Proper way to use a try square when milling stock

[Ron Swanson Jr.]

 

Here's a question/conundrum that's always bothered me, and it's REALLY basic.  

 

It's after i crosscut to length during the milling process that my question comes into play. 

 

If I lay my work piece on the table and put the try square on it, and *only press down on the stock of the square with enough pressure to bring the blade off of the table*, then the result is what looks to my eye to be a pretty close to perfect 90° cut. See first pic. I believe this IS actually a true 90. If i put a protractor on it, it is dead on. 

But. 

If i hold that same piece up to the light and *PRESS the stock of the try square against the side grain*, the result is never, ever good.  The blade NEVER sits flat on the end grain and it looks like it's not even close to 90°. 

 I'm usually putting a fair amount of pressure on the stock of the square to press it against the work piece. See second pic*

I would expect the results to be the same in both methods but they never are. 

***So my question is...***

Can pressing the stock of the try square against the side grain give me an inaccurate result?

How is it SUPPOSED to be done?

 

 

It's more of an annoyance than anything, but when i hold it up to the light, I'd really like to not see any light coming through. Oh and yes, I've checked my try squares and they're true. And this happens with try squares or combination squares. 

 

thanks... 

PS

Sorry i don't know why one pic is upside down. It was taken right side up. 

 

[curlyoak]

test the square for true. Create a straight line on your jointer At least a footlong of dresses stock. Place your square in the middle of the jointed edge.Strike a line on the inside of their square and flip the square and see how the line matches up to the  180 flipped  square. 

[Coop]

Not really sure I understand. Is the first pic prior to the cut and the second, after the cut?
On what are you making the cut, table saw or miter saw?

Just out of curiosity, place your square against the edge of a known flat piece of board and mark the inside edge of your square. Then mark the same spot against the outside edge of the square and see if they line up. 

However, I think the prob is your saw cut and not your square(s). 

[fcschoenthal]

The question I have is about reference edges. Milling lumber is getting two consecutive reference edges and then taking all measurements/readings from those. Are you checking squareness from the reference edge and then the opposite edge? It could be that they aren't parallel.  

[Tpt life]

Never put pressure on the metal blade. There is likely enough flex to deform if you are putting pressure on it. Only put pressure on the wood portion, and lightly touch to the metal. Woodworking is not machinist work. If you cannot get appropriately square, use designs that allow for hand work to fine tune. 
 

EDIT: Also, that is a thick board. How are you ensuring that the square is in exactly the same angle in your two methods? It can be good to check that on top, bottom, and middle. Dull blades tend to push as they cut, so the initial might be great, with deviation as it moves through material. Again, machinist level work is not possible, so think about dragons that allow for fine tuning. 

[Ron Swanson Jr.]

On 7/14/2023 at 10:56 PM, curlyoak said:

test the square for true. Create a straight line on your jointer At least a footlong of dresses stock. Place your square in the middle of the jointed edge.Strike a line on the inside of their square and flip the square and see how the line matches up to the  180 flipped  square. 

Thank you. That's been done multiple times, mentioned in the post. My try squares are true. I see the same result with combination squares also. So i don't believe it's the square.

 

 

Thanks for replying, appreciate it! 

[Mark J]

I think tpt makes some good points.  Looking at the grain pattern of the board it does look like you are measuring the same corner in both instances.  If the cut edge is not flat, smooth and square to the board's faces this might account for the variation, particularly if the blade is not parallel to the board's face.  It may also be that when placed flat on the TS there is a tiny gap, but it's difficult to see since there isn't light behind.

[Ron Swanson Jr.]

Thanks all. 

Let me try explaining it a little differently, hopefully it will make more sense. 

***This is a question about how to use a try square correctly after cross cutting on the table saw.***

If i check it using 1 method, it shows me that it's square. 

But if i used a slightly different method on the same piece with the same try square, it does NOT appear square. 

I have checked the try square, and it's true. So i don't believe that is the culprit. 

 

FIRST METHOD:

1. I set the workpiece on a flat reference surface (saw table.)

2. I set the try square on the saw table and engage it with the workpiece. 

When i check it this way, it appears that my cross cut is a dead 90°. There are no gaps between the work piece and any part of the square. 

 

SECOND METHOD:

1. I pick the workpiece up off the table and hold it up to a light in my left hand. 

2. With the try square in my right hand, i engage it with the work piece. 

3. In this method, I'm pressing the wooden stock of the try square against the side grain of the workpiece. 

When i use THIS method, that same work piece that was looking like a dead on 90° crosscut in method number 1 will NOT appear to be at 90°. I will see light coming through between the square and the work piece. 

 

-------------

 

Hopefully that is more clear. Sorry, it's kind of hard to describe clearly. Maybe I'll try to make a video of each method. 

 

Thanks to all who have weighed in here. 

 

 

 

 

 

[Ron Swanson Jr.]

Hopefully this works 

 

1. Video of method that shows me a true 90° https://drive.google.com/file/d/1oIWutFnF8nymNSAwRVeiZ21BmOX3-3km/view?usp=drivesdk

 

2. Video of 2nd method, does not show 90. https://drive.google.com/file/d/1oMXhgFozPDg2e2COnRQ901OQHqElRyei/view?usp=drivesdk

 

 

[Tpt life]

You need to make those files view only, then give public access. 

[Ron Swanson Jr.]

On 7/15/2023 at 9:58 AM, Tpt life said:

You need to make those files view only, then give public access. 

Ok thanks. Sorry I've never done this before

[Ron Swanson Jr.]

Apologies for the mess that this is turning into. Doing the best I can.

I've changed the permissions on the videos so that anyone can view them and I will repost the links here. I don't see any option to make them read only.

 

First method

https://drive.google.com/file/d/1oIWutFnF8nymNSAwRVeiZ21BmOX3-3km/view?usp=drivesdk

 

Second method

https://drive.google.com/file/d/1oMXhgFozPDg2e2COnRQ901OQHqElRyei/view?usp=drivesdk

[Tpt life]

Slapping that square in, like shown in the first link, is likely slapping the metal tight, but causing the much shorter wooden part to be off. When held like the second, I will bet the force is not the same, and you are getting a more true measure. 

[Ron Swanson Jr.]

On 7/15/2023 at 9:01 AM, Mark J said:

I think tpt makes some good points.  Looking at the grain pattern of the board it does look like you are measuring the same corner in both instances.  If the cut edge is not flat, smooth and square to the board's faces this might account for the variation, particularly if the blade is not parallel to the board's face.  It may also be that when placed flat on the TS there is a tiny gap, but it's difficult to see since there isn't light behind.

TRP makes good points but i don't think that's it. 

You are correct inn that I'm gauging the same corner. 

I hear what you're saying when you suggest there might be a slight gap on the table, butt since there's no light behind it I'm not seeing it. But honestly i don't think that's it either. 

I can see the blade resting on the workpiece when it's sitting on the table. Any of gap there would be too small to matter. 

The only real difference in the two methods of that when i hold it up to the light, I'm pressing the wooden stock of the try square against the side grain. 

It's this pressure that's throwing it off. 

I just don't understand WHY that happens. 

 

I appreciate everyone who has tried to answer. It's difficult to describe accurately.

 

 

[Tpt life]

I over spent on a couple red shinies, that I like because of two long reference legs. I’ve often introduced error when one leg of a square is so short. Please don’t hear anything more than helpful critique. I am back at building for the summer, and attempting for perfection on Celect PVC trim. It requires tuning. I don’t think LN intended this for PVC, but it works. 

[Ron Swanson Jr.]

On 7/15/2023 at 12:08 PM, Tpt life said:

. Please don’t hear anything more than helpful critique.

 

Oh man, not AT ALL. Im very grateful for any and everyone who took time out of their day to weigh in on my question. In some cases, the purposed explanation is something I've considered and successfully ruled out, but yeah I'm very appreciative of everyone's support in here! 

[Mark J]

I wasn't able to view either video, but I think I understand your conundrum.  And for the record, I don't think either of your measuring methods is wrong.  But on or off the TS, it doesn't require a lot of force.

With the board laying on the TS bed try pressing the stock of your square as firmly against the long side of the board as you do in your second method.  Also use the outer edge of the blade to confirm that the long and short edges are actually flat.  If not, you may just be rocking the stock/blade.

[Ron Swanson Jr.]

@Mark J you just nailed it. 

That's exactly what's happening. 

This piece is not square, and when I'm seating the blade of the square that's exactly what's happening. 

When i hold it up to the light, I'm coming from a different direction with the square and it's not rocking the blade. 

 

A sincere thank you to everyone who has weighed inn here. 

I'm trying to get better at milling stock dead flat and perfectly square and this apparent disparity was really bothering me!

 

 

 

[Chestnut]

I always use firm pressure but not so much that i'm making my fingers work.

I also flip the square so the handle is on both sides to see if there is a change.

A third tip is to hold the handle on the side with a large gap and then slowly slide the square down untill it contacts the end.