Dial Indicators for Calibrating Power Tools - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 36 Old 11-15-2018, 01:41 PM
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Quote:
Originally Posted by TomCT2 View Post
...shrinking wood
so what? it shrinks, it grows. stop and think about what you're doing.
you're not trying to set the fence 5.6735" from the blade.
you're trying to have zero distance difference from one end to the other end of the miter slot.
it does not matter if the fence is 5.6735" from the blade or 10.00001" from the blade - is the blade / fence parallel to the miter slot is the question / aim / goal.
if you slide the dial indicator down the fence and it jumps half-way around the dial, that could indicate some attention is required....

How close is close enough?
that is for the individual to decide based on their own needs and degree of workmanship.
however, it does make a difference. the typical thin kerf blade = 3/32 = 0.09375"
if you're happy with +/- 1/64" (0.015625") blade alignment, the saw has to chew out an additional 2x(1/64) - 30+% wider kerf/more wood.

if one makes the effort to align the blade and the fence, I - at least - notice the difference in push force, work piece steering, and eventually end accuracy on furniture size pieces of wood. slicing 1/4" slats off 5/4 rock maple - also noticeable. I'm very prone to cutting stuff over size, then fine cutting it to the final dimension - meaning I'm often taking off less that half a kerf width - so a gliding-no-effort pass thru the saw makes a difference in my world.

I like to keep the saw heel within .002" and the fence within 0.005"
this can be done with a stick or a combi-square, or a dozen other "tools" - or a dial indicator. the degree of bending / stooping / peering / light gapping / effort / experience varies.

I have to chuckle at the dead batteries theory. my digital caliper has an auto shut off - the battery is still going strong at 4 years and counting. the Wexley digital protractor at three years and counting - so it's something I personally can live with - especially as I have a spare battery in the drawer - which by the time I need it, will likely be dead.

"is the blade / fence parallel to the miter slot is the question / aim / goal." Only if you are setting up for a crosscut operation.

Having the fence parallel to the blade IS WHAT YOU WANT for a rip operation. The miter slot is not even needed for a rip except to mount accessories.


George
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post #22 of 36 Old 11-15-2018, 05:09 PM
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Quote:
Originally Posted by TomCT2 View Post
...shrinking wood
so what? it shrinks, it grows. stop and think about what you're doing.
you're not trying to set the fence 5.6735" from the blade.
you're trying to have zero distance difference from one end to the other end of the miter slot.
it does not matter if the fence is 5.6735" from the blade or 10.00001" from the blade - is the blade / fence parallel to the miter slot is the question / aim / goal.
if you slide the dial indicator down the fence and it jumps half-way around the dial, that could indicate some attention is required....

How close is close enough?
that is for the individual to decide based on their own needs and degree of workmanship.
however, it does make a difference. the typical thin kerf blade = 3/32 = 0.09375"
if you're happy with +/- 1/64" (0.015625") blade alignment, the saw has to chew out an additional 2x(1/64) - 30+% wider kerf/more wood.

if one makes the effort to align the blade and the fence, I - at least - notice the difference in push force, work piece steering, and eventually end accuracy on furniture size pieces of wood. slicing 1/4" slats off 5/4 rock maple - also noticeable. I'm very prone to cutting stuff over size, then fine cutting it to the final dimension - meaning I'm often taking off less that half a kerf width - so a gliding-no-effort pass thru the saw makes a difference in my world.

I like to keep the saw heel within .002" and the fence within 0.005"
this can be done with a stick or a combi-square, or a dozen other "tools" - or a dial indicator. the degree of bending / stooping / peering / light gapping / effort / experience varies.

I have to chuckle at the dead batteries theory. my digital caliper has an auto shut off - the battery is still going strong at 4 years and counting. the Wexley digital protractor at three years and counting - so it's something I personally can live with - especially as I have a spare battery in the drawer - which by the time I need it, will likely be dead.
Read the whole post. Almost the entire thing discusses blade runout (wobble) and the non-need for ultra accuracy in measuring it. Too many sloppy factors go into building a common woodworking table saw. Spindles are not straight, bearings are loose, and blade washers are ugly stamped steel affairs. Unless you super accurize the rotating parts of your unit (which is not easy nor cost effective), you WILL have runout on your blade. This runout is why setting up the blade to the miter slot is accurate ONLY if the measurement is taken with the blade in the exact same spot every time. Rotate the blade as little as a quarter turn and your indicator will read a different number. I can align the blade and slot with a metal rule well accurately enough that you would never know the difference performance wise.

I do not crosscut on a table saw because it is almost always more difficult and less accurate to move the work than the tool... and it is almost impossible for a TS cut to be more accurate than a tool with the blade on top where you can align your cut by eye much more precisely. Therefore, at least at this time, I couldn't care less where my miter slot is in relation to the blade.

There are also much faster and easier ways to competently align the fence parallel to the blade without taking complex measurements. And again, none of these measurements are used on the Hubble telescope. There is no need for the blade to be a half a thou to the fence when, again, rotate the blade a quarter turn and lose that half. I will put my table saw performance up against any mass production built saw out there. I have for many years, and still do, make very nice examples of woodcraft. I do not struggle with my tools, nor do they let me down in the accuracy department. Any mistake made is by me, not my tools.

By the way, I'll bet most of you guys and girls lay out the measurements on your boards using a tape measure and pencil. There's your 64th (if not a click more) of an inch loss of accuracy folks.

Cheers,
Mark

Another $000,000,000.02 worth of advice,
Mark
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post #23 of 36 Old 11-15-2018, 05:25 PM
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run out
and
parallel
are.
not.
the.
same.
thing.


RTFM. the guy wanted to know if a dial indicator was handy to help set up his saw.

it is.
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post #24 of 36 Old 11-15-2018, 05:50 PM
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rollout and run out .....

I will bet the arbor has runout and the blade has runout, and the washers/flange has runtout. We either care or we don't.

It may be possible to find a sweet spot where the runout is minimized by rotating the blade relative to the flange. Start with a marked tooth at 12 O'clock, go to 3, 6 and 9 to see what happens.
On my saws I sanded the inner surface of the washers until there are no machining marks. I may have held a stone to the flange surface while it was rotating to true that up, I can't remember but it's solution. That won't fix the arbor shaft if it wobbles, however.... well it could... but you wouldn't want to remove much material at all. If it's really bad, time for major surgery.

This all boils down to the mind set of the guy who inspects the parts as they come off the line. They expect and accept a certain variation, and the better saws have less tolerance, a smaller range of acceptance. Given modern machining practices I would say it's pretty hard to get a messed up arbor, but I could be wrong. Not any threads here on that subject.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 11-15-2018 at 08:18 PM.
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post #25 of 36 Old 11-15-2018, 07:16 PM
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Quote:
Originally Posted by TomCT2 View Post
run out
and
parallel
are.
not.
the.
same.
thing.


RTFM. the guy wanted to know if a dial indicator was handy to help set up his saw.

it is.
If you measure the fence perfectly PARALLEL to the blade, the fence will lose that perfect parallel when you spin the blade half a turn... get this... due to the runout of the blade. You cannot, nor do you need to, align anything on a production made table saw that closely. You will also lose that perfect parallel the first time you move the fence. Nothing on the machine will hold down to one or two thousandths with repeatable accuracy.

"the guy wanted to know if a dial indicator was handy to help set up his saw".

If you want to putz with your machine, have at it. Otherwise, it is not that handy.
FrankC likes this.

Another $000,000,000.02 worth of advice,
Mark
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post #26 of 36 Old 11-15-2018, 07:43 PM
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I don't know how many people here follow Pinterest, it is an eye opener, some of the work arounds that guys in less privileged parts of the world come up are ingenious solutions to problems we can solve with a visit to a local tool store. It kind of takes me back a few decades when I was in a similar situation.

Wise men speak because they have something to say; fools because they have to say something -Plato

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post #27 of 36 Old 11-15-2018, 08:11 PM
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Quote:
Originally Posted by woodnthings View Post
I will bet the arbor has runout and the blade has runout, and the washers/flange has runtout. We either care or we don't.

It may be possible to find a sweet sport where the runout is minimized by rotating the blade relative to the flange. Start with a marked tooth at 12 O'clock, go to 3, 6 and 9 to see what happens.
On my saws I sand the inner surface of the washers until there are no machining marks. I may have held a stone to the flange surface while it was rotating to true that up, I can't remember but it's solution. That won't fix the arbor shaft if it wobbles, however.... well it could... but you wouldn't want to remove much material at all. If it's really bad, time for major surgery.

This all boils down to the mind set of the guy who inspects the parts as they come off the line. They expect and accept a certain variation, and the better saws have less tolerance, a smaller range of acceptance. Given modern machining practices I would say it's pretty hard to get a messed up arbor, but I could be wrong. Not any threads here on that subject.
Stamped blade washers are the leading culprit of a wobbly saw blade. I attempted to turn a pair of washers true, but could only get them "close". They are tough to hold true in the lathe chuck. Precision washers can be purchased, but I made a pair some time ago that work well.

When I reference arbor shaft wobble, I don't mean a damaged shaft. I, like you would assume that very few "bad" spindles get to the production line. But most mass production pieces are fairly rough machined and the threads rolled instead of cut because, well, they're simply cheaper and faster to make. They just aren't required to have the tolerances of a precision machine.

Last but not least are the bearings that are normally installed at manufacture. Again, precision bearings are rarely used in a mass production machine because they cost too much. I just spent 400 bucks on just the two spindle bearings for my Bridgeport mill, as they are ABEC 9 bearings. I'd be surprised if any Craftsman saw had over an ABEC 5 bearing. I've seen arbor assemblies that you could take a bar and "lift" the spindle in the bearing housing (which means the blade could "lift" that same amount), and see it with the naked eye.

The only point I've tried to make is that precision and accuracy are relative terms. If a machine needs to hold extreme tolerances, it should be built to hold those tolerances. And its accuracy must be repeatable. Unless you have purchased a super high end table saw (I believe there are actually a couple of brands out there), your machine was simply not built to hold precision tolerances. But it doesn't have to; woodworking rarely requires such high accuracy. That doesn't mean all of our saws are junk; they aren't. It just means that it is entirely possible, and feasible to tune your tool to do a fine job without complicated equipment or four decimal point measurements.

Cheers,
Mark

Another $000,000,000.02 worth of advice,
Mark

Last edited by Shop_Rat; 11-15-2018 at 08:13 PM.
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post #28 of 36 Old 11-16-2018, 01:14 AM
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Hi


Here is my advice to the O.P., The inexpensive dial indicator from H.F. will work great for what you are planning on using it for. As for what to mount it too, you can do like I did and us some scrap wood and make a holder like this one. And more then likely, after you are done calibrating your tools the dial indicator is going to end up on a shelf for a very long time.
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post #29 of 36 Old 11-16-2018, 09:45 AM Thread Starter
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A big thank you to all who contributed. I got lots of good ideas and advice from everyone.

My original question was (refined and paraphrased):

"I would like to try using a dial indicator to set up my table saw. I found these two old Starrett dial indicators. Should I fix them up or buy a new cheap one?"
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post #30 of 36 Old 11-16-2018, 11:39 AM
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Way too funny!

Quote:
Originally Posted by Tool Agnostic View Post
A big thank you to all who contributed. I got lots of good ideas and advice from everyone.

My original question was (refined and paraphrased):

"I would like to try using a dial indicator to set up my table saw. I found these two old Starrett dial indicators. Should I fix them up or buy a new cheap one?"

Yes, if you want to do it that way, but not required.

Yes, because they are cool! It may be covered under warranty?

Yes, because cheap ones are pretty darn good!

That was too simple.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #31 of 36 Old 11-16-2018, 01:39 PM
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FWIW, I use a dial gage to set the height of my jointer knives and wouldn't do it any other way. So, IMO, yes they are a valuable tool. If I had a Starret I'd be in heaven, but a cheapie has got me by for many years.

Also, I made a thread a while ago about table saw setup...

https://www.woodworkingtalk.com/f12/...p-blog-191466/

And I mark the reference disc and rotate it as appropriate.

YMMV of course.

Dave in CT, USA
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post #32 of 36 Old 11-16-2018, 02:05 PM
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Well I guess it would not be a very interesting hobby if we didn't get to use as many tools as possible, check out some of the machinist groups to see how carried away some guys can get making attachments for their lathes and milling machines, great way to while away an hour or two.

Wise men speak because they have something to say; fools because they have to say something -Plato

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post #33 of 36 Old 11-16-2018, 02:26 PM
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Quote:
Originally Posted by Tool Agnostic View Post
A big thank you to all who contributed. I got lots of good ideas and advice from everyone.

My original question was (refined and paraphrased):

"I would like to try using a dial indicator to set up my table saw. I found these two old Starrett dial indicators. Should I fix them up or buy a new cheap one?"
Fix the Starretts, buy a cheap import to use in the woodshop. Sawdust kills precision measuring equipment pretty easily, don't subject the good stuff to it when you can use the $10 okay stuff. Hurts less killing a Shars...

I need cheaper hobby
etsy.com/shop/projectepicfail
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post #34 of 36 Old 11-16-2018, 03:43 PM
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Quote:
Originally Posted by Maylar View Post
FWIW, I use a dial gage to set the height of my jointer knives and wouldn't do it any other way. So, IMO, yes they are a valuable tool. If I had a Starret I'd be in heaven, but a cheapie has got me by for many years.

Also, I made a thread a while ago about table saw setup...

https://www.woodworkingtalk.com/f12/...p-blog-191466/

And I mark the reference disc and rotate it as appropriate.

YMMV of course.

well, you're doing that all wrong. supposedly you're to use a stick to make the fence parallel to the blade . . . the real pros apparently don't worry about adjusting things to miter slots - must be passe.
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post #35 of 36 Old 11-17-2018, 07:23 AM
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Let's do the geometry ...

Quote:
Originally Posted by TomCT2 View Post
well, you're doing that all wrong. supposedly you're to use a stick to make the fence parallel to the blade . . . the real pros apparently don't worry about adjusting things to miter slots - must be passe.
If plane AA to made to be parallel to plane BB, and plane CC is made to be parallel to plane BB, THEN plane AA is parallel to plane CC. This is where the blade is plane AA, the miter slot is plane BB and the fence is plane CC.

Why use the miter slot? It's the only non-adjustable reference on the table saw top. The blade/trunnion/carrige is adjustable and the fence is adjustable, but not the miterslot, it's milled in at the factory.

Why use the miter slot? As it's name implies it's, used with the miter gauge for crosscutting, the other primary operation performed with the table saw. Here's why. If the blade is "skewed" in relation to the miter slot, none of your cross cuts will be square on the ends and they may result in burned surfaces because your pushing it across the blade at an angle.

Why use the miter slot? If you use a sled it slides in the miter slots as well. If the blade is skewed to the miter slots the same thing will happen as above. If you only adjust the blade and fence to be parallel to one another, that would eliminate a primary function of the tablesaw and that does not make any sense.

Obviously, if the only operation performed on the saw is ripping, you don't need the miter slots for any reason and you could just fill them in with Bondo. Straight line rip saws, the commercial ones I've seen, don't have miter slots. The use a power track type feeder with pads that propels the work through the blade at a rather high rate of speed. I was the "catcher" at the outfeed end of one for a short while and I could barely keep up with the flow.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 11-17-2018 at 07:30 AM.
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post #36 of 36 Old 11-17-2018, 12:20 PM
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Grizzly has a video that is worth watching on how to adjust a table saw:


This video includes a step to check the blade when it is tilted and how to align it, which is often overlooked.

Wise men speak because they have something to say; fools because they have to say something -Plato

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