Recommendations on checking a left hd 5" 8tpi i.d. thread with a pitch of 4.932-4.940

[rosie]

Recommendations on checking a left hd 5" 8tpi i.d. thread with a pitch of 4.932-4.940

I have a new part I'm getting geared up for. Quantities are supposed to be 450+ pcs a year. It is essentially a large nut with the 5" thread for about 1.25"(overall part thickness). I ordered a cheap 4-5" thread mike with interchangeable anvils. I'm planning on making a shop made go nogo gage set up. I don't think that is the best way to check, but I have not done much with internal theads over 1.5". Material will be 4140HT or 4150HT.

I have seen some indicator set ups on ebay. They look like a decent way to go if I had a standard and the rollers were at an 8 pitch.

Starrett Precision Thread Gauging System | eBay

250995860170 = Item number:

I don't mind spending some money on decent equipment. I would like some input/recommendations.

Thanks in advance.
Rosie

 

[The real Leigh]

Can you link to the Starrett product page or one from a distributor?

Ebay links tend to disappear after a short period of time.

- Leigh

 

[rosie]

I'll look more tomorrow. The link still works. You have to put the mouse icon on the print and move around. I'm thinking the ones this person has on ebay are for external theads.

 

[Finegrain]

How about a professionally made hardened go-nogo? It'll be spendy for sure, but if you're doing several hundred per year, it seems like a good investment. Might talk to your customer and look into 2 sets, one for you and one for him. Then you're both measuring the same way.

Measuring the PD won't tell the whole story. I'd be concerned about roundness and other things beyond the PD. The gage will tell you some of these things, that threads mic's can't.

Regards.

Mike

 

[Clive603]

At 5" diameter weight and feel of a conventional go-no gauge may be a problem.

Is there such a thing as an official "tilt gauge" for this sort of job? 30 + years back a (now) long lost acquaintance made it into his employers publicity brochure in a staged photo illustrating QC checks for a rather larger internal thread using what he called a tilt gauge. By my best recollection it was basically a three armed spider extending from a centre post with narrow (round?) thread masters at the end of each arm. Two arms fixed and the third hinging outwards presumably via a spring. Indicator in the top to show how far the hinged arm had sprung out. Obviously could be rotated to check roundness. Dunno if it was bought in or locally made. At the time they were doing stuff for nuclear applications, including threads a foot or two diameter, so things had to be about right.

Clive

 

[UK Graham]

If it was me doing that job I would do it the way you are planning, make a go and no-go guage as that makes checking very quick. Personally I would have made the guages by measuring with 3 rollers, the diffucult bit is the calculations to achieve the result. I have never seen a thread mic that large before so having gone to that expense even if they were cheap you should use it to make your guages. I would also make a female master thread for two reasons, 1 to protect the male threads when not in use, 2 so you know the 'feel' you are aiming for on the next run.

 

[rosie]

I'm sincerly sorry to not replying with an attached picture yet. Work has been crazy, and I just received a PO today for this part to start.

Thank you for the responses and I will get some type of link of what I was thinking to clarify.

I did get my cheap 4-5 thread mike yesterday, so I plan on trying to make some initial gaging in the next week or two.

Please remeber I'm open to any ideas you might have. This is an odd thread as far as I know, but I need some decent set up for production as this is a respectable customer and part.

Thanks again,
Rosie

 

[VMC_Jeff]

Does your customer have a GO - NoGo gage for this part? We do alot of "oddball" threading for one of our customers and they loan us their gaging to check those parts to. That way we are both using the same gages. In the past we have made our own gages for short runs but for longer runs you run into gage wear.

 

[tdmidget]

I'm sincerly sorry to not replying with an attached picture yet. Work has been crazy, and I just received a PO today for this part to start.

Thank you for the responses and I will get some type of link of what I was thinking to clarify.

I did get my cheap 4-5 thread mike yesterday, so I plan on trying to make some initial gaging in the next week or two.

Please remeber I'm open to any ideas you might have. This is an odd thread as far as I know, but I need some decent set up for production as this is a respectable customer and part.

Thanks again,
Rosie

Not odd at all. In the US most industrial threads over 2" are 8 tpi. 5"X 8 tpi is common as dirt in large steam turbines. What might be uncommon is that it is only 1 1/4 " deep. A full nut would be 5".