How to make a gauge tool?

[eventhorizons]

I want to have a custom gauge made that is much like those circular sheet metal thickness gauges you find all over the place. Like the one pictured.

They are precisely made out of tough materials but can be purchased for as little as $10! I'm not aiming for that low of a price but it's got to be reasonable!

What is the manufacturing technique that is used to make these items? Are those really narrow slots cut with slitting saws?

Wire EDM would be good for prototypes or small quantities, but I would think that would not scale well.

I apologize if I'm being dense but I have been pondering this and have not come up with a good answer. Thanks in advance!

 

[technocrat]

How precise do you think the slots are on a sheet metal gauge?
What tolerance do you want for your gauge?

 

[sfriedberg]

Stuff like this (e.g., drill gages with 60 holes all different sizes) is mass produced by punching on a press with a purpose-built die set. When QC says the feature dimensions aren't good enough anymore, individual punches are replaced and, if necessary, the holes in the die are reworked. Frequently die holes are made in replaceable "buttons" so the rework potentially can be quick. I haven't priced die work recently, but assume $5000-$15000 depending on the complexity of the part for construction of the die set. So you need to commit to making lots of them if you do it that way.
An alternative to wire EDM would be high-power laser cutting. (Absolutely not talking about a 50W table-top engraver!) This would be a lot faster, but you'd have to talk to the laser cutting vendor to get an idea of what kind of tolerances and surface finishes they can hold. I've mostly seen the high-power stuff in video clips where a 5 axis head is carving holes, slots and notches out of 1/4" or 3/8" wall tubing, where I am sure the tolerances are not close to "gauge class".

 

[eventhorizons]

I honestly don't know how precise the slots are in the sheet metal gauges.

For my gauge I would want to hold the tolerance at -0.000"/+0.001". The sizes would range from 0.030" to 0.500"

 

[eventhorizons]

...mass produced by punching on a press with a purpose-built die set.

I considered that, especially since ideally the holes would have a non-circular shape.

But my understanding was that when punching that the ratio of the diameter to the hole depth could not exceed a certain ratio and my design would be at least 3:1 for the smallest hole size.

 

[sfriedberg]

You haven't told us a lot, but I suspect that having a die constructed is out of your budget. If if punching would be economical viable for you, save for the tiny holes, remember than you could punch most of the part features and then use laser drilling or wire EDM in a 2nd operation to do the tiny stuff.

 

[jccaclimber]

For lower volume you could also waterjet/laser the blanks and do a more expensive operation for the functional surfaces.
Custom is seldom cheap until you're making tons, low volume is seldom cheap, accurate is seldom cheap. Just how many of these do you plan to make?

 

[eventhorizons]

My apologies for being light on the details!

You are correct that a $15K die is beyond the budget, at least at first. I'm definitely familiar with the good-fast-cheap triangle.

This started as an need for a tool for determining the size of hex wrenches. Something that can be left by the storage bin and would be quick and easy to use as well as being reliable and reasonably accurate.

I thought "Somebody must make something that does this!" But my Google skills have failed me several times and I have found nothing. The closest are hex key stands but they are not accurate enough as they are designed for a different purpose.

It would serve a need for me and I suspect it would be desired by others, though many people would poo-poo it as a waste. "Just use a caliper!"

It could be made just like the drill sizer plates, which I use all the time, but to avoid errors the holes should be hexagonal.

The price point would have to be fairly low. If I could find it on the market at all then I would happily plop down $30 for it. At $60 I would balk but would put it on my Christmas list or my "Mad Money" list.

If it were molded out of plastic it would probably "work" but would not be very durable in service. A precision die-casting may be suitable but would still feel cheap.

I assumed the drill-sizing plates were punched just based on looking at them, but I did not think that the sheet metal gauge could just be punched. It would seem to need something different, probably multiple different operations.

My original question was to gain an understanding of how tools like that are manufactured so that I could both broaden my knowledge and possibly see if it could be applied here. Maybe prototyping one was something I could reasonably do. I was hoping someone would say "Oh yeah, those are made by doing thus and so!"

 

[technocrat]

<snippo>
This started as an need for a tool for determining the size of hex wrenches. Something that can be left by the storage bin and would be quick and easy to use as well as being reliable and reasonably accurate.
<snippo>

screw some socket head screws into a plate

 

[jccaclimber]

Hex keys can be sized with a round hole, you don’t need the hex shape.
My ThorLabs hex key stands don’t allow the next size up to fit in the hole, so they sort as you want. I have not tried mixing inch with metric to see if they sort that as well.

 

[john.k]

To get better size accuracy ,the gauges shown would be punched and then drifted to size with another press process.....not suitable for a one off.

 

[memphisjed]

water jet is better. for your application laser should be fine. You can see if laser will work easy enough. Sendcutsend a drawing off and you have a protype in hand next week.

 

[AD Design]

For my gauge I would want to hold the tolerance at -0.000"/+0.001". The sizes would range from 0.030" to 0.500"

-SHCS mounted in a plate is a cheap/easy idea, so is the round hole. If really wanting a sheet metal type gauge you may have to open the tolerance a bit. I worked for Eklilnd Tool (hex key OEM) and we used a specific supplier or two for all hex key stock just for consistency of size/material. Occasionally Eklind was forced to purchase on the spot market and then the size would change a bit. I can't recall the deviation but it was certainly more than .001 and we had to specify the acceptable tolerance. Specifying a tighter tolerance means a higher price so you either work to the standard tolerance a mill works to, pay a higher price for being fussy, or loosen the tolerance. Working with ONE supplier means you know what to expect, working with several different mill suppliers or different brands of hex stock means you get to adjust your "gauge" every time.

To the OP- Is the design intent of this gauge need to serve as a "Go-No Go" type of function? If so, see the previous half of this post. If this is just for a quick/easy sorting of hex keys like a drill index functions then the SHCS or hole type should work better/faster/cheaper without the need to align the key flats to a hex opening of +.001. Also, have you considered what happens to the nice-n-tight tolerance when a hex key has a burr or slightly deformed end from use? Almost all hex keys chopped off in a stamping die have a minimal deformation/burr on the end from the die.

OBTW- I doubt a water jet or laser is going to be capable of +.001/ -.000 tolerance. None of them I've encountered would. If some of the newer ones are (possible) I doubt you'd like the price.

Not trying to rain on your idea, just presenting what I knew from hex key manufacturing in the 90's that may still hold true today. Hope this was of some help.

 

[john.k]

What about metal printing?........cheapest option for a small number?.....and the design is easily changed.

 

[michiganbuck]

CNC EDM would or high-power laser cutting might be the ticket because making such a gauge in quantity, or even just one on manual machines would be very time-consuming.
To get -0 +.001 would be very difficult in a low priced gauge

QT Op: (The price point would have to be fairly low. If I could find it on the market at all then I would happily plop down $30 for it.)

It would be very tough to retail price that gauge for such a low price.

 

[guythatbrews]

.001 total is very probably not possible with laser or waterjet. In addition there will be a corner radius you may not be able to tolerate.

We don't know your intended market or even really the use of this gage but FWIW I sure wouldn't pay $30 for one. Then again, I'll bet some of the name brand sheet metal gages are that much, if they still make them.

 

[Kingbob]

2 things, I think your tolerance is tighter then needs be for the application and secondly for a few small batches I wouldn't discount wire edm. These could probably be cut in a stack, all you have to do is find a garage shop guy with low to non existent overhead. If you let him take his time and don't bother him too much you might e able to get them at a price point you can live with. Sell the first few batches at cost just to see if there is a market. I'm done being surprised by what people will spend their money on.

 

[FredC]

I looked this thread over and I am not sure if the OP wants one for himself or wants to sell low quantities of these things.

Missed the part about sorting hex wrenches. I will leave the post and the photo as some newbies have probably never seen a "snap gauge"

In machine shop settings "snap gauges" used to be used a lot. I have not seen a new one for sale in a coon's age, but there are probably a bunch of surplus ones around. I have a half dozen in my toolbox that I picked up from somewhere. No recollection of where or when I bought them.

 

[BT Fabrication]

My apologies for being light on the details!

You are correct that a $15K die is beyond the budget, at least at first. I'm definitely familiar with the good-fast-cheap triangle.

This started as an need for a tool for determining the size of hex wrenches. Something that can be left by the storage bin and would be quick and easy to use as well as being reliable and reasonably accurate.

I thought "Somebody must make something that does this!" But my Google skills have failed me several times and I have found nothing. The closest are hex key stands but they are not accurate enough as they are designed for a different purpose.

It would serve a need for me and I suspect it would be desired by others, though many people would poo-poo it as a waste. "Just use a caliper!"

It could be made just like the drill sizer plates, which I use all the time, but to avoid errors the holes should be hexagonal.

The price point would have to be fairly low. If I could find it on the market at all then I would happily plop down $30 for it. At $60 I would balk but would put it on my Christmas list or my "Mad Money" list.

If it were molded out of plastic it would probably "work" but would not be very durable in service. A precision die-casting may be suitable but would still feel cheap.

I assumed the drill-sizing plates were punched just based on looking at them, but I did not think that the sheet metal gauge could just be punched. It would seem to need something different, probably multiple different operations.

My original question was to gain an understanding of how tools like that are manufactured so that I could both broaden my knowledge and possibly see if it could be applied here. Maybe prototyping one was something I could reasonably do. I was hoping someone would say "Oh yeah, those are made by doing thus and so!"

so you are trying to find a hex head bolt head size gauge? grab any hex socket set. its not like anything you cant carry over like full sheets of steel. As having hex shaped holes for some mystery reason is that male or female. male, just use hex bolts, female, use socket head cap screws

 

[TGTool]

I can imagine a completely different approach. It would take off on the antique indicators that were simply a lever with a pivot near the short end so it multiplied the movement. Instead of reading thousandths, it would only have marks for the fractional increments. And it would be faster than something like the wire or sheet metal gauge since you'd never have to try two different slots. However, for cost it might be hard to compete with the carpenters digital caliper that also reads in fractions.

Or there's the simple tapered slot like this sheet metal gauge. Probably accurate enough to sort hex keys and cheaper than lots of slots.