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Bolt gauge

v1ru5879

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Feb 19, 2018
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369
Working on my truck and needing new bolts and some that have been stripped and needing to be tapped. What's a good bolt and thread pitch gauge? Tired of going to the hardware store n trying to match things up. Time to get a gauge so I can make a list and know exactly what I need. Came across a few on Amazon, looks like the thread pitch ones that are the fold out style would be the way to go. The plastic tray type with the holes look simple and I see they also have threads on the back to match up pitch. Would like some suggestions

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Downwindtracker 2

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I have both, the plastic one was a give away. I'm careful with it, it could get stripped pretty easily.
 

darkzero

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SoCal
For machining purposes I have these pitch gages. Plenty of other manufacturer's that make em. But you'll need calipers or a micrometer to measure diameter.
http://www.productsengineering.com/gages/screwpitchgages.html

For quick checking of common bolts sizes I use one of these.
https://www.amazon.com/dp/B003FJW0GK/?tag=atomicindus08-20

The one above is imperial & metric. They also come in just imperial or metric which has more sizes. I was gonna get a wall mount like the kind in hardware stores but went with the one above since I can take it to the thread to be checked instead of having to bring the thread I need to check to the wall mount which sometimes isn't possible.

There are other cheaper brands but beware cause some use labels to mark the sizes which could eventually fall off. The one above the sizes are stamped.
 

king nero

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Belgium
pitch gauges and calipers is what I use.
Not the best tools though for measuring internal threads...
 

Paul_The_Builder

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May 9, 2020
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Dallas, TX
I bought this thread checker on Amazon and am fairly happy with it. Its quick and easy to identify nuts and bolts with it.

If I were to do it again, I would spring the extra money and get this one with more sizes.

The machinist fold-out type checkers are definitely more accurate, but I think the holes and posts on a board are a lot faster and more realistic for doing things like identifying fasteners from a vehicle.
 

RoninB4

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Under My House
I use a "fold out" type pitch gauge and a micrometer because that's what I did as a toolmaker for over 35 years. For most automotive applications you'll only need about 10-12 pitch forms and one of those plastic gauges should do. The biggest problem you'll encounter is whether the fastener is inch or metric. There are several sizes that are only a few .001's (inch) difference between the two and some have almost the same pitch (1/4-28 and 6 x 1mm comes to mind)

"Close enough" is not good enough as it's very easy to strip/ruin the threads in the hole and/or the fastener. It may not even hold the component on and come out somewhere down the road. This is especially true with the crappy fasteners on vehicles lately.

Almost all inch fasteners used in general applications on vehicles are either UNC (coarse) or UNF (fine). Most metric fasteners are coarse threads except for higher vibration applications like motorcycles and they use the less common "fine" variety. It really is a mix out there and it's critical to know what you have in hand.

The grade of fastener is also critical but that's a different discussion.

I'd suggest getting a set of pitch gauges, a micrometer, and a magnifying lens mounted to the bench for the 3 handed operation. Even I have to compare threads to pitch gauge under magnification sometimes.

For most things it would be faster/cheaper/simpler to just have a nut and bolt of the most common sizes mounted on a board for quickly checking. If the nut/bolt don't go together EASILY then something is wrong so it's time to break out the pitch gauge and micrometer.

Apologies for the long rant, it's one of the few things I know anything about.
 

HenryAZ

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Sep 18, 2012
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I own one of those "bolt checkers on a wire" things, but found using it on the wire to be cumbersome, so I made a little rack for the individual pieces from ABS plastic. I can now look down on the different sizes and hold my specimen next to the closest. I also use thread gauges (metric and SAE), and digital calipers.
 

ALinCarolina

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Dec 29, 2014
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NC Piedmont
I have a couple of the checkers on a cable and some plastic card types. Often though I just use the taps I have, especially if it turns out to be something odd. See if the teeth match and judge the diameter then to double check I gently try the bolt in the die.
 
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v1ru5879

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Feb 19, 2018
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369
Thank you for all the great information everyone, I really appreciate all the input. I am definitely gonna get a "fold out" pitch gauge for the times that some of the thread may be chewed up but further up the bolt there are good threads. Here are a couple I was looking at to get sizes of the bolts quickly

https://www.amazon.com/dp/B01GBZ1K4C/?tag=atomicindus08-20

https://www.amazon.com/dp/B01GIQNLGY/?tag=atomicindus08-20

I have a plastic card type but that one only goes up to an m12 so I figured something that has more sizes. I removed the rear bumper of my truck (Nissan Frontier) and one of those bolts was barely hanging in and then I realized it's cause the holes threads were destroyed and the begining of the bolt was chewed. After some googling I finally gave up and just went and did the try it till it matches deal at the store.

Finally decided to take the time and educate myself on how to figure out bolt sizes. I have a set of calipers so that will at least get me the m size of most of the fasteners, but that thread pitch you either have a keen eye and can just tell or in my cause just buy a gauge.

Luckily on most vehicles anymore metric seems to be the most common size of fasteners used. I have a Fastenal about 45 mins away so that's a plus but some hardware stores have such limited selection where I am. So that's what led up to me making this post. Sorry long rant and the coffee is really good this morning

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bwringer

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Jan 1, 2013
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Indianapolis
HA!! I clicked your link just to see what a "plastic gauge " was and found the bolt depot..who knew!! Thank you, that site is now book marked

Thanks! And Bolt Depot is pretty darn fantastic when you need bolts and nuts and such. If I don't want to order a box from McMaster-Carr, I usually get what I need here. Great service and speed.
 

Fatboy148

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Feb 15, 2017
Messages
999
Hopefully Pelican Pines will be along soon to show the pics of his set ups. He removed them from the cable and made wood blocks to store the different pieces in.


ETA....

Hopefully it's OK.... I went and found some of his pics on his profile page. He may have more pick but check these out for starters.

https://www.garagejournal.com/forum/album.php?albumid=6164
 
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v1ru5879

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Feb 19, 2018
Messages
369
Printed out and made a 1/2" binder with the pages in sleeves. Gonna be a huge asset to my garage, no more searching blindly. Once my L gauges arrive I will be set for any bolt or nut

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HaroRider

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Oct 20, 2010
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New York
I am really liking that thread detective set from bolt depot. Looks like more bang for the buck compared to Amazon.
 
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