Quick change tool post

[Claude StanderParticipant @claudestander76574]

[Claude StanderParticipant @claudestander76574]

I purchased a Myford QC tool post from Chronos. I was unable to adjust the 10 & 12mm tools to centre height. I was told to use 8mm. If I were to use a 3" square Boxford QC holder and bush the mounting hole to fit my Myford, I would be able to adjust the tool holder past the top slide. Would this affect the clamping ability of the holder? Why would you make a tool holder to accept a 12mm tool, but not be able to adjust correctly?

I am new to modelling, and would appreciate some advice.

Claude

[JasonBModerator @jasonb]

Posted by Claude Stander on 30/07/2016 05:56:29:

Why would you make a tool holder to accept a 12mm tool, but not be able to adjust correctly?

Certain tools have the "working part" on the centre line of the shank not the top like a turning tool. A boring bar and knurling tool would be two examples.

Look at the thread that came up yesterday about tool sizes, just because the upening is 12mm high does not mean you need to use all of it.

I'll leave the other part of teh question to those with Myfords but if you are thinking of using a 75mm toolpost as opposed to teh 63mm myford be aware that you will have teh tool hanging further away from the topslide which can cause flexing

J

[Nigel BennettParticipant @nigelbennett69913]

I dispensed with my topslide and mounted my toolpost on the cross slide, using a chunk of steel of the appropriate thickness (i.e. a little thinner than the topslide). It gives a much more robust mounting for the toolpost, and I've only used the topslide two or three times since in several years. I think there was an article in ME about it by somebody. (Oh, all right, it was me. ME No. 4366 (2009) p717.)

Edited By Nigel Bennett on 30/07/2016 12:05:28

[AjohnwParticipant @ajohnw51620]

No mention of what lathe the holder is on. I don't own a Myford lathe any more but do recollect that the branded holder would set a 10mm tool on centre height. I expect a Myford owner will comment.

I also had the intention of fitting a branded one to a mini lathe. My Boxford uses a taller version of the usual Myford one that uses the normal myford holder so I could then use the same tools and holders on both with a minor change of the tool height setting.

A quick measurement of a branded Myford holder shows that a 3/8" tipped tool is just about 17mm up from the base of the post when the holder is as low as it can be. Might be 16mm. The 3/8" square indexed tip holders are often sold as 10mm. They usually measure a touch under 3/8".

The bottom thickness of the actual Myford holders is a rather close 1/4" thick.

John

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[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ajohnw on 30/07/2016 15:31:23:

No mention of what lathe the holder is on.

.

… except for the words "to fit my Myford"

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Ajohnw on 30/07/2016 15:31:23:

No mention of what lathe the holder is on. I don't own a Myford lathe any more but do recollect that the branded holder would set a 10mm tool on centre height.

Correct. The top surface of a 10mm HSS tool will adjust to centre height. However, some replaceable tip tooling has the tip sitting proud of the top surface and these will not adjust down to centre height. For this reason I would recommend 8mm square or less for tool holders.

Rod

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 30/07/2016 15:40:46:

Posted by Ajohnw on 30/07/2016 15:31:23:

No mention of what lathe the holder is on.

.

… except for the words "to fit my Myford"

LOL – I probably skipped reading all of it Michael – I only have so much time available. Also I probably couldn't imagine why it wouldn't take 3/8" tooling if it was on a Myford.

One thing I will add is that I have a lot of holders. The thickness of the base the tool sits on varies from around 0.220 up to a massive 0.3". When I ordered the ones that measured at 0.25" Myford did mention that there were 2 sizes but as it isn't really Myford any more the conversation was a bit garbled and the man who should have been able to sort it out walked out of the room while I was talking to sales person.

Most of mine seem to be about 0.220. The 0.3 is a clone. The new ones bought for the mini lathe all 0.25

John

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Edited By Ajohnw on 30/07/2016 20:11:00

Edited By Ajohnw on 30/07/2016 20:12:27

Edited By Ajohnw on 30/07/2016 20:16:20

[John ReeseParticipant @johnreese12848]

If the QCTP will not allow the tools to be set on center I suspect you bought too large a toolpost for your lathe. I suspect the toolholder is bottoming on the topslide. If you can't exchange it for a proper sized toolpost you may want to consider machining enough material off the bottom of the toolholder.

[the artfull-codgerParticipant @theartfull-codger]

I have a genuine dixon toolpost from a boxford & it was too high for the myford & also the centre hole was too large so I turned a bush for the centre & machined some off the bottom of the body & it was really tough but managed ok with a carbide milling cutter on the milling machine,to be honest I have myfords 4 tool holder on most of the time with an eccentric enginering diamond tangential tool in [my favourite tool], & only use the dixon for any repetition work.

[cliff jamesParticipant @cliffjames46755]

Hi

I have a Clarke cl500m and want to change the tool post as its a pain to keep shimming. I would like to put a quick change tool post on it but not sure which one will fit? There are a few on a well known auction web site ? I have just watched a youtube video which shows making a new central bolt to 14mm diameter to hold the post so even more confused now as it also shows drilling the slide to 14mm which means there is no going back.

Has anyone already done this modification and if so what did they buy so I can bolt it on

regards

cliff

[not done it yetParticipant @notdoneityet]

Cliff,

There are options to continual shimming.

Make a shim (or pack) for each tool.

Get, or make, more tool posts and retain tools fitted, ready for use.

Not sure about fitting any particular QCTP to that lathe, but no need for drilling, I suspect (a waisted central bolt would be adequate?). Often changes need to be made to fit them, but usually this can be achieved without modifying the lathe top slide (Ie change the tool post fitting to suit).

[BazyleParticipant @bazyle]

The video shows that the toolpost used has a sleeve anyway to fit it to the bigger bolt. So use the original bolt and a different sleeve. The original bolt is probably too small but you can make a tube bolt that reaches down into the sleeve to meet it and has a handle at the top for convenience.

[Roderick JenkinsParticipant @roderickjenkins93242]

The pukka Myford branded Dickson QC toolholder has a hole larger than the stud on the topslide

and just uses a shouldered washer for location

Works fine.

HTH

Rod

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