I'm trying to figure out what the difference is between "ratchet stop" and "ratchet thimble" micrometer thimbles. I looked at the doc at http://www.mitutoyo.com/pdf/1973_MAC_Product_Fundamentals.pdf and it didn't really clarify much for me. Can anyone help? I'm trying to understand what the differences are, and also figure out which is "better".
ratchet stop vs ratchet thimble on micrometer
- Thread starter scottmlew
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TheGrooveking
Well-known member
Ratchet stop is where the little knob on the end of the thimble ratchets, you would use this to provide a consistent amount of pressure when measuring items. The ratcheting thimble is the same thing except instead of it being a little knob on the end of the thimble it is the thimble itself that rotates and ratchets.
As to is one if better than the other I highly recommend getting either a ratcheting or friction thimble as that it takes years of measuring with a mic to develop a real sense of feel. It doesn't take much at all to affect a measurement with too little or too much pressure while tightening the thimble of a micrometer. So by using a ratchet or friction mechanism on the thimble you've elimated the differential potentially caused by the human element.
Remember when storing a micrometer never leave it the anvils (the measuring surfaces) closed, the reason for this is that if the micrometer goes through a temperature swing it can cause the frame to stretch. This is caused by the expansion of the screw/anvil when it gets warmer, thus putting more force on the "C" portion of the micrometer frame. Kind of like overtightening a c-clamp, when you do that enough the frame will bend.
TheGrooveking
As to is one if better than the other I highly recommend getting either a ratcheting or friction thimble as that it takes years of measuring with a mic to develop a real sense of feel. It doesn't take much at all to affect a measurement with too little or too much pressure while tightening the thimble of a micrometer. So by using a ratchet or friction mechanism on the thimble you've elimated the differential potentially caused by the human element.
Remember when storing a micrometer never leave it the anvils (the measuring surfaces) closed, the reason for this is that if the micrometer goes through a temperature swing it can cause the frame to stretch. This is caused by the expansion of the screw/anvil when it gets warmer, thus putting more force on the "C" portion of the micrometer frame. Kind of like overtightening a c-clamp, when you do that enough the frame will bend.
TheGrooveking
Groove, thanks for the great reply. I do have a question about your post, though.
If I understand correctly, you're saying that the difference between the ratchet stop and ratchet thimble is that with the stop you use the little knob on the end of the micrometer instead of the thimble itself to turn the spindle. If the only difference is where you turn the spindle from (implying that both have ratchets), how does the ratcheting thimble make it easier to get a consistent measurement?
I am definitely an amateur user, and I won't be using the micrometer often, so I'd like as much help as possible getting consistent, accurate measurements.
If I understand correctly, you're saying that the difference between the ratchet stop and ratchet thimble is that with the stop you use the little knob on the end of the micrometer instead of the thimble itself to turn the spindle. If the only difference is where you turn the spindle from (implying that both have ratchets), how does the ratcheting thimble make it easier to get a consistent measurement?
I am definitely an amateur user, and I won't be using the micrometer often, so I'd like as much help as possible getting consistent, accurate measurements.
crewchief888
Well-known member
as stated before micrometer use is a "feel" and takes practice.
for general measurements i'd use a dial caliper, or one of new electronic versions.
Yep, I use my calipers all of the time to measure stuff. My immediate need for a micrometer is to measure things where there is a "lip" I need to overcome before getting to the actual item I need to measure. A good example is to measure the thickness of a piece of metal with rolled edges.
There is an explanation here that is better than the one in the Mitutoyo product fundamentals PDF. Mitutoyo shows the ratchet thimble being used one handed (because it is easier to turn the thimble one handed vs. the ratcheting speeder on the end.) I think I like the standard version since I have the choice at that point and one handed operation is not important to me.
https://ecatalog.mitutoyo.com/cmimages/003/322/2145-MDC-MX.pdf
https://ecatalog.mitutoyo.com/cmimages/003/322/2145-MDC-MX.pdf
Downwindtracker 2
Well-known member
Calipers are considered +/- .005, which most often is good enough. But when I want a a measurement that is +/- .001, I'll spin a mic. To get an exact to the tenth thou measurement, I'll use the ratchet or the friction thimble and the vernier scale. I much prefer using friction thimbles. I picked up a VIS 0-6" set at a pawn shop. They were a ***** to clean and adjust, unlike the easy to adjust mics with the ratchet knobs. Ratchet knob mics from Mitutoto are less expensive last time I looked.
ganymede
Well-known member
Friction thimble is better when measuring pieces near the end of the mics capacity
because your fingers arent over extended.
because your fingers arent over extended.
Joe Piro
Well-known member
It's been almost a year since the last activity on this thread. However I just read this in an industrial online magazine called "Quality"
and it was so clear I thought it should be posted.
The article was titled "Micrometers: Tools of Choice" by Larry Adams (August 1, 2004) . It stated that as micrometer resolutions have gotten finer, the difference between the friction thimble and the ratchet thimble have become more important. And that at a resolution such as 0.00005 inch (not uncommon for electronic digital micrometers) the friction thimble provides better repeatability. Such fine resolutions are sensitive to what they called the "jackhammer affect" of the ratchet thimble. (and they cited the source as: The L.S. Starrett Co./Quality archives.
and it was so clear I thought it should be posted.
The article was titled "Micrometers: Tools of Choice" by Larry Adams (August 1, 2004) . It stated that as micrometer resolutions have gotten finer, the difference between the friction thimble and the ratchet thimble have become more important. And that at a resolution such as 0.00005 inch (not uncommon for electronic digital micrometers) the friction thimble provides better repeatability. Such fine resolutions are sensitive to what they called the "jackhammer affect" of the ratchet thimble. (and they cited the source as: The L.S. Starrett Co./Quality archives.
My preference:
1) Ratchet Stop
2) Ratchet Thimble
3) Friction Stop
Ratchet Stops use a simpler small diameter ratchet mechanism vs the integrated ratchet thimble. Some ratchet thimbles (cheaper imports at least) do not have a small diameter "speeder" at the end for fast adjustment.
The drawback to friction measurements is the screws loosen over time and get tightened by the user changing the breakaway torque. The ratchets tend to be more consistent over the life of the tool.
For those commenting "just use a caliper": Resolution is not the same as accuracy. Even quality Mitutoyo/Starretts will have an easy .001 variation through the scale.
1) Ratchet Stop
2) Ratchet Thimble
3) Friction Stop
Ratchet Stops use a simpler small diameter ratchet mechanism vs the integrated ratchet thimble. Some ratchet thimbles (cheaper imports at least) do not have a small diameter "speeder" at the end for fast adjustment.
The drawback to friction measurements is the screws loosen over time and get tightened by the user changing the breakaway torque. The ratchets tend to be more consistent over the life of the tool.
For those commenting "just use a caliper": Resolution is not the same as accuracy. Even quality Mitutoyo/Starretts will have an easy .001 variation through the scale.
rlitman
Well-known member
WTF are you talking about? On both friction and ratchet mechanisms, the screws are shoulder screws with a positive stop, and no amount of screw adjustment will change the friction. The friction is set by the clock spring inside the barrel.
X1 Mike
Well-known member
I'll take a plain micrometer any day. If after 20 years as a machinist I don't have a better feel than the friction setup I'll sell my tools. Besides, micrometers are just a glorified guessing tool.
Never taken the cheapies apart, have you?
rlitman
Well-known member
Can't say that I have. If I'm using a micrometer, I'm not wasting my time on some pot metal POS, but I guess that explains it. Anyway, if the thimble isn't consistent, it isn't worth using.
Joe Piro
Well-known member
Thanks for all the responses above. I am deciding what brand to buy to replace the set of micrometers I lost by damage from fire water. They weren't burned, but badly corroded.
I had the Mitutoyo with the chrome frames, (Two 101 series and one 103 series and a set of telescoping gauges). They were all metric, but metric to inch conversions were easy enough with a calculator.
I loved 'em. However (and I welcome responses to this)
==> It seems to me looking through their catalog, that you can buy a lot more accuracy at a much lower price (time and the dollar taken into account) than you could 20 years ago when I bought my first set. Is that a correct impression?
I am planning three engine rebuilds over the next year or so and I think the electronic Digimatic models in three sizes will be all I need:
0 to 1" (293-340-30), 1 TO 2" (293-341-30), and 2 TO 3" (293-342-30). These numbers come with the "ratchet stop" but slightly different numbers are the same device but with the "ratchet thimble." (BTW what does the 30 on the end of the number mean?).
It would be great to add a bore gauge, but that gets expensive in a hurry. I'll go with the telescoping gauges and the machine shop can have the final word.
I thought about saving some money with Fowler mics until I saw how reasonable the Mitutoyos were. Although I'm sure I won't wear out even economy mics on only three engines, I still tend to "buy once."
At Zoro prices all three come to about $620.00.
I just had a 20% Zoro coupon but it was not applicable to these items. Did anyone here ever get a Zoro discount on Mitutoyo mics?
Big question is ... I can save about a third by importing directly from Japan ( recently imported from Ehime Machine, and Amazon.jp and Factory Gear so I'm over that learning curve. They even gave me a Japanese name.)
Would you buy micrometers from Amazon Japan? Is there likely to be a warranty problem with Mitutoyo USA or are the devices so reliable that it's worth it. I would compare it to asking Nikon USA to warranty a gray market camera.... No Way!
Thanks in advance for your opinions on all these things: Value, Accuracy, Warranty, Importing, My selections, etc.
I had the Mitutoyo with the chrome frames, (Two 101 series and one 103 series and a set of telescoping gauges). They were all metric, but metric to inch conversions were easy enough with a calculator.
I loved 'em. However (and I welcome responses to this)
==> It seems to me looking through their catalog, that you can buy a lot more accuracy at a much lower price (time and the dollar taken into account) than you could 20 years ago when I bought my first set. Is that a correct impression?
I am planning three engine rebuilds over the next year or so and I think the electronic Digimatic models in three sizes will be all I need:
0 to 1" (293-340-30), 1 TO 2" (293-341-30), and 2 TO 3" (293-342-30). These numbers come with the "ratchet stop" but slightly different numbers are the same device but with the "ratchet thimble." (BTW what does the 30 on the end of the number mean?).
It would be great to add a bore gauge, but that gets expensive in a hurry. I'll go with the telescoping gauges and the machine shop can have the final word.
I thought about saving some money with Fowler mics until I saw how reasonable the Mitutoyos were. Although I'm sure I won't wear out even economy mics on only three engines, I still tend to "buy once."
At Zoro prices all three come to about $620.00.
I just had a 20% Zoro coupon but it was not applicable to these items. Did anyone here ever get a Zoro discount on Mitutoyo mics?
Big question is ... I can save about a third by importing directly from Japan ( recently imported from Ehime Machine, and Amazon.jp and Factory Gear so I'm over that learning curve. They even gave me a Japanese name.)
Would you buy micrometers from Amazon Japan? Is there likely to be a warranty problem with Mitutoyo USA or are the devices so reliable that it's worth it. I would compare it to asking Nikon USA to warranty a gray market camera.... No Way!
Thanks in advance for your opinions on all these things: Value, Accuracy, Warranty, Importing, My selections, etc.
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X1 Mike
Well-known member
Why would you need Digimatics for just 3 engines? As far as buying once you can decide to become a machinist tomorrow and retire with these.
Mitutoyo 103-922 Outside Micrometer Set with Standards, 0-3" Range, 0.0001" Graduation (3 Piece Set): Amazon.com: Industrial & Scientific
Mitutoyo 103-922 Outside Micrometer Set with Standards, 0-3" Range, 0.0001" Graduation (3 Piece Set): Amazon.com: Industrial & Scientific
www.amazon.com
X1 Mike
Well-known member
Wouldn't hurt to give these a shot. Probably from the late 80's early 90's and will last the rest of your life. I still have a set.
Spending a bit more you could have a more complete set. Zero to three is the standard anyone should have but if you have to go bigger it's good to have it. Full disclosure: I have never used new Fowlers that are Chinese. They used to be American then VIS made them for a while and now CCP. For your purposes I'd still take the VIS set from eBay.
VIS Made in POLAND 0-3" Precision Outside Micrometer Set 3pcs 0.0001" EXC. | eBay
Find many great new & used options and get the best deals for VIS Made in POLAND 0-3" Precision Outside Micrometer Set 3pcs 0.0001" EXC. at the best online prices at eBay! Free shipping for many products!
www.ebay.com
Spending a bit more you could have a more complete set. Zero to three is the standard anyone should have but if you have to go bigger it's good to have it. Full disclosure: I have never used new Fowlers that are Chinese. They used to be American then VIS made them for a while and now CCP. For your purposes I'd still take the VIS set from eBay.
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The VIS micrometers have a very well known problem with their plastic locking levers breaking. The older metal levers had no such problem, but their later plastic levers were terrible. If you zoom in on the pictures in that eBay auction, at least two of them are clearly broken. I'd guess that all three are.
X1 Mike
Well-known member
Mine are all metal, besides that fact if they are broken, they are being used wrong. As far as that goes, if they are being used, they are being used wrong. There is no real reason to have a lock on a micrometer. Tell me you have bad technique without telling me you have bad technique. I had an apprentice that locked his mic's down on everything and I took the lock lever off on him. I told him when he learned to use the mic's I'd reinstall the lever.
Besides that, if you are in a machine shop why can't you make a replacement lever?
The plastic locking levers are broken when the mics are absolutely brand new and unused, guy. Bad execution of a poor design.
If you want to recommend something that's broken, but fixable, you should probably make that a bit more clear in your recommendation.
X1 Mike
Well-known member
I've seen plenty of them in one piece, never saw a new one broken. A lot of the ones on eBay have the metal lock levers, besides who cares if something is broken that you shouldn't be using?
Actually, I've handled quite a few of them. I've opened brand new sealed boxes that were shipped directly from Toolmex, themselves. I doubt I've seen more than one that hasn't been broken.
I think a lot of people care. I know I do. Maybe you don't, and I guess that tells me a lot about your recommendations.
Thank you.
X1 Mike
Well-known member
Yeah, when someone doesn't need ultra-accuracy, they are fine and if you tell me a set of mic's are ultra-accurate that tells me everything, I need to know about you.
How many times have you measured a part without a lock being set and had the thimble magically move itself? A need for a lock shows me an extreme lack of skill.
Joe Piro
Well-known member
Wow.... This sort of turned into a flaming contest between X1 Mike and tube-guy. I didn't mean for it to turn vicious. I just need some advice.... well.... not advice really.... just opinions (which I got). I can "advice" myself.
This is the first time in my life that I have considered taking the easy way out with the Digimatics.
Thanks X1 Mike, tube_guy and Mgdoug3 for your thoughts. I'm going to start a new Three Micrometer Questions thread 'cause I don't think many people saw my questions on this old thread.
BTW Mgdoug3, is the Mg for Mg sports cars? Just curious ...
I thought the Digimatics would help with my lyin' eyes. I'm not a young person and I didn't even need glasses to read the menu in a dark restaurant until this year. Suddenly my vision is starting to go. I would like to say that I am the sort of person who respects skill and experience. I believe if a person doesn't know how to read a vernier scale then they need to learn before they have the right to use any shortcuts. That's a basic skill. I just bought a replacement Mitutoyo caliper and just like 20-30 years ago I chose the vernier rather than the dial or digital read-out. Lots of advantages: not reliant on batteries; if society does a total meltdown and people are dropping dead in the streets from the next pandemic, I won't have to make an extra trip outside because my batteries are dead. I may have to run a drive belt from my lathe to my girlfriends treadmill if we're off the grid but I think that would work.
This is the first time in my life that I have considered taking the easy way out with the Digimatics.
Thanks X1 Mike, tube_guy and Mgdoug3 for your thoughts. I'm going to start a new Three Micrometer Questions thread 'cause I don't think many people saw my questions on this old thread.
BTW Mgdoug3, is the Mg for Mg sports cars? Just curious ...
X1 Mike
Well-known member
No flame contest here, it's all good I just was suggesting not overbuying. I understand your thoughts on the digimatics, they just always felt unwieldy to me. I could never get comfortable using them. As far as the bad eyes I'm with you there, I actually use an eye loupe when I'm measuring things or trying to see the small stuff. Even as bad as my eyes are I've won bets with people measuring within 0.002" with a scale and an eye loupe.
As far as calipers I like that you have a vernier and know how to read it. How many guys have a dial caliper with the zero set off to the side because the gear jumped? I know how to fix that and should make a video for it. haha
Joe Piro
Well-known member
And I certainly appreciate your advice about overbuying. There have been too many times when I was younger that I "needed and didn't have" that I tend to prefer "having and not needing." And no kids in college to worry about and social security payment sitting in the bank... So I guess my real question was about the accuracy of inexpensive mic's. I know counterfeits are trash, but there's a big spread between trash and top of the line. So what I hear you saying with any reputable brand it has a lot to do with technique., and without technique it doesn't help to spend more money or depend on digital readouts.
Now I've done a lot of things in my life... but never concentrated on one, so I'm really an apprentice in most of them and an expert in none.
(No regrets, but you "play it where it lands.") So I infer from what you say that let's suppose... with no lock lever... the "feel" means advancing the thimble, but not with enough force to push the internal threads to extreme contact?? I guess you can feel when it's just "not going any further" and that's just a bit too far. Is that the idea?
thanks.....
X1 Mike
Well-known member
You pretty much got it I'm much more concerned about repeatability and ease of use as in ergonomic comfort. A lot of the digit mic's may be tough to fit someplace because they are unwieldy and bulky.
I'm an admitted tool snob and love high quality tools but I really don't see the need in overbuying micrometers though. Especially for someone using it in an automotive environment. You may want to keep in mind that I spent a lot of years on a surface grinder so if I am going to hold a precision tolerance, I would never use a micrometer, I am going to have a part on a surface plate with an indicator and gage blocks.
At the end of the day accuracy isn't even an issue, knowing your tools is much more important. When I pick up a set of mic's and check them, I don't just check them on the low side, I check both. Example:
0-1" mic
Clean anvil faces by closing on a cloth or piece of paper and dragging out.
Close mic's to 0.0000" and confirm.
Open mic's to 1.0000" and confirm.
Doing it that way, I don't care if I have a piece of junk micrometer that reads 0.0000" at zero and +0.001 at the 1.0000" measurement because I can compensate for that.