By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Dial indicator probe threads

All Topics | Latest Posts

Search for:  in Thread Title in  
gerry madden16/03/2019 19:08:15
95 forum posts
43 photos

Does anyone happen to know if there is a standard thread for dial indicators probes ? I need to make some extension bars.

Chris Evans 616/03/2019 19:14:50
1584 forum posts

No standardisation, I have got away with using a "Near Enough" BA thread when making mine and not having any small metric dies. I have several dial indicators and all are different threads.

Michael Gilligan16/03/2019 19:16:28
14920 forum posts
638 photos
Posted by gerry madden on 16/03/2019 19:08:15:

Does anyone happen to know if there is a standard thread for dial indicators probes ?


Several, I'm afraid, Gerry

Try here for starters: **LINK**


Neil Lickfold16/03/2019 19:40:22
585 forum posts
102 photos

A lot of the plunger type indicators , use M2.5 and M3 that I have seen so far. The M2.5 is 0.4mm pitch . The M3 is the standard 0.5mm pitch. I have made several for the plunger indicators. I made my extensions from 3mm and 4mm ejector pins. They are nitrided on the outside, are reasonably straight, cheap, and once through the nitrided coated the steel is not that difficult to turn or to thread cut. I start the thread by thread cutting, then use the die as a chaser to follow and make it to the final size. When I need a flat surface, I use the head end of the ejector pin. But most of extensions have either had a 2.5mm ball retained with loctite, or have been points, or a blade of some sort to get to measure or compare a feature.

I have found the threads on the plunger matches a M2.5 capscrew or M3 capscrew really well, while the tip thread is often loose and undersized by at least 0.1mm in diameter or more sometimes.


gerry madden16/03/2019 19:41:49
95 forum posts
43 photos

Thanks Michael and Chris very much for your inputs. When I read Chris's reference to 'metric dies' I suddenly remembered I have a box of small ones somewhere! Just found them and the 2.5 seems to fit 'acceptably' so just about to try with this.

John Alexander Stewart17/03/2019 10:35:01
758 forum posts
51 photos
Posted by Michael Gilligan on 16/03/2019 19:16:28:

Several, I'm afraid, Gerry

Try here for starters: **LINK**

Just a note - the link mentions M1.7, which is, IIRC, only a JIS metric standard. It's *really* close to a BA size, and my theory is that it was simply metricated way back when so that British equipment in Japan could be repaired. Yes, the thread form is different, but for many applications, it's close enough.

I also think that there's also other BA sizes mapped into odd JIS metric.

Anyway, someone may find this useful, or someone may actually come up with an equivalent chart, or...

Neil Wyatt17/03/2019 17:14:10
17291 forum posts
690 photos
77 articles

Soime digging suggests M1.7 is not on the first,second or third preference series or the coarse and fine pitch series of ISO161. There are 1.75 and 17, but no M1.7.

Quite possibly it is intended as a substitute for 10BA as JAS suggests.

John Purdy18/03/2019 17:38:36
193 forum posts
61 photos

I have 5 dial indicators, 4 of which ( one US one UK and two Chinese ) have 4-48 threads, the other Chinese one has a metric thread. Not sure what the metric thread is but a 4-48 probe will screw in 3 or 4 threads, so is very close to 4-48. 4-48 seems to be the standard for american made units.


Oily Rag24/03/2019 17:30:07
38 forum posts
18 photos

Try a bicycle spoke! Worked for me on several occasions.

Vic24/03/2019 18:32:46
2427 forum posts
12 photos
Posted by Oily Rag on 24/03/2019 17:30:07:

Try a bicycle spoke! Worked for me on several occasions.

What was it like riding the bike afterwards? surprise

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Allendale Electronics
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest