Pre plated thread gages (Ring)

[DanASM]

I have a 5-40 UNC 2A threads that needs to be plated .0002-.0004 thick electroless nickel.

I am looking for some pre plated ring gages to use on this job. I am having no luck. I would have thought their would be something readily available.

I never plate over threads. In the rare instances we have done it in the past, it was mostly just trial and error as far as pitch diameter goes. We thought we left enough room on a zinc job but the threads came back too tight.

I know how to do the math to figure out where it should be prior to plating. I just thought there would be readily available pre plated ring gages.

Is using a UNC-3A gage ok for this? I feel like it would still be too loose. I am wondering if I am missing something as this should be pretty straight forward. Its not like I am the first person to do this.

Any advice is appreciated. At this point I am looking at using the correct gage and making sure the go gage is loose as can be without the no go gage going on. That should give me the tolerance needed for plating. I just feel there is an easier way.

Thanks in advance.

-Dan

 

[DanASM]

So you want a gage that's coated in a "mirror" to what the actual part will finally have? This allows correct gaging of the undersize part to get the buildup on the male threads correct?

Why not just supply regular gages to the plating shop, and let them gage the parts in process? You could even have a pair of gages set to the low and high end of spec, to make sure you're somewhere in the middle.

Or am I misunderstanding what you're trying to do?

I want to make sure that I cut the threads to the correct pitch diameter before they are plated. Plating will add .0008-.0016 to the pitch dia.

I was hoping there would be standard gages for this. I found them for internal threads but not ring gages for external threads.

I did find a go no go set on ebay that has a special no go gage with a pitch diameter that is only .0002 off from the major (pre plated) diameter. This is probably what I am looking for.

I thought it would be much easier to find, as threaded parts get plated everyday.

If I gave the plater the gages, it would not matter. The plating has to be .0002-.0004 thick, regardless. If the threads I cut have a pitch dia. that is too high before plating, then it will be too high after plating. I need to make sure I am low enough before plating but not too low that it is still out of spec after plating.

Currently I am looking at...

5-40 UNC 2A with a pitch dia. of .1080" (Major) and .1054" (Minor).

If I subtract the .0008" - .0016" from the pitch diameter to get the size needed (pre plate), I am at .1064" (major) and .1046" (minor). I guess I am looking for gages that would fit those pitch diameters. Thought I would have better luck.

 

[Thunderjet]

When we do this type of operation, we usually have the finish size ring gage, and then trial and error our way thru the thing.

But we have our own plating shop, so there's that.

I would say to find the finish gage, do the math, and try a series of sizes and send them to the platers. Sending instructions regarding the different samples, and keeping track of them.

Trying to find a ring gage for an ethereal size would be maddening, and almost pointless.

BTW, we're doing this on 00-80 threaded leads in Kovar.

 

[SeymourDumore]

OK, I would have also thought that pre-plate gages were sort-of off the shelf, even though I have had to order them custom made in the past.
You would have to figure out what you need exactly and specify it accordingly to the supplier.
ThreadCheck even has a calculator for it, as well as some info on how to roll your own: Calculating Pre Plate Screw Threads & Gages

With
That
Said!!!

If you want to get serious about measuring OD threads, then a tri-roll setup is very very hard to beat.
Tri-Roll Thread Comparator

 

[DanASM]

I did the math and I know what makes sense to me.

Trial and error was the plan. The plater explained to me a few years back all about electroless nickel. Its all rack and place, which makes the price high per part due to each being handled individually.

Plater is an hour away, so I can drive down if needed. Not a big job and not really worth the drive. Might be able to run sample size lots due to them being a racking plater.

I am sure they will work with me. Small part, 2.00" long X .125" pin. qty 1000 - .35 cents ea.

 

[MaxPrairie]

Is the required EN 0.0004-0.0008? Usually if I have parts with a critical fit I will shrink the tolerance for the plater. For this case I would probably put “0.0006 +/- 0.0001 tight tolerance” on the packing slip. Nickel is pretty easy to get the thickness where it needs to be and it’s more uniform that a chrome or zinc coating.

 

[DanASM]

electroless nickel, .0002 - .0004
Bake to Hardness of Rc 58-62

5-40 UNC 2A

 

[MaxPrairie]

electroless nickel, .0002 - .0004
Bake to Hardness of Rc 58-62

5-40 UNC 2A

Ha. I skipped right over that. That sounds more reasonable.

 

[Zeuserdoo]

I want to make sure that I cut the threads to the correct pitch diameter before they are plated. Plating will add .0008-.0016 to the pitch dia.

I was hoping there would be standard gages for this. I found them for internal threads but not ring gages for external threads.

I did find a go no go set on ebay that has a special no go gage with a pitch diameter that is only .0002 off from the major (pre plated) diameter. This is probably what I am looking for.

I thought it would be much easier to find, as threaded parts get plated everyday.

If I gave the plater the gages, it would not matter. The plating has to be .0002-.0004 thick, regardless. If the threads I cut have a pitch dia. that is too high before plating, then it will be too high after plating. I need to make sure I am low enough before plating but not too low that it is still out of spec after plating.

Currently I am looking at...

5-40 UNC 2A with a pitch dia. of .1080" (Major) and .1054" (Minor).

If I subtract the .0008" - .0016" from the pitch diameter to get the size needed (pre plate), I am at .1064" (major) and .1046" (minor). I guess I am looking for gages that would fit those pitch diameters. Thought I would have better luck.

If you already know where to hold the pitch diameter, you could use a pitch micrometer or pitch wires to keep the pitch at the required undersize diameter.

 

[Joe Gwinn]

Why not take a standard thread gauge, and electroless plate it? This will reduce the ID by the plating thickness, allowing correct gauging of the as-yet un-plated screws.

 

[Goff]

You can order any tolerance/gage size you want. We have 11/16-16 Left Hand Ring Go/NoGo 2A gages from Vermont Gage.
We also bought the Setting Gages. When we need a re-calibration, our local calibration house will verify the setting gages and use them to calibrate the ring gages.

 

[Larry Dickman]

I have a customer who supplies them with their parts as required. They get them off the shelf from Precon

 

[DanASM]

You can order any tolerance/gage size you want. We have 11/16-16 Left Hand Ring Go/NoGo 2A gages from Vermont Gage.
We also bought the Setting Gages. When we need a re-calibration, our local calibration house will verify the setting gages and use them to calibrate the ring gages.

I have had great luck with Vermont Gage for other jobs.

I like the idea of having one plated.

Something I have noticed on some of my in house gages and some I see online is that they say "Go" and "Low" as well as "No Go". The "Low" gages have a little higher pitch diameter on them than what the "No Go" gages say.

I am seeing some "Low" gages with a pitch diameter on them that is very close to what I need. I might take a chance and grab one.

I got the cams in today for this job and it is at 5 seconds. I will try to remember to take a video. I got 4 sets of cams in today, one for a nylon hex nut ( will run water sob coolant in a Brownie).