Quorn Workhead Conundrum.

Hello,

I recently purchased a semi-complete Quorn tool grinder. I was surprised at how cheap it was, until I got it home and inspected it. All the other parts are there and in good condition, apart from the workhead. Which as can be seen by the photo is not according to the drawing!

Can anyone suggest why it would be made with out the support for the Workhead?

Any suggestions on how to correct the part? I am tempted to make a new part out of a machined round bar? As in mill out the right angle support, to almost replicate the original casting, and then follow the instruction from there.

But I am naive, so any suggestions most welcome. I have a Myford lathe with a Rodney, and a recently refurbished horizontal mill, so machine work isn't an issue.

Many thanks,

Nicholas Hill

I don't know why someone would make that part without the support.

It might be of interest to you to search for "A0 Bonelle TCG" this is a fabricated version of the Quorn tool grinder with a built-up part. Could save some work.

Neil

Do you know if the part was turned from a casting or round stock?. As I recall the workhead was not the easiest part to turn, particularly as the bore needs to be concentric with the pivot and the angled faces. Ideally the bore, pivot and angled face would have been turned in one setting of the part in on the lathe. Howerver the boss on the upper surface made it difficult to mount in the chuck of a small lathe.

In addition, there is little space between the boss and the bore to enable you to mount the piece between centres. A chunky purpose-made mandrel relieved on one side may be the solution to thet issue

One of the other challenges if you are starting from scratch is the undercut grooves. If you can salvage the part by fabricating a boss to fit, you could save some extra work, but it may be worth checking the concentricity before you start.

I hope this helps. I would be pleased to know how you get on.

Posted by Nicholas Hill 30/08/2022 19:19:09
Hello,

I recently purchased a semi-complete Quorn tool grinder. I was surprised at how cheap it was, until I got it home and inspected it. All the other parts are there and in good condition, apart from the workhead. Which as can be seen by the photo is not according to the drawing!

Can anyone suggest why it would be made with out the support for the Workhead?

Any suggestions on how to correct the part? I am tempted to make a new part out of a machined round bar? As in mill out the right angle support, to almost replicate the original casting, and then follow the instruction from there.

But I am naive, so any suggestions most welcome. I have a Myford lathe with a Rodney, and a recently refurbished horizontal mill, so machine work isn't an issue.

Many thanks,

Nicholas Hill

Hi,
I does seem odd that this part was made without the means to fix the work head bar,
on the original Quorn parts this part was a steel casting , has your part been made from
a from steel bar , there have been instances where this part has been fabricated in this
way and the part that is missing is bolted on for finish machining.
It may be worth looking on

httpsgroups.iogQuorn-Owners

as there may well be some useful ideas on there.

John

Bolting on a seperate lug has always been an alternative construction method as has making the circular t-slot around the workhead by making the part in two or three pieces and loctiting the assembly together. When these methods were first mooted in ME Professor Chaddock approved!.

As stated above the Bonelle drawings show what is needed. ( Just note that you can get both imperial and metric versions of the Bonelle). I am making a Bonelle at the moment and made these parts a few weeks back.  Hopefully the picture gives an idea - note the different coloured steel above and below the t-slot showing the construction.  (Nothing bolted together at this stage!)

Edited By Bizibilder on 30/08/2022 20:18:48

For my Quorn copy I have bolted the support to the swivel head. Mine was made of metal I had lying around and I machined the top seperate to the shaft then heat shrunk the shaft in to it for finish machining.

It was this component that brought my 50% completed Quorn project to a halt and it has languished under the bench for a few years now. As if a recessed taper on the underside of a one-piece component was not difficult enough to machine and effect a reasonable fit, or at least it was in my case, I made the spindle as a separate component and used Loctite to fix it in the main body, the upper mounting lug is also awaiting a solution on my example. Without being able to refer to the book, which is out in the workshop, I believe Prof C. modified this part because many people were having difficulty in holding the work-piece to machine it. In any event I didn't have this casting in the un-machined kit of castings I bought via a classified ad. and was fabricating the part. As I recall, I found machining the circular tee-slot another nightmare. Obviously, I had to machine a groove and then make two cranked tools, RH & LH, small enough to enter but big enough to make the annular slots to form the tee (I may have just made one tool, inverted it and ran the lathe in reverse to machine the opposite groove, I can't recall now). That's how I did it although other higher skilled machinists may have done it differently. I toyed with the idea of welding a lump of steel on to the top to hold the work-head as against bolting it on but moved on to other projects in the meantime and have not yet gone back to the Quorn. Perhaps you have just inspired me to do so.

Posted by Chris Crew 31/08/2022 01:42:05

It was this component that brought my 50% completed Quorn project to a halt and it has languished
under the bench for a few years now. As if a recessed taper on the underside of a one-piece
component was not difficult enough to machine and effect a reasonable fit, or at least it was in
my case, I made the spindle as a separate component and used Loctite to fix it in the main
body, the upper mounting lug is also awaiting a solution on my example. Without being able
to refer to the book, which is out in the workshop, I believe Prof C. modified this part because
many people were having difficulty in holding the work-piece to machine it. In any event I
didn't have this casting in the un-machined kit of castings I bought via a classified ad. and
was fabricating the part. As I recall, I found machining the circular tee-slot another
nightmare. Obviously, I had to machine a groove and then make two cranked tools, RH
& LH, small enough to enter but big enough to make the annular slots to form the tee
(I may have just made one tool, inverted it and ran the lathe in reverse to machine the
opposite groove, I can't recall now). That's how I did it although other higher skilled
machinists may have done it differently. I toyed with the idea of welding a lump of
steel on to the top to hold the work-head as against bolting it on but moved on to
other projects in the meantime and have not yet gone back to the Quorn. Perhaps
you have just inspired me to do so.

----------------------------------------------------------------------------------------------

Can't really see the difficulty in machining this part ,it is well documented
on pages 33 and 34 of the Quorn book with a very thorough description in the text and 2
setup photographs, i expect that i followed those instructions when i
built mine ,i can't remember it was nearly 40 years ago.

Building a Quorn is useful beginners project.

John

"Building a Quorn is useful beginners project."

John, I admire and respect anyone who has more skill and craftsmanship than myself but I would not class the Quorn as a beginner's project by a country mile. Just the graduating, let alone some of the machining requires workshop accessories which those just starting out would probably not possess. A great project for advancing and testing established skills but not definitely not for a beginner, IMO.

Definitely needs the bolt on workhead clamping block.

here is a view of my first quorn with a perspex infil for the fiducial engraved on the rear face. Looking throght the top face makes for easier viewing. I'm most of the way through an update to bring mine to a better standard. I'm using split cotters instead of split castings so the clearences don't all go to pot. My second rotating base was done in two halves and assembled with loctite to ease the machining of the T slot. The spindle on the rotating base is also a separate item and fixed with loctite.

Regards Martin

I completed a Quorn, to the Mark 3 plans, recently. The workhead is made pretty much exactly according to plan. The two parts are made seperately and bolted together. Pic below. Should be very easy to modify your Quorn. Are there any holes to suggest that the part was bolted on and is missing? Hope that helps.

Sorry but rotating pictures seems to be very difficult on this forum...maybe more difficult than building a Quorn.

Edited By lfoggy on 31/08/2022 20:28:50