# Silly invention?



## Rayanth (Jun 19, 2011)

While at work drilling holes in a $150mln airplane (sure do hope those holes are in the right place...), The thought struck me for this invention. I don't have the steadiest hand with a hacksaw, and that leads to rather rough cuts, which in turn leads to more wasted material (sure, it's not MUCH, but maybe it adds up ;D) than necessary. While I could get a benchtop horizontal bandsaw or something... that takes up space for something that's used far less often than the prime machines of the trade - the mill and the lathe.

The trade is model engines. The core of a model engine is a piston. the piston converts horizontal motion into rotational motion, and later on that turns a propeller or wheel or something. but it's the horizontal/rotational conversion that interests me. If a piston can be used to convert the motion one way... it can also be used to convert it the other. It's merely a matter of where the power is being applied. The mill works on rotary motion, and a piston device can be used to convert that to lateral motion. A hacksaw uses reciprocating lateral motion to cut the material.

You can see where I'm going with this, can't you...

The following images are not to any sort of scale. They are the result of a couple of hours of brainstorming and a rapid mockup in Autodesk Inventor. Parts are colored for clarity. If you wish to attempt to build the following device, I accept NO responsibility for any damage to your machinery, material, or person as a result. I can't guarantee it would work, it's really just some brainstorming that I'm presenting to the group for comment. Even if that comment is "You're an idiot" ;D

The light blue component would chuck into the mill. the piston rod (red) is attached to a post that is offset from the center of the light blue component. That offset determines two things - length of cut, and based on RPM of mill, maximum speed of cut. (depth/pressure of cut is determined by the operator with manual HEAD downstroke... would need to be very light pressure!)

The gray base plates would bolt directly to the mill table, carefully aligned to center the piston sleeve with the center line of the mill head. The piston sleeve (orange) is attached to the baseplate posts via the purple guides, which have a round pin protruding into either side of the piston sleeve to allow pivoting, to help alleviate awkward loads. (This pivoting is actually prevented by the alignment of the piston, but...) the piston itself (dark blue) holds the saw blade via a pin between the two prongs, that would allow the saw blade to pivot at that location anyway.

The other base plate does not permit vertical movement of that end of the saw blade, but does permit lateral movement, by holding the saw blade with a pin that is permitted to slide back and forth in grooved tracks on either side of the riser blocks. Those grooves are open on the back end (not pictured, decided on this later) to permit sliding the pin with ease, and the block is positioned on the table so that at the maximum outbound stroke, the pin cannot fall out, but permitting full movement (with buffer) of the pin in the other direction as well.

The distance between the grooved risers is that of the width of the hacksaw blade, plus perhaps enough space for two washers, but not enough play to allow the blade to shift in the mill's Y direction. The same distance is used between the prongs on the piston.

This device would theoretically allow you to use your mill, at very low speeds to avoid overloading the teeth of the blade, as a powered hacksaw, by transmitting the rotary motion of the head into lateral motion of the piston, giving reciprocating motion to the hacksaw blade. Vertical motion is supplied by the operator, taking care not to press too hard, which would bind the teeth, potentially snap the blade, and cause more harm than good :-[







Comments are welcome, I understand this is probably a thoroughly insane idea, but it gave me something to do for three hours :big:

- Ryan


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## Rayanth (Jun 19, 2011)

aaaand forgot to add that of course the piece to be cut would be held with the vise, in the middle somewhere.

- Ryan

(edit: of course it's thoroughly possible something like this already exists... i didn't bother to look. A lot of my "inventions" turn out to already exist in some similar fashion, and that's far too discouraging. I wanted to let my creative side run free for a little while today)


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## itowbig (Jun 20, 2011)

a mini mini band saw sort of.


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## n4zou (Jun 20, 2011)

Converting a Mill into a powered hacksaw seams a bit inefficient. For about the same material, time, and effort you could build this simple powered hacksaw.

http://www.vintageprojects.com/power-tools/elect-hacksaw.pdf


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## Foozer (Jun 20, 2011)

Or the lathe, you need more work on yer bar, way too much free time 

[ame]http://www.youtube.com/watch?v=ti4N3FabLMs&feature=related[/ame]

Robert

EDIT: not mine, found it on y-toob


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## metalmuncher (Jun 20, 2011)

Hi Foozer, Thats a really simple solution for a power hacksaw, the only thing I would say about it is it needs some weight on it so the blade doesn't bounce. 
             Regards Metalmuncher.


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## cfellows (Jun 20, 2011)

Clever device, but I think the blade must be upside down. He's just wearing that groove in the bar, not cutting it... 

Chuck


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## Tin Falcon (Jun 20, 2011)

Well while your device would work . there are many power alternatives to a hacksaw. Vertical band saws horizontal band saws. Porta band, saws all ,power hack saws etc. A lot of engineering has gone into these and they work.
I think by biggest reservation though is why put such an isolating side load on a precision machine like a mill. Yes mills are designed for varining side loads but I can not imagine such a load would be good for a mill spindle and may in deed do harm. 
Those are nice drawings. 
Tin


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## mu38&Bg# (Jun 20, 2011)

I really don't see the load as being significantly worse than using a fly cutter.


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## dwentz (Jun 20, 2011)

Most of the powered hack saws that I have seen lift the blade in the none cutting direction also.

My little metal cutting bandsaw is one of the most used items in my shop. I could not function with out it. I purchased a little Taig lathe many many years ago. The band saw was way bigger than the little lathe at the time, but it sure made working with this metal stuff so much more pleasant. Ever try to cut a 2 inch round of CRS with a hack saw? 

Dale


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## Rayanth (Jun 21, 2011)

i had considered lifting the blade on the return cut, but there's really no point. a double-cut blade would cut in both directions, so lifting the blade would waste half the work. and a single-cut blade would just 'ride' the groove on the return cut if you kept pressure on it. might break a tooth or two if you put too much pressure on the return cut, but if you're pressing that hard, you've got bigger problems on the next actual cut =P

I didn't foresee problems with sideloads on the mill head. as was mentioned, it wouldn't really be any worse than a flycutter, and the loads are controlled by the pressure being applied. you COULD design it with a 45/45 bevel transition gear, to remove the side loads... but i really didn't want to worry about designing a gear housing on top of everything, so i kept it simple =P

And, as I said, it was just a silly idea that hit me while on a boring day at work (i got paid double time to come up with this junk!). I didn't expect it to gain much popularity ;D

Until my next silly idea (or stupid question)
-- Ryan


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## tel (Jun 21, 2011)

well, not really so silly either - I can see a potential use for shaping operations in the mill. rather that hacksawing (think 'square hole')


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