Dickson QCTP on a mini lathe

[Martin Shaw 1Participant @martinshaw1]

I have been offered a Myford size tool post and holders 2nd hand for not a lot. I would like to fit them to my Sieg 7*16 but I think with 8mm shank tools the centre height won't go low enough. Am I correct in this and has anyone done this?

Martin

[Martin Shaw 1Participant @martinshaw1]

[Swarf, Mostly!Participant @swarfmostly]

Hi there, Martin,

I can't answer your query directly but if you look in my albums there's a dimensioned diagram of the bed, cross-slide, top-slide and basic tool-post of the ML7. If I remember correctly, it's 'cribbed' from G.H.Thomas' book.

This might help you work your dimensional analysis from the opposite (i.e. ML7) direction.

Best regards,

Swarf, Mostly!

[Swarf, Mostly!Participant @swarfmostly]

Hi there, again, Martin,

If you look in the 'tool-holding' section of the on-line MSC catalogue, there are a couple of pages of dimensioned illustrations of the various sizes of Dickson-type QCTP.

Best regards,

Swarf, Mostly!

[JohnFParticipant @johnf59703]

Hi Martin, I have an original Dickson Engineering installation leaflet and for the SO [Myford size] tool block it shows the optimum dimension of 7/8" form the lathe centre height to the top of the top slide and suggests 3/8' tool bits.

Unfortunately its a pdf document so cannot post on here. Hope this helps, if you want a copy of the pdf PM me with your email

John

[Nick WheelerParticipant @nickwheeler]

I used a Myford size Dickson clone on my Clarke CL300 for several years, using 8mm tools. I kept them all when I upgraded to a WM250. Works well on both.

[Martin Shaw 1Participant @martinshaw1]

My thanks to Swarf, John, and Nicholas for their helpful suggestions. I have done some measurements on my lathe and I think Nicholas has shown the way, it works if you use 8mm shank tooling but not 10mm. I of course have 10mm so the options are either, take 2mm or so off the bottom of all the toolholders or the same of the top slide. The former is a lot of work, the latter necessarily reduces the engagement of the toolpost bolt in the topslide which is undesirable or worse. It might just be far easier to live with Arc wedge unit which does actually work, put the eyes back in my head and remove hand from pocket.

Regards

Martin

Edited By Martin Shaw 1 on 18/08/2021 14:16:20

[VicParticipant @vic]

Having posted the question I guess you’d like a QCTP for your lathe, but do you actually need one? The only reason I ask is that I’ve got a little 8” x 14” and could so easily have spent a good amount of money on one. Luckily I didn’t and given the number of tools I actually use it’s proven fortuitous. I believe I’ve not only saved money but preserved the rigidity of my little machine. All my most used tools have packing permanently fixed to the tool holders (carbide inserts) so they’re always on centre height. I also use a Tangential tool but that has height adjustment built in. Just a thought. I would really like a three way tool post but I can’t be bothered to make one!

[Nick WheelerParticipant @nickwheeler]

I have 14 holders for my QCTP, after starting with 4. I buy a couple when I order something from their various suppliers. If you have one tool that will turn and face, a threading tool(which can be persuaded to chamfer), parting tool and a spare then you'll soon realise how useful more will be; having to regularly swap tools in a holder defeats the whole Quick Change purpose. The adjustable tool height is a bonus, not the reason for buying a QCTP.

I think the QCTP has given the best return on any money I've spent equipping the lathe and mill.

 

I wouldn't buy the Dickson type again; I'd go for a wedge type and make my own integral holders for things like scissor knurls, TP grinder, slotting tool, retracting screwcutter etc

 

 

Edited By Nicholas Wheeler 1 on 18/08/2021 17:48:28

[Martin Shaw 1Participant @martinshaw1]

Vic

In actuality I already have an Arc Aloris copy which works perfectly well. My query arose because I have an opportunity to acquire an almost mint one plus holders for a ridiculously small amount, tens rather than hundreds. I could easily take them and sell them straight on and pocket the profit, but it doesn't feel like a very moral thing to do so if I can't use them far better to point the vendor in the direction where others might benefit. As to whether a QCTP is a good idea or not, it is I think a matter of personal choice, but personally if I never see shims again I'll be pleased.

Regards

Martin

Edited By Martin Shaw 1 on 18/08/2021 18:10:44

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