How to chuck a bolt head

[Martin ConnellyParticipant @martinconnelly55370]

For anyone who wants to see this part here is the short version of the link **LINK**

Looking at the picture online I think it looks like the reduced section of the bolt has been made with a grinder. It only has to go down a hole so minimum required for cheapest cost is probably a bench grinder and an unskilled worker.

Martin C

[Philip HardyParticipant @philiphardy41757]

How do I attach the pics?

I know I could grind down the bolt but as I have the lathe I'd like to do the job properly

[Philip HardyParticipant @philiphardy41757]

[Philip HardyParticipant @philiphardy41757]

[JasonBModerator @jasonb]

Had it been a bolt then my fixed steady suggestion would have been ideal as you would have had the fingerts running on the plain shank of the bolt, your image shows a screw so as Nigel said best not to run on the threaded surface

Will he hex head fit down your lathe's spindle? If so drill and tap say a 20mm length of scrap, put a length ways saw cut in it then screw onto the hex head screw so 45mm sticks out. Now hold by the split bush you just made and turn to end down to dia

[Anonymous]

I'd just grip on the thread with a 3-jaw chuck and turn down the end. As long as the workshop gorilla doesn't tighten the chuck the thread will be fine.

Andrew

[Martin KyteParticipant @martinkyte99762]

My immidiate reaction to the problem would be to make a split collet either plain or threaded. Take a piece of brass or steel with a diameter just greater than the corner to corner distance of the head, face both ends to just shy of the length of remaining thread on the finished item in the 3 way chuck and either drill to a bare clearence or thread to the same as the bolt. Before removing from the chuck add a centre pop adjacent to chuck jaw 1 so you can rechuck in the same position. Remove and slit one side lengthways with a saw so that the chuck jaws can clamp between the saw cut (s). It may pay at this stage to add a couple of additional saw cut part thickness at 120° and 240° just to make it a little more flaxible. Clean up and insert the embryo part into the collet and replace in the 3 jaw with the dot next to jaw 1. Tighten the chuck and the bolt will be firmly held and on centre. You can now do whatever maching you like. (It takes longer to write than it does to make one)

regards Martin

Ah just seen that you have 4 inches free thread in which case it will fit in the 3 jaw as Andrew says with the head behind the jaws . Remember my method for much shorter thread length.

Edited By Martin Kyte on 23/09/2022 13:25:00

[BazyleParticipant @bazyle]

Zero precision required on the de-threaded part. Quit faffing around on the computer and have at it with the angle grinder.

edit – make sure you put a nut on the threaded part first, then after trimming the thread undo the nut to clean up the end of the thread.

Edited By Bazyle on 23/09/2022 13:23:07

[Philip HardyParticipant @philiphardy41757]

Thanks guys, really appreciate all your suggestions and advice. Off to have a go on the Myford later today.

Cheers,

Phil.

[Bill DawesParticipant @billdawes]

Hi Philip, this is not having a go at you, just as a matter of curiosity. You are presumably something of a model engineer as you have a lathe so why do you use cm rather than mm.

Model engineers frequently talk in imperial units but that's because most drawings, being of pre decimal age are in imperial, however most of us will be very used to the metric system, cm are not an SI preferred unit. (multiples of 1000)

I'm always having a go at my daughter in law for using cm, she is a teacher and she can't explain why they use cm in preference to mm in schools, i am sure I haver never seen an engineering drawing using cm.

Bill D

[Philip HardyParticipant @philiphardy41757]

Hi Bill, I'm afraid I'm not a model engineer more of a mechanical engineer where I build, repair and service small engines mostly on garden machinery.

I was lucky enough to buy my lathe when a work colleague, (when I was working, now retired), offered it for sale as his grandfather had died and he needed to clear out his work shop for a giveaway price which included many and I mean tools and accesories for it.

I joined the forum to enable me to ask what most on here would consider beginners questions and have been lucky to receive really excellent information.

I realised I should have used mm not cm, but I formed the question late one night and was obviously not fully awake.

[Clive Brown 1Participant @clivebrown1]

For the proportions shown in the picture, I'd think that the screw could be held with the 3-jaw chuck gripping on the threaded secction and the hexagon head beyond the back of the jaws somewhere in the morse taper of the lathe spindle Leave enough sticking out of the chuck for turning down the diameter.

[duncan webster 1Participant @duncanwebster1]

I suspect the head won't go down the spindle of an ml7. I wouldn't have started from here, a length of all thread with either a nut welded on afterwards or 2 nuts locked together would make life easier

[jaCK HobsonParticipant @jackhobson50760]

Another way: get a 20 cm bolt, chuck up 4cm thread, turn down end near chuck, part off. All sorts of things would work as it looks like accuracy isn't required. I might just spin it in a drill against a grinder to take the thread off.

I don't know the 'right way' to do it

[JasonBModerator @jasonb]

Or centre punch the end, put a centre drill in your cordless drill and drill a centre hole in the end of the bolt. Mow hold by the hex in your 3-jaw with support at the other end by a tailstock centre and your job will be well supported

[Nick WheelerParticipant @nickwheeler]

Posted by Bazyle on 23/09/2022 13:21:26:

Zero precision required on the de-threaded part. Quit faffing around on the computer and have at it with the angle grinder.

edit – make sure you put a nut on the threaded part first, then after trimming the thread undo the nut to clean up the end of the thread.

That.

All of it. Although using a bench grinder would be quicker and easier

[Howard LewisParticipant @howardlewis46836]

If yo know the thread on your new long setscrew, why not turn a simple cylinder, drill and tap to match the thread.

Screw a nut onto the setscrew, followed by the tapped cylinder.

Place the " cylinder" about 50 mm from the end of the bolt and lock in place with the nut.

Hold the hexagon in the 3 jaw, and place a steady around the "cylinder", to do what it says, to steady the job.. This will act as a bearing, which you can lubricate, while you turn down the first 40 mm of thread, and chamfer the end

Once that has been done, unlock the cylinder and remove it and the locknut.

You should now have what you sought.

Howard

[Tim StevensParticipant @timstevens64731]

One further factor -for next time – that i don't think anyone mentioned, is that on most modern bolts the hexagon head is not likely to be central to the thread. Pre-war bolts were more often turned from hexagon bar, so the problem hardly arose, but mass production, while cheaper, is not always as 'accurate' in factors which don't matter most of the time.

Do come back if you get stuck again, but try to do this when you are properly awake … !

Cheers, Tim

[Nick WheelerParticipant @nickwheeler]

Another thing to consider is that the forcing screw for a puller should be considered a consumable, as it's very easy to bend them or bugger up the ends. So making them from readily available threaded rod, with a nut welded on one end and a foot of some kind on the other or ground down like your pictured example, is more likely to be of use than spending ages worrying about turning a fancy finish.

 

As an example here's a car hub extractor fabricobbled out of scrapbinium, welded together on the car with no measuring at all:

 

It looks even uglier in the metal as the whole thing took about ten minutes for my own wheel bearing, but has paid back handsomely doing the same job for several other people.

Edited By Nicholas Wheeler 1 on 23/09/2022 22:50:20

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