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View Graham's profile

Expectations for Table Saw Crosscut Accuracy...

by Graham
posted 04-26-2009 11:42 PM


19 replies so far

View Julian's profile

Julian

884 posts in 4131 days


#1 posted 04-26-2009 11:50 PM

What type of crosscut sled were you using? I can get dead on accurate crosscuts with my crosscut sleds I built. Just look at my projects, and you’ll get an idea of what you should have. That said, you also need to make sure the blade is dead on parallel with the miter slot before you can get accurate cuts. When checking your saw for runout, make sure to measure the distance from the blade to the slot using the SAME tooth on the blade. This will cancel any arbor runout or blade deflection that you may have.

-- Julian, Homewood, IL

View Graham's profile

Graham

19 posts in 3941 days


#2 posted 04-26-2009 11:53 PM

Thanks Julian,

I don’t have a crosscut sled. I am using an Incra Miter gauge to make the cuts.

There is about 0.001” of runout, as measured from the same point on the blade, from the miter slot.

View Graham's profile

Graham

19 posts in 3941 days


#3 posted 04-26-2009 11:58 PM

Wow that’s some really nice work on your project pages! I’ll have to put a crosscut sled on my project list. It looks quite useful.

lol and I have just made my first few cuts ever!

View marcb's profile

marcb

768 posts in 4279 days


#4 posted 04-27-2009 12:52 AM

To put that into perspective that is over 1/3 of 1/64th of an inch.

So go get your ruler and look at the 64th side, divide one of those segments you have trouble seeing into 3 parts and thats the amount of difference your seeing.

Also, unless someone trained you on using calipers your probably injecting a good amount of error into the reading yourself.

View Graham's profile

Graham

19 posts in 3941 days


#5 posted 04-27-2009 01:22 AM

yea. It’s pretty small, but is that considered exceptable by cabinet making standards? For most metal working it’s not, which is where my experience lies.

Thanks again.

View gwebb's profile

gwebb

13 posts in 3943 days


#6 posted 04-27-2009 01:41 AM

Just a disclaimer I’m pretty new to woodworking as well but here’s my thoughts.

I’d say for almost all woodworking applications (especially things as big as cabinets) that is more then accurate enough. Since wood has can expand and contract with varying environmental conditions measurements this small would be meaningless to a cabinet maker. The only time I might be worried about measurements that small is on very small, precise puzzles and then you certainly wouldn’t be making those cuts with just a miter gauge (check out this guys cross cutting sled http://www.instructables.com/id/Precision-Puzzlemaking-Primer----Volume-1/).

View Julian's profile

Julian

884 posts in 4131 days


#7 posted 04-27-2009 02:02 AM

.001 runout is acceptable for the blade to miter slot. The runout you have with your incra is not bad. It’s not perfect, but it will work well for you since you are just starting out. I suggest looking around the forum for table saw safety tips, and tricks. There is a wealth of knowledge, and a great group of people here to share with and learn from.

-- Julian, Homewood, IL

View marcb's profile

marcb

768 posts in 4279 days


#8 posted 04-27-2009 02:09 AM

As gwebb said, wood moves so any measurement you take will change depending on humidity, time of day, if you looked at it funny.

.005 is fine for a some metal working too, I’ve welded gaps bigger than that. Machining not so much, depending on spec.

Just to be sure you can also check how much runout you have at the arbor flange, if thats excessive you can clean that up a bit.

View Boardman's profile

Boardman

157 posts in 4367 days


#9 posted 04-27-2009 02:11 AM

There is much talk on these type of forums regarding tolerances, with some people shooting for a couple thou in accuracy. This is pointless in woodworking due to the nature of wood, and it’s ability to absorb and lose moisture, and the resulting changes in net sizes.

We ain’t building the space shuttle.

View Woodchuck1957's profile

Woodchuck1957

944 posts in 4369 days


#10 posted 04-27-2009 02:30 AM

If it can be done on a miter saw, thats where I go.

View Graham's profile

Graham

19 posts in 3941 days


#11 posted 04-27-2009 03:54 AM

Thanks folks.

As a software and motion control engineer I am used to working with non-organic materials like tungsten and various steels on the order of 1/10000 of an inch.

As a newcomer to woodworking I have not established a reference tolerance.

I have spent the last month completely rebuilding my new table saw, becuase the manufacturing and engineering is so shoddy compared to what I am familiar with.

I am trying to establish, from seasoned woodworkers, if I should tweak the saw more or would it be good enough for an expert craftsman as I have limited experience with organic materials

Thanks,
Graham

View PurpLev's profile

PurpLev

8554 posts in 4254 days


#12 posted 04-27-2009 04:13 AM

0.001 runout on the blade/miter guage is considered more than adequate for fine woodworking. with wood movement and esthetics, I think keeping a working scale of 1/64th for parts should be good enough – I believe that in reality, most times you get much better results than that, also thats what I’m seeing in your post (0.005” variations)... sounds like you got it tuned enough in my opinion, I wouldn’t worry about it too much.

althought, I’m surprised you’re getting those variations using an Incra miter gauge… heres what you should check:

1. miter gauge bar has no slop in the miter slot – use the plastic expandable washers to tighten the bar up.
2. make sure you butt the board to the stop, and keep an even pressure against it everytime (making sure that all pieces are pushed equally to the same stop spot)

in addition you could:

3. build a cross cut sled – using 2 runners, would eliminate more of that sloppiness in the slots, and give you a better safer way to crosscut in general

or even:

4. (as woodchuck suggested) use a mitersaw for cross cuts, if you really want the safest, and easiest way about it (space and budget allowing it)

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View TopamaxSurvivor's profile

TopamaxSurvivor

18783 posts in 4281 days


#13 posted 04-27-2009 04:14 AM

A master rifle maker once told me about tolerances, if it’s not distracting to the piece, it’s close enough.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Graham's profile

Graham

19 posts in 3941 days


#14 posted 04-28-2009 05:05 AM

Thanks PurpLev and Topa. That helps me start to establish a tolerance reference. I was able to get the blade runout down to less than 1/4 of a thousandths, which is about down to the noise in the indicator.

After reading my initial post I don’t think I was clear.

All of the pieces cut to the exact same length were dead nuts on relative to each other, but the absolute length was off by 0.000” to 0.005”. So it is extremely repeatable, but not completely on in absolute terms.

Tomorrow my Oneida Dust collector arrives, so I am pretty excited about that. On Friday my Incra TS-LS table fence arrives.

Be well,
Graham

View Don K.'s profile

Don K.

1075 posts in 3932 days


#15 posted 04-28-2009 05:37 AM

Wow…for a guy just starting out in wood working, your starting off with some good tools.

-- Don S.E. OK

View patron's profile

patron

13694 posts in 3947 days


#16 posted 04-28-2009 05:38 AM

in the enviroment i work in ,remodeling , and adding on to pre existing work 1/64” is acceptable .
as i have to hire help ( not allways the same guys ) , i have to go with what i get , and am lucky if they give me 1/16”. the union gives the framers 1/4” !
when i make shop work , i try to cut all wood sequentialy so as to keep any parralelogram or trapizoid variances
referenced the same .
but i do compleet interiors in weeks or 1 or 2 months , so don’t have the lucksury(?) of tacking my time ,
the volume of materials is exaustive and time is at a premium .
glad you have joined us , maybe we will learn tolerances from you .
be safe and enjoy
.

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Graham's profile

Graham

19 posts in 3941 days


#17 posted 04-28-2009 06:00 AM

Woodworking has been a dream for me. I finally made it!

My first projects are going to be a bunch of boxes. lol! I figure it’s a good way to practice various types of joinery.

Thanks again everyone for sharing your expertise. People here are quite nice. I hope I can be a positive contributor to Lumber Jocks.

Graham

View Gary's profile

Gary

9413 posts in 4038 days


#18 posted 04-28-2009 06:06 AM

Just dont mention the “L” word….things go really weird !

-- Gary, DeKalb Texas only 4 miles from the mill

View TopamaxSurvivor's profile

TopamaxSurvivor

18783 posts in 4281 days


#19 posted 04-28-2009 06:09 AM

Graham, I think you’ll find accuracy in angles is more important than cutting to +/- .005”. I don’t even own a dial indicator; wouldn’t know how to use it if I did. I do check my squares for “square” and measure diagonally to be sure.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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