Damaged Screws & QCTP help!!!

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

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.

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

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.

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..

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.

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.

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

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

excellent, now I can breathe again! I think Jason is correct that the old stud is useable

Thanks gentlemen. I have just purchased the relevant machine screws with socket fitting from GWR as per your recommendations.

Jason - I am not sure the original stud is long enough? I tried to photograph it against the QCTP but the phone camera distorts it somehwat. The stud collar is aligned with the base of the QCTP in the pics and to me, looks about 15mm too short?

Sorry about the higgledy piggledy post above - adding photos on a phone is tricky!

Yes looks a bit short to use the existing nut.

What is the diameter of the thread on the old stud, as I said a custom nut with a shoulder that will reach down into the toolpost hole may be all that is needed.

Also to check the size of toolpost to suit your machine what is the thickness from bottom of the old 4-way tool post to the surface that the lathe tools rest on?

It is a fairly minor job to replace/extend that existing threaded part. Best done with an operational lathe, mind. That old stud reminds me of lug studs for fitting wheels to vehicles.

I know it is now irrelevant in this case, but as anyone tried using LH drills to remove stuck screws?

Not always first choice, but is, for sure, for anything broken off flush and stuck.

Not a chance of trying cheap chinese ‘easy-outs’! They are only good for loose screws or the bin.🙂

Margaret,

You have two PMs. Look for the flashing envelope at the top of the screen

Howard

replied to your dm’s. Thank you.

Jason, I’ll check the measurements you suggested tomorrow.

Thanks

Jason

do these photos help at all?

Edited By JasonB on 30/07/2023 20:46:37

Not done it yet - I will be returning the ‘easy outs’ 👍😉