Tool Holders for Dickson Clone

[Dan CarterParticipant @dancarter89683]

Hi all,

I have the warco dickson clone here: **LINK**

They are currently out of stock of tool holders. Does anyone know if any of the ones from the other suppliers fit properly?

Thanks,
Dan

[Dan CarterParticipant @dancarter89683]

[MuzzerParticipant @muzzer]

Some do, some don't. I bought several Soba (Indian) holders for my genuine Dickson post and they fitted nicely but others haven't been so lucky. Must be more likely to find a mismatch if the post itself is a clone. Could you take it along to RGD, Chronos etc and try it in the flesh? Might be the safest option.

[mechman48Participant @mechman48]

I have a number of clone tool holders for my Dickson clone post, a 'Bison' which were bought either from Warco or RDG at previous Harrogate exhibitions some with a 'M' or 'W'… which ever way you look at it, others with non descript dovetail/slots, & all have fitted the post without any hang-ups, or have I just been 'lucky' … Just had a look on RDG site & they are showing QCTP holders in stock.

George.

[Dan CarterParticipant @dancarter89683]

Thanks for replies.

Not close enough to visit – have ordered one from RDG, will report back success or otherwise …

[RICHARD GREEN 2Participant @richardgreen2]

I've just looked on the Warco website and seen this grubby speimen , it dosen't inspire me to buy one……………….

[Clive FosterParticipant @clivefoster55965]

An easily overlooked "gotcha" concerning fit of Dickson clone toolholders on different makes of tool post is fit of the height setting collar in the grooved flange under the hexagonal lock mechanism driver. If the collar is slightly too thick or too large in diameter it may appear to enter the grooved flange but will jam things up before the holder is pulled back cleanly onto the post. Relatively easy to fix once noticed.

Collar and groove variations are most common reason for poor fit on professional range clones. Judging by my collection there is probably something of the order of 30 thou variation from thinnest to thickest in the professional versions. Collar diameters vary too but I've not seen any too large to fit. My feeling is that the fit should be nicely free with at least perceptible slackness. The thinnest ones I have are distinctly slack in the Dickson posts, which have the widest groove, but this doesn't appear to affect performance.

I imagine its possible for economy range versions to be slightly tapered in collar, groove or both. Worth checking as it could cause binding just before the holder locks up. If you have any doubts as to fit I suggest that you remove the height setter before test locking the free floating holder on the post. Maybe use engineers blue to verify where contact occurs. The twin triangle arrangement is relatively tolerant of small dimensional variations but the various faces must be parallel to close limits.

Clive.

[Swarf, Mostly!Participant @swarfmostly]

Hi there, all,

I have a Dickson-style tool-post on my ML7, it's branded 'Elliot' and I think it originally came off a Maximat V10-P.

I have several tool-holders for it, some of which fit well and some of which do not. These are from various makers/suppliers. The holders which came with the tool-post fit OK as do those I bought more recently from A&R Precision.

I find it somewhat very frustrating that many people offering tool-holders for sale do not give any dimensional information.

In researching this topic, I've found three tables of dimensions, one on Lathes.co.uk, one on the Rotagrip web-site and one in the MSC/J&L Tools' 'Big Book'. However, none of these tables of dimensions specify what I think is the crucial parameter i.e. the distance between the Vees (see the photo in Richard Green's post, above). Measuring that parameter is not aided by the fact that some male vees are flat-topped while some of the female vees are flat-bottomed.

One of the top items on my 'to-do' list is to find a pair of dowels and to measure the Vee-pitch on all my tool-holders – the emergence of this thread motivates me to do so sooner rather than later.

I shall be following this thread with interest.

Best regards,

Swarf, Mostly!

[Speedy Builder5Participant @speedybuilder5]

Hi Swarf, Mostly
I too have an Elliot QCTP (S.00 HB) on my Boxford and could do with a few more holders. My cam pin is 0.370" dia and the cam is 0.304"dia. I did find a new cam pin, but it was metric and too large. If anyone finds a supplier or source of suitable holders at a reasonable price, I would be interested too.
BobH

[Tony RayParticipant @tonyray65007]

From my conversations with Rotagrip the Bison and Dickson cams are dimensionally different and they we abel to supply either and so witheir help was able to get the correct one. I have both geniune and Soba (from Chronos) and have not had any significant issues withthe Soba's but have the following observations

The knurling on the adjuster is very variable and the thickness of the flange on same also. When looking at the holder form above the T slot on them is also variable – some will not go on my stoage rack which relies on 1/4" pins. Although there is more than one height of T1 /S1 holder I think the Soba's are skinny on material.

[Neil WyattModerator @neilwyatt]

Posted by RICHARD GREEN 2 on 26/05/2016 10:50:57:

I've just looked on the Warco website and seen this grubby speimen , it dosen't inspire me to buy one……………….

That's just packing grease, although it wouldn't have done any harm to clean it up a bit!

[Clive FosterParticipant @clivefoster55965]

The location geometry of Dickson type tool-holders is quite cunning and well matched to sane production methods. The tight tolerances are angular and so should be well controlled by the set up of the machine(s) whilst the distance ones, which are inevitably subject to variation due to tooling wear, are more flexible. The most precise requirement is that the Vee surfaces are all mutually parallel which should be pretty much a given if all can be done at the same set-up.

Geometrically the classic three point contact ought to guarantee proper location provided they aren't all on one surface. In practice 5 point contact will do so unless serious manufacturing errors are present. Assuming sane machine production. If its been filed from solid all bets are off. Generally two lines and one point will give enough location for moderate cutting loads. Two points and one line being pretty much equivalent. Someday I must take time to blue up mine and see what contacts where but casual inspection of my three posts and 16 + holders shows polished areas indicating pretty much complete two wide line and most of a third is the normal state of affairs. The fourth face appears to have spotty contact.

I have Dickson and Rapid T2 size posts. For Dickson, Rapid and probably at least two other brands of holders the position of the lock-up flange shows negligible variation between various combinations of holders and posts. The final position of the locking spanner handle when locked up for use showing maybe 10 degrees variation between various combinations. Nothing you'd notice although obviously I've not done exhaustive tests. Three posts, 16 holders, three positions per post adds up to 144 combinations. Life is too short. Judging by previous threads on here and comments elsewhere its the inner flange thickness and position relative to the Vee surfaces that is most likely to show unacceptable variations with budget range mixes. Fairly understandable as that's the hardest dimension to control but also the most important if solid lock is to be achieved.

Clive.

[RICHARD GREEN 2Participant @richardgreen2]

A while back I bought a "Rapid Original" QCTP for my Boxford ME10, it came with one tool holder,

My plan was to make a nice set of 4 tool holders to fit it, and put the whole process on the ME website,

This is where I'm up to at the moment,

Richard.

[Dan CarterParticipant @dancarter89683]

so …. no.

RDG version arrived, but does not fit well enough. The v-surfaces appear to be a decent fit, but the cam action does not pull it in far enough to lock solidly.

Ho hum.

[MuzzerParticipant @muzzer]

From what Tony says above, it sounds as if Soba are stocked by Chronos. As all 4 of my Soba holders fit well with my genuine Dickson post, it may be worth trying one of them. I bought a few things from Chronos in the past, so most likely that's where mine came from.

BTW, I have a Bantam – can't recall the size. T2 possibly??

[Dan CarterParticipant @dancarter89683]

Follow up:

I checked the Chronos ones as suggested my Muzzer, but they were out of stock at the time. Ordered one a few days ago once back in, and it fits without any problems.

Inevitably, I got a notification from Warco a day later saying they had them back in stock, but still useful to have an alternative for next time.

Dan

[Martin ConnellyParticipant @martinconnelly55370]

Hi Swarf Mostly,

The Rotogrip website (which you mentioned) tool holder dimensions on at the beginning of page 2 seems to give the distance between vees as 48mm, 62mm, 82mm or 100mm

Martin

[MWParticipant @mw27036]

I can't remember where i bought it but my dickson clone seems fine, i've never had any of the problems described. Lucky winchester maybe? the one that actually worked?

I don't doubt that there are defective ones but at times it seems like a thinly veiled attempt to slander any attempt at a reproduction even when it's decently made. They want to be the club with genuine dickson toolposts! and dont want to share the glory with anyone else. 

Michael W

Edited By Michael Walters on 15/07/2016 14:52:51

[Neil WyattModerator @neilwyatt]

Surely 6-pont contact is the counsel of perfection? 1 plane, one line and one point.

But dovetails work a different way.

Don't forget the depth stop counts as a point

Neil

[MuzzerParticipant @muzzer]

Fundamentally, it's impossible for the Dickson system to mate perfectly, as it uses 2 vees and is thus statically indeterminate – unless you can achieve zero tolerances of course. And the clamp also requires deadly accuracy on the dimensional position of the internal face of the tee slot relative to both vees. The clones don't seem to be able to achieve the accuracy of the authentic Dickson components, hence the problems we see.

My other reservation is the (lack of) rigidity of the locking cam. With heavy loads and long tool overhang, the cam has to withstand some pretty high forces yet the cam spindle isn't very robust and there is very little to provide resilience (preload) unless you count the flex in the cam spindle.

Rather than spend more money on hit and miss clone toolholders, I've instead invested in a Multifix system.

[Neil WyattModerator @neilwyatt]

I think the type that push out are simpler, and therefore more reliable (also much easier to make). As they share the same double vee location system it is no better and no worse than Dickson in that regard.

I suspect the Dickson design was chosen simply because it is so hard to copy accurately.

Neil

[Clive FosterParticipant @clivefoster55965]

Whatever the system perfect mating is impossible without zero tolerances and absolute accuracy. Provided the tips of the Vees don't interfere, adequate stability from the Dickson system with random parts requires only that the Vees are parallel and side angle tolerances of opposite hand on the male and female parts. Obviously manufacture of the Vees has to be pretty precise but the tolerances needed are not unreasonable. Easiest to visualise if you consider the male Vee on the toolpost being toleranced on the smaller side of nominal whilst the females are toleranced wider. Imperfect angle match gives line contact rather than whole area but contact it will. The absolute magnitude of the relative varaitions from nominal simply cause the holder to sit either a little closer to or a little further away from the post centre. Small variations in Vee spacing don't matter either as this simply defines whether the line contacts are on the outside or inside of the male Vees. The bed and saddle of the common, Stark type, precision bench lathe exploits exactly the same principle albeit using only the outside of the male Vee and inside of the female one.

The really important thing is that the two Vees on each component be mutually parallel to each other. Something easily achieved by simutaneous finish grinding.

A bit of maths will show that tolerances on the internal face of the Tee slot don't have to be unreasonably tight by the standards of half decent grinding practice. Witness that there is essentially never any problem with professional market clones. I've yet to see a post – toolholder pair of random makes that fail to mate. The problem with amateur market clones is that the makers can't be bothered to do things right "customer paid, passed QC". That said the mating face of the Tee slot is where all the other tolerances build up so a certain amount of care and understanding of the design when setting the nominal dimension is needed. Blind copying of a sample will lead to trouble.

Although a Dickson like toolpost could be made with only single side male – female parts, like a precision bench lathe bed, there are advantages to the two Vee layout. As SouthBend well knew. In the tool post context the advantages are mostly concerned with being better able to cope with contaminated surfaces and improperly cleared swarf which can reduce line contacts to points. That said the Dickson isn't particularily tolerant of swarf. If properly made and kept clean, inside too, the grip is more than adequate and it won't come loose. If there were any real arguments against it the Dickson desing would not have become so widely used. Fact is the Dickson price performance ratio has always been about the best of any of the professional units. I'll bet that the profit margin for the makers was always very good too as its relatively easy to make if the factory is set up properly.

Clive.

 

Edited By Clive Foster on 15/07/2016 23:54:46

Edited By Clive Foster on 15/07/2016 23:56:22

[MWParticipant @mw27036]

I'm almost tempted to measure mine because i'm quite confident of it's grip and fit, It looks like a professionally made item. I frankly couldn't care how much they made out of me because i'm happy in the knowledge that it's an integral part of my methods of production. I don't buy the argument that the words cheap and copy should automatically lead to a bad association, an interesting one but not bad.

The only time when it ever looses it's grip is when it's subjected to heavy shock loads like a hammer blow. So under normal turning conditions, if it's coming loose 9/10 times it's because i'm doing something wrong rather than my equipment being at fault. If i set up the machine properly i can use it as a genuine "quick" change and go through 5 or 6 tool holder changes and confident, each and every time, that it will not loosen it's grip.

I don't know if it's genuine and i don't care, it serves my needs perfectly. If people have found another system that works for them, then best of luck to them but i don't want to fork out for something for where a need has already been served.

You ever get that feeling where things are constantly going wrong on one operation or part and think to yourself "is the machine trying to tell me something here?". Yes it probably is. 

Michael W

 

Edited By Michael Walters on 16/07/2016 00:36:36

[Martin ConnellyParticipant @martinconnelly55370]

Michael, what angle does your cam rotate from fully out to locked? Mine originally only turned about 90 degrees. I put a clock on the part that pulls the tool holder in and checked how much movement there was from the locked position to the fully retracted position and it was 1.25mm. I then made a new one of these parts to pull the holder that was 1mm longer from the hole to the working face. This allowed the cam to rotate close to 180 degrees and gives a much more positive clamping and locking action. This is possibly the problem with clones, what is probably a critical dimension is wrong on some of the clones. It is a relatively simple part to make so might be worth a try to see if it stops the holder coming loose in use.

Martin

[MWParticipant @mw27036]

I will mark the boss with sharpie and let you know how much it rotates.

Michael W

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