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post #1 of 25 Old 01-15-2010, 08:04 PM Thread Starter
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Share your caliper knowledge with me

I just bought a HF caliper model 66541 http://www.harborfreight.com/cpi/cta...unction=Search
I looks like it is all I need and so far it is fun to play around with. But my question is this...
What does a better one offer me? This one easily measures 1/10" on the slide and 0.001" on the dial.
I see that the better ones offer more measurements on the slide and I am not sure about on the dial.
This one lists for $19 and was on sale at the store for $15. Maybe I'll watch the sales and consider returning this one and get a better one if you can tell me what I am missing. But for now this is good enough to learn on.
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post #2 of 25 Old 01-15-2010, 09:32 PM
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For woodworking, comparing drill bits to dowels, and checking fasteners
it will be fine. Maybe checking sheet metal gauge and such.

The better ones just last longer. I am still using my first one, Craftsman
1962, which I paid $19.95, a weeks pay at the time. $300+ by todays
rate.

+ or - .001 is way above most wood working needs.

Keep them and get a better set later. When you drop them on a
cement floor, the floor don't know prices!

I have a cheaper set I use around the shop and get the Craftsmans
out when I feel I need them. I also have a full set of micrometers.
Which I seldom use these days.

When you decide to get a better, get a good set, like this:

http://www.nationaltoolwarehouse.com...qx/product.htm

Top of the line at a decent price and your great grand children can
use them.

This is my tool of choice in the shop for general checking. Mine is
brass and very old and dead on!



http://www.amazon.com/Central-Tools-6506-Stainless-Caliper/dp/B000OQJG0K




Last edited by BHOFM; 01-15-2010 at 09:52 PM.
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post #3 of 25 Old 01-15-2010, 10:01 PM
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I would recommend a digital over a dial. The older I get the easier they are to read.






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post #4 of 25 Old 01-15-2010, 10:15 PM
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Quote:
Originally Posted by cabinetman View Post
I would recommend a digital over a dial. The older I get the easier they are to read.






Tell us again about how you planted the redwoods!



Sorry


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post #5 of 25 Old 01-15-2010, 10:42 PM
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Quote:
Originally Posted by BHOFM View Post
Tell us again about how you planted the redwoods!



Sorry
Cutting by cutting...

Use the right tool for the job.

Rich (Tilting right)
Huntington Beach, California
Remember that when we have the "BIG ONE" everything east of the Rockies falls into the ocean.
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post #6 of 25 Old 01-15-2010, 10:47 PM
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For two bucks, you can't go wrong with this one, or six. Seriously, I have three or four laying about the shop.

http://www.harborfreight.com/cpi/cta...temnumber=7914

It reads to 1/128" which is more than enough for woodworking.

Just when you buy them, make sure that when they read zero when the jaws are closed. You can generally squeeze them closed while still in the package.

Use the right tool for the job.

Rich (Tilting right)
Huntington Beach, California
Remember that when we have the "BIG ONE" everything east of the Rockies falls into the ocean.
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post #7 of 25 Old 01-15-2010, 10:48 PM
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Daryl,
I have a dial one I got from Rocklers. It reads in fractions of an inch, which to me, corresponds to woodworking much easier that decimals. Unless you are used to decimals that is.
Mike Hawkins
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post #8 of 25 Old 01-15-2010, 11:52 PM Thread Starter
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Well, its a good thing that my woodworking skills are not as precise as all of you guys are. I've been trying to get an acurate measurement of my blade-to-mitre alignment. I get a differant measurement nearly every time. Apparently the slightest deviation from holding the caliper perfectly level will knock the measurement way off. Same with holding the caliper precisely perpendicular to the blade. I can see where a indicater would work better for this.
I understand what kind of variation I am looking for between the front and back of the blade. But can someone explain how to eliminate deviations on measurements taken repeatedly at the same spot?
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post #9 of 25 Old 01-16-2010, 12:01 AM
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Quote:
But can someone explain how to eliminate deviations on measurements taken repeatedly at the same spot?
It comes with time. Just practice on something.
Clamp a piece on the saw as a rest.

Yes. for checking saw blades a dial indicator is better.


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post #10 of 25 Old 01-19-2010, 02:39 AM
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I will offer some advise. First off I have repaired and calibrated thousands of tools and gages, not just calipers, so hopefully I can help you out a little bit.

First off, I would also recommend a digital over a dial caliper. The reason is not readability. The dial calipers use a set of gears that contact the rack. These will eventually become clogged up (sawdust?) and make the caliper more difficult to use over time, I have seen some bad enough to skip teeth but that is rare. When you do not use the caliper, either keep it in the case or place it upside down (reading face toward the table) so dust cannot get into the moving parts. A digital caliper uses a magnetic strip with an encoder and does not have as many problems with dirt and dust. Usually the gib (dial and digital both have) just gets dirty.

Next, the repeatability of your measurements depends on a number of factors. Pressure, the thumb wheel on the base provides a means of applying pressure when taking a measurement. Typically for metalworking this would be light, enough that you would create a slight drag when moving the part around inside the jaws. There are specific numbers (in oz of force), but don't know off the top of my head. The end of the jaws have a knife edge, metal won't compress enough to cause a noticeable change on the caliper, but wood is soft and the knife edge could cause a change in reading.

From my experience, the gib screws on cheap hand tools are almost always too loose or too tight. The gib screws are the two on the top of the caliper. If you place one finger on the top where the gib screws are, and your thumb on the bottom (where the thumb wheel is) and rock the assembly against rack, you should feel no movement. If you do, give the gib screws a slight turn to tighten them up. The screws may also be so tight you cannot slide the caliper, or it could mean the caliper is just clogged with dirt. Either way, DO NOT REMOVE THE GIB SCREWS on a dial caliper. If you remove them and the gib comes out, you will loose tension on the hairspring and the caliper will not repeat a measurement. If you have never tightened a hairspring before, it is a royal pain, that and you need gage blocks to check for accuracy anyway. A very loose gib can cause the whole assembly to rock, causing the caliper to read off a little bit.

If you are measuring a flat surface, considering you are using the same amount of pressure and are not using the knife edge. If you rock the caliper a little bit, the lowest number will be the reversal point (the actual reading). On a curved outside point, the highest number will be the reversal point. On a curved, inside surface, the reversal point will be the highest number. A flat inside surface, the lowest number will be the reversal point.

Wood also has other little things that will change your measurement. Wood has a different surface texture. Metal work usually has specific roughness, or finish specifications. Wood usually is very rough and has grain that is not smooth. You may have a tough time seeing it, but most calipers are accurate to within 0.002 inch (+/- 0.001 inch). Dust, dirt and the grain will play huge factors.

What is the difference between a Harbor Freight tool and a quality Mitutoyo, Brown & Sharpe or Starrett? Well a number of things. I can take a five year old Mitutoyo caliper and check the linearity, step, depth and inside measuring surfaces and almost every check will be at nominal with one or two at 50% of it's tolerance. I take a tool from Harbor Freight, NSK or Fowler and most all of the measurements are at their limits. So in a few years time the caliper has to either be reworked or replaced because it has worn out of tolerance. The cheap tools often use soft metals that nick easily, making them more difficult to slide. The more expensive tools usually have anti-backlash mechanisms, etc.

For my money, Mitutoyo makes the best caliper. I like some of the older Starrett dial calipers, but they were never able to make a decent digital version. The earlier versions were plagued with electronic problems, and the new versions are just cheap. Starrett also uses an odd sized battery for the calipers that you cannot get at a department store. Starrett hardly makes any tools in the US anymore either. Typically is you see a "J" at the end of their model numbers, it stands for jeweled, and you will find higher quality parts inside (ie metal gears). The hard plastic cases are cheap and crack, the older cases used to be either soft plastic or wood. It is kinda sad, considering how many machinists buy their products because they are American, I hope they change their ways.

Hope I could help!
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post #11 of 25 Old 01-19-2010, 03:31 AM
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digital - inch to the thousands and Metric to the billemeter
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post #12 of 25 Old 01-19-2010, 05:11 AM Thread Starter
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Cheese.
Thanksor taking the trouble to write all of that. Thats a lot of very good information.
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post #13 of 25 Old 01-19-2010, 06:36 AM
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Just remember that you will be using these for woodworking, not metal machining. The requirements are entirely different. What is adequate for woodworking would be virtually worthless for machining.

In woodworking I find the majority use of a caliper is to compare and find the nominal size of something. I have two very old slide style calipers which have done all that I asked of them.

One feature that I especially like on a caliper is the ability to lock the jaws in place. This is especially useful to me when I am trying to compare two items.

George
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post #14 of 25 Old 01-19-2010, 06:55 AM
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Cheese, that was a very interesting read. Thanks for sharing what you've learned.

That said, I have an old cheap Vernier caliper. I use it mostly for measuring screws, bolts, etc. Rarely do I have a use for a caliper in woodworking. I have a 12" combo square from Bridge City Toolworks(sadly, they are defunct) which is calibrated in crisp, precise, 1/32" gradations. This is what I use to measure wood thicknesses, depths/widths of grooves & joints, etc. As long as my eyes remain good on the close up reading, it works for me.
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post #15 of 25 Old 01-19-2010, 08:38 AM
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Cheese, I just learned more than I thought possible from your post. Thank you.
Now, with your experience, can you tell me why a digital caliper can not be turned to become a left handed model??
As a one-handed woodworker, (left), I find my caliper is usually facing away from me or upside down. Starrett says their frame is proprietary and can't be turned and the Mitutoyo is waaay too expensive.
Sorry if this looks like a high-jacking to the OP.

Do like you always do,,,, get what you always get!!
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post #16 of 25 Old 01-19-2010, 11:33 AM
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I use a HF digital caliper and like it. It was pretty much the same price as the dial one. It is .001 +- which is accurate enough for me to use on my metal lathe, which machines to an accuracy of .001. It is cool because it also displays in fractions of an inch for my woodworking projects.

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post #17 of 25 Old 01-19-2010, 12:56 PM
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Originally Posted by rcp612 View Post
Cheese, I just learned more than I thought possible from your post. Thank you.
Now, with your experience, can you tell me why a digital caliper can not be turned to become a left handed model??
As a one-handed woodworker, (left), I find my caliper is usually facing away from me or upside down. Starrett says their frame is proprietary and can't be turned and the Mitutoyo is waaay too expensive.
Sorry if this looks like a high-jacking to the OP.
A number of reasons, the magnetic stripe would have to be on the other side of the rack. The depth rod that sticks out, has it's own groove and would need to be on the other side.

However, I think I have a solution, page 134. It is a vernier not a caliper, but could suit you needs. I have seen a digital version, but I don't recall the model#. I'll look later at work if I get a chance.
http://www.mitutoyo.co.jp/eng/produc.../Caliper_1.pdf
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post #18 of 25 Old 01-20-2010, 01:44 AM
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I looked through a few different catalogs, the only thing that I could find was the left handed Mitutoyo vernier. It might make sense, how much would it cost to retool an entire line for only a few calipers. They make calipers by the thousands usually.
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post #19 of 25 Old 01-26-2010, 04:57 AM Thread Starter
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I took my dial caliper back to HF today and got a digital one. IThe one I got is a 4 incher and measures in decimal and mm. It seems to be easier to repeat measurements with the digital. With the dial the measurements never repeated accurately. The only thing I am having trouble with is a chart on the back side of the caliper. I do not know what it means and the instructions do not say. Can anyone enlighten me...
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post #20 of 25 Old 01-26-2010, 08:29 AM
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Machine screw thread

Major dia. of the screw, root diameter and drill size of Metric machine screws. bill

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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