Woodpecker's Align-A-Saw

[Chainring]

Alright, Anthony. How many corner sharpness tests have you done? Multiple focal lengths and apertures? I know that one all too well.

 

[jeffinsgf]

I'm going to mention something I ran into while working on the Align-A-Saw video, while trying to get the saw in my shop under .001" (something I would not recommend to anyone no matter how OCD).

If I ran my angle and/or height adjustment all the way to the stop and locked it, I would get a different reading than if I brought it to the stop and then just removed the backlash and ever so slightly released the tension against the stop.

I mention it because the error was weirdly non-linear, like you're seeing.

I've made the tension release part of my routine when making adjustments, and it seems to be yielding consistently better results.

 

[Cheese]

If I ran my angle and/or height adjustment all the way to the stop and locked it, I would get a different reading than if I brought it to the stop and then just removed the backlash and ever so slightly released the tension against the stop.

I mention it because the error was weirdly non-linear, like you're seeing.

I've made the tension release part of my routine when making adjustments, and it seems to be yielding consistently better results.

Jeff, that's also what the Saw Stop video is referring to...if I understand both comments correctly. The Saw Stop comment comes at the 2 minute mark of the video.

 

[Birdhunter]

I found a lot more variation in the miter slot to the SawStop Industrial fence than in the miter slot to the blade. My guess is the there is more blade deflection in the wood while cutting than the measurements being discussed here.

If I need a high precision cut, I make the first cut proud and then make the final cut to the exact desired dimension. In no case do I expect metal machining accuracy for wood cuts.

 

[jeffinsgf]

Jeff, that's also what the Saw Stop video is referring to...if I understand both comments correctly. The Saw Stop comment comes at the 2 minute mark of the video.

Apparently I stumbled into a known issue without knowing it.  [big grin]

 

[box185]

If I ran my angle and/or height adjustment all the way to the stop and locked it, I would get a different reading than if I brought it to the stop and then just removed the backlash and ever so slightly released the tension against the stop.

I think Steven Woodward also discovered this problem.

 

[ChuckS]

Snip
This is within the tolerances of ≤ 0.010 for a SawStop PCS, per the video:Snip.

I didn't know about the tolerances for the PCS until now.

I know my PCS cuts really well, and have never had any ripping issues. But curiosity drove me to do an alignment test based on the SawStop video.

Tools used after cleaning and marking the tooth (WWII blade)                                                  Result
[attachimg=1]                                                [attachimg=2]

The above was repeated one more time, and a similar result was obtained.

Even allowing for some checking inadequacy, the 0.001 to 0.0015 deviation proves the saw (miter slot to blade) is perfect in practical terms.

 

[4nthony]

I've given up on on the Saw Plate.

I backed off the height as Jeff suggested and that improved the tooth to tooth alignment on a couple saw blades.

- My 40T Ridge Carbide tested above improved to .004".
- The 80T SawStop and the Freud thin kerf improvements were

 

[Cheese]

Hey [member=75283]4nthony[/member],
I just looked at the Woodpeckers Align-A-Saw video and noticed that they use a 2-step grinding process. The first step is for an outside service to blanchard grind the saw plate and then the saw plate is brought in-house where it is surface ground. To put things into perspective, blanchard grinding is a process used to get material surfaces "close" to flat while precision surface grinding is a process used to get surfaces "perfectly" (within .0005" to .000001" or less) flat.
Blanchard grinding is typically used to condition a flywheel or pressure plate surface and thus a surface flatness of .002" to .004" would be good enough given the end use of these items.

When I first looked at your photos the other day, the first thing I noticed was the strong blanchard grinding marks on your saw plate and thought that was unusual because they were deeper/more defined than they should be which would skew your indicator readings.

However, now knowing that Woodpeckers utilizes a double grinding process, I think your saw plate was blanchard ground and for some reason never went through the final surface grinding operation.

Blanchard grinding will leave circular grinding marks on the surface, while precision surface grinding will leave long parallel grinding marks on the surface. I'd have a long conversation with Woodpeckers about this because there is no area that I can see on your saw plate that has been surface ground.

Here's what your ground saw plate looks like.

[attachimg=1]

And here's what a surface ground plate should look like. This is certainly not the best example (rather crude really) but it does show the straight line grinding pattern that's missing from your saw plate.

[attachimg=2]

 

[4nthony]

Hey [member=75283]4nthony[/member],
I just looked at the Woodpeckers Align-A-Saw video and noticed that they use a 2-step grinding process. The first step is for an outside service to blanchard grind the saw plate and then the saw plate is brought in-house where it is surface ground. To put things into perspective, blanchard grinding is a process used to get material surfaces "close" to flat while precision surface grinding is a process used to get surfaces "perfectly" (within .0005" to .000001" or less) flat.
Blanchard grinding is typically used to condition a flywheel or pressure plate surface and thus a surface flatness of .002" to .004" would be good enough given the end use of these items.

When I first looked at your photos the other day, the first thing I noticed was the strong blanchard grinding marks on your saw plate and thought that was unusual because they were deeper/more defined than they should be which would skew your indicator readings.

However, now knowing that Woodpeckers utilizes a double grinding process, I think your saw plate was blanchard ground and for some reason never went through the final surface grinding operation.

Blanchard grinding will leave circular grinding marks on the surface, while precision surface grinding will leave long parallel grinding marks on the surface. I'd have a long conversation with Woodpeckers about this because there is no area that I can see on your saw plate that has been surface ground.

Interesting find. There's a night and day difference in the two sides of my plate. The side with the logo is so smooth that the dial indicator left a bunch of streaks. The other side, with the faded sharpie numbers, not so much. In the Deep Dive video, Jeff uses both sides to take measurements. And if both sides are supposed to be surface ground, then you're right in that mine missed a step.

I was out in the garage OCD'ing over this tonight, because, Saw Plate...

I also saw their "production update" video, and it's mentioned that the tolerances are "one-thousandth of an inch", not the .002" on the website description.

Though, what caught my eye was the guy measuring flatness:

A lightbulb turned on and I realized what Jeff meant when he said:

Do you have a stand or a 1-2-3 block where you could use your dial indicator to measure the plate with it flat on the table top? If it's out of spec, please get in touch with Customer Service.

I rigged up my dial indicator onto a piece of scrap and clamped it as snug as possible to the 1-2-3 block. I slid the block along the table and noted some deviation.


Then I started thinking my tables are probably not perfectly flat and maybe the 1-2-3 block is riding across undulations in the table. Do I want to check every inch of cast iron to look for a perfect 12" section that I can use to check if the plate is flat? How far down this rabbit hole do I want to go?

I still haven't heard back from Woodpecker's customer service, though this isn't the first time I've tried to contact them via the website and didn't hear back. I'll pick up the phone on Monday and see where it gets me. Hopefully the person I get on the phone will also know the difference in grind types.

Thanks [member=44099]Cheese[/member] !

 

[rvieceli]

[member=75283]4nthony[/member] You really need a CALIBRATED reference surface plate and an indicator holder with no flex to take meaningful measurements of the plate.

Woodpeckers has a 30 day return policy for a full refund without a restocking fee. You would normally be required to pay shipping. Given that you seem to have gotten an example that slipped through quality control, I'd be sure to request a return shipping label on their dime.

Up to you on whether you want to try again with another one or toss in the towel and just get the refund.

Ron

 

[derekcohen]

I rigged up my dial indicator onto a piece of scrap and clamped it as snug as possible to the 1-2-3 block. I slid the block along the table and noted some deviation.

Are you measuring the plate or your table?

Regards from Perth

Derek

 

[Michael Kellough]

A guy like you should have a granite test plate. More generally anyone who owns a dial indicator should have a truly flat reference surface and a couple of ways to hold the indicator.

To properly test that WP plate you need to clamp the opposite side arbor area on top of a 1-2-3 block which is on top of a granite surface plate/stone. (You need to test whether the part that engages the arbor is parallel to the surface you are try to make parallel to the miter slot. To that end, both sides of the plate should be surface ground.)

Then mount your indicator to a stable enough fixture that you can run it across the same surface plate. An 8x10 stone might be big enough but bigger is better.

But your test is good enough to show that your WP plate should be replaced, or if you’re generous, just don’t use that really bad end.

 

[Cheese]

There's a night and day difference in the two sides of my plate. The side with the logo is so smooth that the dial indicator left a bunch of streaks.

That's exactly what the indicator tip should do, it should leave marks on the precision ground surface.  [smile]
While at the same time, if you place some Dykem on the end of the indicator tip and move it along the blanchard ground surface, that surface will probably remove some of the Dykem from the indicator tip.

Like Ron, Derek & Michael mentioned, you should think about "owning" a flat surface.  [smile]  I purchased one of these from Woodcraft for around $35, Woodcraft puts them on sale about every 6-8 months. For the money it really is a steal and you can also attach 3M lapping film on it and flatten the backs of chisels or plane blades. The equivalent item with the equivalent specs would cost $206 if it has the Starrett name on it.
https://www.woodcraft.com/products/granite-surface-plate-9-x-12-x-2-a-grade

 

[4nthony]

Are you measuring the plate or your table?

I considered that, hence my previous comment:

Then I started thinking my tables are probably not perfectly flat and maybe the 1-2-3 block is riding across undulations in the table. Do I want to check every inch of cast iron to look for a perfect 12" section that I can use to check if the plate is flat? How far down this rabbit hole do I want to go?

I did a few more tests, passing the plate under the dial indicator. My thinking was the 12" of plate would pass over any changes in table flatness. I thought I had a clip of the surface ground side but I guess I only hit record on the blanchard ground side.


Is the glass I rested the block on flat? None of my cast iron is perfectly flat. I'm chasing perfection in an imperfect environment.

Woodpeckers has a 30 day return policy for a full refund without a restocking fee. You would normally be required to pay shipping. Given that you seem to have gotten an example that slipped through quality control, I'd be sure to request a return shipping label on their dime.

I'll see what they say on Monday. Unfortunately, I tossed the packaging it came in on the day it arrived.

My local Woodcraft has the granite plate in stock. Maybe I'll dive just a tiny bit deeper down this rabbit hole...

Thanks all!

 

[grbmds]

Woodpeckers has always provided the highest level of service to me; at least once beyond even what I would have expected. If the plate doesn't meet their stated specs, I believe they would replace it. I can't believe they would want you to be dissatisfied because their product didn't meet their specs.

 

[dicktill]

Ah, one of my pet peeves of indicator measuring, and extremely common. With this type of indicator, the arm needs to be parallel (or as close as possible to parallel) to the surface being measured or you get the dreaded "cosine error". In the screen capture above, the arm is about 45 degrees to the surface being measured, and hence a change in the surface of say 0.010" will read about 0.007" on the dial, i.e. 0.010" times cosine 45 degrees = 0.010" times 0.7071 = ~0.007".

With the "other type" of dial indicator (plunge type), a similar error can occur if the plunger isn't perpendicular to the surface being measured, but this is less commonly abused to a great extent.

You can confirm my analysis by sticking a 0.010" feeler gauge under the arm or plunger and see what reading you get.

 

[Cheese]

Ah, one of my pet peeves of indicator measuring, and extremely common. With this type of indicator, the arm needs to be parallel (or as close as possible to parallel) to the surface being measured or you get the dreaded "cosine error".

Ya, that's always been an issue and most people are not aware of it. Brown & Sharpe and Starrett claim the difference is negligible if the arm angle is 15º or less, while Interapid indicators are designed to give a true reading when the arm angle is 12º.

I find it easier to adjust the arm angle to 15º or so rather than trying to place the indicator at 12º, although I'm sure Interapid's method is more accurate. Interapid even refers to its vertical & horizontal indicators as the INTERAPID® 312 Vertical & Horizontal Models.

 

[dicktill]

Ah, one of my pet peeves of indicator measuring, and extremely common. With this type of indicator, the arm needs to be parallel (or as close as possible to parallel) to the surface being measured or you get the dreaded "cosine error".

Ya, that's always been an issue and most people are not aware of it. Brown & Sharpe and Starrett claim the difference is negligible if the arm angle is 15º or less, while Interapid indicators are designed to give a true reading when the arm angle is 12º.

I find it easier to adjust the arm angle to 15º or so rather than trying to place the indicator at 12º, although I'm sure Interapid's method is more accurate. Interapid even refers to its vertical & horizontal indicators as the INTERAPID® 312 Vertical & Horizontal Models.

Makes sense: the cosine of 12 degrees is 0.978, and of 15 degrees is 0.966, so only "a-couple-three" percent error anyway, even if they didn't calibrate at that/those spots. It's when you get into larger angles that the error soars.

 

[4nthony]

I spoke to Woodpecker's this morning. They are sending out a new plate as a warranty claim.

Thanks everyone for the feedback.

Edit:

On the topic of flatness, I found this video interesting: