Specialty Screw Clamps, By Ulma Doctor

[Tim9]

Some of those meat grinders I see on the Food Channel look very intimidating sometimes. Definitely wouldn’t put my hand anywhere near the blade without first cutting power at panel and locking it out. Remind me of an outboard motor in a garbage can.

 

[Ulma Doctor]

Curious why you choose that type of thread? I see were you state they seat the blade firmly against the clamp but couldn't the same be said of a rt hand thread?

i chose the trapezoidal thread due to its strength and longevity, plus i have a little less than a 6 ft stick of T14x3.0 rod that was begging to be utilized.

truth be told, i made a prototype with right hand threads and 60° v threads- it didn't function correctly
as the clamp was tightened, the rotational force of the screw had the nasty habit of spitting the blade right out of the clamp, thus defeating the purpose of the clamp.
the left hand threads direct the forces (and the item to be held) to the clamp instead of away from the clamp

 

[Ulma Doctor]

Far out! My dad's uncle was a high end tool and die maker that used to fly all over the country doing unusual jobs. One of his stories was about getting the contract to build the first spiral ham cutting machine. I always wondered what that looked like, a machine that could chuck up irregular pieces and make a uniform type of cut. I bet you see some far out machinery in your line of work!

Hi pontiac428,
yes sir, i see all kinds of cool equipment.
i have worked on many spiral ham slicers.
the most popular types are vertical slicers.
the bone in ham is set on a driven lazy Susan with the big end on the lazy Susan
a centering devise clamps with spring pressure onto the small end of the ham.
the bone is the central axis.
a spring applies torsional force to a blade, directed to the bone.
the knife runs up and down on a shaft parallel to the axis of the lazy Susan, driven by a slight pitch of the blade as the ham is rotated.
the thin blade is constantly trying to cut to the bone, but doesn't actually cut the bone- it does leave cut marks on the bone but no material is removed.
some are capable of spiral cutting a ham in less than 2 minutes.

thanks for reading and commenting!

 

[Ulma Doctor]

Looks good UD! That’s the same idea/principal the clock repair folks are using on clock plate clamps. They don’t sharpen the plates LOL, but use the clamps for supporting the plates for better working conditions.
Just wondering? Why the left hand threads?

thanks Chips!
the LH threads pull the blade into the clamp socket- i tried with RH threads first, but the blade could be pushed out during the tightening sequence

 

[Ulma Doctor]

Some of those meat grinders I see on the Food Channel look very intimidating sometimes. Definitely wouldn’t put my hand anywhere near the blade without first cutting power at panel and locking it out. Remind me of an outboard motor in a garbage can.

funny you should say something about hands and grinders...
many moons ago ,we had a guy who tested the big warning sign that resides on the front of the machine

well, he didn't.

i received a distress phone call from a local Fire Department, requesting directions on how to reverse a meat grinder that was minding its own business when an operator decided to accidentally ram a hand into the business end of its moving feedscrew.
you can guess the rest.
luckily his hand was not ripped off, but he lost a couple digits.

 

[Ulma Doctor]

Well done sir.

Not only well done, Mike, but very well conceived! Great job!!

very nice !

Thank you gentleman

 

[Nutfarmer]

Thanks for showing the machine. Love production equipment. Worked making pop top can ends for many years..Now repairing farm equipment.

 

[hman]

truth be told, i made a prototype with right hand threads and 60° v threads- it didn't function correctly
as the clamp was tightened, the rotational force of the screw had the nasty habit of spitting the blade right out of the clamp, thus defeating the purpose of the clamp. the left hand threads direct the forces (and the item to be held) to the clamp instead of away from the clamp
<and in post 696291>
the LH threads pull the blade into the clamp socket- i tried with RH threads first, but the blade could be pushed out during the tightening sequence

I'm trying to wrap my mind around why one thread direction would push in, and the other push out.

Best theory I can come up with is that -either- the blade notch isn't absolutely square with the axis of the screw (so the left side of the notch (where the periphery of a RH screw would be moving outward, inward for LH) is just a tad lower) -or- the blade itself is slightly tapered along its arc. If the latter, the in/out action of the screws would be the opposite if the clamps were placed on the "other side" of the blade, and users would have to be cautioned about where/how to apply the handles.

Needless to say, I'm totally fascinated by this "engineering problem."

Also wondering if it might not be a good idea to round the ends of the clamp screws, so they make contact with the blade only at their centers.

 

[mmcmdl]

i received a distress phone call from a local Fire Department, requesting directions on how to reverse a meat grinder that was minding its own business when an operator decided to accidentally ram a hand into the business end of its moving feedscrew.
you can guess the rest.
luckily his hand was not ripped off, but he lost a couple digits.

I'm sure you've heard the story about the guy that got caught in the pickle slicer ……………………………………..they both were fired . ( old joke but this reminded me of it )

 

[Ulma Doctor]

I'm trying to wrap my mind around why one thread direction would push in, and the other push out.

Best theory I can come up with is that -either- the blade notch isn't absolutely square with the axis of the screw (so the left side of the notch (where the periphery of a RH screw would be moving outward, inward for LH) is just a tad lower) -or- the blade itself is slightly tapered along its arc. If the latter, the in/out action of the screws would be the opposite if the clamps were placed on the "other side" of the blade, and users would have to be cautioned about where/how to apply the handles.

Needless to say, I'm totally fascinated by this "engineering problem."

Also wondering if it might not be a good idea to round the ends of the clamp screws, so they make contact with the blade only at their centers.

Hi hman,
I was dumbfounded when my first prototype failed.
the left hand thread was the very first answer to the problem.
it worked, although i can't tell you why.

i had also considered (and may still implement) a swivel foot, not unlike a c-clamp foot, to negate the problem altogether