Workholding questions!

[Chris ParsonsParticipant @chrisparsons64193]

Looks like I will be OK? If I take it slow, once one side is done it will sit a bit further into the chuck perhaps? Feels pretty solid, I guess when it flies past my ear I will know how solid…

The image below shows the cap screw supplied with the 4 jaw, and a bolt fitted from the 3 jaw. The difference between the two is 4mm, but my logic is if the shorter bolts (16mm) are OK for the 3 jaw they will be OK for the 4 jaw – and there are 4 bolts not 3 as well

Thanks for all the help and advice everyone

Chris

[blowlampParticipant @blowlamp]

Posted by Chris Parsons on 18/02/2013 22:32:39:

Looks like I will be OK? If I take it slow, once one side is done it will sit a bit further into the chuck perhaps? Feels pretty solid, I guess when it flies past my ear I will know how solid…

The image below shows the cap screw supplied with the 4 jaw, and a bolt fitted from the 3 jaw. The difference between the two is 4mm, but my logic is if the shorter bolts (16mm) are OK for the 3 jaw they will be OK for the 4 jaw – and there are 4 bolts not 3 as well

Thanks for all the help and advice everyone

Chris

That looks like a pretty iffy setup to me Chris, judging by how much the jaws are hanging out of the chuck and by how little of the jaws overlap the bar.

Martin.

[NJHParticipant @njh]

Chris

I agree with Martin – I think your set up looks very iffy.

It might not fly past your ear but instead hit you in the face and take your eye out – I really advise you not to proceed like this.

Always work carefully

Norman

Edited By NJH on 18/02/2013 22:59:35

[MadMikeParticipant @madmike]

Chris that does not look secure. It is hopefully an optical illusion but your jaws do not appear to be past the centre of the workpiece, and they need to be on the round bar you are using. Should that be the case you stand a very serious risk of the component launching itself when you start machining it.

[Chris ParsonsParticipant @chrisparsons64193]

Right, OK – looks like I'll have to clamp it to the crosslide and get a flycutter to put in the 3 jaw, means a bit more effort but it is a bit of a lump to turn into a projectile.

It's 30mm diameter, I guess a bit smaller and I might be alright but I have no problem trying the other approach, and as I am learning it's hard to judge what is acceptable (or not!)

Chris

[jason udallParticipant @jasonudall57142]

Posted by Chris Parsons on 18/02/2013 09:16:22:

Got my four jaw chuck out of the box for the first time on Sunday with the aim of cutting a short, round bar into a rectangle (to create a tapping block)

..

 

why not make you blocks concentric like this….

 

if not obvious,parallel faces,drilled and tapped square to faces

about 5-10 leads thick and V' eed if you feel the need.

or have I missed something?

Edited By jason udall on 18/02/2013 23:54:30

[Ian S CParticipant @iansc]

Chris, when you go for bolts for your chuck, either black cap head screws, Allen head. Or hex head 8.8 or better, these are high tensile bolts, others of lower strength may be OK, but best to get the best.

If worst comes to worst, you can always attack the first side with a hacksaw and file, you can clean it up afterwards in the lathe. Ian S C

[JasonBModerator @jasonb]

Do what I said earlier and saw down the length to make it a "D" section then it will go back far enough in the chuck to start turning.

J

[jim’Participant @jim11037]

the cap screws are wrong, you need bolts. (no space for allen key.

the cap screws are to bolt the chuck to a back plate

[Ian S CParticipant @iansc]

Friends got a combination lathe/mill with cap screws, a key is made by getting a bit of 3 mmx 25 mm x 150 mm+ steel, drill a hole near one end, cut a short bit of an Allen Key, drive it into the hole, braze it in place, it only needs to protrude 5 or 6 mm. Hex head will save a bit of trouble, but the short key idea is useful anyway.

If you make a fly cutter, make it with a substanial shank, with reasonable length, and keep the cutting radius down, say 30 mm max,and take it quietly, even .010" per pass will get you there quite quickly, your not making 10,000 pieces.    Ian S C

Edited By Ian S C on 19/02/2013 12:18:51

[Chris ParsonsParticipant @chrisparsons64193]

 

Jason B – Thanks, I considered sawing down the length but this seemed like hard work, and I am treating this almost as an challenge now – after seeing your images showing the crosslide mounting I can imagine lots of occasions when this would be useful, ie perhaps using a slitting saw mounted on a mandrel in the chuck so thought this was worth investigating.

I appreciate the remarks about the chuck mounting, never thought about the cap screws being for a backplate, you are correct about using an allen key, no room

The bolts I am waiting for are 8.8 high tensile – 16mm and to be honest I don't find it too hard to fit them, the problem with the cap screws were that they were just too long, period, but if they were not intended for mounting the chuck on the mandrel then this makes more sense!

As an aside, it is interesting that you can spend a substantial amount of time (and money) on this hobby but if you are like me you are truly stuck unless you have someone to talk to about it, this is why I did my course at Axminster, but this really only scratches a very small part of the surface.

It is interesting to consider how you learn all this, from scratch/trial and error? Do it as part of an apprenticeship? Be lucky enough to have a 'mentor'? I had never used a lathe until the course, and the dozen (probably) books I have does not always prepare you for the real thing,

I am a 'technical' diver and all the training from day one is with an experienced mentor (a 'buddy' who when you start is capable of not only teaching you but also rescuing you when things go horribly wrong…not quite the same but a lot of divers who dive solo (ie no buddy) do not always survive, but I digress

Regards

Chris

Edited By Chris Parsons on 19/02/2013 12:50:38

[MadMikeParticipant @madmike]

Chris, although your workpiece appears to currently be too far forward and thus not allowing the jaws to grip safely, you could simply measure the distance it need to be set back and file a flat with a coarse file. Leave a piece of the full diameter at the end so that you can easily measure the amount you have removed when machining. Simply placing the filed flat to the face of the chuck should do the job and allow you to get a full grip and carry on. Just make sure that the face of the workpiece is parallel with the face of the chuck if your filing skills have yet to be fully developed. Just mount a clock on the cross slide and adjust until it is parallel. HTH.

Where have people developed their skilss? Well in my case it was as a toolmaker apprentice initially about a 1000 years ago, followed by a working lifetime in engineering based companies. Others have learned from friends and mentors, joining a local model engineering society, and yet others by trial and error. many books are written on the various engineering techniques but I have mainly found them useful as light reading, but that is probably due to my backgroung I guess. Other experiences are available and I hope that yours is a most enjoyable one. I don't do model making, using my machinery to make parts for the motorcycles that i collect and restore, but I do very much enjoy visiting this site. There are some very experienced people here are generous with their advice and even after a working life like mine I impressed with what they achieve and always manage to learn something on here.

Keep visiting and keep asking questions. If you happen to be near Leicestershire you are welcome to pop in for advice, help or simply a cup of tea etc.

[KWILParticipant @kwil]

Whilst it may be my eyes, but MadMike's bold typeface is not at all easy to read.

[1Participant @1]

Thank goodness it's your eyes Kwil, I thought it was mine!

[Chris ParsonsParticipant @chrisparsons64193]

Thank you Mike – I could try filing or cutting a flat to get the 'lump' further into the jaws but was worried about losing the flat surface, but of course I could use a dial gauge (I do have one of these!)

Thank you for the kind offer of tea and advice – I live in Exeter so it is a long trip but who knows

I wish I had more engineering skills, I am an office wally (write computer software) and find the 'hands on' stuff a refreshing change, wish I had done more of this at school and college but my career took a different path. Think I have always been a frustrated engineer, this is what started me building model aeroplanes a few years ago.

As an aside, I don't know if it's intentional but the typeface you are using is bold – equivalent of 'shouting' in IT terms, not that it bothers me particularly but you will see it does one or two others from the looks of it.

This is a very nice forum, very friendly and even the heated debates are courteous, makes a refreshing change actually. You want to see some of the snide and nasty comments on the diving forums I subscribe to, you are clearly all gentlemen

Have a nice weekend

Chris

[D.A.GodleyParticipant @d-a-godley]

Posted by Chris Parsons on 18/02/2013 22:32:39:

Looks like I will be OK? If I take it slow, once one side is done it will sit a bit further into the chuck perhaps? Feels pretty solid, I guess when it flies past my ear I will know how solid…

The image below shows the cap screw supplied with the 4 jaw, and a bolt fitted from the 3 jaw. The difference between the two is 4mm, but my logic is if the shorter bolts (16mm) are OK for the 3 jaw they will be OK for the 4 jaw – and there are 4 bolts not 3 as well

Thanks for all the help and advice everyone

Chris

Chris,

Give the bar a bit of wellie with an angle grinder to create a flat sufficient to move the centre of the bar within the chuck jaws, put it on slow revs auto crossfead and go have a cup of tea.

Simple's .

[Sub MandrelParticipant @submandrel]

Only to agree with all that's been said, you only need it to move backa few mm, so filing is OK, then when you have the machined flat on the other side, reverse it and create a second parallell surface. If you now turn it through 90 degrees and hold the machined surfaces with the jaws that's three sides, one more turn and its square (to a first approximation).

I still think the best answer is to turn your screws into studs. They are high tensile steel but ordinary medium carbon steel nuts will do. As well as being easier to fit, the nuts will wear out and can be replaced at virtually no cost. repeatedly fitting and removing screws will gradually wear teh threads in teh chuck.

Neil

[BazyleParticipant @bazyle]

You can make a flycutter from a 1 inch length of your bar to hold 'normally' in either chuck. Drill a hole axially off center and another ar 45 degrees for round tool bits.

This and other tips does not come from an apprenticeship or course but just reading loads of old MEs while watching TV – no better tutor.

[Chris ParsonsParticipant @chrisparsons64193]

I had not thought about wear on the chuck threads – so I think I will do this, if nothing else it will save having to work out which holes in the spindle to use

What would you do, just cut the heads off the cap screws, clean up the threads and screw them in as far as they will go? Or use loctite? Ordinary nuts/with or without washers/flange nuts?

I am considering filing/cutting a flat on my bar but still fancy learning how to use a fly cutter and crosslide to broaden my experience – found a very interesting article (on another site) on how to grind the tools – **LINK**

Chris

[JasonBModerator @jasonb]

You can cut off the screws you have and screw them in tight, I'd do it without loctite as it will be easier to get them out if you want to revert to hex head screws/bolts.

Nut and washer is best and thats what all the flange mounted ones from the likes of Warco, Chester etc use.

J

[Gordon WParticipant @gordonw]

On my chester lathe the chuck was fixed with 3 cap head M8 screws from the back. The back of the spindle flange is counterer-bored to take the heads. Very fiddly to get the screws in and use the cut-down hex. key. I fitted studs in the chuck, used threadlock ,still unscrewable if needed. Made 3 cylindrical spacers the same as cap screw heads but just long enough to allow the chuck to be tightened with standard hex nuts. This makes changing chucks much easier.

[BazyleParticipant @bazyle]

I have nuts + washers on my Hobbymat chucks. Keep dropping a washer in the pile of swarf. Need long nose pliers to get them into position. Someone should invent a simpler system, maybe using cams…..

[Peter TuckerParticipant @petertucker86088]

Hi Chris,

I have similar to Gordon W with my chuck mounting.

You should definitely make and use a fly cutter, if you are concerned that it may come loose from the chuck drill and tap through the centre and hold it in place with a draw bar through the lath spindle.

All the best with your endeavours.

Peter.

[Ian S CParticipant @iansc]

To solve any problem (what problem) of the flycutter coming out of the chuck, make the bit of the shank of the cutter say 10 mm or more longer than the chuck jaws, and the bit beyond the jaws a larger diameter that the bit held in the jaws, only needs a few mm greater dia. Ian S C

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bazyle on 20/02/2013 18:39:32:

Someone should invent a simpler system, maybe using cams…..

.

Nice one Bazyle. Many a true word …

However; as Chris appears to be new to this game, we had better mention "proper" lathes.

[Chris] … take a look at this.

MichaelG.

[Author]

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