How to clamp ----Innovative

[Ashish B]

Hi,

This question is not related to CNC, but to its Innovative scope, I have posted here -


As you can see in the attachment,

On "Part 1", 2 sets of "Part 2" resort on either sides.
Screws (A & B) are bolted as shown in figure.


I was looking for some arrangment/mechanism such that -
By screwing/unscrewing a single nut, both the screws (A & B) should operate. (Either both should move closer or move far)

SOUNDS INTERESTING BUT VERY CONFUSING...

Ash

[ImanCarrot]

What about drilling a hole through part 2, part 1 and the other part 2. Tap a thread on the first part 2, Tap a reverse (left handed) thread on the other part 2, get a rod and thread the ends to match (one right handed, the other left handed. Stick a hex head or a screwdriver slot in the end of the rod.

That way as you rotate (tighten) the rod the two part "2"'s will move towards part 1.

You could have two locating pins on part 1 and matching holes in the part 2's to stop it flopping about.

[Zirok]

Extermelly brillant buddy.........


This stuff is so simple, unique. Literally, you won't believe that i was thinking to do some sort of rack & pinion mechanism for the same. I really sometimes want to kick myself for thinking such stupid things.

I got your concept, but i need 1 clarification.

As you told that a rod should be inserted inside Part 1 & both the Part 2.
It will enter through 1st Part 2, then through Part 1, but it will not enter in the 2nd Part2 as it has a reverse threading...I think it will come out...I am also confused...

Zirok

[ImanCarrot]

Let's call the first part 2, 2a and the second 2b.

The hole goes through 2a, part then 2b,

2a is threaded normal
2b is threaded reversed (left handed)

The hole through part 1 is not threaded at all

The rod is threaded normaly at the right- hand side and reverse threaded on the lefthand side (immagine twqo bolts stuck together by their small ends.

Now as you turn the rod clockwise the parts HAVE to move together

If you google hand held chisel sharpener the principle is the same- that have a double thread so that turning the screw brings the two side clamps together to hold the chisel.

[Ashish B]

Hi

Please refer attachment. As per your wonderful support, i have designed the mechanism.

Please check whether my interpretation is right or wrong.....


Ash

[Ashish B]

Sry.. Attachment was missing.

[ImanCarrot]

Yep! exactly... I would draw it exactly the same way, but was just too busy to do it.

Obviously, the "provision for allen key head" would need to be added after assembling the unit- could loctite a nut on one end of the threaded rod and use a spanner to tighten, or chop off the head from hex head bolt, drill it, thread it and use that with loctite, or simply hacksaw a grove in the end of the rod and use a normal screwdriver heh.

In fact! why not totaly do away with Part 1 by using two long pins going all the way from 2a to 2b, one on the left of the rod, the other on the right. Two fixed to 2a and the others able to go through 2b- cheaper! unless Part 1 is needed for some other purpose...

Iain

[Ashish B]

Three cheers...

Thanks

Actually, i resorted to allen head because allen keys get lock more firmly (so tighting will be more firm) as comparsion to spanner...


I could not locate "chisel sharpener" on web. Can you post the link over here.

Thanks for your superb idea.
Ash

[Ashish B]

Also, I am curious to know the name of this mechanism.
So, i could reasearch more deeply into it before manufacturing to avoid problems thereafter.


Also, i wish I could get a "Rod - Plain in the middle & threaded with left & right hands on either sides" Readymade avaliable in market which will really save my lot of time.

Thanks
Ash

[Geof]

There is another way to do it that does not use a left handed thread.

On one end use a coarse thread, for instance 3/8 - 16 and on the other end use 3/8 - 24. Now when you turn the clamping screw one revolution one thread advances by 0.0625" and the other by 0.0417". This means the spacing of the clamps changes by (0.0625 - 0.0417)" = 0.0208".

This is called a compound screw and it can give a very powerful clamping action because the effective pitch is the difference between the two individual pitches. One application of compound screws I have heard about is for the focussing optics in astronomical telescopes; if one thread is 20 tpi and the other is 25 tpi one revolution of the barrel only moves things 0.01".

[ImanCarrot]

Also, i wish I could get a "Rod - Plain in the middle & threaded with left & right hands on either sides" Readymade avaliable in market which will really save my lot of time.

Could always get a bit of threaded studding, cut it in two, turn one over and join them together

Drill the ends, thread them, stick a smaller threaded studding in there with superglue to join the studding together... job done.

Or you could take the two halves of the studding, drill and tap one half and turn a protruding "stud" on the other then use a die to thread that... the two would screw together (again with loctite/ superglue)

[Ashish B]

hMMM...Got your Point.


Also i was concerned about joining the allen head to one end.

I think i should thread the stud (M6) at one end. Than insert a M6 bolt into it. (The head of this bolt will be used to insert allen key) ..(Refer attachment)

To constraint the movement of M6 Bolt, i use feviquick, or the best weld it

Ash