Damaged Screws & QCTP help!!!

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hi all,

No need for anyone to feel bad. It is part of my learning curve – proving to be costly and a headache but I guess that's how we learn.

Update: Everything is now apart – thanks Jason for your suggestion and input. I heated the ring a little and tapped it and again, it came apart.

I just need to find a way now to get those damaged screws out – otherwise that part is scrap.

For the toolpost stud, I just don't know what to do. I am not sufficiently experienced to make my own (as I am sure a lot of you guys are able to) nor do I have the tapping equipment etc. I have emailed both Amadeal and Arceuro to see if they can help. It seems the CJ0623b is slightly larger than a mini-lathe. I have nothing to compare so I don't know.

It's such a headache.

Thanks again for all your input and help, it is very much appreciated.

Margaret

[Howard LewisParticipant @howardlewis46836]

My guess for the countersunk screws is that they would be M6. (6 x 1 mm pitch )

The screws that you get in this country might very well be better quality than those that you have removed.

With regard nto the stud for the QCTP being threaded at both ends, obviously, the longer thread is intended for the locking handle.

You need to measure diameters and lengths of all the parts.

This leaves the question of the shorter thread at the bottom end.

What size is the serrated part of the original bolt?

If it is smaller than the stud, you may be able to tap out the hole.

MAY is the operative word. Hopefully the new stud is M8 or M10., (Check with a nut ), and the serrated portion of the original bolt is smaller, 6.8mm will allow the hole to be tapped out to M8, or 8.5 mm to tap out to M10.

If this is not possible, you are looking to open up the hol;e and then bush it, so that it can be tapped to suit the thread on the bottom end of the stud.,

This puts you into the Catch 22, of needing a lathe to make the bushing. And to open up the bore in the baseplate.

So the original set up will need to be reinstated for some of this work.

The alternative would be to turn up a bush with a bnore to match the existing bolt, and an OD to match the bore of the QCTP. But it might be a very thin wall, and the lengths may not be suitable..

Don't go past the point of no return, until you are certain of what you are doing

Do NOT rush!

Howard

[Howard LewisParticipant @howardlewis46836]

If the worst comes to the worst, and you cannot sirt the problem, where are you located?

You might need to take the bits to some kind soul, relatively near, who will use their lathe to put you back on track.

Having bitten off a bit more than you can presently chew, you will still have learned, and having someone else help you will extend your knowledge even further.

No experience is ever wasted. Although buying some books and reading them will be money and time well spent.

If you want some suggestions, PM me.

You are almost certainly going to need Zeus Charts, drills (To tap threads, you will almost certainly need some Metric drills incrementing by 0.1 mm. Or buy one othe Sets of Taps and Tapping drills. Not as good as having the correct size of drill, and a First cut, Second cut and Bottoming (or Plug ) Tap.

Howard

[Robert Atkinson 2Participant @robertatkinson2]

I doubt the part with the sheared screws is scrap. Worst case is you drill them out and re-tap for M8. The corresponding holes and countersinks in the other part would have to be enlarged as well. Another, possibly better option is a helicoil type repair. A couple of random examples:
https://www.engineeringsupplies.co.uk/m6-x-10-metric-coarse-thread-repair-kit.html
https://www.amazon.co.uk/DAYUAN-M6x1-0mm-Restoring-Compatible-Repairing/dp/B0B48NK2SC/
https://www.machinemart.co.uk/p/040216677/

You drill out with the supplied drill. Tap with the supplied special tap and fit the spring like repair insert.

Robert.

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hi Howard,

Thanks for your suggestions. I have definitely bitten off more than I can chew, and the disappointing part is that it all looked such a simple swap on the YouTube and ArcEuro videos I watched. Had I known what I was letting myself in for, I wouldn't have attempted it. I am near Coventry.

Unfortunately, the shaft cap and larger diameter part of the original stud is larger than the newer threaded stud.

Stud cap: 15.18mm

Knurled part of stud shaft: 10.37

Fatter part of stud shaft: 10mm

New stud thread: 7.5mm

All the best

Margaret

[Howard LewisParticipant @howardlewis46836]

Margaret,

You will gain experience and confidence from this; daunting as it might seem at present.

I'll PM you

Howard

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hi Robert

Thank you for your suggestion – that is excellent. I didn't realise you could do that. If I can't get the screws out that is my next option.

I appreciate it.

Many thanks

Margaret

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Margaret, there are a few different ways of getting the broken threads out, but I doubt you will not have the experience or the gear to do some of them. Easy-outs are one way, but as they have sheared off, these may not work, drilling them to the tapping size, will very often allow the remains to be pulled out with nose pliers, but of course they will need to be drilled on centre, building them up with weld is a very successful way, but will require a good amount of skill on such a small size, but drilling a blind hole about half the diameter a soldering/brazing a rod into the hole, would have a good chance, but again will need an amount of skill. If you have a small engineering firm near you, they may be able to help, but of course that will have a high kind of price, but an ME club might do it for next to nothing.

Regards Nick.

[Margaret TrelawnyParticipant @margarettrelawny34058]

ps: Robert, the M6 repair might be the better option because fortuitously, I found several matching bolts in a drawer which had come as spares with an Ikea kitchen. The are exactly the same and M6!

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hi Nick,

You are right, I don't have the equipment nor the experience to attempt this kind of repair unfortunately. I will likely use the option Robert suggested above with the helicoil system.

I don't know of any ME clubs around me, although I am sure there are some.

Many thanks for your suggestions.

All the best

Margaret

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hi Howard,

It has certainly given me a few grey hairs!

[MickBParticipant @mickb25219]

Margaret

Speaking from very extensive experience I strongly suggest that you ask Howard L for his assistance. I have visited him a number of times this year and his help has been invaluable. He is a very knowledgeable and kind man.

You cannot go wrong

Regards

Mickb

[Margaret TrelawnyParticipant @margarettrelawny34058]

Thanks Mickb

[duncan webster 1Participant @duncanwebster1]

Posted by Margaret Trelawny on 29/07/2023 21:07:12:

Hi Nick,

You are right, I don't have the equipment nor the experience to attempt this kind of repair unfortunately. I will likely use the option Robert suggested above with the helicoil system.

I don't know of any ME clubs around me, although I am sure there are some.

Many thanks for your suggestions.

All the best

Margaret

Coventry Model Engineers are **LINK**

I'll bet someone there will take pity. Don't go down the helicoil route until you've exhausted all possibilities of getting the existing screws out. We can then look at adapting the existing plate with 3 holes to accept the threaded stud.

Of course the simplest might be to see if the supplier will take back the QCTP. If you bought it mail order (which includes interweb) he is legally obliged to.

Edited By duncan webster on 29/07/2023 21:45:12

[MacolmParticipant @macolm]

Presumably you now have access to the back of the damaged screws. If you can lay hands on small self tapping screws about 3.5mm to 4mm outside diameter, you can drill 3mm holes right through the remains of the headless screws. Try to keep the holes centred, but this does not need to be very good. Then screw in the self tapper from the back, and with a bit of luck this will fetch out the remains, leaving the original thread undamaged. If locktite is suspected, enter the self tappers, then heat the part to 150C and unscrew while hot (hold in a cloth).

In this sort of operation, the danger is that the self tapper (or easyout, or whatever) expends the part being removed, thus wedging it tighter. Therefore if it does not turn at reasonable pressure, quickly resort to heat.

[Howard LewisParticipant @howardlewis46836]

Avoid using Easyouts like the plague. TOTALLY mis named. They are likey to expand the remains of the screw in the hole and make them impossible to remove.

Go and join the Coventry Club, and ask for practical help. Lots, and advice on many subjects should be available.

My preferred method would be to use a 5 mm drill to centre each hole under a drilling machine,

Once centred, clamp in place.

This should just "spot" the screw, so that a centre drill can make a proper centre, to be followed by successively larger drills until 5 mmm is reached. 5 mm is tappoing size for M6 so possibly the threads can be picked out with a scriber, or a first cut tap used to remove metal, as if tapping the thread from virgin.

Mick b may be right, YOU can't go wrong, but I CAN and often do!

Howard

[Neil AParticipant @neila]

Margaret

Just thinking about the tool post stud, ARC do a replacement stud for the Myford lathe which is the sort of thing you are looking for. They don't give any detailed dimensions, but imply that it fits in a 7/16" hole in the top slide. The chances are that it will not be exactly what you need, but something similar could be easily produced.

With regard to the sheared off screws, I have always found that easy-outs have caused me more trouble than just carefully drilling drilling down the centre of the screw with progressively larger drills until I can collapse what is left into the hole using a scriber.

If you do make a mistake, then a Heli-coil type thread insert is a good reclamation. We used them as a standard feature of our original designs in aluminium castings at work.

As the others have said, sit down, take a breath and have a think about it. It's all fixable, just needs a little modification. It has happened to all of us at one time or another, it can be very frustrating.

Hopefully you can get some help from someone or a club close by.

Neil

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hello Duncan – thanks for the link to Coventry Model Engineers. I will bear them in mind. I bought the 250-000 from arceurotrade – and although the post has been taken out of the bag, it hasn’t been used. Some oil has leaked off the parts onto the cardbord packaging – but I noticed the boxes for the holders already had oil stains on anyway.

It seems though I have made another mistake in buying too small QCTP. Because the swing over is 12cm, I should have purchased a 250-111. So I am hoping to exchange it.

Malcolm – thanks will try your suggestions first.

[Bill PhinnParticipant @billphinn90025]

Posted by Howard Lewis on 29/07/2023 22:09:13:

Avoid using Easyouts like the plague.

I'm not sure what comes under the heading of Easyouts, but I've had consistent success with Dormer M100 extractors.

[Margaret TrelawnyParticipant @margarettrelawny34058]

Thanks Neil and Bill for your input.

I am pleased to say we got the damaged screws out! As suggested, starting with a 2mm drill, worked all the way up in .5mm increments carefully until we were able to gently wind a 5mm tap into the holes which split the remainder of the cores and they wound out. Yey!

Now, should I replace them with cross heads or torx? Stainless?

Appreciate you all and your generosity in helping.

… now to sort out that pesky stud…. Not sure the arc one is correct as you say Neil. Will speak to both arc and Amadeal Monday and see if anyone can help.

[DiogenesIIParticipant @diogenesii]

I'd suggest 'Countersunk Socket Head Screws' in self coloured (plain black) 10.9 steel from a dedicated fastener supplier. Length includes head IIRC with these so M6x10 should do it.

..something like these?

GWR Fasteners Ebay Store – Socket Countersunk Screw…

..looks like 2.60 or so brings 5 (or 10) to the doormat..

[Bill PhinnParticipant @billphinn90025]

Posted by Margaret Trelawny on 30/07/2023 00:12:45:

Now, should I replace them with cross heads or torx? Stainless?

Assuming the originals were M6 and the right length at 10mm, I’d go for these.

What you need to be aware of, however, is that the diameters of the heads of CSK machine screws can vary with the type, so it’s best to check first before buying in case replacements don’t fit down the existing holes.. Kayfast have useful tables of such things.

The three holes on your part look unnecessarily deep for CSK screws – a case of the factory erring exaggeratedly on the side of caution, probably.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Margaret, well done for getting your old screws out. I would replace them with hex socket head ones, not Torx, and I've had plenty from those that Diogenes has linked too, and they have always been very good quality, but I do agree with Bill, that the countersunk holes look overly deep, and personally I would be inclined to put a small countersink into the threaded holes, up to about one thread deep at the most, which you can do with a 10mm twist drill quite easily, just in case the countersink on the screws are protruding through the holes a little, which may have jammed them up in the first place.

Regards Nick.

[JasonBModerator @jasonb]

Although you may be canging posts and therefor stud I have afeeling the old stud would do.

Also although swing or ctr height of the lathe does come into it what is more important when sizing a toolpost is the distance between lathe ctr line and the top of the cross slide. Look at the details on ARC's site about how to size your toolpost and work out which will allow you to get the tools to the correct height.

Supplied stud with the toolpost is I believe 10mm and threaded M10. Your existing stud looks to have a 10mm body so will pass through the toolpost unlike the Myford one which won't hence the need for a different stud.

New stud looks like it might be the right length to protrude above the toolpost so at best all you would need is a large washer to replace the supplied flange nut and then tighten with your existing toolpost nut. If you short then a custom nut with extension to reach down would not be hard to make.

It is quite likely that whatever toolpost you choose some alteration to the stud may be needed

Edited By JasonB on 30/07/2023 08:01:43

[SillyOldDufferModerator @sillyoldduffer]

Posted by Margaret Trelawny on 30/07/2023 00:12:45:

…

I am pleased to say we got the damaged screws out! As suggested, starting with a 2mm drill, worked all the way up in .5mm increments carefully until we were able to gently wind a 5mm tap into the holes which split the remainder of the cores and they wound out. Yey!

Now, should I replace them with cross heads or torx? Stainless?

…

Well done you! Though painful, a valuable learning experience. It will be useful in future. But ask again, the best way to approach the blasted things varies. I'm not sure why these jambed, unlikely to have been thread-locked, possibly over-tightened by a factory gorilla.

The originals seem to have been very ordinary, which made them easier to remove. Higher-grade screws would have put up a proper fight! I don't think the screws need to be anything special. Torx are over the top, and I'd avoid stainless because they can spall and stick. Slotted screws are easily chewed up unless the correct screwdriver blade is used and held straight. Cross-head (actually cruciform) are better, but beware – the two common types (Phillips and Pozidrive), chew each other up : it's important to use the right blade! I like Allen Heads – harder to get the keys wrong, and they have excellent grip. Allen, Torx and other special headed fasteners are usually made of tougher, stronger alloy than ordinary types. They should be done up tight, but not too tight. If the bolt is stronger than the female overtightening can strip the thread in the socket, which is another pain to fix.

Bottom line though, once replaced, it's unlikely these screws will ever be touched again. Almost anything that fits will do.

Dave

[Author]

Posts