LumberJocks

Marking error

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by MrRon posted 12-28-2011 02:48 AM 1476 views 0 times favorited 17 replies Add to Favorites Watch
View MrRon's profile

MrRon

3926 posts in 2705 days


12-28-2011 02:48 AM


As the sketch shows, marking a dimension with a lead pencil will result in an error of almost 1/64” greater than what you want. Using a marking knife can bring that error down to just a couple of thousands.


17 replies so far

View TCCcabinetmaker's profile

TCCcabinetmaker

930 posts in 1817 days


#1 posted 12-28-2011 07:05 AM

So you’ve never heard “take the line” before?

On this kind of duplicating you always take the line, otherwise you’ll add. I however use a .5m pencil so So theat reduces my inaccuracy by a 256th anyways. Marking knives are great in some cases, but not all. They have their place, and I’ve even pulled out a pocket knife to mark in a pinch before….

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View doordude's profile

doordude

1085 posts in 2445 days


#2 posted 12-28-2011 07:19 AM

i also use a .5m pencil. you’ve got to decide to take the line or leave it when you cut.
or leave the line and sand or plane down to it.

View David Craig's profile

David Craig

2136 posts in 2570 days


#3 posted 12-28-2011 07:44 AM

Very good demonstration on how much difference there is between a pencil mark and a marking knife Mr. Ron. I agree that slicing is much more accurate than penciling.

I am getting older and my eyes are not the same as they were a few years ago. I use a mechanical pencil so I can see the line better. I have learned that, as long as the marking device and the decision to “take the line” or not “take the line” is consistent, the rest works itself out naturally by relativity. When I get into trouble is when I change pencils and grab whatever is close to me, change measuing device in the middle of a project (tape measure one minute, folding ruler the next) or cut to the line or wipe out the line inconsistently with each cut.

David

-- There is little that is simple when it comes to making a simple box.

View TCCcabinetmaker's profile

TCCcabinetmaker

930 posts in 1817 days


#4 posted 12-28-2011 07:48 AM

David,
I carry several brands of measuring tapes, not because I like one over the other, but because if someone else gives me a measurement, the stanly doesn’t always line up with the craftsman, the lufkin and so on. If I know they use a stanley fatmax, I can match them fairly closely, if they use a craftsman tape… so on and so forth.

But most of my pencils are .5s, though I do have som .7s but I have no lead for those lol.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View David Craig's profile

David Craig

2136 posts in 2570 days


#5 posted 12-28-2011 07:56 AM

Then you know the drill TCC :) There was one time a buddy and I ended up on an unexpected cutting and fitting project and neither one of us had a measure on us. We ended up doing all of our measuring by using the span of his thumb and forefinger, which he knew was 9 inches in between. It wasn’t a large, exacting project, but the ratios on everything were correct and it was kind of amusing to say the least.

-- There is little that is simple when it comes to making a simple box.

View MrRon's profile

MrRon

3926 posts in 2705 days


#6 posted 12-28-2011 08:24 PM

I use 0.7mm leads because they don’t break as easily. You can also get 0.3mm leads, but they are too fragile.

View PurpLev's profile

PurpLev

8523 posts in 3110 days


#7 posted 12-28-2011 10:50 PM

as long as you cut all the parts at the same time, that 1/64th error will transfer to all the parts involved and will not make any difference to the final project.

markings only go so far and are only used in certain stages of the project. not all parts rely on free measured markings. thats why gauges and transfer techniques and tools will always have a place in the shop.

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

View Viking's profile

Viking

878 posts in 2657 days


#8 posted 12-29-2011 03:38 AM

Woodworking to a 64th?

-- Rick Gustafson - Lost Creek Ranch - Colorado County, Texas

View jeth's profile

jeth

249 posts in 2300 days


#9 posted 12-29-2011 04:33 AM

I think at the end of the day any method of marking is only as good as your eyes and measuring and marking devices permit. Real accuracy comes from always using a reference, when I mark a line, even with a knife, it is normally a rough guide, a little over size, and the tools are then used to fine tune, planing, sanding etc to fit.

View MrRon's profile

MrRon

3926 posts in 2705 days


#10 posted 12-29-2011 05:24 PM

I’m not trying to get everyone to work in thousands or even 64’s. I personally try to work to as close as I can get to a line. I know I will still be off, but the resultant error will be much smaller.

View Nomad62's profile

Nomad62

726 posts in 2420 days


#11 posted 12-29-2011 06:28 PM

I do as WudnHevn does, I make the marks and move my straightedge to where my #2 pencil puts it’s point to the wood and it’s mark. I make an awful lot of mistakes, and it’s irratating when things don’t work right ; so, while working down to a 64th may seem overkill, sometimes it’s what it takes for a hack like me to get something close enough for a reasonable level of satisfaction. Nice post, good info.

-- Power tools put us ahead of the monkeys

View NBeener's profile

NBeener

4808 posts in 2636 days


#12 posted 12-29-2011 08:59 PM

I’m grateful for the graphic message, too.

I started off with the venerable #2 pencil, but … rather quickly switched to 0.5/0.7mm mechanical pencils, and/or marking knives/utility knives for just that reason: it turned out to be less important to have a highly visible line, then … to have one be … exactly where I needed it to be.

In any case, you still have to pay close attention to the angle at which you hold … whatever marking implement you use. While a regular pencil may amplify this effect even more … so can nearly anything, if used wrong.

Also … it’s a simple matter to take a #2 pencil TO your cut line, to increase its visibility—pretty important for THIS LumberJock ;-)

-- -- Neil

View MrRon's profile

MrRon

3926 posts in 2705 days


#13 posted 12-29-2011 11:14 PM

Whenever I cut wood, if the cut needs to be exact, I always cut a acrap piece of wood, measure it; make adjustments as needed until the cut is exact before cutting my work piece. It takes more time, but I think it’s time well spent. If you cut something too short, you can’t get it back.

View hObOmOnk's profile

hObOmOnk

1381 posts in 3589 days


#14 posted 12-29-2011 11:31 PM

Excellent illustration!

I follow the Japanese way and always compensate for my maker when laying out cut lines. I cut to-the-line not on-the-line. In order of preference, I mark cut lines with the following tools:
1. 0.5mm mechanical pencil.
2. Sumisashi – a bamboo Japanese ink line pen that can be sharpened to a knife edge.
3. Marking knife or a kebiki (Japanese marking gauge).

I use a Japanese sashigane square, which has a lift-off at the edge that allows marking directly at edge, or even slightly under.

Blessings.

-- 温故知新

View ChuckV's profile

ChuckV

2880 posts in 2989 days


#15 posted 12-29-2011 11:36 PM

I use this mechanical pencil with very thick 3mm lead. It does not break during use. You can put a very fine point on the lead with the sharpener built into the pencil. With such a sharp point, you can mark just as close to the ruler as with the thin lead as long as you angle the pencil so that the side of the point is perpendicular to the surface of the wood, which is very easy to learn.

If I am about to do a lot of marking, say for dovetails, I use sandpaper to sharpen the tip of the lead like a marking knife. It works great.

Another advantage to the thick, strong lead is that you can have a long length of it sticking out so that the body of the pencil does not interfere.

-- “Big man, pig man, ha ha, charade you are.” ― R. Waters

showing 1 through 15 of 17 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com