Myford ml7 toolpost bolts

[not done it yetParticipant @notdoneityet]

Posted by ega on 12/07/2022 10:17:52:

GHT considered cap screws to be acceptable for this purpose. Chips in the hex recess have never troubled me but I do use a ball-ended driver. Another reason to use cap screws would be losing the square key!

Someone mentioned that cap screws were prohibited in coal mines except where they were installed upside down.

That was simply a common sense safety issue. Coal dust explosions can be made even more dangerous if the initial problem is aided by coal dust becoming airborne! It is why racks of limestone dust are suspended in the gates, so that any explosion flame front is prevented from spreading too far from the coal face.  There were normally 3 racks, about 20-30m apart, as I recall.

Same as any coal milling building where all horizontal surfaces are piled with sand until it runs off, so that coal dust cannot collect, be disturbed, and add to the risk of increasing any explosion occurring.

Even flour mills take precautions – I don’t suppose many remember the Maxwell House factory exploding in Banbury, back in the early ‘70s? That was caused by a cornflour dust explosion when a hopper was severely over-filled. It made the top floor of the building seriously larger than the lower floors.🙂

Edited By not done it yet on 13/07/2022 17:45:52

[Chris MurphyParticipant @chrismurphy94983]

Hi,

Ive been searching around for these bolts but can’t seem to find the right ones anywhere .

I’ve seen some on Amazon, but most don’t say what the tip is, mine are 20 tip.

any ideas from anyone.

thanks

chris m…..

[SillyOldDufferModerator @sillyoldduffer]

Posted by Chris Murphy on 13/07/2022 18:17:16:

Hi,

Ive been searching around for these bolts but can’t seem to find the right ones anywhere .

I’ve seen some on Amazon, but most don’t say what the tip is, mine are 20 tip.

…

What do you mean by '20 tip' Chris?

Dave

[roy entwistleParticipant @royentwistle24699]

TPI ?

Roy

[SillyOldDufferModerator @sillyoldduffer]

Posted by roy entwistle on 13/07/2022 19:28:40:

TPI ?

Roy

Like it, makes sense, ta!

Aren't all BSW 1/4" bolts 20 TPI? If so could explain why many websites don't bother stating it.

Dave

[Clive Brown 1Participant @clivebrown1]

Posted by SillyOldDuffer on 13/07/2022 19:40:29:.

Aren't all BSW 1/4" bolts 20 TPI? If so could explain why many websites don't bother stating it.

Dave

[Chris MurphyParticipant @chrismurphy94983]

It’s obviously a misspelling.

tpi teeth per inch

chris m….

[Richard S2Participant @richards2]

They are all over the place on ebay. Search for seller Fixaball 1/4" Whitworth socket cap screws. It is where I obtained some and quality is/was good. 3/16" allen key required. Other outlets will also have them

[Howard LewisParticipant @howardlewis46836]

No Chris,

A good try!

We are talking about bolts and setscrews (threaded fasteners in general ) so tpi means THREADS PER INCH.

Sorry to be pedantic, BUT

A wrongly worded question will get the wrong answer to what is really puzzling you.

You really need to learn the correct terminology, otherwise the question in your mind and which you ask will get the wrong answers.

A little more study will reduce the number of questions that you feel the need to ask.

We all want to help newcomers to the hobby, but not trying to help yourself makes it difficult for the rest of us.

If you cannot get square headed setscrews for your toolpost, you should be able to make nthem.

You will need a 1/4 BSW die, and a Die Holder, and a file (Assuming that you do not have a milling machine )

Take some round mild steel bar, probably 10 mm diameter. Youwill need sufficient to make eight, and have some still held as a chucking piece.

10 mm will pass through the 2MT headstock of your ML7.

Assuming that the screws that you need have 1/2" of thread, you will need to have about 7/8" sticking out of the chuck.

Face the end of the bar.

Turn down 1/2" long (Or the same length as the thread length of the existing screws ) to 0.245 /0.247" diameter and put on a chamfer of 0.036" deep (Thread depth )

Using a Tapping Lubricant (Such as Trefolex, or Rocol RTD ) die cut a thread for 1/2" long (make the same length as the existing screws.

(Use an existing screw to adjust the die to cut the right size. Actually set the die to a slightly loose fit, to allow for some wear in the screws and threads that are there. ) You can check the setting by removing the bar from the chuck,and trying the thread in the one of the vacant holes in the Toolpost. You do not want a loose fit in the toolpost.

Once the Die is correctly set, do not alter the setting. (The middle screw will expand a split Die if it is too tight a fit. The oter two screws will close the Die if it too loose a fit. The adjustment is quite delicate.

Do not be heavy handed.

Having cut a suitable thread, pull the bar further ouit of the chuck, and part if off leaving enough metal for a plain collar above the thread,(Say 0.100" ) and a little more than 1/2" for where you will be filing the flats.

When you have made eight embryo screws, revesrs then in the chuck to face and lightly cjamfer the ends.

Ideally the screws should be screwed into a piece of nexagon bar tapped 1/4 BSW, or into two nuts. The cutting forces will probably jam the screw into the nuts, but it can be removed.

Once all eight have been made, you change jobs, from turner to fitter

Grip each screw in the soft jaws of a vice an acrefully file a flat, 1/2" wide (Long ) Each flat should be 0.277" wide, to produce a square 0.556 Across flats. Check frequently that the surface that you are filing is square to the adjacent ones, so don't try to make the first flat all in one goe. make a flat, say 3/8 -7/16" wide and then start filing the next one square to it. REpeat until you have four incomplete flats, Tjhis will leave you some metal to correct any errors..

When the square is complete, gently break the sharp edges on the corners.

Now you will need a spanner with which to tighten / slacken the screws.

You can either take the easy way out and cut a slot into a piece of plate (At least 3/8" or 10mm , maybe 12mm thick and file a slot 0.560" wide and 0.560 deep., or you can make a socket spanner.

This will entail drilling a hole 14 mm diameter into a piece of 18 mm or 3/4" diameter bar, 5/8" deep. You then file out the hole to produce a square that just bfits over the screws that you have made.

Part off the bar, say 1.5" long.

Face / chamfer the end.

Drill a hole onto it ( Say 3/16" diameter) through, and tap it 1/4BSW. Take a piece of bar (Ideally 1/4" diameter, or turn down another bit of 10 mm bar ) and screw it into your new socket spanner to act as a tommy bar.

As the late John Stevenson would have said, "Job's a good 'un"

DO tell us how you get on!

Howard

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 14/07/2022 13:23:06:

No Chris,

A good try!

We are talking about bolts and setscrews (threaded fasteners in general ) so tpi means THREADS PER INCH.

Sorry to be pedantic, BUT

A wrongly worded question will get the wrong answer to what is really puzzling you.

You really need to learn the correct terminology, otherwise the question in your mind and which you ask will get the wrong answers.

[…]

Grip each screw in the soft jaws of a vice an acrefully file a flat, […]

.

[Clive Brown 1Participant @clivebrown1]

There's no way that I would bother to make square-headed set-screws for a toolpost. Apart from the work involved, mild steel is too soft and weak, especially in 1/4" Whit size. The lower end, where it presses on the tool, will distort and the screw itself will quite easily bend or even shear.

Cap screws are made of much tougher stuff, usually 12/9 material which will stand up to use much better and, despite what's been written here, very suitable for the purpose IMO.

[Nick WheelerParticipant @nickwheeler]

I'm with Clive: eight new whitworth screws are about £2 and a couple of minutes at any industrial supplier – as long as you know what to ask for! Making square headed ones just to avoid occasionally having to clean the key holes is pure masochism.

[Howard LewisParticipant @howardlewis46836]

My rear toolpost has been in constant use for many years, and the square headed clamp screws were made to match those supplied in the front toolpost.. (Look at my albums, or the article on it in MEW.

Admittedly, they don't see many tool changes.

Yes, the easy way is to use Capscrews. (Which is what I did, many years ago, when making a rear toolpost for my ML7 )

I suggested that Chris made his, since he seems to having trouble finding what he wants..

And as an obvious newbie, the work would provide him with the experience and confidence that he needs, in both lathe work and fitting..

Howard

[Author]

Posts