Clarkson radius grinding attachment

[Andrew TinsleyParticipant @andrewtinsley63637]

I have an early (Mk1?) Clarkson radius grinding attachment. It is missing the toolholder, so I shall have to make another. Can anyone give me the basic dimensions as I may as well keep to the Clarkson standard.

I attach a photo of the toolholder mount that I have on my unit.

Thanks,

Andrew.

 

[renardiere7Participant @renardiere7]

Thought I might be able to assist but mine is a MkII and looks nothing like that. Sorry.

[noel shelleyParticipant @noelshelley55608]

I do not recognise the picture as a standard mounting. The one I have has 3 holes and a ridge in the middle.   The bedroom workshop would be a good place to look. There may be a drawing.  Good luck. Noel.

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Noel,

I am absolutely certain that it is a standard toolholder mount. From what I can gather, there appears to be two types on the Mk1 and a third on the Mk2. The one with 3 holes is definitely one of the Mk1 variations. The toolholder has three slots either of which can sit on the raised crosspiece of the toolholder.

The one I have is the alternative toolholder. Hopefully someone has this toolholder mount and an give me some rough dimensions.

Thanks both,

Andrew.

 

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Noel,

I think that my toolholder mount must be quite an early one (?) I have only found one photograph of a similar type of RGA which has the longitudinal slot as opposed to the far more common raised ridge at right angles to the toolholder mount. I think I shall have to draw up the toolholder from scratch.

As a matter of interest can anyone tell me what the bore of the toolholder is and its centre height from the top of the toolholder mount? It isn’t essential information, but I would be interested nevertheless.

Thanks,

Andrew.

[noel shelleyParticipant @noelshelley55608]

Hi Andrew, I believe, but only from memory that it is 1.25″ bore.  Good luck.  Noel.

[Clive FosterParticipant @clivefoster55965]

Andrew

Did you find this thread :-

https://www.model-engineer.co.uk/forums/topic/clarkson-radius-grinding-fixture/

Pictures and drawings may be useful.

So far as I’m aware the principle dimensions of both earlier and later tool-holders are the same. Only difference being that the central ridge to engage your carrier projects below base. The actual flat base on your holder should be made to give the same centre height as the bases of the cross ridges on the alter version.

Best way to confirm would be via the dimensions of the vaguely Z shaped carrier in both later and earlier versions.. The important dimension being the height of the tool tip in relation to the various pivots on the base.

Clive

 

[Charles JambonParticipant @charlesjambon]

Good morning Andrew,

I have a MK1 that came without a head. I found a drawing on the web that indicates a centre height of 1 3/8 inch and a bore 1 1/2 inch diameter with the more common 0.5 inch lateral slots and threaded holes in the base. I subsequently made two but in cast iron. I happy to share the drawing but it is not in a format that can be uploaded (docx or pdf).

 

kind regards

[Andrew TinsleyParticipant @andrewtinsley63637]

Thanks Charles, Clive and Noel, Your input has been most helpful. One or two interesting points. The graduated circle that fits into the normal universal head of the Mk1 (nothing to do with the RGA!) is a perfect fit in my RGA tool mount, even down to the normal bolt that holds the universal head together! I am assuming this is a fluke!

For my tool mount I would expect the normal 3 hole toolholder to be a good first attempt, assuming that I have a step machined on the base to fit the longitudinal slot. This would give the same functionality as the much more common 3 slotted tool holder.

The only thing that puzzles me about this solution, is that there is a suitable hole for the fixing bolt in the tool mount. But what on earth is the much narrower slot (either side of the fixing hole) for??? Take a look at the photograph to see what I mean!

Regards,

Andrew

[Clive FosterParticipant @clivefoster55965]

Usually a slot with a hole partway along it  or at one end is part of a quick detachable, captive bolt, mounting system. A bolt, screw or cap head drops down through the hole whilst the slot is only wide enough to take the shank so things can be tightened up when slid sideways.

Of course given the age of the parts its quite possible that things have been modified to make removal more convenient than completely unscrewing a bolt or nut off a stud.

Bearing in mind that I’ve never seen a complete example of any vintage to me tha slot implies that the original had one bolt, or stud, allowing it to be slid along the slot whilst the the later one with three holes merely has three positions for the head.

Clive

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