Woodpeckers Protractor (ruler)

[Michael Kellough]

Packard, “When I need to feel confident on a measurement, I fall back to mechanical devices.”

Same here. The digital stuff that is accurate in the 1/10th * range is fine for mitering trim (except for very large crown) but when I need the be as accurate as possible I use a vernier protractor.

A vernier protractor can be directly read to 1/12th * which is not much finer than the digital stuff but by noting the position of the ends of the arms you can pretty accurately find intermediate angles.

You can do the same with the digital protractors (the longer the arms the better in both cases) but I just trust the analog instruments more.

 

[Cheese]

...but I just trust the analog instruments more.

That's the reason I own 5 dial calipers and only 1 digital caliper.  [big grin]  The digital caliper is used less than 10% of the time. For the most part I use it to measure a dimension in a restricted area that's impossible to see the dial face of the dial caliper. With the digital caliper, I measure the part, then hit the zero button and after I've removed the caliper I can return it to the closed position and read what the part measured. It does work great for that.  [smile]

 

[Michael Kellough]

...but I just trust the analog instruments more.

That's the reason I own 5 dial calipers and only 1 digital caliper.  [big grin]  The digital caliper is used less than 10% of the time. For the most part I use it to measure a dimension in a restricted area that's impossible to see the dial face of the dial caliper. With the digital caliper, I measure the part, then hit the zero button and after I've removed the caliper I can return it to the closed position and read what the part measured. It does work great for that.  [smile]

Great tip!

 

[Packard]

For critical work, I set that saw’s angle as near to perfect as I can, then make a test cut.  If needed, I will make the adjustments to bring the cut within acceptable accuracy.

I’ve never made angle cuts with the track saw.  How accurate is that scale?

I use a method shown in Fine Woodworking where I cut the pieces to size and make the miters against a sacrificial fence.  I cut a relief in the sacrificial fence so that the trimmed piece will not kick-back. Mostly it just rattles around in the free space created by the relief.  It has never kicked back, but still, I stand aside for safety.

 

[Packard]

...but I just trust the analog instruments more.

That's the reason I own 5 dial calipers and only 1 digital caliper.  [big grin]  The digital caliper is used less than 10% of the time. For the most part I use it to measure a dimension in a restricted area that's impossible to see the dial face of the dial caliper. With the digital caliper, I measure the part, then hit the zero button and after I've removed the caliper I can return it to the closed position and read what the part measured. It does work great for that.  [smile]

Great tip!

For a long time I stuck with vernier calipers, but when mine lost a tiny screw I switched to dial calipers so I could finally enter the 20th century, just prior to actually entering the 21st century. [big grin]

 

[smorgasbord]

The refresh rate is also important on digital protractors. Most of them let you move a shocking amount (relative to how much move the blade on a table saw when making a fine adjustment) before the display changes. And very few of them specify the refresh rate.

Can you explain more about this? I searched the web, and the best hit I could find was this:https://www.touchdro.com/resources/scales/dro-scale-parameters.html#:~:text=If%20the%20refresh%20rate%20is,noticeably%20laggy%2C%20resulting%20in%20overshoots.

Finally, refresh rate should not be overlooked. If the refresh rate is too low there will be perceivable lag between the machine's movement and the DRO display. A refresh rate of 20Hz or above feels pretty much "real-time", while 5Hz and less is noticeably laggy, resulting in overshoots.

But, that seems different than what you were saying, which might be more akin to "backlash." Again from that link:

Third important characteristic is the hysteresis, which will determine how much "backlash" the DRO will have. Most glass and magnetic scales have very small hysteresis, and the parameter is usually listed on the specifications sheet. capacitive scales, and especially inexpensive calipers can have rather large backlash, but the manufacturers don't list this parameter, unfortunately.

 

[Michael Kellough]

Stick a magnetic digital inclinometer (like Wixey or Beale) on a table saw blade and tilt the blade quickly. You’ll probably see nothing change on the display until you stop because these inexpensive units have a pretty slow refresh rate. That’s what I’m calling it but what I mean is that the device does not constantly check attitude so you can move the blade and the device won’t notice until it refreshes. And if the blade has moved less than .05* the Wixey display won’t change. The Beale should since it displays .05* but when I used the Beale it seemed very inconsistent and since it’s accuracy is just .2* I went back to the Wixey and resolve to move the blade veeery slowly.

I’ve made some weird stuff in the past that I had to model in 3D cad to find the bevel angle. Then used the vernier protractor to make the angle and used that or a sliding bevel to set the table saw blade angle. When you’re used to that method and then see how much the blade moves before the digital thing registers the change (put a sliding bevel on one side of the blade and stick the D.I. on the other side) you realize the digital stuff isn’t good enough for extreme accuracy.

Backlash may not be an issue with the digital inclinometers but it may be with digital sliding bevels, especially the cheap ones.

 

[smorgasbord]

Stick a magnetic digital inclinometer (like Wixey or Beale) on a table saw blade and tilt the blade quickly. You’ll probably see nothing change on the display until you stop because these inexpensive units have a pretty slow refresh rate. That’s what I’m calling it but what I mean is that the device does not constantly check attitude so you can move the blade and the device won’t notice until it refreshes. And if the blade has moved less than .05* the Wixey display won’t change. The Beale should since it displays .05* but when I used the Beale it seemed very inconsistent and since it’s accuracy is just .2* I went back to the Wixey and resolve to move the blade veeery slowly.

OK, interesting. My son has a digital inclinometer, so I'll check this out on Monday/Tuesday when I see him. My other Wixey stuff (tablesaw fence DRO, drum sander DRO, and now WR418 digital protractor all update the screen as soon as I start moving. The protractor is especially fast. On the tablesaw, I've found that I can nudge the fence the tiniest bit without the screen updating, but that is probably because I've moved it less than the resolution of the DRO. I suspect the inclinometers to be different than the other devices because it doesn't have a "track" against which it's taking readings.

I thought about getting a venier protractor, but I think my AngleWright (see post way above) is just as accurate, easier to set/read, and although limited to 45 to 90 angles, it's sturdy enough to use as a guide for holding stock to be cut. It'll be interesting to see how the Wixey compares to that.

As for digital inclinometers, the best specs come from CMT's version +/-0.1º versus +/-0.2º for just about everyone else, but I haven't bothered to try that one. It's under $45, so maybe worth a try with Amazon's 30 day return policy....

EDIT: I may be wrong about the drum sander DRO update speed, now thinking about it more. The way it's mounted has a lot of slop in the sander's movement, but I'll have to try it again to see if there's a delay and if so, how much. Barry Wixey has answered emails in the past, so maybe I'll ping him.

 

[Mini Me]

Stick a magnetic digital inclinometer (like Wixey or Beale) on a table saw blade and tilt the blade quickly. You’ll probably see nothing change on the display until you stop because these inexpensive units have a pretty slow refresh rate.

Michael, I think you are causing confusion by using the term "refresh rate" and not resolution when referring to the amount of movement needed to see a digital change on the screen.

 

[Packard]

I have several CMT items (their flexible router template is genius), but until today I did not know that they made measuring instruments.  I don’t know whose fault that is, mine or CMT’s.

Their digital protractor is just $43.00 and that is enticing.

 

[smorgasbord]

I have several CMT items (their flexible router template is genius), but until today I did not know that they made measuring instruments.

The question is whether CMT is actually making them, or just putting their name and color on yet another Chinese version of the same basic item.

 

[smorgasbord]

I couldn't find CMT's spec sheet on the web anymore, but I did find the Owner's Manual:https://www.cmtorangetools.com/downloads/5648/228/DAG-001-2022-istruzioni WEB_VERS-2022-06.pdf

[attachimg=1]

CMT's Digital Protractor (DAF-001) only has a "resolution" spec, not an accuracy spec.https://www.cmtorangetools.com/na-en/systems-and-accessories/digital-angle-finder

That makes me doubt the usefulness of its 0.05º "resolution." I suppose if someone had a granite reference surface and sine bars, they could perform accuracy tests, but that's way beyond my capabilities...

 

[Packard]

I couldn't find CMT's spec sheet on the web anymore, but I did find the Owner's Manual:https://www.cmtorangetools.com/downloads/5648/228/DAG-001-2022-istruzioni WEB_VERS-2022-06.pdf

[attachimg=1]

CMT's Digital Protractor (DAF-001) only has a "resolution" spec, not an accuracy spec.https://www.cmtorangetools.com/na-en/systems-and-accessories/digital-angle-finder

That makes me doubt the usefulness of its 0.05º "resolution." I suppose if someone had a granite reference surface and sine bars, they could perform accuracy tests, but that's way beyond my capabilities...

The image you posted shows “accuracy”.  What is that referencing?  It says 1/10th of a degree.  Does that mean the total of accuracy and resolution is 0.2 degrees?

 

[Michael Kellough]

Stick a magnetic digital inclinometer (like Wixey or Beale) on a table saw blade and tilt the blade quickly. You’ll probably see nothing change on the display until you stop because these inexpensive units have a pretty slow refresh rate.

Michael, I think you are causing confusion by using the term "refresh rate" and not resolution when referring to the amount of movement needed to see a digital change on the screen.

It really is two different things.

With the D.I. attached to the circular saw blade, change the angle of the blade slowly and the display will change to the next “increment” when the movement exceeds 50% of the resolution.

Change the angle a lot (well more than the resolution) quickly and the display won’t change until the next scheduled update/refresh (reading speed) at which time it will show the new position.

Something I forgot to add before, to set a table saw blade to an angle in between the two closest angles that can be confirmed, use two sliding bevels set to those two angles, use feeler gauge to find the difference, than add the appropriate feeler gauge to smaller angle sliding bevel.

Of course what counts is the resulting cut. Expect to make an adjustment no matter how carefully you set the angle.

 

[Packard]

When I cut miters on the table saw (usually 30, 45, 60 and 90 degrees) I will check the cut with my try square or my combination square.  It is is really critical, I will make test cuts and check for fit. 

But I have one always-do-this-rule:  I will make as many test cuts as required until I get a satisfactory result.  I will not skip 15 minutes of setup and then fix it with 2 hours of filler and sanding.  I test until it is right.  It is frustrating sometimes, especially if I think the equipment is failing me.  But then I remember how frustrating using filler and sanding is.  So setup wins every time.

 

[Mini Me]

Stick a magnetic digital inclinometer (like Wixey or Beale) on a table saw blade and tilt the blade quickly. You’ll probably see nothing change on the display until you stop because these inexpensive units have a pretty slow refresh rate.

Michael, I think you are causing confusion by using the term "refresh rate" and not resolution when referring to the amount of movement needed to see a digital change on the screen.

It really is two different things.

With the D.I. attached to the circular saw blade, change the angle of the blade slowly and the display will change to the next “increment” when the movement exceeds 50% of the resolution.

Change the angle a lot (well more than the resolution) quickly and the display won’t change until the next scheduled update/refresh (reading speed) at which time it will show the new position.

Something I forgot to add before, to set a table saw blade to an angle in between the two closest angles that can be confirmed, use two sliding bevels set to those two angles, use feeler gauge to find the difference, than add the appropriate feeler gauge to smaller angle sliding bevel.

Of course what counts is the resulting cut. Expect to make an adjustment no matter how carefully you set the angle.

I have never heard or seen the term recovery rate when talking DRO's but most of my recent experience has been with linear DRO's for measurement and you are talking of angle measurement. I have used a lot of angle digital cubes in setting up race car geometry as well as woodworking machines and never seen it there either. My use of digital angle measurement goes back over 10 years so it is not a recent thing. To clear up things for those who are not familiar with this stuff linear measurement resolution is generally set by the tape the DRO relies on to make it work but the latest stuff coming out of China which I am using can have the resolution changed internally in the DRO. Angle cubes rely on a movement sensor in the DRO and those sensors are rated for how much movement is needed to change the reading. The sensitivity of the sensor is usually specified in the specs of the instrument.

 

[PaulMarcel]

I have and love the Bridge City Angle Master Pro v2 (AMPv2). You could think of it being the Shinwa gauge but with a digital Mitsutoyo (real, not Amazon) caliper on the hypotenuse. Printed on the body is a table for quickly converting angles to calipers or calipers to angles with a pretty fine resolution. There was a web app for doing the calculation if you wanted more resolution than the tables (IIRC, they went to ~1º). I used it to make a cabinet with each tier having 16 compound cuts. At the end, the last two pieces only had less than a 1/16" discrepancy. That convinced me I didn't have to look further.
I don't think the web app is still around after the transition to Harvey. I did, however, pull the sources long before that and write it up in an iPad app.

 

[festal]

...but I just trust the analog instruments more.

That's the reason I own 5 dial calipers and only 1 digital caliper.  [big grin]  The digital caliper is used less than 10% of the time. For the most part I use it to measure a dimension in a restricted area that's impossible to see the dial face of the dial caliper. With the digital caliper, I measure the part, then hit the zero button and after I've removed the caliper I can return it to the closed position and read what the part measured. It does work great for that.  [smile]

Great tip!

Yep !!!

 

[Packard]

...but I just trust the analog instruments more.

That's the reason I own 5 dial calipers and only 1 digital caliper.  [big grin]  The digital caliper is used less than 10% of the time. For the most part I use it to measure a dimension in a restricted area that's impossible to see the dial face of the dial caliper. With the digital caliper, I measure the part, then hit the zero button and after I've removed the caliper I can return it to the closed position and read what the part measured. It does work great for that.  [smile]

Great tip!

Yep !!!

A great way to “hold” the number for reference a little later.  I will try that too. 

 

[smorgasbord]

I have and love the Bridge City Angle Master Pro v2 (AMPv2). You could think of it being the Shinwa gauge but with a digital Mitsutoyo (real, not Amazon) caliper on the hypotenuse.

Thanks for the pointer - I didn't know about that product. Years ago (1990s), I got the AngleWright after looking at BCTW's protractor and deciding it wasn't close enough to what I needed.

Your 'Shinwa with a DRO' comment, though has me thinking about retrofitting or building the sliding hypotenuse type design with a DRO. Mine Shinwa is 60cm long so there's plenty of ruler travel.

Interesting that the BCTW design goes from 90º to 180º, my AngleWright goes from 45º to 90º, and the Shinwa goes from 20º to 135º (not so accurate on the higher end, though), and the Wixey digital is 0º to 360º (readout flips at 180 to countdown again).  I also appreciated your discussion of fractional degree settings on the BCTW using plain ole linear interpolation and still being super accurate - that's probably why my eyeball setting of 22.5º on the Shinwa brought up 22.5º on the digital Wixey.

Maybe an adopted Shinwa design using a linear DRO along a 60cm or so length would be a good way to set an angled fence on a tablesaw sled. Hmmm...