Anyone know where I can get hold of 'Gauge Rods'

Hi guys please forgive me for as I get a lot of help / advice from our US friends sometimes the different jargon gets confused. What I am looking for is precision ground small round rods to use to hold against micro items being machined to assess whether it is the right length. Yes there are many alternatives to measuring micro items but i like the sound of this method and wish to source suitable gauge rods. Sizes would be in order of say 0.100 inch and i would need a fair range around this.

regards

Chris

If holding the rod at right angles to the turned length then "pin gauges" would be the UK term where the diameter of the rod is used as the Gauge. These tend to come in sets covering a range of size sfrom 1mm to 6mm or the imperial equivalent and can set you back several hundread pounds.

Not seen any where the rods come in different lengths

Most in teh UK would use gauge blocks which are as they say blocks not rods, you can get these in sets to make up 0.001" or 0.01mm increments again several 100s for new

Maybe ask your expert for a make or link to a supplier, even if US based it would enable you and us to see what you are looking.

Edited By JasonB on 05/09/2019 10:33:50

Can't say I've ever come across length gauges for comparison purposes. Apart from anything else how are you going to compare the lengths to check the size? As JasonB says pin gauges are readily available, but expensive; the diameters are accurate, length isn't. They exist because measuring the diameter of small holes is difficult. Length is easy, use a micrometer. The only common length rods I've seen are for checking micrometers, and they only come in a very limited range and have rounded ends.

Full sets of gauge blocks allow setting in 0.0001" and 0.001mm increments.

Andrew

Thanks Andrew and Jason yes pin gauges is the UK equivalent and yes they can be very expensive. If I am just using the known diameter to match / gauge what I am cutting on a micro item would machining my own variants from say 3 inch EN1A leaded or Silver steel suffice?

Regards

chris

If you are checking lengths, then the most accurate way is as already suggested, Slip gauges (Jo Blocks etc )

BUT DO use the protective slips at each end of the gauge block,

Would a depth mic not do the job, as a simpler and cheaper alternative??

Howard

confounded emojis!

Edited By Howard Lewis on 05/09/2019 11:13:20

I'll look up slip gauges but I suspect they will for some reason not be approriate...but let me look first Howard

Chris

As Andrew says a depth micrometer would be better for accurately measuring length rather than eye or finger nail comparing a round item against a length.

If slip gauges are not appropriate I am now really confused as to what you are trying to measure.

I say measure, but you say you want to 'hold the round rod against the part being machined'. Holding a gauge of any sort against the part does not seem an accurate way to measure. (Its all relative really as steel rules, magnifying glasses and good eyesight can produce accurate parts)

One simple question, do you want to measure length or diameter?

Ian P

Are you holding the dia of the rod against a finished face and touching the tool against the rod to set how far it is from the face eg to gauge the position of a cut? Gauging by eye, gauging by feel or something else. If the first option the gauge blocks will be better than rods.

OK this picture might help. For diameters I will use a micrometer. For lengths holding a pin gauge under magnification against the cut as in photo. Now back to the question can I make a collection of various diameters on my lathe that will suffice and if so EN1A leaded or Silver Steel? Remember this is micro machining.

Regards

Chris

Edited By Chris TickTock on 05/09/2019 11:50:20

I'm sure others will know better ways of measuring distances like you show, but a steel rule will be inherently better than eyeballing the edge of a cylindrical gauge.

Other than that why not just use the indexing on the lathe feedscrew dial (or a DRO or DTI) and make the part the correct length?

Ian P

As a follow up question gape pins need calibration is this essential or more dependant upon actual use?

Chris

Gauge blocks would do what you show and easier to compare the flat side with the faced shoulder and they will be more accurate than home made.

If you want to turn your own then EN1A will be fine as they are unlikely to get enough use to wear. or need callibration.

I assume Gape pins are the same as pin gauges

Edited By JasonB on 05/09/2019 12:19:38

Thanks Ian, look on a forum you get many opinions and that's good right and proper. The various methods of measuring are many and I have looked into them and arrived for better or worse at the point that I will be using the micrometer for diameter and the gauge pins for length. Every method that can be used can introduce errors especially when measuring so small stuff. As I agree there are viable alternatives but I am sticking for the present with my advisors advice.

Chris

Another option to save you making a load of pins is to use the shanks of drill bits, just check the actual shank with your micrometer as they may be 0.1mm below nominal size so just use one that measures what you want. I often do this to gauge the width and depth of small grooves.

With Gauge blocks you tend to group then together known as "Wringing" so for say 0.221" you would combine 3 blocks 0.200 + 0.020 + 0.001

Edited By JasonB on 05/09/2019 12:25:03

Yes you can turn the various required diameter pins yourself, silver steel/mild steel will be ok for these or just use the lead screw hand wheel if you have one to achieve the required step distance.

Tony

How accurate are you hoping to get. It seems that you are comparing rather than measuring, so why not use slips under a microscope or some other optical comparator. I am sure there is someone here who worked in an inspection department that could make a recommendation.

We need to go back to basics. How accurate do the lengths need to be? That's not the same as how accurate you want them to be.

To use a comparative method the reference item needs to have a sharp edge. All my gauge blocks have slightly rounded edges. Gauge pins might be better but not perfect. A sharp edge may damage the work when using them for the intended purpose of checking hole size.

I suspect the parts are too small for depth micrometers to be practical. I'd just use the dial on the lathe top slide, should be good to a thou or so.

These people sell HSS and carbide drill blanks:

**LINK**

To make a 0.221" stack I'd use 0.1" and 0.121" blocks; my set doesn't contain 0.02" or 0.001" blocks.

Andrew