Weight sensitive clicker

No luck googling using terms like this. I am looking for a device that will make an audible warning similar to a torque wrench when an adjustable amount of weight is applied to a rope pulling something. For example I have the device in line with my rope between the object I am pulling on. I set the clicker or other audible to a desired weight and it goes off when I hit that weight. I can’t figure out what to call it when searching. Put this under wrong subject and cannot delete it, sorry.

Reported for forum change.

Way ahead of you.

13 seconds behind, actually. :smiley:

Would you be looking for a torque pulley?

That sounds like it is worth looking up, will do now and let you know.

An audible scale? like something you could hang a fish on.

Load scale.

What I am doing is monitoring the weight I am pulling an a bow as I build it. I have the bow hanging from a scale or mounted on a board with the scale hanging from the string. I use a rope and pulley to draw the bow as I monitor it. As I build it I have to watch the shape of the bow which is what I am adjusting, the distance I am pulling it and how hard I am pulling it. Too many things to watch at once, setting the scale for an audible signal would relieve a a lot of stress on building these all wood bow which tend to explode if you go too far one way.

I think the link I posted has what you need.

That would do exacxtly what I want but a bit too sofisticated for my needs. I think manual tension gage with audible might be what I need, it just came to me.

There ya go!:smiley:

Some terminology to help with the search:
You are in fact measuring force, not weight. Weight is the force on two masses due to gravity. Of course, you could weigh a bow but once you apply tension in addition to gravity, welcome to forceville. The difference is subtle and often the terms are used interchangeably in conversation but if you direct your searching at force gauges rather than scale, I think you’ll find more to your liking. Many gauges have lbf and/or kgf (f for force, not feet!) as a unit of measure as a nod toward this distinction and many have newtons which is not a unit of weight at all.

A force gauge used in tension is sometimes called a dynamometer, especially at higher capacities, say, over 500lbf.

A device which does ‘something’ when a certain load(s) is reached is often said to have setpoint(s). You sometimes hear this called an alarm but this is usually reserved for protecting the gauge or other device like an overhead crane from an approaching overload condition.

I’m pretty familiar with many type of gauges and force measuring instruments and can’t think of a mechanical gauge which clicks in the same way that a torque handtool indicates a preset value. I also can’t think of a mechanical gauge which is easily adjusted to the tension of your choice. Mechanical gauges are also pretty low resolution.

I think the OP is really best off locating a digital force gauge with programmable setpoints to perform this pull testing. I further recommend an S-beam type load cell which can be used in tension and compression and has a pretty low headroom height which is often a real advantage in these applications. The mounting is simplified with threaded holes on either side of the cell.

Very helpful info, I have a 300# max load cell which would work but we do a lot of field trips and camping trips, a tiller tree for mounting the bow may have several users at any given time so something more rugged and manual would be preffered. I could probably build one easy enough using a spring and a ball detent. I thought sure I would find somethign ready made but nothing is popping up.

You could rig something up using a click wrench. Put a 12 inch bar on the drive head and either rely on the indicated reading or test with a known weight. You’d have to keep your parallels parallel and your tangents tangent but it might work if the pull distance is pretty similar every time.

But I’d really reconsider a proper electronic gauge. I think you’d wind up finding all sorts of uses for it. And there’s a reason they don’t use springs in even fish and luggage scales anymore.

You can get a nice little meter the size of a Cracker Jack box, runs on 4 AA batts (or anything 7-28VDC), std RS232 comport for data export, two setpoints, available IP65 environmental protection for $250-300ish (Linked one is for panel mount, add’l accys needed). And your 300lb cell could probably hold 0.05lbf resolution, more if it’s a fair or better one.

How about something like http://upload.wikimedia.org/wikipedia/commons/4/4f/Weeghaak.JPG , a sliding electrical contact, and a conductivity tester?