Have you looked at alternatives to the Quorn?  Famously many model engineers have a set of castings (possibly part finished) maturing under the bench.  If your object is just to sharpen cutters then there are designs like the Worden and  Acute which are quicker to build.  There is an excellent forum for Quorn users & builders here where other alternatives are described such as Bonelle and Tinker, plus there’s a lot of useful build information and they are a very helpful bunch.  I inherited a Quorn that my father built, to be honest I seldom use it though I did make a new workhead to take R8 collets as I use these on my mill.  I also made an Acute which certainly works well for end teeth.

Gray, have you described the air bearing make anywhere please?  Do you use an ER25 extension chuck in it as the moving element?

Hi Baz,

For once the Sun is shining and I have managed to take a couple of up to date photographs.

The Work Heads now have an additional guide rail so that the setting is not lost should the work head need to be moved to or fro.

The two work heads are held with a single M5 cap screw. Which re-aligns the work head so no settings are lost. This also shows how the additional guide rail works. The guide rails can if needs be, be removed in seconds

The Air Bearing has a annular clearance of about 0,025 mm or 0.001″. The design of this was based on an article which appeared in Home Shop Machinist. I think the author was Philip Duclos, but I am not sure on that.

In its original state shown in the first photograph the air consumption was too great for my workshop compressor. To slow down the loss I added two Phos Bronze end pieces. These have an annular clearance of 0.001 mm about 0.0004″ and they also have a Labyrinth Seal incorporated in them. This is now run through a regulator at 40 PSI and the compressor hardly cuts in during a grinding session. The loss of drag when the air is on is very noticeable.

I regret to say I have given up on writing articles. Model Engineering is no longer my main hobby.

Regards

Gray,

Having mentioned linear bearings I wonder if they provide precise free rotation that could be used for a flute grinder. I only have experience of them built into my printer so can’t asses their movement unencumbered.

I think the HSM forum has run a thread on air bearings, probably at the time of the article.

The Bonelle a no-casting Quorn. You’ll find blueprints all over them interwebs, there’s even a metric version. I’m working on one of those now: https://www.model-engineer.co.uk/forums/topic/new-guy-from-norway-planning-a-bonelle-grinder/

The original Quorn spiralling head does away with the tooth rest and provides positive positioning for the cutter. There is a suggested description of how to generate the spiral cams using an end mill as a pattern. No doubt with a modern CNC mill with a 4 th axis spiral cams would be easier to make provided one can measure the helix accurately.

regards Martin

On 6 January 2025 at 13:05 Graham Meek Said:

Hi Baz,

For once the Sun is shining and I have managed to take a couple of up to date photographs.

 

The Work Heads now have an additional guide rail so that the setting is not lost should the work head need to be moved to or fro.

The two work heads are held with a single M5 cap screw. Which re-aligns the work head so no settings are lost. This also shows how the additional guide rail works. The guide rails can if needs be, be removed in seconds

The Air Bearing has a annular clearance of about 0,025 mm or 0.001″. The design of this was based on an article which appeared in Home Shop Machinist. I think the author was Philip Duclos, but I am not sure on that.

In its original state shown in the first photograph the air consumption was too great for my workshop compressor. To slow down the loss I added two Phos Bronze end pieces. These have an annular clearance of 0.001 mm about 0.0004″ and they also have a Labyrinth Seal incorporated in them. This is now run through a regulator at 40 PSI and the compressor hardly cuts in during a grinding session. The loss of drag when the air is on is very noticeable.

I regret to say I have given up on writing articles. Model Engineering is no longer my main hobby.

Regards

Gray,

Hi Gray,

I just want to take the opportunity to thank you for all of your excellent articles over the years especially in improving the FB2 milling machine for example.

The world of model engineering will be a poorer place without your knowledge and first class designs that are on a par with George Thomas.

Can I ask what is your main hobby now that you have moved away from model engineering?

All the best

Derek

Derek & Andy,

Thank you for your kind words and appreciation of my work. Having been friends with George, and lucky enough to have him as a Mentor. I know first hand what he was capable of. For myself I do not consider to be in the same league as George, but I thank you all the same.

As regards my future hobbies they will revolve around Woodwork and another recently acquired gift from an old friend of a No 10 Meccano Set. Woodworking was my first hobby and has always been in the background. Meccano started my interest in Engineering, so I guess you can say I have now gone full circle. This latter hobby allows me to stay indoors during the cold months. This is something I have come to realise I need to do health wise. Plus I want to add Radio control to my work, something I have had nothing to do with in the past.

Apologies for hijacking the post.

Regards

Gray,

When we start out and learn a bit it’s easy to to imagine we know everything.When we really begin to understand, we realise just how much there is to know and how we can only ever grasp a fraction of it. It’s quite humbling really.

There are always people who know more than I do.

The thing about GHT is that even though I never met him I like him just through his writing.