Author Topic: One screw clamp  (Read 1769 times)

Offline sbwhart

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One screw clamp
« on: February 13, 2018, 06:56:40 AM »
Another handy bit of kit I found in an old copy of American machinist magazine,

A one screw clamp, again it can be used with just one hand so that its less fiddly to use than a two screw toolmakers clamp.







Stew
A little bit of clearance never got in the way

Offline bent

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Re: One screw clamp
« Reply #1 on: February 13, 2018, 08:39:19 PM »
Can never have too many clamps. ;)

Offline sbwhart

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Re: One screw clamp
« Reply #2 on: February 14, 2018, 06:50:06 AM »
Can never have too many clamps. ;)

I'd agree with that.

Drawings are attached.

Stew
A little bit of clearance never got in the way

Offline Lew Hartswick

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Re: One screw clamp
« Reply #3 on: February 16, 2018, 08:48:43 PM »
Drawings are attached.

Stew
Decided to do one of these clamps before the depth "transfer" tool.  It really is a transfer deice like a telescope gauge or a small hole gauge.
 So first thing to do was see what UNC / UNF screws are close and then what Murican steel can be "close enough". :-)
 settled on 2 -56,  4 -40  nd 1/4 - 28 screws, and 1/2 x 1/2 for the jaws, and 1/2 (trimed a bit) x some gauge or other that is about .110 tck.)
So got those parts roughed out. No school Mon so it'll be Tue before I can do any more.  I'll keep you posted and a pix or two later.  If anyone
wants the US equivalent dwgs when finished I'll be happy to supply.   :-)  If it really works. :-)
   ...lew...   

Offline sbwhart

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Re: One screw clamp
« Reply #4 on: February 17, 2018, 07:49:01 AM »
Hi Lew interested to see your progress.

One of the guys at the club who's a semi retired clock maker made one with a slight modification he extended the length of part 5 Bottom Jaw so that he could grip the extension in the bench vice and grip small clock parts with the clamp.


Stew
A little bit of clearance never got in the way

Offline Lew Hartswick

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Re: One screw clamp
« Reply #5 on: February 21, 2018, 09:37:22 PM »
Progress:  Got the jaws made and the X parts but may have to re do them.  Changed the screw to 1/4-20, the 28 tpi may make the adjustment too slow.  Am having a bit of re-design problem with the clip that lets the screw back up the jaws. :-)  More work tomorrow as
there is only one class , first one in the morning, so have the rest to play. :-)
   ...lew...

Offline Lew Hartswick

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Re: One screw clamp
« Reply #6 on: February 25, 2018, 07:52:35 PM »
A brief follow-up. :-)


more later.
   ...lew...

Offline GailinNM

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Re: One screw clamp
« Reply #7 on: August 22, 2018, 06:15:52 PM »
When this thread started I  was getting ready to build an improved Third Hand  to use when working on PC boards under the microscope. My  requirements were that the board would be held parallel to my work surface so the board would remain in focus when movin the board around and that it be low enough to clear the microscope  head.  After seeing this thread I decided to use the basic design for the one screw clamp. 

Firs off the clamp was made much smaller.  The clamp jaws are made out of 1/4 inch square brass bar.  I spring loaded the jaws to open them rather than use clip in a groove of the screw head.  To make sure that the clamp gripped on the tip of the jaw, I moved the slots in the jaw 0.010 inch inward towards the center line of the clamp.  This makes the back of the clamp 0.020 open , minus play in the linkage, when the tip of the jaws touch.

The base of the Third Hand is made of 1/4 inch acrylic so it will  not short out the circuit when using it for holding powered up PC boards for testing.  The balls are all 1/4 inch diameter theat were purchased on eBay.  They were drilled 1/8 inch diameter for use on the main support bar and 3/32 diameter to make he short double ended connector bars.  The connection links have pockets put in with a 1/4 in ball end mill and are 3/64 inch deep.  All the clamping screws are 4-40 socket head cap screws with the knurled head pressed on.  Assembly screws are 0-80. All linkage bushings are made from 1/8 ich diameter brass rod.

The main mounting bare is supported by sliding clamp that can be positioned along the vertical bar.  This clamp  has a slot on one side that indexes it on the vertical support.  By loosening  the screw the bar cam be rotated for working on either side of the board.  The clamp can also be revered and the smooth side allows the support bar to be positioned at any angle.

Gail in NM
I would like to be the kind of person my dog thinks I am.

Offline Steamer5

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Re: One screw clamp
« Reply #8 on: August 22, 2018, 06:22:30 PM »
Looks very useful Gail. File that one away for the future

Cheers Kerrin
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Offline zeeprogrammer

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Re: One screw clamp
« Reply #9 on: August 22, 2018, 07:07:52 PM »
I'd forgotten this thread. I'm glad it popped up again.

Nice job Gail.  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline GailinNM

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Re: One screw clamp
« Reply #10 on: August 23, 2018, 06:47:29 PM »
Thanks Kerin and Carl.
After using the fixture for a while I have a couple of mods to make on it.

Most of the time I run a ground trace around the edge of the PCB so climping on it is fine.  One mod is to put a couple of protruding screws in the fixture to connect scope grounds to. This will pick up the board ground through the clamps.  The other is for boards without this ground trace.  I am going to make up some additional clamp jaws out of Delrin so I can clamp on non-grounded areas of the PCB with out shorting out anything. 

Gail in NM
I would like to be the kind of person my dog thinks I am.

Offline Lew Hartswick

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Re: One screw clamp
« Reply #11 on: August 23, 2018, 08:13:11 PM »
I guess I forgot o post the pix of the one I made quite a while ago. It works OK but is a bit "ungainly" for most work. :-)

   ...lew...

Offline bent

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Re: One screw clamp
« Reply #12 on: August 24, 2018, 06:53:47 PM »
I like those scissor jack clamps, may have to borrow that idea!