Myford thread dial bolt size

[Allan BParticipant @allanb]

I have just bought myself a thread gauge to add to my Myford, but dose anyone know what the thread is in the right hand side of the carriage? It doesn’t come with the bolt, but I’m not to good with imperial bolt sizing and I would like to make a knurled thumb bolt ready to fit.

Thanks in advance

Allan

[Allan BParticipant @allanb]

[Jon GibbsParticipant @jongibbs59756]

Hi Allan,

The thread is 1/4" BSF but mine is a stud and nut.

HTH

Jon

[roy entwistleParticipant @royentwistle24699]

So is mine

Roy

[Nigel BennettParticipant @nigelbennett69913]

Allan – it doesn't just bolt straight on to the apron; Myford provide a couple of red fibre washers to space the unit off the apron in order to get the graduations to line up properly with the fiducial mark when the half-nuts are engaged. You need to fiddle about and choose the correct thickness combination of washers to do that.

As Roy & Jon have said, it's 1/4"BSF.

[Allan BParticipant @allanb]

Thanks all, love how much information is on this forum.

I will have a look for a stud and a tap so I can make a thumb whee, I have got numerous washers I can use to get a size, then a bit of nylon I can make a spacer out of as a final fix.

Allan

[Jon GibbsParticipant @jongibbs59756]

Posted by Nigel Bennett on 16/03/2017 08:39:21:

Allan – it doesn't just bolt straight on to the apron; Myford provide a couple of red fibre washers to space the unit off the apron in order to get the graduations to line up properly with the fiducial mark when the half-nuts are engaged. You need to fiddle about and choose the correct thickness combination of washers to do that.

….Ahhh, that would explain why mine doesn't line up exactly when engaged then – I have no fibre washers on mine.

Thanks Nigel.

Jon

[Allan BParticipant @allanb]

Now this might be sacrilegious but would an M6 stud do the same job (me penny pinching as normal with what I have in stock lol

1/4bsf is 6.35mm but it’s always cut a little under for threading so say 6.25mm,it is a 26tpi which comes out as 0.977mm, which is almost an M6X1 stud size, the only thing u would wonder is how much force it needs to take as it would only be holding by 3/4 of the thread area.

Allan

[Brian OldfordParticipant @brianoldford70365]

Go on, you know you want to do it properly. http://www.ebay.co.uk/itm/261467361177?_trksid=p2057872.m2749.l2649&var=560347081093&ssPageName=STRK%3AMEBIDX%3AIT

[Jon GibbsParticipant @jongibbs59756]

Allan,

Well if you're wanting to get into threading (otherwise why else would you want the threading dial on?) then why not turn a bit of the lathe?

The stud is plane 1/4" under the dial body rather than threaded – less wear over time although most of the time it'll stay put I know.

1/4" BSF is 26 TPI and you can leave the half-nuts engaged and reverse the tool out as you'd have to do for metric threads to avoid the threading dial issue.

If you need a 1/4 BSF nut to test fit then borrow one from elsewhere on the lathe. The banjo uses two of them and you could manage without one for a moment or two.

HTH

Jon

Edited By Jon Gibbs on 16/03/2017 09:38:48

[Jon GibbsParticipant @jongibbs59756]

You could always buy a die **LINK** or **LINK**

The Chronos price is delivered.

Jon

[Allan BParticipant @allanb]

OK I have bitten the bullet and bought some BSF nuts and will make the stud to match them, have got some HSS I can grind to the specified 55 degrees.

Allan

[not done it yetParticipant @notdoneityet]

There are so many options – as long as the thread into the casting fits. Threaded rod, bolt (not favourite), a stud with any thread you choose on the other end, metric, imperial, cycle? Nut, thumbwheel, wing nut. Any combination with the other end 1/4 BSF!

The usual reasoning with studs into cast is coarse in the cast end and (possibly) a finer thread for the nut. With a finer thread the nut gets undone and not the stud and is better for high clamping force applications. This is not a high clamping force application, of course. Think cylinder heads for high clamping force requirement.

Threads wear over time with continued use. The stud is easier to replace than the threads in the casting. Remember also that the thread dial has a clearance hole (for the relevant sized stud). Fitting a smaller stud should not be contemplated, even though you 'might get away with it'.

[Allan BParticipant @allanb]

OK so if I am going to do this properly, and before the actual part arrives, could someone please measure how long the hole through the the tread gauge is, and also what the ID is, then I will make a stud with 1/4 BSF on one end, M6 on the other, and then a thumb wheel to match

Allan

[Jon GibbsParticipant @jongibbs59756]

Here's my stud in situ. The stud is exactly 0.250" in diameter (calipers below). You should be able to tell how deep the threaded hole is on your apron perhaps.

Jon

[Jon GibbsParticipant @jongibbs59756]

Posted by Jon Gibbs on 16/03/2017 11:12:45:

Here's my stud in situ. The stud is exactly 0.250" in diameter (calipers below). You should be able to tell how deep the threaded hole is on your apron perhaps.

Link to original image here… **LINK**

Jon

[Allan BParticipant @allanb]

Jon

Thank you for that, I now know what tonight’s job is 😀

Allan

[Jon GibbsParticipant @jongibbs59756]

Happy turning!

Edit: When I think about it, it'd be really strange if the stud wasn't symmetrical end-for-end so that ought to give you everything you need.

Jon

Edited By Jon Gibbs on 16/03/2017 11:20:01

[Harry WilkesParticipant @harrywilkes58467]

Posted by Nigel Bennett on 16/03/2017 08:39:21:

Allan – it doesn't just bolt straight on to the apron; Myford provide a couple of red fibre washers to space the unit off the apron in order to get the graduations to line up properly with the fiducial mark when the half-nuts are engaged. You need to fiddle about and choose the correct thickness combination of washers to do that.

As Roy & Jon have said, it's 1/4"BSF.

Thanks for the info Nigel I was not aware that you needed to adjust the fibre washers, when I acquired my S7 in came with a thread gauge but it was not fitted so I'll check it out.

H

[roy entwistleParticipant @royentwistle24699]

I always thought that the fibre washers were so that it could be engaged and disengaged without using a spanner

Roy

[Jon GibbsParticipant @jongibbs59756]

I think Roy is more likely to be right than Nigel, now that I've examined my threading dial in more detail.

The pinion is free to rotate and is held simply with a cap-screw and washer onto the bottom of the indicator shaft. So, it can be positioned anywhere to adjust its position, irrespecitive of any fibre washers.

I think you just need to engage the half-nuts, mesh the pinion, align the indicator with the witness mark and snug up the cap-screw from below?

Jon

[Richard S2Participant @richards2]

Posted by Jon Gibbs on 22/03/2017 17:31:39:

I think Roy is more likely to be right than Nigel, now that I've examined my threading dial in more detail. Jon

Seems both can be right !. Myford ML7 Manual mentions the Fibre Washers are provided for alignment of the Dial markings with the zero mark on the Indicator Body (page 28, fig 39).

They (washers) can also serve to provide suitable resistance to permit engaging and disengaging of the indicator with the Leadscrew by hand pressure as many have found to be a handy procedure, but is not mentioned in the Manual.

Regards

[Jon GibbsParticipant @jongibbs59756]

Thanks for the reference to the figure in the manual – I obviously don't know that manual as well as I should.

When I look at other indicators on ebay they clearly don't have a capscrew holding the pinion gear on, which would obviously change the adjustment possibilities dramatically.

and

I am therefore beginning to wonder whether my thread dial indicator is either an old one or has been modified because it still seems to me to be much easier to align things by adjusting the retaining screw than trial-and-error with fibre washers that will compress over time. To boot, mine is also missing any fibre washers.

Jon

[Brian OldfordParticipant @brianoldford70365]

Posted by Richard S2 on 22/03/2017 19:57:41:

. . . . . . . . .

They (washers) can also serve to provide suitable resistance to permit engaging and disengaging of the indicator with the Leadscrew by hand pressure as many have found to be a handy procedure, but is not mentioned in the Manual.

Regards

I'm happy to be proven wrong but I've never seen a need to disengage the indicator from the lead-screw. Surely any increased wear is going to be immeasurable?

[Philip RoweParticipant @philiprowe13116]

I also never disengage mine, apart from the rare occasions when removing for cleaning/maintenance my thread dial has been permanantly engaged since 1973 and I can't detect any wear.

Phil

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