Miter gauge tolerance

[jussi]

Well after an hour of banging at the table and misinterpreting the measurements of the dial indicator (I'm not gonna explain further because I'll feel too stupid) I finally got it to 2-3 thousandths difference. I tried to get it closer but I quickly found it was a losing battle and figured that was as good as I could get.

Btw, I'm wondering if the pressure from the dial indicator skewed my results. It's an HF brand if that makes a difference. I'm just going to assume it didn't because I don't want to go through that again Thanks for all the input.

[ragswl4]

Well after an hour of banging at the table and misinterpreting the measurements of the dial indicator (I'm not gonna explain further because I'll feel too stupid) I finally got it to 2-3 thousandths difference. I tried to get it closer but I quickly found it was a losing battle and figured that was as good as I could get.

Btw, I'm wondering if the pressure from the dial indicator skewed my results. It's an HF brand if that makes a difference. I'm just going to assume it didn't because I don't want to go through that again Thanks for all the input.

Great, getting it to your satisfaction is what counts no matter how you do it. However I may retire my dial indicator and use C-Man's method. Sounds easy, accurate and quick. Besides, I like the coffee idea. (Thanks C-Man)

[poolhound]

I finally got it to 2-3 thousandths difference.

OMG J, how could you possibly leave it there you could drive a truck through that

Seriously you have got it nailed. Dont forget that you can easily introduce errors way bigger than that simply by marking your pencil cut line off a tad. A 0.5mm pencil lead is .020"

[jackellis]

I wrestled with this for about five minutes before I came to the conclusion Cabinetman did. We're talking about wood here and wood is going to move. If I'm within 1/64th, I'm pretty happy because that's about as small as I can reasonably measure something. I have a dial indicator but I'm not sure fussing over thousandths is worth the headache.

However...I also rarely use my miter gauge. Instead, I have two sleds. One that I like to think is more accurate though it does not slide easily in the miter gauge, and another that is somewhat less accurate but good enough for certain projects. Even on my Jet cabinet saw, the miter gauge bar moves around more than I'd like so it typically gets used only for quick and dirty cuts.

[SARGE..g-47]

I'm probably going to have a lynch mob gather at my shop door but.. I am going to make a statement here that I have truly been led to believe...

My BIL is a shop foreman in the machine shop at Delta Air Lines here in Atlanta. I worked for years with guys who restore old muscle cars and build engines. They are machinist and Need a Dial Caliper. I am a WW and simply do not.

Probably the saddest thing I have seen since I started WW'ing 37 years ago is putting a dial caliper in the hands of woodworkers. And especially when in many cases they don't really know how to use them and then how to evaluate what they did read.

I would suggest a cheap $5 feeler gauge from a local Auto Parts store. Take a good look at the .001.. .005.. .010.. .015 blade and you will realize that you couldn't force a Nat through a gap of .010 even if you strapped C-4 plastic explosives to his hinny and tried to blast him through.

You will compress Wood more than .005 on a glue-up with clamp pressure. Straigth wood with moiture content will move more than that over-night after you rip it before it regains balance as the cut exposes fresh wood that doesn't sit on the surface. Tension wood will move way more. I could go on but you should get the point.

If you don't physically notice a problem with your cross-cuts and rips then please don't dig out dial calipers and try to create one. If you work for NASA and engineer space capsule components.. you need them. If you are just a WW and are building something that is wood which will move season to season for the remainer of days of it's life with humidity.. leave the micro adjuster in the drawer where it belongs.

Sorry if this offends anyone but just one of my pet peeves....

[jackellis]

Sarge, you're sounding like an engineer!

I have an old drill press I bought used. It clearly has some runout and once I have it in a place where there's room to work on it, I'm going to see if I can fix it. Meanwhile, I don't have to worry about using slightly oversized bits when making holes in wood so bolts will slide easily.

If I had to make precise holes in metal parts, I'd ask my wife's BIL for help. He manufactures telescope mounts and has proper metalworking equipment.

[SARGE..g-47]

Sarge, you're sounding like an engineer!

I have an old drill press I bought used. It clearly has some runout and once I have it in a place where there's room to work on it, I'm going to see if I can fix it. Meanwhile, I don't have to worry about using slightly oversized bits when making holes in wood so bolts will slide easily.

If I had to make precise holes in metal parts, I'd ask my wife's BIL for help. He manufactures telescope mounts and has proper metalworking equipment.

Excessive is excessive, Jack. But.. I often wonder if many know just how much .005 really is and the reason I suggest everyone buy a cheap feeler gauge and just take a look occasionally. I believe that the manufacturers have taken advantage of this by marketing the various gizmos available on the market by WW suppliers.

I have seen some so convinced their machines must be .0000 before they can safely turn them on and make a cut.. much less actually build a bird house... they spend months in a attempt to get them fine tuned as a match grade rifle using in competition shooting.

On another forum a young gentleman started a thread about having .004 variance in a ripped board 36" long from front to rear. I asked why he felt that it mattered? His replay was he had purchased a Woodrat and that it requires exact stock dimentions fed to it to get an accurate outcome.

The bad news was that before I ask the question of why.. 7 people had already answered giving info on how to tune his TS and fence. I just find it rather sad with the current trend of precise.. precise.. precise before you can actually just go build something.

I suppose I should shake my head and not get involved to stay out of controvesy but.. this phenom just gets under my skin and I want to at least convey the message of:... just give it some thought and ask why you need to be under .001 which any race engine builder would be satisfied with any day of the week is really necessary with wood?

I'll get off my soap box now as I have to go tune by TS.. jointer.. planer.. and BS for the Daytona 500 tomorrow. And don't forget a coat of fresh wax to help air drag in the "draft"..

[gimpy]

Sarge, I am so sorry that you posted this comment when you did. I wish you had posted it earlier and that I had read it earlier. I just ordered me a dial indicator from Grizzly this past week :>( (haven't even received it, yet). Reading this would have saved me about $30. Oh, well, as my old boss used to say, "I spit on money" :>). JK.

Frank

[jackellis]

Article by Tom Hintz on accuracy: http://www.newwoodworker.com/accurcy.html

[SARGE..g-47]

Sarge, I am so sorry that you posted this comment when you did. I wish you had posted it earlier and that I had read it earlier. I just ordered me a dial indicator from Grizzly this past week :>( (haven't even received it, yet). Reading this would have saved me about $30. Oh, well, as my old boss used to say, "I spit on money" :>). JK.

Frank

Frank... the dial indicators have their place. But.. be sure you know how to use it and the proper methods of using it. Basically the same thing can be done with simplier equipment as pointed out by Cabinetman and others but.. the dial indicator will work.

I think the biggest issue is once you have used it correctly.. to not over analyze the significance of what you find. .005 does have significance to a machinist.. .005 doesn't really to a WW. Can you imagine how many pieces of furniture and cabinets have been built with a Uni-saw?

A Uni-saw is notorious for having on average a .008 arbon run out and if the blade is not perfectly machined and balanced that will transfer to even more. But... pieces have been built using them since 1937 when they arrived and other saws which are basic clones. When a craftsman builds a piece you cannot distinquish he used a Uni-saw.. Sawstop.. high $$ Felder.. etc.

There is a reason for that and it has little to do with a machine which has run-out as all (Repeat All) of them do. The manufacturers of the current measuring devices have done an excellent job of marketing them IMO.. and this is not a good thing for those just getting started. They seem to get brain-washed into thinking you must have all machines honed and tuned to extremely tight tolerances and these devices will detect when they are not and lead you to the "promised land".

The truth is.. you can do the same things with things you may already have around the shop and tolerances with Wood are no where near critical as they are with metal as wood moves and metal doesn't.

So.. use the device you have coming. Just use it wisely and with the knowledge that a machine doesn't have to be absolutely perfect to build a piece from wood. If it did... there would be no significant pieces ever built until the last decade and that as you know is just not the case.

If a machine needs real tuning.. it will tell you if you observe and start to understand it from the cut.. assembly.. etc. And.. if it ain't broke, don't attempt to create one with what has been thrown out for the public with clever marketing.

Good luck...

[poolhound]

I think the biggest issue is once you have used it correctly.. to not over analyze the significance of what you find. .005 does have significance to a machinist.. .005 doesn't really to a WW.

Wise words Sarge. I must admit I agree with all you say and being in the marketing field myself understand more than most how some folks can sometimes "overdo" the marketing.

As it happens I do own a dial indicator but just a HF cheapie. It helps to provide a visual indication of whatever adjustment one is trying to make but as you point out once you have something "close" you dont need to sweat it down to .001", as I pointed out earlier taking care with layout is much more important as cutting to one side or the other of a pencil line can make a .020" diifference. And of course thats not even getting into the issue you already eloquently discussed related to the fact that the stock you cut will probably change overnight between milling/cutting and glue up!

Even with the Dial indicator I still use the basic pan head screw and lump of wood technique (which worked perfectly for me) its just easier to look at the DI scale than listen for the same "ding" of tooth on screw