# Need help for metric sizes...



## MT Stringer (Aug 15, 2012)

I have several Drill Press locking clamps like these.

I would like to use them on my work bench but the stud isn't long enough to protrude thru the bench top. What I would like to do is attach a coupling and a short stud to allow the the clamp to be attached through one of the 3/4 inch holes in the top.

I couldn't find what size the threads were so I took the bottom piece to the hardware store and discovered the threads are 12mm. :sad:

Now I am not a metric guy so that's where I need the help. The store didn't have any couplings so I would like to order a half dozen off the internet.

What does 12mm mean? It seems metric stuff has other numbers that I don't have any idea what it means.

So what do I need to order? Your advice is appreciated...and a link would be really helpful.
Thanks
Mike


----------



## bobj3 (Jan 17, 2006)

Hi Mike

I'm sure you can find all you need from the link below

McMaster-Carr

===



MT Stringer said:


> I have several Drill Press locking clamps like these.
> 
> I would like to use them on my work bench but the stud isn't long enough to protrude thru the bench top. What I would like to do is attach a coupling and a short stud to allow the the clamp to be attached through one of the 3/4 inch holes in the top.
> 
> ...


----------



## Phil P (Jul 25, 2010)

Hi Mike

The metric size is the outside diameter of the rod from, which the threaded part is formed, so 12mm means that the thread will be M12. The other thing you will need to know is the pitch of the thread, expressed in mm. e.g an M8 fine thread commonly has a pitch of 1mm (25.4 per inch) although 0.75mm pitch is also available (33.8 per inch). Metric fine pitch is roughly analageous to UNF. Your M12 rod is probably be M12 x 1 (25.4 per inch), M12 x 1.25 (20.3 per inch) or M12 x 1.5 (16.9 per inch) if it is a fine pitch thread. There is also another thread type, metric coarse, for which a 12mm thread would be M12 x 1.75 (14.5 per inch). Be measuring the number of threads in an inch you should be able to work out exactly which nut you need. A useful reference table for metric threads can be found here

Regards

Phil


----------



## N'awlins77 (Feb 25, 2011)

Mike, actually both metric and standard sizes, you would need to know some "other" numbers. And that number is the thread pitch. That's how many threads per in or mm the screw has. Every size has more then one pitch. 1/4-20, 14/28. 5/16-18, 5/16-24. In your case, you have three choices. 12mm X 1.75 - 12mm X 1.5 - 12mm X 1.25. 

You could pick up a thread pitch gauge at a Sears or some other supplier. But easiest thing to do, since you probably wouldn't use the pitch gauge again, is take your locking clamp to a hardware store, Home Depot or what not, and go through their bends of nuts and try one on until you get the nut that fits. Then you can read on the bag, or the tag on the bend, the thread pitch size, then you'd know what to order online. OR, here in New Orleans, and I'm sure in most cities or large towns, there's supply houses that specialize in fasteners. Matter of fact, I've just checked your profile and see you live near Houston. There's a company called Fastenal Company located at 12636 Market St. in Houston. Or there's one in Deer Park. Just Google "Fastenal Company". We have one in every decent size town here in the New Orleans metro area. If they don't have what you are looking for, they can order it for you, and unless you are in a hurry, they'll get it coming on their regular delievery, to their place and you pay no shipping. Or if you are in a hurry, I'm sure they can get it shipped to you as fast as needed. I deal with Fastenal's, in about 4 towns and they are great people. 
Hope this helps!


----------



## tooler2 (Aug 11, 2012)

It might be more elegant to insert a metal plate tapped for your 12mm at various locations on the bench. A cheap tap should be good for at least 10 holes in 3/8'' steel, or you could weld a nut under a 1/8'' thick piece. It is nice not to have to reach under the bench to hold a nut. 
Rob


----------



## harrysin (Jan 15, 2007)

tooler2 said:


> It might be more elegant to insert a metal plate tapped for your 12mm at various locations on the bench. A cheap tap should be good for at least 10 holes in 3/8'' steel, or you could weld a nut under a 1/8'' thick piece. It is nice not to have to reach under the bench to hold a nut.
> Rob


I have an identical clamp, made in the USA and I've just checked the thread and it appears to be UNC 1/2" 13tpi. How about a Tee nut recessed under the bench top or a shouldered threaded insert.


----------



## MT Stringer (Aug 15, 2012)

Thanks for the helpful info and suggestions - all of ya.
Now I have more to think about. 
Since I have clamps bought at Harbor Freight as well as a couple that I linked to, I need to check each one for the correct size.

These clamps would really come in handy when I am building the framework for the custom cooler...of which I am in the middle of building six for customers for Christmas.

The Fastenal Store in Deer Park is only a hop skip and jump for me...just across the ship channel, so that is a good option.

Several plates with nuts welded on the bottom is a really good option - no undrneath the table stuff.

My table top is made from a 2 inch thick solid core door with Formica on top.

Thanks again.
Mike


----------



## jw2170 (Jan 24, 2008)

Hi mike.

As I have posted earlier, I bought a set of "thread detective" for both imperial and metric.

This covers most common sizes.

I have not yet failed to correctly identify a thread in nut or bolt.

Metric Thread Detective Screw Thread Gauge - Amazon.com


----------



## billg71 (Mar 25, 2011)

Phil P said:


> Hi Mike
> 
> The metric size is the outside diameter of the rod from, which the threaded part is formed, so 12mm means that the thread will be M12. The other thing you will need to know is the pitch of the thread, expressed in mm. e.g an M8 fine thread commonly has a pitch of 1mm (25.4 per inch) although 0.75mm pitch is also available (33.8 per inch). Metric fine pitch is roughly analageous to UNF. Your M12 rod is probably be M12 x 1 (25.4 per inch), M12 x 1.25 (20.3 per inch) or M12 x 1.5 (16.9 per inch) if it is a fine pitch thread. There is also another thread type, metric coarse, for which a 12mm thread would be M12 x 1.75 (14.5 per inch). Be measuring the number of threads in an inch you should be able to work out exactly which nut you need. A useful reference table for metric threads can be found here
> 
> ...


WOW! Metric is soooo easy to work with! :sarcastic::sarcastic:

At least so I'm told.....


----------



## N'awlins77 (Feb 25, 2011)

Mike, nice looking coolers there!! Well, except for those logo's. A fleur de lis would look so much better on those!! ;o)


----------



## Phil P (Jul 25, 2010)

billg71 said:


> WOW! Metric is soooo easy to work with! :sarcastic::sarcastic:
> 
> At least so I'm told.....


Think about this, then. If you want to build a jig which adjusts in 1mm increments you simply choose a thread with a 1mm pitch - turn a nut through 6 flats (or 360 degrees) and you have a 1mm increment. Try that with UNF....... :blink:

In reality the threads that we commonly use in woodwrking jigs are M4x0.5, M5x0.5, M6x0.75, M8x1 and M10x1 - all of which are stock sizes. Other pitches are available, but here if you ask for a threaded rod M4, M5, M6, M8 or M10, that's what you'll get. All others you have to specify

Regards

Phil


----------



## AndyL (Jun 3, 2011)

Phil P said:


> Think about this, then. If you want to build a jig which adjusts in 1mm increments you simply choose a thread with a 1mm pitch - turn a nut through 6 flats (or 360 degrees) and you have a 1mm increment. Try that with UNF....... :blink:
> 
> In reality the threads that we commonly use in woodwrking jigs are M4x0.5, M5x0.5, M6x0.75, M8x1 and M10x1 - all of which are stock sizes. Other pitches are available, but here if you ask for a threaded rod M4, M5, M6, M8 or M10, that's what you'll get. All others you have to specify
> 
> ...


Are you sure you've got that the right way round Phil? Almost every metric fastener I see is the coarse variety. If you see "M6" with no pitch specified I would expect that to be M6x1.0. The fine threads are fairly uncommon in my experience. Brake caliper mounting bolts and hydraulic banjo bolts are a couple that spring to mind, with the banjo bolts using the extra-fine option because they're hollow.


----------



## MT Stringer (Aug 15, 2012)

N'awlins77 said:


> Mike, nice looking coolers there!! Well, except for those logo's. A fleur de lis would look so much better on those!! ;o)


Thanks Lee. Three down, three to go.


----------



## Phil P (Jul 25, 2010)

AndyL said:


> Are you sure you've got that the right way round Phil? Almost every metric fastener I see is the coarse variety.


Hi Andy

Those are all sizes in my "bits box" bought from the local engineering wholesalers. Don't know what B&Q sell, however. It's why I pointed to the tables because outside of my own locality I have no idea what other people sell as their "standard", especially outside of the UK

Regards

Phil


----------



## OPG3 (Jan 9, 2011)

The point that I haven't seen touched-on is the fact that this type of clamp has a (male) threaded post with threads to match the (female) lock-ring. This type of clamp doesn't need to go through matching threads when there is accesss for the lock-ring to go on the other side. This type of clamp is commonly used on and supplied for drill press tables. I am yet to be introduced to a factory-made drill press table without open holes in it. The only reason someone would even need to be concerned about the (male) threads is if there is no access for the lock-ring.


----------



## MT Stringer (Aug 15, 2012)

OPG3 said:


> The point that I haven't seen touched-on is the fact that this type of clamp has a (male) threaded post with threads to match the (female) lock-ring. This type of clamp doesn't need to go through matching threads when there is accesss for the lock-ring to go on the other side. This type of clamp is commonly used on and supplied for drill press tables. I am yet to be introduced to a factory-made drill press table without open holes in it. The only reason someone would even need to be concerned about the (male) threads is if there is no access for the lock-ring.


As I stated earlier, I want to use the clamps on my work bench/assy table/outfeed table. It is 2 inches thick. The threaded post is not long enough so I can screw the locking piece on from underneath. That is my dilema. :-(

I will have to persue this later, maybe next week. Too much going on right now to stop and modify anything.

I appreciate everyones thoughts. You have me thinking more about how to go about coming up with a solution. Before I do anything, I want to get my new table saw set up (which I hope to order today or tomorrow). I should be through with all of my cutting by this weekend, so I can move my saw out and clean up a little before the new one is delivered. I have decided on a Grizzly 1023 cabinet saw. I am almost 64, so it should be my last one.


----------



## giltic (Sep 27, 2010)

So Mike;
If I understand the threaded rods (M12) of the clamps are not long enough to go through your workbench and you want to extend it?
Why don't you extend it by welding a piece of threaded rod (with whatever thread you like) at the end of metric rod?


----------



## AndyL (Jun 3, 2011)

Phil P said:


> Hi Andy
> 
> Those are all sizes in my "bits box" bought from the local engineering wholesalers. Don't know what B&Q sell, however. It's why I pointed to the tables because outside of my own locality I have no idea what other people sell as their "standard", especially outside of the UK
> 
> ...


I believe the coarse thread is the default for any metric application, unless there's some specific design reason to use a fine thread. If Mike's clamps have an M12 thread, I'd be very surprised if it's anything other than the coarse 1.75mm pitch.


----------



## MT Stringer (Aug 15, 2012)

giltic said:


> So Mike;
> If I understand the threaded rods (M12) of the clamps are not long enough to go through your workbench and you want to extend it?
> Why don't you extend it by welding a piece of threaded rod (with whatever thread you like) at the end of metric rod?


Thanks. that would be an easy fix if I 1) knew how to weld, and 2) had welding equipment.  

Now that being said, I do have a friend that could do it. I hate to bother him because he is putting in a pool and cabana and all sorts of stuff, but he is a good friend.

Your suggestion is actually the best for me to get the results I want. I am headed to the store now to pick up some lumber. I will cruise the hardware isle one more time and see if they have some short pieces of 12 mm rod in th parts bin.

Thanks
Mike


----------



## jcliff (May 10, 2012)

AndyL said:


> Are you sure you've got that the right way round Phil? Almost every metric fastener I see is the coarse variety. If you see "M6" with no pitch specified I would expect that to be M6x1.0. The fine threads are fairly uncommon in my experience. Brake caliper mounting bolts and hydraulic banjo bolts are a couple that spring to mind, with the banjo bolts using the extra-fine option because they're hollow.


The ISO specs say that if you specify a metric thread without quoting a pitch you default to the coarse pitch with medium tolerances. So M3 x 0.5, M4x0.7, M5x0.8, M6x1, M8x1.25, M10x1.5, M12x1.75, M16x2.0 

For lots of tables of dimensions and geeky data on the subject check:
roymech.co.uk/Useful_Tables/Screws/index_screws.htm

That site has all sorts of good stuff on all sorts of subjects related to mechanical engineering and materials.


----------



## papasombre (Sep 22, 2011)

Hi, Mike.

May be near your home there is a metal working shop. You can take the piece to them and ask about its dimensions.


----------



## giltic (Sep 27, 2010)

Gosh, what a fuss. It's just a metric thread and not a rocket science. 
Just extend the M12 rods by welding 3/8" threaded rods (whatever length you need) at the end of the metric rods . And also buy a new 3/8" nuts to fix the clamps to the table.


----------



## MT Stringer (Aug 15, 2012)

giltic said:


> Gosh, what a fuss. It's just a metric thread and not a rocket science.
> Just extend the M12 rods by welding 3/8" threaded rods (whatever length you need) at the end of the metric rods . And also buy a new 3/8" nuts to fix the clamps to the table.


Not gonna work because then the bottom piece that screws on the threaded rod won't fit.

Plus I still want to be able to use them elsewhere. That is why my original plan was to find a coupling and use the same type of threaded rod.

Best I can tell, it is the 12mm 1.75 pitch, the standard metric coarse thread. I will look into it after Christmas.


----------



## giltic (Sep 27, 2010)

_Not gonna work because then the bottom piece that screws on the threaded rod won't fit._
That's why you would also buy a new 3/8" nuts.

_Plus I still want to be able to use them elsewhere._
You could use them elsewhere anyway. Still, you could just cut off entire metric threaded rod and weld other threaded rod on that place. Of course, you would need new nuts.

_Best I can tell, it is the 12mm 1.75 pitch_
Correct. For standard M12 the pitch is 1.75mm. But if it's not standard, it could also be M12x1.5 or M12x1 or M12x1.25.

Anyway, good luck with the clamps and best regards;


----------



## giltic (Sep 27, 2010)

Well, there is one more thing I can do. I can teach you how to measure the pitch. You will need a peace of paper, a digital caliper and of course a screw or a threaded bar in your case. I've used M8 screw in my example. 
1. I pushed the paper against the screw with my fingers - the footprint of the screw is now on the paper.
2. There are 30 threads between point 1 and point 2 (look at the attached image) - just count them and mark with a pencil.
3. Measure the distance between first thread (point 1) and last thread (point 2) - in my case the distance is 37.54mm
4. Calculate the pitch: 37.54 / 30 = 1.25mm and this is the pitch of my M8 screw.

Regards


----------



## harrysin (Jan 15, 2007)

The fact that the clamp is identical to mine and made in AMERICA, the chances are that the one you have is too, that being the case, don't you think it most unlikely that the thread is METRIC, more likely what I said earlier, UNC 1/2" 13tpi. in which case there shouldn't be a problem!


----------



## bobj3 (Jan 17, 2006)

you can pickup a thread pitch gauge from just about any auto parts store,most come with SAE and the Metric and are about 2.oo to 5.00 bucks.

Amazon.com: thread pitch gauge: Tools & Home Improvement

==


----------



## harrysin (Jan 15, 2007)

That Bob is exactly how I checked the thread on mine which checked out at 13 tpi and this was and exact match to 1/2" UNC x 13tpi.


----------



## harrysin (Jan 15, 2007)

That Bob is exactly how I determined that the thread on mine was 13tpi and UNC 1/2" was a perfect match.


----------

