own miter bar (and it is), the only thing that needs to be parallel are the two slots on top of the 520 fence (which I haven't measured but I assume are).

Think about the Miter Set. You don't need to have the built in miter slot in the Miter Set pointed parallel to the miter slots in the main table to use the Miter Set to accurately set the angle of the miter gauge head relative to its miter bar because the accuracy is built into the jig. Same here. As long as the twp miter slots on top of the fence are parallel (again I'm making an assumption they are) and the Incra miter head is accurate (and I know it is), it will produce the same angle on the Shopsmith miter gauge head relative to the Shopsmith miter gauge bar. And that is all one needs to do to set a miter gauge.

[JPG]

+1
Including the assumptions.

[RFGuy]

I see this as more of a quick check method, analogous to drawing two lines with a square by flipping the square around and comparing the gap between the lines. I have several high end squares in my shop, all of differing lengths and such to accommodate any tool that needs aligning. I prefer to make them the reference (gold standard) and always use them to set square on my miter gauges. IF you trust that your Incra Miter Gauge is at a perfect 90.0°, then you can make it the reference in your shop instead of using a high end square - which is what you are showing here on this thread. Just make sure it is at 90.0°. That particular square has an alignment procedure (step 2 of the V120 manual), so I know it is not guaranteed aligned and must be checked/adjusted against a high end reference square to ensure orthogonality.

https://incra.com/manuals/MiterV120_manual_new.pdf

[dusty]

Neat but I have one question. Is the miter track on the fence "dead on parallel" to the miter track in the table? If not.....well, you figure.

Another though. Is the input table rail at 90 degrees to the miter slot. Mine is. Use the front rail as the reference surface and flip the miter gauge upside down on the miter slot to set it to 90.

Keeping the fence parallel to the miter slots and the miter slots parallel to the blade are very important for accurate and safe cuts and I've just checked mine and everything is bang on within a few thousandths.

But none of that actually matters for setting or checking the angle of your Shopsmith miter gauge protractor using the method illustrated in my post. In fact, I could take the fence off the table and move the fence over to my bench for this purpose. As long as the head on my Incra miter gauge is accurate relative to its own miter bar (and it is), the only thing that needs to be parallel are the two slots on top of the 520 fence (which I haven't measured but I assume are).

Think about the Miter Set. You don't need to have the built in miter slot in the Miter Set pointed parallel to the miter slots in the main table to use the Miter Set to accurately set the angle of the miter gauge head relative to its miter bar because the accuracy is built into the jig. Same here. As long as the twp miter slots on top of the fence are parallel (again I'm making an assumption they are) and the Incra miter head is accurate (and I know it is), it will produce the same angle on the Shopsmith miter gauge head relative to the Shopsmith miter gauge bar. And that is all one needs to do to set a miter gauge.

Yes, I can see better now!! I had not given it enough thought to realize that you had both miter bars in the rip fence miter slots which are adequately parallel to one another. The only issue might be the level of play with tyhe Shopsmith miter bar in the miterr slot.

[algale]

I see this as more of a quick check method, analogous to drawing two lines with a square by flipping the square around and comparing the gap between the lines. I have several high end squares in my shop, all of differing lengths and such to accommodate any tool that needs aligning. I prefer to make them the reference (gold standard) and always use them to set square on my miter gauges. IF you trust that your Incra Miter Gauge is at a perfect 90.0°, then you can make it the reference in your shop instead of using a high end square - which is what you are showing here on this thread. Just make sure it is at 90.0°. That particular square has an alignment procedure (step 2 of the V120 manual), so I know it is not guaranteed aligned and must be checked/adjusted against a high end reference square to ensure orthogonality.

https://incra.com/manuals/MiterV120_manual_new.pdf

You are right that the Incra needs to be aligned from the factory. But once the Incra is aligned it holds alignment. And mechanically it always returns to the same 90 position after being set to other angles.

You are right that you can set the 90 degree on the Shopsmith (or Incra) with a precision square. But the intriguing thing here is the Incra will let me set the Shopsmith gauge to any angle, I want -- not just 90. There are some precision protractors that could be used to do that,too, but I don't own one. I view this set up as an alternative to the Miter Set if you already own the 520 and a Shopsmith-edition Incra miter gauge that will fit in the 520 fence slots.