By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Startrite Mercury drill

Feed stop nuts thread specification

All Topics | Latest Posts

Search for:  in Thread Title in  
David Galt20/04/2020 20:07:50
5 forum posts

Hi All,

I have a Startrite Mercury floor standing drill. Unfortunately I have lost the knurled two feed stop nuts off the top of the feed stop. Looking to replace them I measured the thread (male part). It was measuring as 14tpi with and approx 15.9mm over thread. From this I assumed it was a 5/8” BSF and ordered a couple of lock nuts. Of course they did not fit!

Can anyone confirm what the thread specification is?

not done it yet20/04/2020 22:38:28
6748 forum posts
20 photos

What thread form is used on the rest of the machine? Could they have used a non-standard thread?

Michael Gilligan21/04/2020 00:05:15
avatar
20112 forum posts
1044 photos
Posted by David Galt on 20/04/2020 20:07:50:

[…]

From this I assumed it was a 5/8” BSF and ordered a couple of lock nuts. Of course they did not fit!

.

That does seem an eminently reasonable assumption

... Have you inspected the new nuts ?

MichaelG.

Pete.21/04/2020 00:12:39
avatar
796 forum posts
235 photos

7/16 14tpi

Pete.21/04/2020 00:15:59
avatar
796 forum posts
235 photos

I just checked mine with a thread gauge, that's what it was on mine.

David Galt21/04/2020 06:33:37
5 forum posts

On the basis that 7/16 BSW takes a 11.5mm clearance drill, I ruled that out as my thread externally was nearly 16mm

David Galt21/04/2020 06:39:23
5 forum posts

I have minimally inspected the new nuts with a vernier only, as I don’t have thread gauges. Internal diameter inside the nut is 15.5mm. It’s difficult to measure the tpi

Michael Gilligan21/04/2020 07:21:14
avatar
20112 forum posts
1044 photos
Posted by David Galt on 21/04/2020 06:39:23:

I have minimally inspected the new nuts with a vernier only, as I don’t have thread gauges. Internal diameter inside the nut is 15.5mm. It’s difficult to measure the tpi

.

Just screw the nut onto a wooden dowel, David ... Then measure the tpi of the the impression.

MichaelG.

Clive Brown 121/04/2020 08:46:02
807 forum posts
39 photos
Posted by David Galt on 21/04/2020 06:39:23:

I have minimally inspected the new nuts with a vernier only, as I don’t have thread gauges. Internal diameter inside the nut is 15.5mm. It’s difficult to measure the tpi

The minor dia. for 5/8" BSF is about 14mm, so whatever you have been supplied with doesn't seem to be that.

Nearer to 11/16" BSF in fact.

Edited By Clive Brown 1 on 21/04/2020 08:50:12

Oldiron21/04/2020 09:52:58
963 forum posts
40 photos

Do you have the tools to make a new set of nuts ? Or even a new stop bar.

regards

Gary Wooding21/04/2020 10:17:10
969 forum posts
254 photos

In the following chart the tapping drill size should indicate the ID of the nut.

imperial threads.jpg

Pete.21/04/2020 10:40:51
avatar
796 forum posts
235 photos

Might as well buy a thread gauge, if you don't want a decent one, you can buy a cheap one for a couple quid, it'll pay for itself by dodging one wrong order.

Martin Kyte21/04/2020 11:03:55
avatar
2728 forum posts
48 photos

I Have a bench mount Startrite and the nuts on that are 14 TPI 5/8" BSF if that is any help.

regards Martin

Hopper21/04/2020 11:07:51
avatar
6217 forum posts
321 photos
Posted by David Galt on 21/04/2020 06:33:37:

On the basis that 7/16 BSW takes a 11.5mm clearance drill, I ruled that out as my thread externally was nearly 16mm

BSW is irrelevant to BSF. Different TPI, different thread depth. And clearance drill? Do you mean tapping size drill? Clearance size drill for 7/16 would be 15/32".

Edited By Hopper on 21/04/2020 11:08:38

not done it yet21/04/2020 11:47:18
6748 forum posts
20 photos

I’ll stick with metric, unless the OP confirms the rest are imperial. No age given for this machine and it is a common mistake by the inexperienced to measure the distance between ten crests instead of eleven...

But still only guessing. Initially I thought that maybe they had used a bastard thread, like 16mm x 1.75mm pitch (some manufacturers are known to do this sort of thing), but now I reckon it could be 16mm coarse thread.

Rod Renshaw21/04/2020 12:26:05
376 forum posts
2 photos

My 1970s vintage Mercury bench-top drill appears to be built to Imperial standards and the depth stop thread measures as 5/8 " X 14 TPI and the thread gauge seems to confirm 55 degree angle thread, though I can't find an actual nut to confirm, all my stuff is smaller than that. I wonder if the O P has been sent the wrong size nuts, it does happen, young people now only get taught about metric!

Anyone got a spare 5/8" BSF nut they could send him?

Rod

Martin Kyte21/04/2020 12:30:02
avatar
2728 forum posts
48 photos

I concur with that. Thats what mine is.

regards Martin

Farmboy21/04/2020 12:31:09
167 forum posts
2 photos

Can't tell you the size as it is completely missing on mine and replaced with a bit of threaded rod and nuts, but spares do seem to be available ( for more than I paid for the whole drill ) from Machine Spares Ltd.

Mine is actually a benchtop model but I believe the head is the same as the floor standing one, although there are several models, I believe.

Mike.

Edited By Farmboy on 21/04/2020 12:39:34

David Galt21/04/2020 12:31:10
5 forum posts

Metric? Ok, I have just had a look over the drill and there are m8 bolts holding the motor down and m5 holding the cowl on.

M16 x 1.75? Funny you should say that, because I have a standard M16 nut which starts for a couple of threads but then tightens. The 5/8-14 BSF doesn’t even start.

I include the enclosed photo of pitch. I set my vernier to 25.4mm and took the photo. I count 14 pitches.

25.4/1.75 is 14.28 so I think you may be correct.

next question is if it is M16x1.75, then where would I buy a couple of half nuts? Or even better, knurled thumb nuts?

Many thanks for your help so far.

not done it yet21/04/2020 12:52:43
6748 forum posts
20 photos

The standard pitch for 16mm is 1.5mm and 16mm coarse is 2mm. I doubt if 16mm x 1.75mm pitch anything is available - unless to special order. Fingers crossed that the new nuts supplied were metric instead of imperial!

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
cowells
Dreweatts
Rapid RC
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