Measuring/Marking/Cutting strategies

[balzac.thegreat]

I find myself always ending up with shorter dimensions than I had planned because I guess I'm not leaving enough "wiggle room" for when my marking and cutting between workpieces isn't exactly the same (which is pretty much always).

Can you guys talk about your measuring and marking strategies to avoid these kinds of imprecisions or talk about how best to mitigate them. As a general rule of thumb what "extra" do you leave on a cut to account for this if any?

Any tips and tricks about accurate marking between multiple workpieces would be most helpful as well.

Thanks in advance!

[chopnhack]

From cutting and installing a lot of trim, you need to become more accustomed to cutting to your marked line. As you mentioned, you are not being consistant. Improve on that first - when you measure something, use the same measuring device, same technique. Use a fine pencil or mechanical pencil. Visualize your intended cut/joint - was the measurement you took exact or did it need to be long/short - that will determine whether or not you should cut to the line, leave the line on, etc. Start on a small project that has repetitive cuts/sizes to be made and see how close you can make each piece. Try making a multisided object to see what happens with cumulative error - i.e. take some plywood and cut the appropriate bevel to make a 8 sided box - the last cut will show your cumulative error.
Hope this helps you some.


Edit: Forgot, for making multiple cuts to a same size, set up a repetitive stop, measure once and you can batch cut all your pieces. Do a search on rep. stop systems on web, rockler etc. for photos.

[leehljp]

On multiple cuts, I use a jig or stop. I tend to cut things a smidgen too big and have to keep cutting and cutting (a thousands of an inch at a time) until it is too small. Once I get the perfect right size, I set my jig to the correct size piece.

On cutting single boards or pieces of plywood, I use a very fine pencil or scribe. My eyes are good but my hands are not. I keep fiddling and fiddling until I can cut the outside edge of a narrow scribe line. If by chance I hit the middle of the scribe line, I cut that. I just try to make sure that I am not cutting too much.

This is much different than construction/contractor saw cuts where 1/16 inch is often seen as perfection.

[LinuxRandal]

Cut ONE and mark it template. Use it to mark all the others, and since all pencil lines have two sides, always cut on the same side of them (so it becomes second nature). You do try to cut exactly on the line (depends partially on pencil type), but sneak up on it from the same side.

Save your templates if you think you may make another one later, or in case of screwing up a part, that you have to remake.

[MilDoc]

Take a look at this. Made my measurement / cutting much better.

http://www.newwoodworker.com/cutlines.html

[balzac.thegreat]

Great responses so far. I hadn't seen that NewWoodworker article before. Thanks for the link!

My usual way of measuring stuff involves using the tape measure, making a mark at the right spot, and then grabbing the combination square and making a straight mark. Then when I get to the saw I hope that all my lines are in the same spot. This is where the stop block and templates would come in handy!

[jackellis]

Get yourself one of these http://www.rockler.com/product.cfm?p...92&filter=rule or something like it from any number of manufacturers (I have a HF model).

I also have a six inch rule that measures in 32nds, 64ths, tenths and 100ths for checking setups and the exact size of some measurements.

A healthy dose of patience helps, and I second everyone who mentioned stop blocks. Make all the difference in the world.

[JimD]

I often do not mark my pieces. I use a steel rule to set my stop and then cut. I almost never mark width for ripping. I set the rip fence and cut.

I try to make the big parts and then the small ones. If you are making a dresser, make the carcase and then the drawers. You can adjust the drawers to fit the openings. 1/16 difference in the drawer size will not show if the drawer fits the opening. It will show a lot if the drawer is too small and won't fit if the drawer is too big.

If you can use one part to size another, do it. Don't measure anytime you can avoid it.

If the size is critical, set the stop a little long and then use old business cards against the stop to gradually get to the right size. For width, use the micropositioner.

Jim

[SARGE..g-47]

Same tape or rule.. measure twice.. make template if multiples.. stop blocks if multiples.. cut once!

[balzac.thegreat]

I often do not mark my pieces. I use a steel rule to set my stop and then cut. I almost never mark width for ripping. I set the rip fence and cut.

I try to make the big parts and then the small ones. If you are making a dresser, make the carcase and then the drawers. You can adjust the drawers to fit the openings. 1/16 difference in the drawer size will not show if the drawer fits the opening. It will show a lot if the drawer is too small and won't fit if the drawer is too big.

If you can use one part to size another, do it. Don't measure anytime you can avoid it.

If the size is critical, set the stop a little long and then use old business cards against the stop to gradually get to the right size. For width, use the micropositioner.

Jim

This is something I've also been thinking about. I'm in the design stage of a pair of bookcases and I'm trying to come up with the best way of dimensioning them. But then I think I just need to figure out generally how big I want it and go for it. Conceivably, one could lay out the 1 major cut of the project (say the side of a book case) and cut it. Then you match the opposing side to that cut and then fill in the blanks of the rest of the piece. To me this seems like a viable way of working if "built-in" type accuracy is not required. The less fiddling I have to do with 13/16ths and 1/32nds the better.

[Garasaki]

I've found that practice is the best thing for me on this issue.

At first I had a tough time making accurate marks, and remembering where to cut on each mark.

Over time, I've sort of got it. Part of the trick is to measure as little as possible. Typically it dosent matter if your box is 12 1/8" long or 12" long, just as long as the parts are all the same size.

I usually don't measure on the wood, I measure on the fence position to inside of blade for rip cuts, and measure the distance from inside of blade to my stop block on crosscuts.

When I do have to measure and mark on wood, I make sure to understand which side of the blade my mark needs to be on. Most of the marking I do is for mortises, which is forgiving because I then make my tenons to fit the mortises and can address small imperfections by modifying the tenons.

It took about a year and a half, but I actually trust myself working with a tape measure now. I used to remeasure a lot, hold uncut pieces together to make sure, etc etc - now I have enough faith that I can mark something, cut it, and it should be awful darn close.

[iceman61]

Ditto on everything that has been posted so far on this topic. Everyone thus far has given you some excellent advice. I actually measure 4 times & cut once in that I measure the area that needs the part twice, then I measure & mark my cut line, then I re-measure & make sure I marked it correctly.

Try to use steel rules when you can instead of a tape measure. Understand that the hook on the end of a tape measure "moves" & understand why it moves. There is a reason to this seemly sloppy movement.

Try to use a round pencil instead of a carpenter's pencil (rectangular shaped), even more use a mechanical pencil. A mechanical pencil will always have a sharp point & will always draw a sharp line. Always cut on the side of a line & never right down the middle.

Most of my measuring & cutting tends to either exact or just a bit too much so that I have to make a final clean up cut with a ROS with 220 sand paper. Heck, right now I'm building a 20' x 24' x 9' cabinet that I'm calling a shop LOL. It's better to cut just a hair too long than too short in that you can always cut just a little more off, but you can never "add to" a cut.

[radhak]

As a learner myself, have got only one point for you : remember that all saw blades have a kerf (thickness), and not taking it into account can cost you that last bit of exact length.

DYDAMHIKT ! (that's "don't you dare ask me ..." )

[Bruce Cohen]

WhatI don't see in all the helpfull tips, is to cut always to the waste side of your mark, never split the mark down the middle.

Also I always cut about a 1/32 larger than I need, you can always sand, scrape or plane off this slight extra.

Additionally, always sight the ruld at the same angle otherwise parallax will screw where you draw the mark

Bruce.

[Ed62]

I always rip everything that is the same width before resetting the fence. Same goes for the length, usually on the MS, with stop blocks. Like some others, I don't like to mark the workpiece, but instead measure the fence or stop block settings.

Ed