Chinese camlock studs

[Adam HarrisParticipant @adamharris13683]

I am thinking of buying a set of D1-5 camlock studs from China (brand Vykom) about 1/4 the price one can get from respectable western dealers, for my 10″ Bison chuck. Is this utter madness Health & Safety wise? Any thoughts? Is there a better chinese brand of such studs that one could buy with more confidence? Vykom had the best reviews I could find, albeit no idea how reliable Alibaba reviews are

[Adam HarrisParticipant @adamharris13683]

We are talking £48 incl delivery and all taxes, as opposed to £200 just for a set of studs

[peak4Participant @peak4]

I guess it depends if you need imperial or metric, but you could keep an eye out for a complete catch, face, or backplate, and just use the studs.
e.g. £95  https://www.ebay.co.uk/itm/286009812105

Bill

[Adam HarrisParticipant @adamharris13683]

Thanks Bill I did not see that.  I will check it. My chuck is a Bison and takes studs with 12 x 1.0 mm thread. D1-5 camlock is rare here in the UK (unlike in Germany or US) and I do have a spare D1-5 backplate I think for a Burnerd or Colchester chuck which unfortunately has studs with an imperial 1/2″ thread. Are you of the opinion utter madness? I wonder what brand those backplate studs are

[Adam Harris]

On 2 September 2024 at 21:12 Adam Harris Said:

Any thoughts?

I think D1-5 has six studs. How many need to fail simultaneously to create a hazard?

What mode of failure is likely in a stud?

What is the minimum cross sectional area of a stud? If it were made of the lowest grade steel possible, at what load roughly would it yield? And would it be a brittle or a plastic failure?

I have seen chucks of this and larger series chucks with only three of the pins installed.

Buy one extra, give it a torture test and see if you can make it fail. Given its shape, that might not be so easy. I am not sure how you would grip the spindle end of it to do any sort of tensile test on it. Use that result to advise yourself whether you can use the remaining ones in the chuck or throw them in the bin.

[peak4Participant @peak4]

You could try this outfit, apparently in Ireland, but no idea about the company, or whether these studs are imperial or metric.
CAMLOCK BOLT D 1-5"

Bill

[Adam HarrisParticipant @adamharris13683]

Yes DC31k 6 studs.  OD of thread 12mm, body of stud 3/4″ reduced by less than a half at the cam interface so conservatively speaking the thinnest part equivalent to an M10 bolt? I think unlikely much will happen if one or two fail, but am also thinking less risky if careful to always be using a tailstock centre. An upside is if material is softer than genuine Bison ones, less chance of damaging the cams on the lathe head (I’d much rather have easily replaceable studs damaged than cams)

[Adam HarrisParticipant @adamharris13683]

Thanks Bill yes those look identical to the generic chinese product being offered by Vikyom and others

[Adam HarrisParticipant @adamharris13683]

Sorry the brand is Vikyom (not Vykom) if that means anything to anybody…

[Adam HarrisParticipant @adamharris13683]

Bill I looked closely at the studs on that faceplate you pointed out and I think they look rather knackered at the edges which might indicate chinese also. My Rohm chuck has original studs and they are in perfect condition after over 2 decades of use some of it commercial

[Clive FosterParticipant @clivefoster55965]

Adam, DC31k

Any potential issues will be with the gripping action of the locks in the scooped out side of the stud rather than simple stud failure. As you say the cross section of the stud is so large that it is essentially impossible for it to be weak enough to fail in tension unless it’s already seriously cracked.

Although I have the official specification drawings and tolerances for the studs I’ve no idea what the maximum deviation from design dimensions and tolerances is before things will no longer lock sufficiently well to be safe. I imagine the factors of safety is pretty large. But D1-5 goes on pretty hefty machines like my P&W model B so, potentially at least, there could be large forces involved. Especially on a clonk, clonk, clonk job.

When I treated my SouthBend Heavy 10 to a nice new Pratt Bernerd three jaw from Rotagrip I opted to save a few £ by getting a part finished, import, D1-3 backplate rather than the official P-B fully finished one. All worked fine but there was a noticeable disparity between the angles by which the cam-locks had to be turned to go from free to locked. This disparity remained when I transferred the chuck and backplate to the Smart & Brown 1024 that replaced the Heavy 10.

The British made chucks and backplates that came with the 1024 show essentially no variation in turn angle from free to lock which indicates greater consistency of manufacture.

The D1-5 studs on the chucks and backplates that came with my wartime built P&W Model B are similarly consistent. As are those on the new-old-stock Bison 3 jaw I lucked into for it.

Having more chucks and backplates than studs I bought some extra studs from Rotagrip to put the catch plate into service as a basis for modifications to mount a special job. I believe these were import studs and showed more variation in angle from free to lock that the originals or the Bison chuck. The threads were also looser. The job was a clunk, clunk, clunk one but I had no issues with things loosening off. The feel of the studs when locking is a bit different too.

My feeling is that any stud able to be satisfactorily adjusted to lock within the specified angle will be close enough to nominal dimensions to be safe in practice. One of my D1-5 extras needs all the permitted turn angle to lock. But as it’s one of 6 and the application was as a drive plate for a long job supported by the tailstock centre I was unworried. If it had been a D1-3 on a chuck with only 3 studs to handle overhung loads from both the weight of the chuck and the job could be expected I wouldn’t have been so sanguine. it would have been changed.

Clive

[Neil LickfoldParticipant @neillickfold44316]

I have seen the Chinese studs out here, and they seem fine to me. The more expensive ones are made and heat treated, where the eastern ones look to be made from just bar stock. Not done a hardness test to see what tensile grade they are.

For home hobby use and not trying to take the largest possible interrupted cuts they will work fine.

You can make your own set from 4340 or similar high tensile bar and know what you have. Takes a bit of time but sometimes making parts is fun in itself.

[JasonBModerator @jasonb]

I suppose it depends on what use you will put them to. If regularly taking big heavy cuts and working on large items that will put a lot of load onto the studs than maybe better to go with known good quality, th esort of thing where you need a hoist to lift the work to the chuck. If you are mostly doing light hobby work then the good quality far eastern studs may well be perfectly adequate.

[DC31k]

On DC31k Said:

On 2 September 2024 at 21:12 Adam Harris Said:

Any thoughts?

…

What mode of failure is likely in a stud?

…

This is the line of thinking I’d take.  Others make the same point : how well made a stud needs to be depends on the duty it is put to.

• If Adam is an amateur, then the duty is likely very low.  Home-made studs in mild-steel should be ‘good-enough’
• If Adam is a 3-shift business doing jobs requiring frequent chuck changes, then the duty is likely much higher.  The studs take a battering, making plain mild-steel much less likely to be ‘good-enough’ .

What are cam-lock chucks for?   They provide fast reliable chuck changes, a feature that’s valuable when time is money, and the owner is paying himself or a worker to operate the machine against the clock with results gauged by an accountant.   In this environment, it pays to tool-up with equipment that can take a hammering.  Extra true when the chuck is so heavy that mechanical help is needed to move it, bump, bang.

When time isn’t money and chucks are light enough to move manually, as in most hobby workshops, the need for equipment that can take a hammering is much lower.  It’s nice to have rather than essential.   Thus Myfords are fitted with screw-on chucks and Far Eastern hobby lathes with bolt-ons.   No problem, except changing the chuck takes time.

Another question is, why are studs so expensive?   What does the purchaser get for his money?   Possibilities include:

• Reassuringly expensive where the brand-name is used to increase profit.
• Low-risk the stud won’t fit because they are accurately made to specification.
• Stud made of a strong alloy carefully hardened to maximise life in a high-duty environment.
• Stud a proprietary variant necessary to fit a particular brand.
• Reliable performance out of the box.

In other words, Adam is advised to assess how hard he has to work the studs.  How many times per hour is the cam-lock system used?   If the answer is low, typical of hobby work, then he can take an Alibaba gamble that’s likely to pay off.   If the answer is high, and his livelihood depends on machine up-time, then he should de-risk by buying the industrial product.

Dave

[Adam HarrisParticipant @adamharris13683]

Thanks Dave. Yes strictly an occasional amateur. I had not been thinking of the purpose of studs, namely quick change, and indeed I will not be changing chucks quickly nor frequently.  I’ll go ahead and get these Vikyom studs and avoid heavy cuts. I did initially think that many here would regard buying cheap chinese studs for a 10″ chuck as sheer lunacy and I am very happy that appears not the case for my usage. I will see how they fare and report back.

[Adam HarrisParticipant @adamharris13683]

Thanks Jason, yes light work only and proceeding with caution

[Adam HarrisParticipant @adamharris13683]

Thanks Clive – very interesting. I will be sure to check how consistent the closure positions of the camlocks are.

[Tony Pratt 1Participant @tonypratt1]

I would give the Chinese studs a go, you might be pleasantly surprised or not.

Tony

[Clive Foster]

On Clive Foster Said:

All worked fine but there was a noticeable disparity between the angles by which the cam-locks had to be turned to go from free to locked.

As indeed you would expect there to be given that both the studs and the cams are made to tolerances.

Your post reads as if it is casting doubt on the quality control of the stud manufacturer. I do not think that can be inferred from what you describe.

It is exactly in order to accommodate manufacturing tolerances that there is a locking range shown on the spindle, usually denoted by two little V’s. As long as the stud locks roughly in the middle 50% of that range, it will be OK.

As there is nothing in the stud specification nor in any backplate specification that requires a particular clock position for either the male or female thread to start (relative to the scoop out for the cam), there will be natural variation in the projection of the stud (you can do the maths: I think it could be up to 1/2 a thread pitch).

When you first set up a camlock chuck, you are supposed to adjust and swap around all the studs to get the best locking action on all the cams. That is why the spindle and chuck normally have a witness mark, so that once the initial adjsutment has been done, the same stud goes into the same hole in that spindle every time forwards. Difficulties can occur if you want to use the chuck on two diffeerent spindles…

This old post has very useful information on the topic.

https://yarchive.net/metal/camlock_stud_fiddling.html

 

[Adam HarrisParticipant @adamharris13683]

 

Many thanks DC31k – very interesting and I have printed off that old post and labelled it in my files as Camlock Studs Operating Instructions

[jimmy bParticipant @jimmyb]

I fully agree with SODs comments.

 

I along with thousands of others have Chinese camlock studs and not had any issues.

 

Jimb

[Clive FosterParticipant @clivefoster55965]

DC31k

Too right I am indeed saying that significant variation in the turn angle needed to go from free to locked in a set of cam lock studs is a reason to doubt the makers level of quality control.

The aim of a good cam lock set up is to achieve lock somewhere in the middle 50 % of the operating arc. One look at the system design makes it clear that the angle of turn is very susceptible to tolerance build up related effects and the actual lock up position strongly influenced by the relative rotational timing between the thread’s on the stud and those in the backplate. The coarser the threads the worse the timing mismatch effect gets.

My experience with my UK and American made studs is that variations in angle of turn from free to lock can be small enough not to be readily noticeable. Perhaps 5° range overall. Which I reckon is good going overall considering the number of potential infelicities in the system. As I recall things the stud swop dance tightened the variation range a bit, perhaps by half, but the first, random, try was probably perfectly acceptable.

In an ideal world everything would be the same. In a practical world tolerances mean there may well be differences between studs sourced from different makers but all should give a turn angle ending within the proper range. If studs are made with high levels of quality control variations within a one make set should be small. Large variations within a one make set are indicative of either wider tolerances or poor quality control.

In a practical world it’s effectively impossible for normal folk to figure out whether such things are in tolerance and what the expected deviation when assembled ought to be. But consistency of angle of turn from free to lock is good indicator of how much effort the maker has put into ensuring they all come out “the same” aka made to close tolerance. Even if all the lock positions are within, or very close to, the preferred range significant within a set  variation does make you wonder  “why” and “has anything been skimped”.

A question quite apart from whether the lock position is in an appropriately safe range. I think it’s fair to say that anywhere within, or close to the 50% range will be fine even if you still have some discrepancies after the usual fiddling around to find the best positions. Which fiddling can be a right pain in the ass if handling a hefty chuck

Obviously if things lock up outside the appropriate range you need to seriously consider how trustworthy it will be in practice.

As mentioned above I have one that, in its best position, is right on the edge of the locking range but I consider it useable given that the catch plate it is fitted to was modified to use in a tailstock centre supported job and will probably never have any other employment.

First time I needed it in 20 years.

But it wouldn’t do for chuck duties. All the chucks on my P&W model B are hefty but the 10″ heavy duty four jaw is right on the edge of what I care to lift. (I have a 10″ Taylor, sans backplate, that will never get fitted simply because of the outrageous weight.) With that much mass spinning round I want them well and truly tied on.

Trying to figure out exactly what makes a cam lock set-up secure makes my head hurt. Seems to me that the locks need to both pull on the stud to hold the backplate hard up against the short locating taper and push it over against the side off the hole in the spindle so that all is solidly jammed up.

Clive

[peak4Participant @peak4]

I would have thought that most of the far eastern imported lathes with D type chuck mounts would use similar studs, but who knows exactly from which factory they originate.
I’d have suggested Warco or Chester as a supplier of replacements, but I’m not sure they list D1-5 accessories.
The company in Ireland I linked to earlier also supply imported OPTIturn lathes to the EU, so hopefully will be up to speed with regulations and possible recalls etc.
I wonder if Excel Machine tools might have D1-5 studs, as I think they also sell the same brand of lathes.

Bill

[Michael GilliganParticipant @michaelgilligan61133]

I don’t know if this is just ‘teaching granny to suck eggs’ … but it’s quite nicely done:

https://youtu.be/V4X39vj2M8k?feature=shared

Shop Talk: How To Install Camlock Studs for Lathe Chucks

MichaelG.

[MacolmParticipant @macolm]

I have experience with only the lowly D1-3 Camlock. The taper provides the location and takes the machining and dynamic forces (otherwise the whole thing would be pointless), and on releasing the cams, the taper still needs to be dislodged. The studs therefore only provide a tension force, and the integrity of the mounting is down to the combination of the taper interface and the studs.

Incidentally, when mounting a new backplate it is clearly prudent to ensure that the taper is fully engaged, and in particular that the faces are pulled together tightly (look for any chink of light, and of course that the taper is tight with the cams undone). With one new backplate, I needed to face off perhaps 0.02mm to get a snug fit on the taper; not sure if they come with an allowance for that. Do that, if necessary, before machining the register.

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