quorn cutter grinder

[joseph tatlerParticipant @josephtatler55359]

I wonder i anyone can help??

 

Just bought the book by Chadwick on building the quorn..In the addendum it details fabrication of the rotating base rather than from a casting.

It was to late for the book it says wondering if anyone has the fabrication details as i am intending to build it without the castings.

 

joe

[Graham MeekParticipant @grahammeek88282]

Hi Joe,

I posted my example of a Quorn recently on another topic.

It is a scaled down version where 1 mm equals a 1/16″ on the original. It still uses the same motor but the wheels are attached using the Unimat 3 Spindle Nose dimensions, i.e. M14x1 thread.

 

I have in recent years done away with the swivelling action around the front bar. I now have two linear guideways to traverse the tool in front of the wheel. I have also added an ER 25 spindle so that I can use collets. The item in the foreground is an air bearing for doing the flutes of cutters.

Hope this helps.

Regards

Gray,

[John HaineParticipant @johnhaine32865]

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?

 

[BazParticipant @baz89810]

Grey, very interested in your air bearing, could you be persuaded to publish a few details as the Clarkson ones are as rare as hens teeth and when you find one they are rusted solid due to using damp air. I have tried unsuccessfully in the past to make one but could not get the spindle to float.

[Graham MeekParticipant @grahammeek88282]

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,

[BazParticipant @baz89810]

Grey many thanks for the info, I had around a thou clear in my attempt and kept running out of air. I shall resurrect the bits and try the phos bronze ends, also I now know what air pressure to aim for. I shall also search out the Philip Duclos article.

[BazyleParticipant @bazyle]

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.

[Graham MeekParticipant @grahammeek88282]

Most linear bearings I have worked with are constrained to work in a straight line. Those which allow rotation as well as linear motion are a lot more expensive and considerably larger in diameter. Those which I have examined also seem to require a lot more clearance to operate, which is defeating the object. That is not to say the more exacting bearings are not out there, but I would imagine the cost of these will be even more, expense it seems goes up as the precision requirements go up.

The shafting would also need to be hardened and this also has to carry the collet arrangement. Not something easily handled in the Home Workshop. It would also require some good sealing, which may add to the drag.

The air bearing shown above just uses ground and lapped Silver Steel. The grinding being done with a toolpost grinder. One beauty of such a bearing is it automatically keeps the grinding dust out.

Regards

Gray,

[FulmenParticipant @fulmen]

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/

[John HaineParticipant @johnhaine32865]

Thanks for the air bearing details Gray.  I did have a go at making one based on the HSM design but never got it to float convincingly.

A few times a very nice Quorn was exhibited at the ME shows that used chromed steel bars and had a linkage to positively move the workhead along them using a parallel linkage IIRC.  As that took care of axial movement he only needed a rotary bearing holding the cutter being sharpened.  Still used a finger tooth rest to make it “spiral” (or should we say helix!).

John Purdy described a CNC flute grinder in MEW years back – the articles and drawings (his versions not the published ones) are on the Quorn website.  That had steppers to rotate and advance the cutter, and he described a simple way to measure the cutter lead.  Advantage was that both movements were positively applied.  A modernised version could use GRBL (he uses Compucut which is no longer available I believe), and setup could be even easier using probing I think.

[Martin KyteParticipant @martinkyte99762]

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

[John HaineParticipant @johnhaine32865]

If you have a CNC mill with 4th axis (as you would need anyway) and some sort of probe the machine can measure the helix automatically.  How-to is described in John Purdy’s article.

[Graham Meek]

On 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

[Andrew CrowParticipant @andrewcrow91475]

Well said  Derek, I think you’ve expressed exactly what many of us would agree with.

And thank you Gray for all your designs over the years, they have been a pleasure to read even if not always totally applicable to my machines.

Still in the process of making the screwcutting clutch for the myford.

Andy.

[Graham MeekParticipant @grahammeek88282]

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,

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